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In this work, we report the synthesis and characterization of three novel ruthenium(II) p-cymene complexes coordinated with acylthiourea ligands (L1−L3), of general formula [Ru(η6-p-cymene)(PPh3)(L1–L3)Cl]PF6 (1–3). Single-crystal X-ray crystallography of the free ligands and their complexes [Ru(η6-p-cymene)(PPh3) (κ1-S)-(N-benzoyl-N´-cyclopropylthiourea)Cl]PF6 (1), Ru(η6-p-cymene)(PPh3) (κ1-S)-(N-2-furoyl-N´-cyclopropylthiourea)Cl]PF6 (2), [Ru(η6-p-cymene)(PPh3)] (κ1-S)-(N-thiophene-2-carbonyl-N´-cyclopropyl thiourea)Cl]PF6 (3) revealed that the acylthiourea ligands act as neutral monodentate donors, coordinating through the sulfur atom (κ1-S). Application of the Extended Transition State–Natural Orbitals for Chemical Valence method demonstrated that the dominant interaction in complexes 1–3 originates from the overlap between the sulfur lone pair of the ligands and a Ru d-orbital, which plays a decisive role in their stability. The Interacting Quantum Atom analysis showed that both the free and coordinated acylthiourea ligands stabilize their structure through an intramolecular N–H···O=C hydrogen bond. The cytotoxicity of complexes 1–3 was evaluated against the A549 (lung) and MDA-MB-231 (breast) human cancer cell lines. To assess their selectivity, the compounds were also tested against two non-cancerous cell models: MRC-5 (lung fibroblasts) and MCF-10 A (breast epithelial cells). The study revealed high cytotoxicity against the MDA-MB-231 cell line, with IC₅₀ values of 0.62 ± 0.05 μM (1), 0.66 ± 0.12 μM (2), and 0.53 ± 0.12 μM (3). Activity against the A549 cell line was also significant, with IC₅₀ values of 1.05 ± 0.11 μM (1), 2.60 ± 0.25 μM (2), and 1.04 ± 0.21 μM (3). The combination of phosphine and acylthiourea ligands appears critical for achieving high cytotoxic activity.

Chalcogen bonding (ChB), defined as the non-covalent interaction between an electrophilic chalcogen atom and a Lewis base, is now recognized as a powerful tool across a wide range of chemical applications. The strength of the ChB depends on the nature of the chalcogen atom; consequently, tellurium species exhibit the strongest ChB, compared to their sulfur and selenium analogues. This review aims at providing the readers with an overview of systems involving electrophilic tellurium atoms engaged in ChBs with Lewis bases, both in the solid state and in solution. In early studies-predating the widespread adoption of the σ-hole concept-the presence of ChBs was proposed on the basis of the geometrical parameters obtained from the X-ray single crystal structures. Specifically, interatomic distances below the sum of van der Waals radii and the near-linearity of the interactions were considered key indicators of ChB formation. This review is organized in sections highlighting the ability of tellurium to participate in ChBs at different oxidation states (0, +1, +2, +4 and + 6). Beyond structural analysis and characterization, the aim of this review is to underscore the different roles of ChB, ranging from the stabilization of reactive or unstable species to their involvement in catalytic processes and crystal engineering.

Collagen VI is an extracellular matrix protein forming complex microfibrillar networks in connective tissues. Specifically, we focused on its role in innate immunity, in particular on cationic sequence motifs from the α3(VI)-chain, which exhibit strong antibacterial properties against both Gram-positive and Gram-negative bacteria in vitro and in vivo. Cytotoxicity assays revealed minimal to no adverse effects, even at concentrations effective against bacterial pathogens. This favorable safety profile suggest that these antimicrobial peptides selectively target bacterial membranes while sparing host cells, making them promising candidates for therapeutic development. The membrane structure and interactions of two antimicrobial peptides were investigated in quantitative detail using solid-state NMR, CD and fluorescence spectroscopies. Whereas calcein release was somewhat more pronounced from POPE/POPG 3/1 vesicles when compared to POPC/30% cholesterol, this activity is about two orders of magnitude increased when POPC/POPG 3/1 liposomes are investigated. This pronounced lipid dependence was reproduced with magainin 2, a well-known linear cationic AMP. In lipid titration experiments both collagen-derived peptides showed a transition from predominantly random coil to helical conformations. Quantitative evaluation of membrane association required the presence of PEGlipids which are known to prevent the agglutination of POPE/POPG 3/1 liposomes. A dissociation constant in the 260 µM range was observed for GVR28 while the binding isotherms reveal an intermediate state when SFV33 associates with bacterial membranes. 2 H solid-state NMR reveals considerable membrane disorder of the deuterated PG palmitoyl chain in POPE/POPG membranes. The ensemble of biophysical data suggest two distinct modes of action for the collagen derived peptides.

In this manuscript, we report the synthesis and X-ray characterization of a series of solvates and co-crystals involving triaryltelluronium salts and various Lewis bases. In some cases, the triaryltelluronium cation is able to interact with acceptor atoms simultaneously through its three sigma-holes and through a “pocket” formed by the three electron-deficient aromatic rings linked to tellurium. The latter interaction involves an acceptor atom that shows close contacts with both the ortho-hydrogens of two aromatic rings and the electron-deficient pi-system of the third ring. Interestingly, the co-crystal formed between the triaryltelluronium cation and ditopic nitrile ligands provides three-dimentional supramolecular networks that combine Te•••N chalcogen bonds, CAr-H•••N hydrogen bonds and N lone pair•••pi interactions

Abstract The development of efficient circularly polarized electrochemiluminescence (CP‐ECL) probes is still at its infancy and examples are still very limited. Yet, their achievement would enable gathering a readout that carries privileged information on the probe's chiral environment by monitoring luminescence polarization bias with high signal‐to‐noise ratio. Notwithstanding, this is a highly challenging task and requires judicious chemical engineering of chiral ECL‐active emitters. Herein, we aim at expanding the palette of CP‐ECL luminophores by presenting a novel class of enantiopure heterobinuclear Ir(III)–Au(I) complexes, which are investigated thoroughly by means of chemical, structural, and (chiro‐)optical techniques. The ground and excited state properties are also elucidated by using density functional theory (DFT) approaches including spin‐orbital coupling (SOC) perturbation. The chiral‐at‐metal complexes display luminescence with a polarization bias of the emitted light that is function of the helical arrangement of the coordination sphere around the Ir(III) center. Overall, the photo‐ and electro‐active complexes unraveled in this work combine unparallelly high photoluminescence quantum yield in the orange region, excellent circularly polarized luminescence (CPL) brightness up to 4.5 M −1 cm −1 with a notable ECL activity. Finally, these features provide emitters with CP‐ECL efficiency that encompass remarkably by a factor 3.5 that of the well‐known benchmark tris ‐(2,2′‐bipyridyl)ruthenium(II).

Plutonium (Pu) is a chemically and radiologically toxic element, primarily of anthropogenic origin. Reagents that specifically sequester Pu have been developed in the frame of nuclear waste processing and storage. Other potential applications of Pu chelators are in vivo decorporation and environmental remediation. Although the medical application has been addressed for a long time by the development of Pu-specific binders, studies concerning the environmental application are scarce. A desferrioxamine-B ([(DFO)H4]+)-derived tetrahydroxamate chelator, 1H4, which was originally designed for the sequestration of Zr4+ for 89Zr-ImmunoPET applications, was grafted on a commercial hydrophilic resin, CM Sephadex C-25®. The resin beads were subsequently embedded in an agarose gel, and the resulting material was used for the extraction of 238Pu(IV) from dilute aqueous solutions at pH 6.5. Comparison of the results with those obtained using the commercial Chelex®-100 resin and the H3DFO-based CM Sephadex C-25® extracting materials showed that Pu was more strongly bound to the 1H4-functionalized resin than to Chelex®-100 and the H3DFO-based resins, which confirms that the tetrahydroxamate chelator 14− forms a more stable Pu(IV) complex than the trihydroxamate DFO3− siderophore. The fabricated material could be considered in the development of diffusive gradients in thin-films (DGT) devices for the environmental monitoring of Pu.

Background -The detection of dispersion forces in enantioselective liquid chromatography (LC) is rather challenging because selectand, selector and mobile phase molecules may participate in multiple types of intra-and intermolecular noncovalent interactions of different strength. In this frame, the LC system can be used as a tool to evaluate the impact of changing the structures of selectand, chiral selector and separation medium, through fast analytical screenings. In the last few years, we studied the enantioseparations of chiral compounds containing the ethynylferrocene moiety as a test probe to identify dispersion forces in LC by using amylose carbamate-based CSPs.</p><p>Results -The results of the study have been reported in a series of three papers. In Part II, we confirmed that the high affinity observed for the second eluted (Rp)-enantiomer of the 1-(iodoethynyl)-3phenylferrocene toward amylose phenylcarbamate-based selectors could be reasonably based on dispersion forces. In the present Part III of the series, we focus on the impact of changing the 3-aryl substituent of 1-(iodoethynyl)-3-arylferrocenes on the enantioseparation, considering the 1-(iodoethynyl)-3-phenylferrocene as reference for comparison. On this basis, the enantioseparations of seven planar chiral ferrocenes were performed and compared by using amylose-based CSPs. n-Hexane-based mixtures, polar organic solvents and aqueous organic mixtures were used with the aim of evaluate the impact of mobile phases of different polarity on the enantioseparations. The results of the chromatographic analyses confirmed the high and unique affinity of the second eluted (Rp)-enantiomer of the 1-(iodoethynyl)-3-(4t-butyl)phenylferrocene toward the amylose-based CSPs.</p><p>Significance -By using 1-(iodoethynyl)-3-arylferrocenes as test probes, this study confirmed that dispersion forces may turn steric repulsion into attraction with a strength depending on the structure of the 3-aryl group and on mobile phase polarizability. Furthermore, the possibility to deconvolute hydrophobic and dispersion forces in aqueous mobile phases was also demonstrated.

Three meso-substituted Schiff base porphyrin derivatives were designed and synthesized by condensing the amine group of 5-(4-aminophenyl)-10,15,20-triphenylporphyrin (APTPP) with 4-formyltriphenylamine (2), 4,4′-diformyltriphenylamine (3), and 4,4′,4″-triformylphenylamine (4). These molecules were developed for their potential interest in optoelectronic applications. The resulting compounds were thoroughly characterized using 1 H and [Formula: see text]C NMR, UV-vis spectroscopy, mass spectrometry, fluorescence, and cyclic voltammetry. Theoretical calculations were performed using DFT. The electrochemical properties were studied by cyclic voltammetry (CV).

Over the last few decades, allenes have evolved from objects of curiosity to central elements of organic synthesis. Among them, N-allenamides, allenes featuring an electron-withdrawing group on the nitrogen, stand out for their great stability and versatility. Their unique reactivity has made them valuable platforms for numerous chemical transformations. Their interest is reinforced by their ability to efficiently lead to multisubstituted enamides, motifs present in many bioactive natural products but notoriously challenging to synthesize with high regio-and stereocontrol. Driven by our deep interest in the reactivity of activated N-allenamides, particularly those with fluorinated units, we present here new transformations leading to the construction of heterocyclic fluorinated structures and complex enamides, two motifs with significant relevance in medicinal chemistry.

Abstract IspG (also known as GcpE) is a key [4Fe‐4S] metalloenzyme that catalyzes the penultimate step of the methylerythritol phosphate (MEP) pathway, a well‐established target for the development of new antimicrobials. This oxygen‐sensitive enzyme mediates the reductive dehydroxylation of 2‐ C ‐methyl‐ d ‐erythritol 2,4‐cyclodiphosphate (MEcPP) to ( E )‐4‐hydroxy‐3‐methylbut‐2‐en‐1‐yl diphosphate (HMBPP), requiring electron transfer proteins to deliver two electrons needed for catalysis. To probe the mechanism of IspG and access new mechanism‐based inhibitors, we synthesized a substrate analogue, monofluoromethyl‐ d ‐erythritol cyclodiphosphate, in which the natural methyl group of MEcPP is replaced by a CH 2 F group. This analogue proved to be a potent inhibitor of IspG. This study also demonstrates that electron capture is a prerequisite for inhibition and that the inhibitor leads to fluoride release in the IspG‐catalyzed reaction. Together, these results provide further support for the involvement of a carbanionic intermediate in the IspG mechanism.

In quantum information processing, qudits-quantum systems with d levels-have been a major challenge for their potential to accelerate certain computational tasks. Spin transport measurements on tris(phthalocyaninato)-dinuclear rare-earth(III) molecules offer a promising platform for nuclear spin qudits with increased Hilbert space. However, the absence of radicals in these systems has hindered studies on the coupling between lanthanide ions and conduction electrons.</p><p>In this study, we report the synthesis of (phthalocyaninato)bis(porphyrinato)-dinuclear rare-earth(III) complexes functionalized with thiomethyl groups. The tailored oxidation levels in the neutral complexes facilitated the conversion to air-stable radicals. CASSCF calculations and static magnetic measurements revealed a radical-lanthanide exchange coupling constant, J Rad-Ln = -0.45 cm -1 . Dynamic magnetic measurements demonstrated a shift in the magnetic properties due to exchange interaction, namely from field-induced single-molecule magnets (SMM) to zero-field SMM. The findings of this study, along with the potential of the strong bond between thiomethyl group and gold electrode, highlight the potential of these molecules as novel materials for the implementation of nuclear spin qubits with an increased Hilbert space.

Quantum computing has recently been emerging in theoretical chemistry as a realistic avenue meant to offer computational speedup to challenging eigenproblems in the context of strongly-correlated molecular systems or extended materials. Most studies so far have been devoted to the quantum treatment of electronic structure and only a few were directed to the quantum treatment of vibrational structure, which at the moment remains not devoid of unknowns. In particular, we address here a formal problem that arises when simulating a vibrational model under harmonic second quantization, whereby the disruption of the closure relation (resolution of the identity) -- which occurs when truncating the infinite bosonic basis set -- may have some serious effects as regards the correct evaluation of Hamiltonian matrix elements. This relates intimately to the normal ordering of products of ladder operators. In addition, we discuss the relevance of choosing an adequate primitive basis set within the present context with respect to its variational convergence properties. Such fundamental, yet consequential, aspects are illustrated numerically in the present work on a one-dimensional anharmonic Hamiltonian model corresponding to a double-well potential showing strong tunneling, of interest both for vibrational spectroscopy and chemical reactivity.

In the pursuit of CuII-responsive MRI contrast agents with enhanced CuII affinity, we report the synthesis and characterization of two LnIII-DO3A-C3AmpicGH complexes (LnIII = GdIII, EuIII), featuring a tetradentate CuII-binding moiety, along with the corresponding mononuclear CuII-C3AmpicGH complex. The chelator coordinates CuII through two amide groups, a pyridine and an imidazole ring. The use of a propyl-amide linker between the LnIII- and CuII-binding moieties allowed an increased separation between the two metal centers. As a result, both LnIII–CuII-DO3A-C3AmpicGH and CuII-C3AmpicGH complexes exhibit the same CuII-affinity (log K = 11–12 at pH 7.4) and good selectivity over competing physiological metal ions, particularly ZnII (up to at least 500 equivalents). While the GdIII complex displayed no relaxivity changes upon CuII binding, the EuIII analogue showed a luminescence turn-off response. Spectroscopic analyses as well as density functional theory (DFT) calculations provide insights into the coordination environments of both metal ions, notably confirming the absence of amide coordination to the LnIII center, even in absence of CuII.

A series of six silver(I) complexes, namely bromo(1-benzyl-3-cinnamyl-benzimidazol-2-ylidene)silver (I) (1a), bromo[1-(4-methylbenzyl)-3-cinnamyl-benzimidazol-2-yliden]silver(I) (1b), bromo[1-(3-methoxylbenzyl)-3-cinnamyl-benzimidazol-2-yliden]silver(I) (1c), bromo[1-(3,5-dimethoxy-benzyl)-3-cinnamyl-benzimidazol-2-ylidene]silver(I) (1d), bromo[1-(naphthalen-1-ylmethyl)-3-cinnamyl-benzimidazol-2-ylidene]silver(I) (1e) and bromo[1-(pyren-1-ylmethyl)-3-cinnamyl-benzimidazol-2-yliden]silver(I) (1f), were synthetized and characterized by microanalyses and mass spectrometry and characterized by FT-IR and NMR spectroscopic techniques. The in vitro effects of silver(I) complexes on trophozoites of two Acanthamoeba isolates obtained from patients with keratitis were investigated. The parasites were exposed to concentrations of 10, 100 and 1000 µM for 24, 48 and 72 h. The complexes exhibited potent, dose- and time-dependent activity. Complete inhibition was observed within 24 h at a concentration of 1000 µM. At a concentration of 100 µM, complexes 1c–e exhibited reduced viability to less than 10% within 48 to 72 h. At a concentration of 10 µM, partial inhibition was observed. Preliminary morphological changes included the loss of acanthopodia, rounding, and detachment. These effects were not observed in the presence of the pre-ligands or commercially available silver compounds. Furthermore, molecular docking was utilized to analyze the molecules against Acanthamoeba castellanii CYP51, A. castellanii profilin IA, IB, and II. The highest recorded interactions were identified as −9.85 and −11.26 kcal/mol for 1e and 1f, respectively, when evaluated against the A. castellanii CYP51 structure.

<div><p>We study the quantum dynamics of a strongly correlated electron pair in a one-dimensional lattice, focusing on the occurrence of local dissociation/pairing mechanisms induced by a site energy defect. To this end, we simulate the time evolution of two interacting electrons on a finite-size chain governed by an extended Hubbard Hamiltonian including on-site Coulomb repulsion U and nearest-neighbor interaction V , along with single-electron hopping J. By introducing a local site energy defect with amplitude ∆, we show that a transition between spatially paired/dissociated electrons can occur in the vicinity of this site. Such mechanisms arise in a strongly correlated regime with non-zero nearest neighbor Coulomb interactions and under the conditions (U ∼ V ∼ ∆) ≫ J. To rationalize these phenomena, we reformulate the two-electron dynamics of the original Hubbard chain as an effective single-particle problem on a two-dimensional network. Within this framework, we show that the pairing/dissociation dynamics are driven by resonances between two distinct families of two-electron eigenstates: (i) states with two spatially well-separated electrons with one located at the site defect, and (ii) states with locally bound electron located away from the defect. At resonance, these states hybridize, allowing transitions from locally paired to dissociated electrons (and vice versa) in the vicinity of the defect. These results provide new insights into exotic pairing phenomena in strongly correlated electronic systems and may have implications for the design of tunable many-body states in low-dimensional quantum materials.</p></div>

The 1:1 complex of a bis(acridinium‐Zn(II)porphyrin) host and a tetrapyridyl free‐base porphyrin guest shows a remarkable interplay of energy and electron transfer (eT) processes, finely tuned by the solvent polarity or the selection of the photoexcited component. A more polar environment (CH 2 Cl 2 ) favors uncommon parallel intramolecular and intermolecular eT processes, while in an apolar solvent (toluene) the intermolecular eT process is hampered. Notably, the apolar environment also enables a rare energy transfer process from the porphyrin guest toward the charge‐transfer emissive state of the tweezer host. In total, no less than four different excited states were probed, which can be sketched by an inverted pyramid diagram highlighting directional path selection.

Chemodynamic therapy (CDT) is regarded as an emerging strategy with high specificity for tumor therapy by producing highly toxic reactive oxygen species (ROS) in tumor cells by a Fenton or Fenton-like reaction. Excessive ROS can cause mitochondrial damage and induce ferroptosis in cells, leading to the death of cancer cells. However, the generally low efficiency of the Fenton reaction has limited the effectiveness of CDT. Herein, two-dimensional MoS₂ decorated with PB NPs is used as a co-catalyst to promote Fe^III/Fe^II conversion and thus enhance the efficiency of the Fenton reaction. The photothermal properties of both MoS₂ and PB NPs further enhance the Fenton reaction, eventually producing a large amount of ROS. Mitochondrial damage and ferroptosis caused by ROS are evidenced in vitro and in a tumor-bearing mouse model and jointly lead to a decrease in heat shock protein content, further enhancing the photothermal effect of PB NP/MoS₂ nanosystem. This chemodynamic/photothermal synergistic therapy allows achieving good anticancer therapeutic effect. Statement of significance: CDT is a promising cancer treatment that selectively generates toxic ROS to eliminate tumor cells. Nevertheless, its efficacy is often limited by the low efficiency of the Fenton reaction. This study presents a nanocomposite composed of MoS₂ nanosheets decorated with PB NPs, which enhances CDT by improving Fe^III/Fe^II conversion and increasing ROS production. In addition, the photothermal properties of the material further amplify its therapeutic effects. In cell and animal models, this synergistic approach effectively induces mitochondrial damage and ferroptosis, thereby weakening the defenses of the cancer cells. This work provides a significant advancement in CDT, offering a more potent strategy for cancer therapy.

<div><p>This study shows that the nanoparticles produced by the reductive decomposition of a cobalt (+III) metallacycle derived from 2-phenylpyridine upon treatment with the highly nucleophilic Na[Et3BH] are capable of promoting the Kumada-Corriu cross coupling of aryl halides with aryl-bromomagnesium compounds (Grignard reagents) in various conditions and in the presence of various stabilizing ligands to afford the non-symmetric organic bisaryl product in reasonable yields. This study provides further proof that incidental Co nanoparticles are endowed with a reasonable capability in homogeneous catalysis, complementing thus a prior report on their capability to promote the hydrosilylation of unsaturated organic substrates such as nitriles. Co nanoparticles were characterized by HRTEM, EDX, EELS, and SAED techniques. TEM analyses revealed that the nanoparticles were uniformly spherical in shape, with a size distribution that is quite narrow; no nanoparticles above 3 nm were observed. EDX analysis displaying a characteristic Co signature at about 7 keV. The magnetic behavior of the nanoparticles studied by SQUID analysis in toluene using a temperature varied from 2 to 300 K, and a low magnetic field (10 -3 T) in ZFC-FC conditions.</p></div>

<div><p>We report the design and synthesis of ratiometric 19 F-ATCUN (Xxx-Zzz-His) peptide probes for the selective and reversible detection of Ni 2+ and Cu 2+ by 19 F NMR spectroscopy. In contrast to fluorescence-based approaches, 19 F NMR enables backgroundfree detection in biological media, due to the absence of fluorine in native biomolecules. The probes remain stable and functional in complex cell media (DMEM), enabling the detection of Cu 2+ and Ni 2+ by 19 F NMR with a limit of detection (LOD) of 4 μM and quantification (LOQ) of 10 μM, relevant for studying copper-related pathologies.</p></div>

Cooperative multielectron transfer is central to electron storage strategies and small-molecule activation and involves a thermodynamically favored second electron transfer occurring after the first electron transfer. This is the trademark of molecular systems with inverted redox potentials, but it is counterintuitive from an energetic point of view, and the nature of the transient intermediates involved has remained elusive. Using a nickel complex with inverted redox potentials, we show that a weakly coordinating anion (WCA), such as BArF4– ([B(C6H3(CF3)2)4]−), can act as a kinetic trap for the second electron to be transferred. Combined electrochemistry, UV–visible spectroscopy, advanced EPR studies, and theoretical calculations support its existence as a stabilized, confined unpaired electron, close to the concept of a solvated electron. This work sheds light on the nature of energized intermediates in cooperative electron transfer and the possibility of influencing that process through counterion effects.

Fundamental rationalization of the structural–circularly polarized luminescence (CPL) activity relationship is a challenging task. Herein, a pair of enantiopure, heterobimetallic IrIII–AuI complexes IrAu‐4 featuring chirality‐at‐metal is thoroughly investigated by means of spectroscopical and computational techniques, also including spin‐orbital coupling (SOC) effects. Upon resolution of the racemic mixture of the starting chloro‐bridged dimer via a chiral auxiliary ligand, the complexes IrIII–AuI are straightforwardly prepared in a stepwise procedure with retention of configuration in good yields. The IrAu‐4 complexes display moderate orange phosphorescence arising from an admixed metal‐to‐ligand and ligand‐to‐ligand charge transfer (3MLCT/3LLCT) excited state and good chiroptical activity, as shown by both electronic circular dichroism (ECD) and CPL spectroscopy. A comparison between the parental mononuclear pairs Δ‐Ir(ppy)2(acac) and Λ‐Ir(ppy)2(acac) and the binuclear IrAu‐4 counterparts also provides interesting insights. The latter possess higher dissymmetry factor (glum) values despite the very similar ECD activity of the lower‐lying 1MLCT band with enantiospecific polarization bias of the light dictated by the chiral‐at‐metal configuration. The different nature of the emissive excited state between the two families of complexes and its implication onto the radiative rate constant and the dipolar force is tentatively accounted for the increased CPL‐activity observed in IrAu‐4.

The intermediate scattering function is interpreted as a correlation function of thermal wave packets of the scattering centers perturbed by the scattering particles at different times. A proof of concept is given at the example of ballistic moving centers. The ensuing numerical method is then illustrated at the example of CO adsorbed on Cu(100).

A simple method proposed in an insightful paper by A. J. Vega [J. Magn. Reson. 65 (1985) 252-267] is applied for calculating the effects of chemical exchange on magic-angle spinning (MAS) NMR spectra in the case of a two-site rotational jump motion. This approach which only requires two basic expressions of T2 for the limiting cases of fast and slow exchange is compared with exact numerical calculations for arbitrary rates of motion and spinning frequencies. This comparison justifies the application of relaxation theory (RT) to calculate fast-exchange lineshapes but the slow-exchange T2 time constant originally derived by A. Schmidt and S. Vega [J. Chem. Phys. 87 (1987) 6895-6907] using Floquet-perturbation theory (FPT) fails to account for the differences in the spinning sideband linewidths. In this paper, the complete FPT (cFPT) expression of the MAS spectrum is shown to account for all details of differential sideband broadening observed in the slow-exchange regime. Moreover, the RT and cFPT solutions give insight into the effects of molecular dynamics on the MAS spectra and decrease dramatically the computation time. The calculation procedure using the RT and cFPT formulas yield lineshape simulations that are in very good agreement with exact numerical results except in the intermediate-exchange regime when the sideband linewidths become comparable with or larger than the MAS rate. This is a minor drawback in practice as fast relaxation then makes quantitative measurements difficult.

The cationic chloro-P-{[4-(diphenylphosphanyl)phenyl]-N,N-dimethylmethanammonio (norbornadiene)rhodium(I) complex was encapsulated inside a self-assembled hexameric capsule. This capsule was obtained through a reaction involving 2,8,14,20-tetra-undecylresorcin[4]arene and water in chloroform. The formation of an inclusion complex was deduced from a combination of spectral measurements (UV-visible spectroscopy, 1 H, 31 P{ 1 H} NMR and DOSY). The rhodium complex was evaluated in the [2+2+2] cycloaddition between N,N-dipropargyl-p-toluenesulfonamide and arylacetylene derivatives. In the presence of two equivalents of arylacetylenes in water-saturated chloroform at 60 • C for 24 h, the 4-methyl-N-(prop-2-yn-1-yl)-N-((2-tosylisoindolin-5-yl)methyl)benzenesulfonamide, the homocycloaddition product of 1,6-diyne is predominantly formed. In the presence of the supramolecular capsule, a selectivity inversion in favor of 5-aryl-2-tosylisoindoline is observed, with heterocycloaddition products formed in proportions between 53 and 69%.

Abstract The syntheses of calcium carborates, Ca[HexCB 11 Cl 11 ] 2 , 1 , Ca[HCB 11 Cl 11 ] 2 , 2 , and Ca[MeCB 11 Cl 11 ] 2 ·2( o ‐DFB), 3· 2( o ‐DFB), ( o ‐DFB = 1,2‐difluorobenzene) including the structure of 2· 4( o ‐DFB) are described. The large size of the Ca 2+ cation is reflected by the coordination geometry with the Ca center being coordinated by three Cl donors from each of the carborate anions and one F donor from each of the two coordinated solvent molecules. Based on 11 B NMR and DOSY NMR studies, the salts 1 , 2 and 2· 2( o ‐DFB) form close ion pairs in PhBr and o ‐DFB solutions. The Fluoride Ion Affinities (FIA) in PhBr for the salts 1 and 2· 2( o ‐DFB) were DFT‐calculated (ωB97XD/6–31 + G**) at 211.3 kJ mol −1 and 217.5 kJ mol −1 , respectively, which is below that of the landmark Lewis acid B(C 6 F 5 ) 3 (241.5 kJ mol −1 ). The Ca 2+ center in salt 1 is sufficiently Lewis acidic to coordinate 1,5‐cyclooctadiene (1,5‐COD) and 2,6‐octadiyne and to catalyze the hydrosilylation of 1‐hexene and several alkynes, albeit slowly. Compound 1 also displays moderate activity as a catalyst for transfer hydrogenation catalysis and carbonyl‐olefin metathesis (COM), a first for Ca compounds.

Purpose of review: Although the biological mechanism of skin sensitization is a quite complex multistage process, the sensitization potency (or absence of potency) of a chemical is dependent on its chemical properties. Here we present an overview of the advances that have been made in our understanding of the chemical properties that determine sensitization potency, and how this understanding can be applied to rationalize existing data and to make predictions for new chemicals. Recent findings: It has been known for many decades that for a chemical to be a sensitizer it must be able to form a covalent reaction product with skin protein. There are several reaction mechanisms by which these covalent products can be formed. Five major mechanisms in which the sensitizing chemical is electrophilic are recognized. For each of these mechanisms we summarise how these are related to chemical structure and what is now understood about the relationship between chemical properties and sensitization potency. A further mechanistic domain recently recognized, covering chemicals reacting as nucleophiles, is also discussed. Recent developments have made it possible to investigate free radical chemistry in cutaneo, and we discuss how these can be applied to investigate free radical sensitization mechanisms.

<div><p>Quantum mechanical tunneling (QMT) is the mechanism by which a particle can pass through a high potential energy barrier. Although rooted in quantum physics, QMT influences key chemical reactions in a number of ways. However, the significance and scope of QMT are not adequately considered by our current knowledge of chemical reactivity and catalysis where its contribution remains challenging to assess. Here, we show that a new iridium dihydride complex IrH2 bearing a N,B-bidentate pyridine carboranyl ligand [(C 5 H 4 N)CB 11 H 10 ] undergoes H•••H exchange coupling via QMT, as supported by variable temperature NMR studies showing large temperature-dependent exchange coupling constants J H-H (99-162 Hz), non-linear Arrhenius behavior of the exchanging hydrogens and the absence of detectable J H-D coupling in the deuterium enriched complex IrHD. These observations agree with the predicted existence of quantum exchange coupling in metal dihydrides reported by Zilm and Heinekey [J. Am. Chem. Soc. 1990, 112, 3, 920-929]. The observed high relaxation rates T 1,min (0.250-0.262 seconds) support the assignment for IrH2 as being a metal dihydride rather than a nonclassical dihydrogen complex, thus ruling out any major involvement from a classical scalar coupling to the observed large J H-H coupling constants. The reactivity of complex IrH2 against various bases, nucleophiles and electrophiles was investigated, and X-ray photoelectron spectroscopy (XPS) as well as computational studies were conducted, all of which support an Ir in the formal +III oxidation state for IrH2.</p></div>

Three-coordinate, paramagnetic CrII complexes of type [Cr(amido)nBnm(NHC)], NHC = N, N’-bis-(2,4,6-trimethylphenyl)-imidazol-2-ylidene (IMes); N, N’-bis-(2,6-di-isopropylphenyl)-imidazol(in)-2-ylidene, (S)IDiPP; N, N’-bis-(2,6-di-isopropylphenyl)-imidazol-4-ylidene, (aIDiPP); amido = N(SiMe3)2, NH(DiPP); Bn = benzyl, n = 2, m = 0; n = 1, m = 1, were prepared by substitution or aminolysis and thermolysis methods from [Cr{N(SiMe3)2}2(THF)2] or [CrBn2((S)IDiPP)], respectively. Depending on the nature of the NHC and the amido ligands, different geometries at CrII (ranging from distorted trigonal planar, to extended Y-, compressed Y-, and distorted T-shaped) and conformations, were observed. HFEPR spectroscopy was employed to accurately determine spin Hamiltonian parameters, consisting of zero-field splitting (axial D and rhombic E components) and g-values, of five S = 2 complexes exhibiting D and E/D in the range from −2.98 to −1.63 cm−1 and 0.026 − 0.069, respectively. AC magnetometry established slow magnetization relaxation in three complexes, operating by Raman or combined Raman-Orbach processes. Ab initio calculations provided computed zfs values, in good agreement with those obtained by HFEPR. Magnetostructural comparisons are made within this three-coordinate CrII family, as well as with previously studied two- or four- coordinate CrII complexes.

The synthesis of a series of six chloro[N-alkyl-N-cinnamyl-benzimidazol-2-yliden]silver(I) complexes was successfully achieved, wherein allyl (3a), methoxymethyl (3b), benzyl (3c), 3-fluorobenzyl (3d), 4-fluorobenzyl (3e) and 4-methyl-benzyl (3f) substituents were grafted on the benzimidazole ring. The isolated silver N-heterocyclic carbene (NHC) complexes were identified by microanalyses and mass spectrometry and characterized by FT-IR and NMR spectroscopic techniques. Conclusive evidence for the structures of complexes 3c and 3d was provided by single-crystal X-ray crystallography. The in vitro inhibitory activity of the six Ag-NHC complexes was tested against trophozoites and cysts of the pathogenic Acanthamoeba castellanii strain and the efficacy sequence is as follows: 3d &gt; 3c &gt; 3f &gt; 3a &gt; 3b &gt; 3e. At a concentration of 100 µM in complexes 3c, 3d and 3f and after 72 h of incubation, 5.3, 3.2 and 6.3% A. castellanii trophozoite viabilities were observed, respectively. The utilization of elevated silver(I) drug concentrations, 1000 µM, resulted in the near-total eradication of pathogenic protozoa.

This review highlights how advances in silico techniques have shed new light on phenomena in confined supramolecular resorcinarene-based systems. Computational studies have provided detailed insights into capsule formation, their dynamic behavior, guest encapsulation and reaction mechanisms within these hosts, often revealing information that experimental methods cannot reach. The focus is placed on the self-assembly of resorcin[4]arenes, pyrogallol[4]arenes, velcrands, and octa acid systems. These computational studies complement experimental findings and, in many cases, offer new perspectives that are inaccessible using experimental techniques alone. Supramolecular architectures are growing in complexity the role of in silico approaches is becoming indispensable. They offer a way to design rationally and understand host–guest chemistry more deeply.

<div><p>The cell plasma membrane acts as a semi-permeable barrier essential for cellular protection and function, posing a challenge for therapeutic molecule delivery. Conventional techniques for crossing this barrier, including biophysical and biochemical methods, often exhibit limitations such as cytotoxicity and the risk of genomic integration when viral vectors are involved. In contrast, cell-penetrating peptides (CPPs) offer a promising non-invasive means to deliver a broad range of molecular cargoes, including proteins, nucleic acids and small molecules, into cells. CPPs, typically 5 to 30 amino acids long and rich in basic or non-polar residues, interact favourably with different cell membranes. These peptides have evolved since the discovery of the HIV-1 TAT peptide in the 1980s, expanding into various CPP families with diverse therapeutic applications. CPPs can form covalent or noncovalent complexes with their cargo, influencing their stability and efficacy. Based on their sequence properties and interactions, CPPs can be amphipathic or non-amphipathic, with distinct mechanisms of membrane penetration, such as direct penetration and endocytosis. While their uptake mechanisms are complex and not fully elucidated, ongoing optimization aims to enhance CPP specificity and efficacy. CPPs have demonstrated potential in drug delivery, gene therapy, cancer treatment and vaccine development, addressing key safety and efficiency concerns associated with viral vectors. This review explores the classification, mechanisms of action and therapeutic potential. It focuses on the intracellular vesicular trafficking of CPPs, highlighting their role as transformative tools in advancing cellular therapies and medical treatments.</p></div>

<div><p>The reaction of tris [3,5-bis(trifluoromethyl)phenyl]telluronium tetrakis [3,5bis(trifluoromethyl)phenyl]borate (BArF -) salt with phosphine oxides O=PR3 in 1,2dichloroethane is exothermic and leads to the population of the three Te -holes. Quite unprecedented, careful adjustment of the stoichiometry of reagents allowed the selective crystallization of the Lewis adducts containing one, two or three Te-bonded O=PR3, according to X-ray diffraction. 1 H and 19 F Diffusion ordered NMR spectroscopy-monitored titrations of the telluronium salt by O=PPh3 reveal the growth of the hydrodynamic volume of the various cationic adducts, alongside a unique behavior of the BArF -counter-ion that suggests its aggregation at high cationic molecular sizes. Isotherm Titration Calorimetry experiments show that the association equilibrium constants of O=PR3 binding to Te -holes follow the order Ka1 &gt; Ka2 &gt; Ka3, with respective values decreasing by 1 up to 2 orders of magnitude as the -holes are populated. Analysis of Te-O bonding by DFT methods confirms their dominant coulombic character. The minor covalent character is nonetheless required to ensure the telluronium-ligand cohesion. DFT calculations of the association thermochemistry raise the tangible contribution of ion 'pairs' to the association enthalpy as a major issue for modeling: the allegedly "non-coordinating" BArF -taking part in elusive multipolar ion-pairs is far from being an irrelevant thermochemical contributor.</p></div>

<div><p>In the last decade, by integrating experimental and computational analyses, it was demonstrated that halogen bond (HaB) may contribute to binding and enantiorecognition mechanisms underlying the HPLC enantioseparation of halogenated chiral analytes by using cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC)-based chiral columns and n-hexane-based mixtures as mobile phases. When used as a pivotal component of the mobile phase in supercritical fluid chromatography (SFC), carbon dioxide is often considered as an n-hexane-like nonpolar solvent because of its low dielectric constant and zero molecular dipole moment. On the other hand, carbon dioxide may also serve as hydrogen bond (HB) and HaB acceptor due to the presence of nonbonding electrons on the two oxygen atoms, interacting with analyte enantiomers, chiral selectors, and co-solvents. On this basis, we report herein the results of a study aiming at evaluating the impact of using carbon dioxide in SFC in place of n-hexane in HPLC on halogen-dependent enantioseparations by using atropisomeric halogenated 4,4′-bipyridines as analytes and Lux Cellulose-1 as CDMPC-based chiral column. The experimental investigation was complemented by a computational study performed using (a) quantum mechanics (QM) calculations to map and quantify noncovalent interactions possibly underlying the contact of the analytes with carbon dioxide and with the distinctive pendant groups of the CDMPC and (b) molecular dynamics (MD) simulations to visualize noncovalent interactions acting in the analyte 1/CDMPC chromatographic system in different media. The use of MD simulations to model enantioseparations performed in carbon dioxide-based media was not reported in the literature so far.</p></div>

Dielectric and magnetoelectric (ME) studies were conducted on polycrystalline samples of the molecular spin triangle [Fe 3 O(O 2 CPh) 6 (py) 3 ]ClO 4 .py (Fe 3 ) and on its diamagnetic isostructural Ga III analogue (Ga 3 ). Dielectric studies revealed a thermally activated process between approx. 15-60 K, attributed to the freezing-unfreezing of the crystallographically disordered pyridine solvates, with a paraelectric behavior above ~68 K. Magnetoelectric studies revealed a second-order ME effect for Fe 3 , which remained significant above liquid-nitrogen temperatures. Similar experiments on Ga 3 allowed to control for the instrumental baseline response and to confirm the origin of the signal as the ME effect of Fe 3 . The thermal evolution of the ME coupling coefficient (α ME ) showed no discontinuities around the temperature of the freezing-unfreezing processes, indicating that it is unrelated to them. These latter are assigned the disordered-diamagnetic sublattice consisting of the pyridine solvates and perchlorate counteranions. In turn, the ME coupling is assigned to the ordered-magnetic sublattice consisting of the Fe 3 trinuclear cations. These results demonstrate that Fe 3 can directly transform magnetic perturbations to electric signals at the single-molecule level, without the need of structural transformations or long-range magnetic ordering.

Abstract Promising results in preclinical diagnosis based on 89 Zr‐immunoPET have fostered the development of efficient chelators for this tetravalent metal. Leads in this area are octadentate ligands obtained by extension of the desferrioxamine B trihydroxamic acid DFO with a fourth bidentate ligand. In the approach reported here, the latter is a natural 6‐membered cyclic hydroxamic acid deriving from ( L )‐ornithine. Its coupling to DFO via an ( L )‐lysine spacer required that the genuine amine function of the DFO terminus be changed to a carboxylic acid. Such a requirement prompted us to explore short sequences of chemical transformations that would challenge total syntheses leading to the same products. As a matter of fact, the target C ‐terminal DFO analogue was obtained in benzyl‐protected form in three steps from commercially available DFO in 16% overall yield. Our short‐step approach allowed us to implement other functionalities without DFO extension: ‐OH, ‐OTs, ‐CHO, ‐C(O)CH 3 , and ‐CH═CH 2 .

Four cis-chelating diphosphanes derived from cyclodextrins (CDs), each featuring a distinct intracavity environment, compel NiII or PdII metal centers to reside within α- or β-CD cavities. Nickel(II) complexes of these metal-confining ligands act as active catalysts in ethylene oligomerization upon activation with modified methylaluminoxane (MMAO). The size of the cavity and the position of the P2Ni fragment relative to the cavity affect both the activity and selectivity of the reaction. In all instances, 1-butene is the major product (up to 98% C4 products and 90% 1-butene within the C4 fraction). Extensive theoretical studies with state-of-the-art methods carried out on the most selective system suggest that the CD cavity restricts isomerization pathways by limiting the mobility of the coordinated olefin in this constrained supramolecular environment, thereby enhancing α-olefin formation.

Geochemical and isotopic analysis of bitumen lining potsherds from the al-Qusur monastery (second half of the 7th c. CE and the middle of the 9th c. CE), at the central part of Failaka Island (Kuwait Bay), confirms the presence of two distinct compositional categories that can be matched to contemporary sources from two different areas of Iran: the Kermanshah province on one side, and the Khuzestan–Fars–Busher provinces on the other side. Potsherds comprise different types: TORP-S amphorae, TORP-C amphorae, SPORC storage jar, turquoise alkaline-glazed jar (TURQ.T), and CREAC jar. There is no relationship between the type of potsherd and the origin of bitumen. The bitumen coating SPORC jar, first identified as a kind of juice strainer to filter the «garum-like juice», was examined in greater details to try to identify traces of fish sauce mentioned in the Arabic kitchen books as ‘murri’, and quite similar to the Roman garum. The mineralogical analysis exhibits the classical minerals of archaeological mixtures (quartz, calcite, dolomite) and no halite. Hydrocarbons, alcohols, and methyl esters show a typical biodegraded bitumen signature but no fatty acids and terpenoids. It seems that the bitumen matrix has not adsorbed any molecules from the presumed «garum» filtered in the basin.

Abstract The first soluble and stable Mg 2+ dication stabilized only by weakly coordinating and chemically robust carborate anions [HexCB 11 Cl 11 ] − is described. Mg[HexCB 11 Cl 11 ] 2 ( 1 ), prepared by reaction of Mg( n Bu) 2 with 2 equiv of [Ph 3 C][HexCB 11 Cl 11 ], consists, in the solid state, of a central Mg 2+ surrounded by two [HexCB 11 Cl 11 ] − anions. In solution, experimental and classical molecular dynamics simulations (cMD) agree with cation/anion association being retained, reflecting the high electrophilicity of the Mg center. Yet, reflecting only weak anion/cation interactions, species 1 polymerizes 1‐hexene and coordinates alkynes. However, 1 displays no reaction with HSiEt 3 at room temperature, consistent with a low hydridicity of the hard (HSAB) Mg 2+ center. Contrasting with 1 (FIA = 264 kJ mol −1 ; FIA: Fluoride Ion Affinity), salt Mg[( n Bu) 3 NB 12 H 4 Cl 7 ] 2 ( 2 ), incorporating the more basic ammoniododecaborate [( n Bu) 3 NB 12 H 4 Cl 7 ] − anion, is significantly less Lewis acidic (FIA = 214.7 kJ mol −1 ) and unreactive with alkenes and alkynes. Salt 1 effectively catalyzes alkene/alkyne hydrosilylation via an initial alkene/alkyne coordination/initiation, as suggested by experimental and computational data. It also efficiently catalyzes (with a catalyst loading down to 0.1 mol%) the hydrosilylation of CO 2 to CH 4 in the presence of HSiEt 3 . Salt 1 smoothly promotes the catalytic transfer hydrogenation of 1,1‐diphenylethylene, and it is also an active imine hydrogenation catalyst in the presence of H 2 .

Ru complexes are widely studied in photodynamic therapy. The type I mechanism of action is based on a photoinduced electron transfer from the complex to O 2 and needs an electron donor to be catalytic. Little is known about electron donors among physiologically relevant compounds. Hence, we investigated the oxidation of ascorbate, NADH, cysteine, and glutathione with the canonical [Ru(bpy) 3 ](PF 6 ) 2 as well as a derivative with a peripheral disulphide unit, [Ru( S-S bpy)(bpy) 2 ](PF 6 ) 2 . The established reactivity order is ascorbate 4 NADH B cysteine 4 glutathione. Scheme 1 Hypothetical mechanism of the oxidation of the reducing agent (S red ) catalyzed by [Ru(bpy) 3 ] 2+ upon irradiation (left) and structure of the [Ru(bpy) 3 ] 2+ and [Ru( S-S bpy)(bpy) 2 ] 2+ complexes (right).

Hypersaline environments, including brines and brine inclusions of evaporite crystals, are currently of great interest due to their unique preservation properties for the search for terrestrial and potentially extraterrestrial biosignatures of ancient life. However, much is still unclear about the specific effects that dictate the preservation properties of brines. Here we present the first insights into the preservation of cell envelope fragments in brines, characterizing the relative contributions of brine composition, UV photochemistry, and cellular macromolecules on biosignature preservation. Cell envelopes from the model halophile Halobacterium salinarum were used to simulate dead microbial cellular remains in hypersaline environments based on life as we currently know it. Using different Early Earth and Mars analogue brines, we show that acidic and NaCl-dominated brine compositions are more predisposed to preserving complex biosignatures from UV degradation, but that the composition of the biological material also influences this preservation. Furthermore, a combinatory effect between chaotropicity and photochemistry occurs, with the relative importance of each being brine-specific. These results provide an experimental framework for biosignature detection in hypersaline environments, emphasizing the need for laboratory simulations to evaluate preservation properties of each potential brine environment, on Earth and elsewhere in the solar system.

Carbon─nitrogen (C─N) bond-forming cross-coupling reactions catalyzed by palladium-based systems, known as Buchwald-Hartwig aminations, are widely used in natural product synthesis, pharmaceuticals, agrochemicals, and materials science. However, these reactions typically require organic solvents and inert atmospheres, such as argon, increasing environmental, health, and safety concerns. Using electron-rich bulky phosphine ligands in combination with [Pd(π-cinnamyl)Cl] 2 , a highly active palladium catalyst capable of achieving efficient C─N bond formation in the solid state is generated. Remarkably, while previous studies showed that the formation of this palladium-phosphine complex occurs only in protic solvents such as water or alcohols, but not in classical organic solvents, its generation in the absence of any solvent is demonstrated, as confirmed by solid-state 31 P nuclear magnetic resonance, supporting its role as the active catalytic species. This process enables the coupling of a broad range of aryl bromides and chlorides with amines, anilines, amides, carbamates, or ureas, delivering good to excellent yields. This mechanochemical method operates with minimal palladium loading and proceeds efficiently in air, offering a practical and sustainable alternative to traditional solution-phase reactions.

The role played by the distal coordination site’s flexibility on oxygen reduction was investigated by rotating ring-disk electrode experiments for a bipyridine-strapped iron(III) porphyrin mimic of cytochrome [Formula: see text] oxidase. Compared to a phenanthroline counterpart, the more flexible bipyridine strap improved by up to 15% the selectivity of the four-electron reduction of oxygen to water over the two-electron reduction in the presence of copper(I) coordinated to the distal bipyridine and [Formula: see text]-methylimidazole bound at the proximal site. The more modest gain in overpotential observed for the bipyridine-strapped porphyrin than for the phenanthroline derivative was attributed to a difference in stability of the iron(III) porphyrins that affects reduction to iron(II) and oxygen binding. Overall, the rotational flexibility imparted by the bipyridine strap allows the ferric porphyrin to remain relatively flat, thus improving its electrocatalytic performance.

<div><p>Photogeneration of electrons from amorphous phase and anatase phase thin films of titanium oxide in contact with water was monitored by Electron Paramagnetic Resonance. The semiconducting oxide thin films were deposited on glass fibers of 250 µm diameter by Reactive Magnetron Sputtering and were centered inside capillaries of ca. 1 mm diameter filled with aqueous solution of a paramagnetic probe molecule. This proof of concept, non-restrictive to titanium oxide, makes it possible to reuse of the same fiber for multiple measurements and, as it respects the cylindrical symmetry, it should provide mechanistic investigations with reliable and quantifiable data on photogenerated electron transfer at the semiconductor/water interface.</p></div>

(M,N) codoped TiO2 nanoparticles (with M = Nb, Ta, or W) were synthesized via a sol-gel process, followed by a thermal nitridation in ammonia. The doping cation role in determining the codoped materials' physicochemical properties and their photocatalytic activity was studied. In situ temperature-dependent XRD analysis indicated an inhibition of rutile formation due to cation doping for all codoped TiO2 nanomaterials. Depending on the thermal nitridation conditions, two types of absorption behaviors have been identified for each (M,N) codoped sample family: mild nitridation induced an absorption increase between 400 and 550 nm, while harsh nitridation induced additional absorption at a longer wavelength (>550 nm). Furthermore, the presence of W in the TiO2 lattice has been revealed to be more favorable than Nb and Ta to promote nitrogen insertion. A similar charge compensation mechanism, involving defects such as oxygen vacancies, was revealed for (Nb,N) and (Ta,N) codoped materials: low defect concentrations were achieved by the mild nitridation, while the harsh nitridation created a large amount of Ti3+ acting as charge recombination centers. On the opposite end, the defect concentration for (W,N) codoped TiO2 nanoparticles remains low under both mild and harsh nitridation conditions. Additionally, for (W,N) codoped TiO2 samples, W5+ was created by the harsh nitridation condition instead of Ti3+, resulting in an improved visible light photocatalytic activity.

Photoallergic contact dermatitis is a skin disease caused by combined exposure to photoreactive chemicals and sunlight. Exposure to allergens and the risk of skin sensitization is an essential regulatory issue within the industry. Yet, only few non-validated assays for photoallergy assessment exist as the pathogenesis is not fully deciphered. Improving such assays and/or developing new ones require an understanding of the chemical mechanisms involved. The first key event in the photosensitization process, namely chemical binding of the photoallergen to endogenous proteins, is thought to proceed via photo-mediated radicals arising from the photoallergen. Moreover, the mechanism of action of these radicals if formed in the epidermis is not known and far from being unraveled. We present here an original proof-of-concept methodology to probe radical generation from allergens in contact with photoexposed skin, using electron paramagnetic resonance and spin trapping in a reconstructed human epidermis model mimicking real-life exposure scenarios.

Cathelicidin-BF (CatBF) is a LL-37 homologous antimicrobial peptide (AMP) isolated from Bungarus fasciatus with an exceptional portfolio of antimicrobial, antiviral, antifungal, and anticancer activities. Contrary to many AMPs, it showed a good pharmacological profile with a half-life of at least 1 h in serum and efficacy against bacterial infections in mice. To evaluate its potential against resistant nosocomial infections, we assessed its activity against 81 clinically relevant resistant bacterial isolates. CatBF exhibited minimum inhibitory concentrations (MICs) as low as 0.5 μM against carbapenem-resistant Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli. Its wide-ranging activity, unaffected by resistance mechanisms or Gram phenotype, prompted us to investigate its molecular mode of action. NMR spectroscopy, paramagnetic probes, and molecular dynamics (MD) simulations were employed to define its structure, penetration depth, and orientation in various membrane models, including micelles, bicelles, oriented bilayers, and vesicles. We found that CatBF's potent activity relies on its strong charge, allowing membrane neutralization at low peptide/lipid ratios and selective recruitment of charged phospholipids. At higher concentrations, a change in peptide orientation reveals membrane invagination and the formation of transient pores possibly leading to bacterial death. Our findings highlight the potential of CatBF as a model for developing resistance-independent agents to combat multidrug-resistant (MDR) bacterial infections.

We study the stationary states and energies of the hydrogen atoms when they are adsorbed on the palladium surface. Our calculations are performed with the improved relaxation method based on the Multi-Configuration Time-Dependent Hartree (MCTDH) ansatz for the solution of the Schrödinger equation. In order to simulate an infinite surface in our calculations, a periodic approach is adopted. It includes an elementary cell given by a slab of five Pd layers where each one contains 3×3 Pd atoms. Vibrational eigenstates reveal several significant quantum mechanical phenomena. In particular, we were able to show in this study the presence of tunneling effects and of a Fermi resonance coupling the localized vibrational modes of the system.

Cu(II) coordination complexes are emerging as promising anticancer agents due to their ability to induce oxidative stress through reactive oxygen species (ROS) generation. In this study, we synthesized and characterized two novel Cu(II) metallopeptide systems, 1/Cu(II) and 2/Cu(II), derived from the oligocationic bipyridyl cyclopeptides 1 and 2, and designed to enhance the transport of Cu(II) into cells and increase ROS levels. Spectroscopic and electrochemical analyses confirmed the formation of stable metallopeptide species in aqueous media. Inductively coupled plasma mass spectrometry (ICP-MS) studies demonstrated that both metallopeptides significantly increase intracellular Cu(II) accumulation in NCI/ADR-RES cancer cells, highlighting their role as efficient Cu(II) transporters. Additionally, ROS generation assays revealed that 1/Cu(II) induces a substantial increase in intracellular ROS levels, supporting the hypothesis of oxidative stressinduced cytotoxicity. Cell-viability assays further confirmed that both 1/Cu(II) and 2/Cu(II) exhibit strong anticancer activity in a number of cancer cell lines, with IC 50 values significantly lower than those of their free cyclopeptide counterparts or Cu(II) alone, showing an order of activity higher than that of cisplatin. Finally, molecular modeling studies provided further insights into the structural stability and coordination environment of Cu(II) within the metallopeptide complexes. These findings suggest that these Cu(II) cyclometallopeptide systems hold potential as novel metal-based therapeutic agents, leveraging Cu(II) transport and ROS increase as key strategies for cancer treatment.

Two bis-ruthenium(II) complexes, namely N,N′-{5,17-diamino-4(24),6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]arene}-bis-[dichloro-(p-cymene)-ruthenium(II)] (1) and N,N′-{5,11-diamino-4(24),6(10),12(16), 18(22)-tetramethylenedioxy-2,8,14,20-tetrapentylresorcin[4]arene}-bis-[dichloro-(p-cymene)-ruthenium(II)] (2) were synthesized and tested as catalysts in the N-alkylation of primary amines with arylmethyl alcohol using the green “hydrogen borrowing” methodology. The catalytic results were compared with those obtained when the N-{5-amino-4(24),6(10),12(16),18(22)-tetramethylenedioxy-2,8,14,20-tetrapentyl-resorcin[4]arene}-[dichloro-(p-cymene)-ruthenium(II)] (3) complex was employed as catalyst. The rate of the N-alkylation of aniline with benzyl alcohol increased in the order 3 &lt; 1 ≪ 2, which highlights the importance of the relative positioning of the two metal centers on the upper rim of the resorcin[4]arene. Theoretical investigations suggest that the grafting of the two “RuCl2(p-cymene)NH2” moieties on two distal aromatic rings of the cavitand allows a cooperative effect between a ruthenium atom and the coordinated amine of the second metal center.

This study investigates the antimicrobial and antibiofilm potential of three silver(I) complexes derived from Nalkylbenzimidazole derivatives: bis[(Z)-1-styryl-benzimidazole]silver(I) nitrate ( 4), bis[(E)-1-styryl-benzimidazole]silver(I) nitrate (5), and bis(1-cinnamyl-benzimidazole)silver(I) nitrate (6). Detailed synthesis and characterization of these complexes are followed by assessments of their efficacy against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. Among the tested compounds, complex 6 exhibited the highest antimicrobial activity, with a minimal inhibitory concentration of 6 µmol/L against P. aeruginosa, and significant antibiofilm activity, achieving 67.72 % inhibition at a concentration of 3 µmol/L. These interesting findings led us to conduct a molecular docking study to understand the mechanisms of action by investigating the interactions between the silver(I) complexes and some key protein targets involved in bacterial and fungal biofilm formation, including (p)ppGpp synthetase/hydrolases, FtsZ proteins, and pyruvate kinases. This comprehensive approach, combining experimental and computational analyses derived from N-alkylbenzimidazole derivatives, particularly complex 6, which exhibits remarkable efficacy against various pathogens, reveals promising therapeutic applications of these silver(I) complexes and advances our understanding of their potential mode of action against biofilm-associated infections.

The α7 nicotinic acetylcholine receptor is a pentameric ligand-gated ion channel that plays an important role in neuronal signaling throughout the nervous system. Its implication in neurological disorders and inflammation has spurred the development of numerous compounds that enhance channel activation. However, the therapeutic potential of these compounds has been limited by the characteristically fast desensitization of the α7 receptor. Using recent high-resolution structures from cryo-EM, and all-atom molecular dynamic simulations augmented by Markov state modeling, here we explore the mechanism of α7 receptor desensitization and its implication on allosteric modulation. The results provide a precise characterization of the desensitization gate and illuminate the mechanism of ion-pore opening/closing with an agonist bound. In addition, the simulations reveal the existence of a short-lived, open-channel intermediate between the activated and desensitized states that rationalizes the paradoxical pharmacology of the L247T mutant and may be relevant to type-II allosteric modulation. This analysis provides an interpretation of the signal transduction mechanism and its regulation in α7 receptors.

The photocatalytic recovery of noble metals on photosensitive semiconductors such as TiO2 is well-established for forming M/TiO2 but has notable drawbacks. TiO2 suffers from low conversion efficiency due to significant recombination of photogenerated electron–hole pairs. Its wide energy band gap (3.2 eV) also restricts excitation to high-energy UV light, limiting its use with solar energy. This study proposes an efficient alternative using hybrid polyoxometalate (POM)–porphyrin copolymers for the photocatalytic recovery of Ag and Pt under visible light. Copolymeric films composed of hybrid polyoxometalates and porphyrins have been obtained by the electrooxidation of 5,15-(di-p-tolyl)porphyrin (H2T2P) or 2,3,7,8,12,13,17,18-octaethylporphine zinc(II) (ZnOEP) together with Keggin or Wells–Dawson-type organosilyl polyoxophosphotungstate ([PW11Si2O40C26H16N2]TBA3 or [P2W17Si2O62C26H16N2]TBA6). In these films, porphyrin subunits can be excited under visible illumination, acting as photosensitizers that transfer electrons to the polyoxometalate catalysts. Notably, POM–porphyrin films demonstrated high efficiency in Pt(IV) photoreduction over repeated cycles without catalyst degradation.

The presence of defects in carbon materials, such as electronically unsaturated carbon sites, can profoundly affect their magnetic ordering and chemical reactivity. The detailed analysis of these species (edge states, σ free radicals, or carbene), which are pivotal for many applications, remains a significant challenge for carbon bulk materials. Today, the engineering of defective carbon materials often relies on the use of hardly up-scalable physical methods not accessible to synthetic chemists. It is therefore important to develop simple and scalable methods to generate well-defined electronically unsaturated sites in carbon materials. Herein, we followed the transformation and evolution of surface oxygen functional groups of various oxidized carbon materials during thermal treatment under an inert atmosphere using various analytical techniques and ab initio molecular dynamics, with the aim of producing stabilized localized electronic states from condensation reactions. Synchrotron-based in situ XPS analyses show a decrease in the number of carboxylic surface groups with a concomitant increase in the number of defect sites upon defunctionalization, which is expected from condensation reactions. Echo-detected field-swept EPR spectra show the apparition of a signal only upon defunctionalization, particularly for samples showing a high proportion of prismatic surface. The contribution of these electronically unsaturated carbon sites to the catalytic activity for the catalytic oxidative dehydrogenation of indoline is moderate, and the surface oxygen functional groups are the main active sites.

The present study details the synthesis and characterization of a robust, monomeric Al-H aluminate supported by a tridentate tris-phenolate ligand, isolated as [2][Li(THF)4] and [2][N( n Bu)4] salts, which were then exploited as CO2 hydroboration catalysts. As initial reactivity studies, it was observed that the nucleophilic Al-H anion in [2][C] (C = counter cation [Li(THF)4] + or [N( n Bu)4] + ) reacts fast with CO2, to afford the corresponding Al formate complexes [3][C], which were isolated and structurally characterized. Such anions were then exploited as potential CO2 reduction catalysts. Salts [2-3][N( n Bu)4] are efficient and robust CO2 hydroboration catalysts in the presence of pinBH or Me2S-BH3 as hydroborane sources to selectively afford formate-equivalent or methanol-equivalent products (TON up 1920), depending on reaction conditions and the nature of the counter-cation. As deduced from detailed DFT calculations, the Al formate anion [3] -acts as a nucleophilic catalyst (for borane activation) but also as an electrophile (through the AlOCO carbon) allowing CO2 activation/functionalization and thus the reduction catalysis to occur, a process thermodynamically driven by the stability of the reduction products. The anionic nature of [2] -and [3] -aluminates, resulting in an enhanced nucleophilicity (vs. neutral analogues), may thus be crucial for catalytic activity. In contrast, according to DFT calculations performed with a model anion of [3] -and pinBH, a CO2 reduction processing via an Al-O/B-H s-bond metathesis appears kinetically unfavored. The proposed mechanism involving an electrophilic/nucleophilic dual activation mode also rationalizes the importance of countercation [C] + in [2-3][C] for catalytic activity and selectivity, as demonstrated by the higher performance of [2][N( n Bu)4] vs. [2][Li(THF)4].

To mimic the structural aspects of staurosporine, a potent but unspecific kinase inhibitor, several coordination compounds based on two readily available diimine ligands containing hydrogen bonding donor/acceptor sites (NH-CO fragment) have been designed and synthesized. These complexes are constructed around Ru(II) and Pt(II) metal centers. A total of 9 compounds, named Ru(1)-(5) and Pt(1)-(4), were obtained through straightforward synthetic approaches. The cytotoxicity of the compounds was evaluated on AGS gastric cancer cells (GC) through standard MTT assays. All ruthenium and platinum complexes with low toxicity, i.e.Ru(3), Ru(5), Pt(3) and Pt(4), were docked in the ATP binding pocket of two protein kinases (S6K1 and MST2). The docking scores highlighted a preferred affinity of Ru(5) for the MST2 binding pocket, whereas the platinum compounds are predicted to bind stronger to the S6K1 binding site. Inhibitory activity of the metal complexes on the MST2 and S6K1 signaling pathways was evaluated by analyzing via western blot experiments the phosphorylation state of YAP, a downstream component of the Hippo pathway and the protein expression of S6 and its phosphorylated analogue p-S6. A clear difference of behavior between the Pt(II) and the Ru(II) complexes depending on the type of kinase was observed.

Detecting low concentrations of viruses in sewage water is crucial for monitoring the spread of emerging viral diseases. However, current detection methods, which involve concentrating viruses using traditional materials such as gauze or cotton, have limitations in effectively accomplishing this task. This study demonstrates that graphene oxide (GO), a two-dimensional carbon material, possesses strong viral adsorption capabilities. However, it lacks efficiency for effective viral release. Therefore, we designed a series of new GO-based materials, which exhibited a viral adsorption similar to pristine GO, while significantly enhancing their release performance by attaching alkyl chains and hydrophilic functional groups. Among the synthesized materials, 1,8-aminooctanol grafted to GO (GO-NH 2 C 8 OH) has emerged as the most promising candidate, achieving a viral release rate higher than 50 %. This superior performance can be attributed to the synergistic effect of the alkyl chain and the terminal OH group, which enhances both its affinity for viruses and water dispersibility. Furthermore, we have successfully applied GO-NH 2 C 8 OH in a new protocol for concentrating viruses from sewage wastewater. This approach has demonstrated a 200-fold increase in virus concentration, allowing PCR detection of this type of pathogens present in wastewater below the detection limit by direct analysis, underscoring its significant potential for virus surveillance.

Background/Objectives: This study investigates the structural and biophysical properties of the wild-type antimicrobial peptide LyeTx I, isolated from the venom of the spider Lycosa erythrognatha, and its analog LyeTx I-b, designed to enhance antibacterial activity, selectivity, and membrane interactions by the acetylation and increased amphipathicty. Methods: To understand the mechanisms behind these enhanced properties, comparative analyses of the structural, topological, biophysical, and thermodynamic aspects of the interactions between each peptide and phospholipid bilayers were evaluated. Both peptides were isotopically labeled with 2 H 3 -Ala and 15 N-Leu to facilitate structural studies via NMR spectroscopy. Results: Circular dichroism and solid-state NMR analyses revealed that, while both peptides adopt α-helical conformations in membrane mimetic environments, LyeTx I-b exhibits a more amphipathic and extended helical structure, which correlates with its enhanced membrane interaction. The thermodynamic properties of the peptide-membrane interactions were quantitatively evaluated in the presence of phospholipid bilayers using ITC and DSC, highlighting a greater propensity of LyeTx I-b to disrupt lipid vesicles. Calcein release studies reveal that both peptides cause vesicle disruption, although DLS measurements indicate distinct effects on phospholipid vesicle organization. While LyeTx I-b permeabilizes anionic membrane retaining the vesicle integrity, LyeTx I promotes significant vesicle agglutination. Furthermore, DSC and calcein release assays indicate that LyeTx I-b exhibits significantly lower cytotoxicity toward eukaryotic membranes compared to LyeTx I, suggesting greater selectivity for bacterial membranes. Conclusions: Our findings provide insights into the structural and functional modifications that enhance the antimicrobial and therapeutic potential of LyeTx I-b, offering valuable guidance for the design of novel peptides targeting resistant bacterial infections and cancer.

The concept of photoresponsive coordination polymer (CP) single crystal platforms (CPSCPs) is based on photoresponsive olefin CP single crystals, which can undergo photocycloaddition reactions under light irradiation through a single-crystal-to-single-crystal (SCSC) transformation. Taking advantage of the coordination of olefin ligands to metal ions of Zn 2+ , Cd 2+ , etc., a pair of C�C double bonds is positioned adjacent to each other in space at a suitable distance and orientation to allow [2 + 2] photocycloaddition triggered by UVvis irradiation, affording cyclobutanes in the CPs. The single crystal nature of CPs allows their structures to be determined by X-ray diffraction, providing details of the arrangements in space of the C�C double bonds. These CPs are promising platforms for the synthesis of organic molecules, such as cyclobutanes and derivatives, with high regioselectivity and stereoselectivity without any catalyst. The [2 + 2] photocycloaddition reactions may induce structural modifications like expansion or shrinking of unit cells, resulting in macroscopic changes (e.g., cracking, bending, etc.) of the whole CP single crystals and leading to changes in chemical and physical properties. Applications take advantage of their optical properties, including luminescence and absorption, and allow the detection of guest molecules and photomechanical motions. Although much effort has been devoted to such studies, it remains challenging to develop systematic investigations aiming at increasing the diversity of CPs and properties to meet practical needs. Moreover, more efficient methods are desirable to investigate the reaction mechanisms in the solid state and monitor the structural changes occurring during the process. In this Account, we introduce our research on the design and applications of photoresponsive CPSCPs. It is divided into three parts. First, the design and construction of various CPs with different olefin ligands are discussed. Through a suitable and sometimes sophisticated choice of metal ions and auxiliary carboxylate ligands, these olefin ligands meet the requirements to undergo [2 + 2] photocycloaddition reactions in CP structures, allowing for the precise synthesis of cyclobutanes and their derivatives. These compounds could be subsequently extracted from the CPs to give pure organic products. Second, we introduce new strategies, such as a combination of single crystal X-ray diffraction (SCXRD) with thermal/phototreatments of CPs and in situ fluorescence spectroscopy, to monitor the structural changes occurring on the olefin ligands during the reaction. Furthermore, the fast stepwise photoreaction could also be visualized with high resolution. These data significantly strengthen our understanding of solid-state [2 + 2] photocycloaddition reactions in CPs. Third, applications of photoresponsive CPs are described, which focus on optical and photoinduced mechanical properties. Considering the optical properties, the conjugated structures of the olefin ligands change during the reactions, and circular dichroism (CD) and fluorescence were used for their detection and imaging. Furthermore, the photoinduced mechanical properties of CPs could be significantly expanded through the combination of CP crystals with polymers. Lastly, we point out the challenges and directions for future research in the field. We hope this Account will provide an overview of research on photoresponsive CPSCPs, attract more attention from the community, and inspire future research.

Archaeal membranes exhibit remarkable stability under extreme environmental conditions, a feature attributed to their unique lipid composition. While it is widely accepted that tetraether lipids confer structural integrity by forming monolayers, the role of bilayer-forming diether lipids in membrane stability remains unclear. Here, we demonstrate that incorporating diethers into archaeal-like lipid assemblies enhances membrane organization and adaptability under thermal stress. Using neutron diffraction, we show that membranes composed of mixed diethers and tetraethers exhibit greater structural order and stability compared to pure lipid systems. Contrary to expectations, monolayerforming tetraethers alone display increased variability in lamellar spacing under fluctuating temperature and humidity, whereas mixed lipid membranes maintain a consistent architecture. Furthermore, neutron-scattering length density profiles reveal an unexpected density feature at the bilayer midplane, challenging conventional models of archaeal monolayer organization. These findings suggest that molecular diversity of lipid molecules, rather than tetraether dominance, plays a critical role in membrane auto-assembly, stability, and adaptability. Our results provide new insights into archaeal membrane adaptation strategies, with implications for the development of bioinspired, robust synthetic membranes for industrial and biomedical applications.

Peptide stapling has emerged as a versatile approach in drug discovery to reinforce secondary structure elements especially α‐helices and improve properties of linear bioactive peptides. Inspired by the prevalence of arginine in protein‐protein and protein‐DNA interfaces, we investigated guanidinium‐stapling as a means to constrain helical peptides. Guanidinium stapling was readily achieved on solid support, utilizing two orthogonally protected lysine or unatural α‐amino acid residues with an amino function. This method allows for easy modulation of the nature and size of the staple as well as helix propensity. Evaluating a set of guanidinium‐stapled peptides for their interaction with different protein targets identified several binders with increased target affinity. X‐ray structure determination of four complexes revealed that all stapled peptides adopt a helical conformation upon protein binding. Notably, the disubstituted guanidinium generally exhibits a distinct cis / trans conformation and, in one instance, retains a conserved hydrogen bond with the protein surface. By identifying, for the first time, the guanidinium moiety as an effective helical peptide stapling group, this research significantly expands the repertoire of α‐helix stapling techniques for the creation of useful protein mimics.

Reported herein is a route to functionalized chiral heteroaromatic polycyclic compounds leveraging two unfriendly catalytic cycles in a one-pot sequential process. α-Heteroaromatic-γ-butyrolactones were engaged in a highly regio-, diastereo-and enantioselective Lewis base Asymmetric Allylic Alkylation (AAA) with alkyne functionalized Morita-Baylis-Hillman (MBH) carbonates. Gratefully to the low Lewis base catalyst loading, subsequent gold catalyzed Friedel-Crafts type cyclization, entailing the formation of fused polycyclic compounds, proceeded efficiently affording structurally complex highly enantioenriched products.

Rationale: In this study, we applied cross-linking mass spectrometry (XL-MS) to characterize the oligomeric states of a PGLa/magainin 2 mixture and gain insight into the heterodimerization previously suggested in the literature. Both peptides have shown a synergistic enhancement of activity when tested in antimicrobial assays; however, the mechanism of action is still not well understood. Methods: Peptides solutions were prepared in HEPES buffer in the presence of membrane-mimicking DDM detergent micelles or POPE:POPG 3:1 vesicles. Cross-linking experiments were performed using disuccinimidyl suberate (DSS) or disuccinimidyl glutarate (DSG), and MALDI-MS was used to follow the cross-linking performance. Nano liquid chromatography coupled to mass spectrometry was conducted on a Q Exactive Plus orbitrap to achieve linkage sites determination using pLink2 for data interpretation. Trypsin or pepsin digestion was performed for the characterization of intermolecular links. Results: XL-MS performed in a DDM micelle environment provided direct evidence of a specific PGLa/magainin 2 heterodimer, but no other oligomeric states were detected. Monitoring the reaction using MALDI-MS allowed unambiguous characterization of the cross-linked stabilized oligomers and facilitated a rapid optimization of conditions to achieve the best balance between stabilizing complex formation and avoiding unspecific aggregation. Comparison of the cross-linked species in detergent micelles and lipidic POPE:POPG bilayers revealed different behaviors suggesting that interaction between the peptides might occur differently in both membrane-mimicking media. Conclusions: This study revealed that XL-MS was relevant at the peptidomic level. However, the cross-linking workflow had to be adjusted compared to its use in large-scale protein–protein interaction mapping in order to avoid technical bias arising from the rapid nature of the cross-linking reaction.

In this study, water‐soluble colloidal platinum nanoparticles (Pt NPs) have been stabilized with novel thiolated cyclodextrins (CD‐SH) and their catalytic performance has been investigated. We varied the size of the CD cycle (α‐CD/β‐CD), the degree of thiolation (one or two thiol groups per CD), and the CD/Pt molar ratio (0.5; 0.2; 0.1; 0.05) to find the best performing water‐soluble, air‐stable hydrogenation catalyst. An organometallic approach for the Pt NP synthesis resulted in the formation of small well‐dispersed NPs of 1–2 nm in size, as shown by TEM. XPS analysis confirmed the formation of a Pt−S interaction, rationalizing the strong NP stabilization by a small quantity of CD‐SH, while preserving the NP catalytic properties. Only 0.1 equivalent of CD‐SH was enough to obtain a promising hydrogenation activity with preserved stability of the colloidal dispersion. Performing catalysis in biphasic conditions allowed simple separation of the products and reuse of the catalyst five times without deactivation.

Trying to export ab initio polaritonic chemistry onto emerging quantum computers raises fundamental questions. A central one is how to efficiently represent both fermionic and bosonic degrees of freedom on the same platform, in order to develop computational strategies that can accurately capture strong electron-photon correlations at a reasonable cost for implementation on near-term hardware. Given the hybrid fermion-boson nature of polaritonic problem, one may legitimately ask: should we rely exclusively on conventional qubit-based platforms, or consider alternative computational paradigms? To explore this, we investigate in this work three strategies: qubit-based, qudit-based, and hybrid qubit-qumode approaches. For each platform, we design compact, physically motivated quantum circuit ansätze and integrate them within the state-averaged variational quantum eigensolver to compute multiple polaritonic eigenstates simultaneously. A key element of our approach is the development of compact electron-photon entangling circuits, tailored to the native capabilities and limitations of each hardware architecture. We benchmark all three strategies on a cavity-embedded H$_{2}$ molecule, reproducing characteristic phenomena such as light-induced avoided crossings. Our results show that each platform achieves comparable accuracy in predicting polaritonic eigen-energies and eigenstates. However, with respect to quantum resources required the hybrid qubit-qumode approach offers the most favorable tradeoff between resource efficiency and accuracy, followed closely by the qudit-based method. Both of which outperform the conventional qubit-based strategy. Our work presents a hardware-conscious comparison of quantum encoding strategies for polaritonic systems and highlights the potential of higher-dimensional quantum platforms to simulate complex light-matter systems.

IspH is the last enzyme of the methylerythritol phosphate pathway. It catalyzes the reductive dehydroxylation of ( E )‐4‐hydroxy‐3‐methyl‐but‐2‐en‐1‐yl diphosphate into isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), which are precursors for the biosynthesis of terpenoids, essential molecules for the survival of all living organisms. This pathway is absent in humans, making it a promising target for drug discovery. Escherichia coli IspH harbors an unusual [4Fe‐4S]²⁺ cluster linked to three conserved cysteines with a unique iron site proposed to be coordinated to three water molecules. Here, the first resonance Raman spectroscopic study of the cluster of IspH in the 2+ oxidation state is reported. Using isotopic labeling with ²H₂O and H₂¹⁸O, the bands of the cluster that are sensitive to water coordination or hydrogen bonding are identified. The change of geometry of the cluster upon binding of the substrate, an alkyne diphosphate inhibitor, and the two enzyme products is also analyzed. Distinct binding modes to the cluster may indeed be at the origin of the different distribution of IPP and DMAPP observed during catalysis.

Tricyclic and tetracyclic terpane ratios are used as biomarker proxies for depositional environments and to classify crude oils and source rocks. However, the biological precursors and diagenetic drivers of these proxies are not well understood. This study reports on the discovery of tricyclic and tetracyclic breakdown products of pentacyclic hopanoids that co-elute with 14α-C₁₉ and βα-C₂₀-C₂₂ cheilanthanes and C₂₄ tetracyclic terpane in gas chromatograms. This includes hopanoid breakdown products (HBPs) that are identical to 14α-C₁₉ cheilanthane and C₂₄ tetracyclic terpane, biomarkers that are commonly used as indicators of terrigenous organic matter in source rocks and their derived hydrocarbon products. These HBPs were generated by pyrolysis of C₃₀ diplopterol, a common compound found in the cell membranes of almost all hopanoid-producing bacteria, some lichens and higher plants. HBPs are common in rock-extracted bitumens and crude oils from the Neoproterozoic to the Cenozoic and across a wide range of thermal maturities. Comparison of the relative abundance of HBPs and cheilanthanes against commonly used tricyclic and tetracyclic terpane parameters shows that HBPs can drive or strongly influence terpane-based paleoenvironmental proxies. This study begins to rationalise why some of these parameters indicate specific depositional environments and proposes new ratios that quantify the impact of HBPs on biomarker proxies.

Gold nanoparticles (AuNPs) have gained significant attention for their applications in catalysis, sensing, electronics, diagnostics and therapeutics, necessitating scalable and reproducible production methods. Currently established protocols of AuNPs synthesis restrict up-scalability, and thus prevent its industrialization into biomedical fields that could otherwise exploit their ground-breaking assets. This study explores a continuous hydrothermal process for the synthesis of AuNPs using gold trihydroxide (Au(OH)₃) as a chloride-free precursor, compatible with a lab-made industrial-grade equipment. Batch synthesis was first used to determine optimal reaction conditions based on the Turkevich-Frens method, employing trisodium citrate as a reducing agent. These conditions were adapted to a continuous setup operating at high pressure (250 bar) and variable temperatures (100°C-400°C). Under high pressure, well-dispersed AuNPs with different sizes and morphologies were successfully synthesized. Characterizations of sizes, shapes and localized surface plasmon resonance confirmed successful particle formation, and provided information about dispersion state and optical properties. The system enabled steady AuNPs production with minimal loss, demonstrating a promising route for scalable and controlled AuNPs synthesis suitable for biomedical applications.

Several copper-ligands, including 1,10-phenanthroline (Phen), have been investigated for anticancer purposes based on their capacity to bind excess copper (Cu) in cancer tissues and form redox active complexes able to catalyse the formation of reactive oxygen species (ROS), ultimately leading to oxidative stress and cell death. Glutathione (GSH) is a critical compound as it is highly concentrated intracellularly and can reduce and dissociate copper(II) from the ligand forming poorly redox-active copper(I)-thiolate clusters. Here we report that Cu-Phen2 speciation evolves in physiologically relevant GSH concentrations. Experimental and computational experiments suggest that at pH 7.4 mostly copper(I)-GSH clusters are formed, but a minor species of copper(I) bound to one Phen and forming ternary complexes with GSH (GS-Cu-Phen) is the redox active species, oxidizing quite efficiently GSH to GSSG and forming HO• radicals. This minor active species becomes more populated at lower pH, such as typical lysosomal pH 5, resulting in faster GSH oxidation and HO• production. Consistently, cell culture studies showed lower toxicity of Cu-Phen2 upon inhibition of lysosomal acidification. Overall, this study underscores that sub-cellular localisation can considerably influence the speciation of Cu-based drugs and that minor species can be the most redox- and biologically- active.

Iron-copper complexes have been extensively studied in the search for efficient cytochrome c oxidase models. Whereas most dinuclear materials usually focus on fine-tuning the coordination of heme-Fe, this work shows that the coordination of copper in cytochrome c oxidase models should be carefully taken into consideration. A β-cyclodextrin dimer was built around a bipyridine linker and combined with Fetetraphenylsulfonatoporphyrinate (FeTPPS) to generate a self-assembled hydrosoluble cytochrome c oxidase model. Cyclic voltammetry and rotating ring disk electrode experiments showed that this model with a tetrahedral coordination of copper(I) is efficient for the reduction of molecular oxygen with an average of 3.6 electrons indicating a preference and efficiency for the four-electron reduction to water.

A series of chiral ^A*Flu‐NHC‐gold(I) complexes, where ^A*Flu‐NHC is an N‐heterocyclic carbene (imidazolin‐2‐ylidene or benzimidazolin‐2‐ylidene) bearing a chiral 9‐alkyl‐9‐fluorenyl N‐substituent and a 2,6‐diisopropylphenyl or benzyl N’‐substituent, were straightforwardly prepared in few steps from readily available 2,6‐diisopropylamine, imidazole or benzimidazole. The chirality of the N‐substituent lies in the presence of a chiral alcoholic alkyl chain on the fluorenyl, which results from the opening of commercially available chiral styrene oxide, yielding to a 2‐hydroxy‐2‐phenylethyl or a 2‐hydroxy‐1‐phenylethyl group. Four [AuCl(^A*Flu‐NHC)] complexes were tested as precatalysts in an enantioselective cycloisomerization of a 1,6‐enyne. Notably, the best inductions were observed with the benzimidazolin‐2‐ylidene derivative bearing a 2‐hydroxy‐1‐phenylethyl group on the fluorenyl ring, showing that a constrained rotation around the N−C fluorenyl bond and a chiral center in α position of the fluorenyl ring are determining factors. Interestingly, a strong improvement of the induction with up to 72 % ee was observed using AgOTf as activator. The presence of a hydrogen bond between the hydroxyl group and OTf − in the in situ generated active cationic gold(I) species probably stiffens its structure. This type of ligand‐counteranion interaction represents a novel strategy for optimizing chirality transfer in asymmetric gold(I) catalysis.

Oxidatively induced reductive elimination (OIRE) has become a crucial chemical process to enable the effective formation of otherwise much less accessible products. The chemically, electrochemically, or photochemically triggered oxidation of appropriate metal complexes leading to a reductive elimination process otherwise chemically unfavorable has long been studied in stoichiometric metal‐centered reactions. However, its conscious inclusion and targeted application in catalysis is a rather recent development. Ruthenium and Group 9 metal complexes are particularly representative examples of how the observed OIRE abilities can be modulated using different coupling partners. Parallels can be drawn between rhodium and iridium, which have a long history as efficient catalysts, and their more readily available 3d row metal neighbor, i.e. cobalt, with ruthenium also providing a parallel reactivity. This review explores the history of OIRE reactions throughout the last few centuries, highlighting the role of Ti, Mo, Fe, Ru, Ni, Hg and group 9 transition metals as key players in C‐H bond functionalization and OIRE chemistry, discussing the most relevant studies published in the field whilst pinpointing research gaps that require new theoretical and mechanistic studies, with the final goal of unlocking the full potential of OIRE chemistry in organometallic homogeneous catalysis.

Photomechanical crystals, capable of transforming light energy into mechanical work, hold significant promise for applications in intelligent actuating devices, artificial muscles, and microrobots, but this calls for more research on the influence of irradiation wavelengths. Here we report a discrete Cd(II)based complex [Cd 2 (CH 2 OH-1,3-bpeb) 4 (3,5-FBA) 4 ] (1; CH 2 OH-1,3-bpeb = 5-hydroxymethyl-1,3-bis((E)-2-(pyridin-4-yl)vinyl)benzene, 3,5-FBA = 3,5-difluorobenzoate) which undergoes stepwise [2 + 2] photocycloaddition reactions under visible and ultraviolet light, forming mono-and di-cyclobutane products, respectively, through a single-crystal-to-singlecrystal transformation. This wavelength-controlled process involved the cleavage and subsequent reconstruction of Cd-O bonds within the crystal framework, along with the corresponding lattice contraction and expansion. Those photochemical reactions at different wavelengths initiate various crystal motions, which stem from the stress within the unit cell caused by anisotropic contraction/ expansion. This work opens a new avenue for regulating wavelengths to achieve photocontrolled structural transformations and macroscopic photomechanical motions of molecular crystals.

Functionalization of layered oxides to convey a reactive function prone to coordinate metal cations in-between the inorganic layers is a challenge with respect the potential reactivity of the oxides with these groups. Here, silanization by amine-bearing alkoxysilanes was proposed as a convenient way to bring in free amine groups in the interlayer space. Yet, silanization in itself has seldom been explored for layered oxides. This study presents a microwave-assisted multistep approach for functionalizing the Aurivillius Bi₂SrTa₂O₉ phase by organosilanes. Three different organosilanes were inserted in the interlayer space, triethoxyoctylsilane, 3-(aminopropyl)triethoxysilane and N-[3(trimethyoxysilyl)propyl]ethylenediamine. The synthetic pathway described here constitutes a fast and efficient approach to silanize the interlayer space of layered perovskites, while preserving the layered structure. The compounds were fully characterized, notably by X-Ray Diffraction (XRD) and solid state Nuclear Magnetic Resonance (NMR), which demonstrated that the organosilanes were effectively grafted onto the oxide layers, forming stable Si-O-Ta bonds, and allowed to precise the grafting scheme, evidencing the very limited formation of siloxane network. Using this approach, free amino groups were introduced in-between the inorganic oxide layers due to the preferential reactivity of the oxide sheets with the alkoxysilane groups compared to amine. These amino groups are available for further coordination by transition metal ions using a post-synthesis complexation reaction. As a proof of concept their complexation ability towards Cu²⁺ ions was demonstrated by UltraViolet-Visible (UV-Vis) and Electron Paramagnetic Resonance (EPR) spectroscopies. This soft chemistry strategy constitutes a new versatile, fast and efficient method to introduce transition metal cations into layered oxides and paves the way for the design and synthesis of complex architectures, specifically designed for application, in catalysis, sensors, metal cation remediation or luminescence for instance.

Imaging extracellular Cu²⁺ in vivo is important due to its role in physiological and pathological processes. Magnetic resonance imaging is a promising modality for this purpose but developing contrast agents selective for Cu²⁺ over abundant Zn²⁺ ions remains a challenge. We synthesized and characterized two novel ligands, DO3A‐picG and DO3A‐picGH, containing a macrocycle and a pendant arm for Cu²⁺ complexation inspired from the ATCUN site of human serum albumin. The corresponding Ln³⁺ complexes were studied in the presence and in the absence of Cu²⁺ through UV‐visible, fluorescence and EPR spectroscopies, as well as relaxivity measurements. These studies show that Gd‐DO3A‐picG and Gd‐DO3A‐picGH are non‐hydrated complexes, in which the pyridine‐amide moiety remains coordinated to Ln³⁺ even in the presence of Cu²⁺. While Gd‐DO3A‐picG does not respond to Cu²⁺, a sizeable relaxivity increase is observed for Gd‐DO3A‐picGH. This increase is attributed to an increased second‐sphere contribution to the relaxivity, i. e. a higher number of H₂O molecules retained in close proximity to Gd³⁺ through H‐bonding. Finally, we show that Gd‐DO3A‐picGH binds Cu²⁺ with a μM affinity, and is selective for Cu²⁺ vs Zn²⁺.

Abstract Recent theoretical studies have shown that placing a spin‐crossover ion in a field of radical ligands can induce local superpositions of spin states (see Ref. [1,2]). The stability of this phenomenon, termed spinmerism , is called into question when spin‐orbit coupling is included. Thus, we investigate the competition between spinmerism and spin‐orbit coupling in a d 2 metal ion with two radical ligands. Our results show that competition between spinmerism and spin‐orbit coupling can induce distinct states which may potentially open new avenues for quantum technologies.

The Aromatic Cope Rearrangement (ArCopeR) is a highly challenging chemical reaction under thermal conditions, primarily attributed to the loss of aromaticity during the initial [3,3]-sigmatropic step of the process. Such rare transformation typically requires high temperatures and specially engineered 1,5-hexadiene scaffolds, making it impractical for straightforward synthesis of new molecules. Here, we demonstrated that gold(I) catalysts significantly lower the energetic barriers associated to ArCopeR, enabling the reaction to be carried out at low temperature (rt to 70°C) in dichloroethane or hexafluoroisopropanol with high yields. Specifically, phosphine gold(I) complex ((p-CF3Ph)3PAuOTf) permits for the diastereoselective and divergent aromatic Cope rearrangement from various α-allyl-α'-heteroaromatic γ-lactone or malonate derivatives, while N-heterocyclic carbene gold(I) (IPrAuNTf2) allows the selective dearomatization reaction. Extended quantum mechanics calculations, consistent with experimental observations, reveal that (i) an interweaved transformation occurs instead of the expected ArCope cascade made of formal [3,3]-sigmatropic rearrangement and [1,3]H-shift steps, and that (ii) van der Waals interactions between the catalyst and substrate contribute to the interrupted ArCope process leading to dearomatize products. This study presents the first catalytic and synthetically useful protocol to promote ArCopeR under mild conditions.

Due to the importance of biaryls as natural products, drugs, agrochemicals, dyes, or organic electronic materials, a green alternative biaryl synthesis has been developed based on easy-to-prepare and cheap copper(I)-exchanged zeolite catalysts. CuI-USY proved to efficiently catalyze the direct homocoupling of either phenols or aryl boronic acids under simple and practical conditions. The CuI-USY-catalyzed oxidative homocoupling of phenols could conveniently be performed under air either in warm methanol or water with good to high yields. In methanol, a small amount of Cs2CO3 was required, while none was necessary in water. The homocoupling of aryl boronic acids was best performed also in warm methanol, without an additive. These mild conditions showed good functional-group tolerance, leading to a variety of substituted (hetero)biaryls (28 examples). The heterogeneous CuI-USY catalyst could readily be recovered and reused. Interestingly, the homocoupling of vinyl boronic acids was successfully coupled to a Diels–Alder reaction, even in a one-pot process, allowing access to highly functionalized cyclohexenes.

<div><p>The lipid cis-trans isomerase (Cti) is a periplasmic heme-c enzyme found in several bacteria including Pseudomonas aeruginosa, a pathogen known for causing nosocomial infections. This metalloenzyme catalyzes the cis-trans isomerization of unsaturated fatty acids in order to rapidly modulate membrane fluidity in response to stresses that impede bacterial growth. As a consequence, breakthrough in the elucidation of the mechanism of this metalloenzyme might lead to new strategies to combat bacterial antibiotic resistance. We report the first comprehensive biochemical, electrochemical and spectroscopic characterization of a Cti enzyme. This has been possible by the successful purification of Cti from P. aeruginosa (Pa-Cti) in favorable yields with enzyme activity of 0.41 μmol/ min/mg when tested with palmitoleic acid. Through a synergistic approach involving enzymology, site-directed mutagenesis, Raman spectroscopy, Mössbauer spectroscopy and electrochemistry, we identified the heme coordination and redox state, pinpointing Met163 as the sixth ligand of the Fe II of heme-c in Pa-Cti. Significantly, the development of an innovative assay based on liposomes demonstrated for the first time that Cti catalyzes cis-trans isomerization directly using phospholipids as substrates without the need of protein partners, answering the important question about the substrate of Cti within the bacterial membrane.</p></div>

Abstract In this review, the difference between π‐mers (pimers) and π‐dimers (pi‐dimers) will be discussed. Often interchanged or confused in the literature, these two radical interactions lead to different or even opposite physico‐chemical behaviors. This review aims at clarifying the terms π‐mers and π‐dimers and at describing their main physico‐chemical properties to address their differences. Finally, selected literature examples exhibiting the successive formation of π‐mers and π‐dimers within the same systems will be detailed to emphasize the physico‐chemical changes occurring upon conversion.

We have successfully synthesized the dichloro-bis[(Z)-1-styryl-benzimidazole]-zinc(II) complex, which was fully characterized by IR, elemental analysis, and mass and NMR spectroscopy. The solid-state structure definitively shows that two benzimidazole moieties are coordinated to the zinc atom, which adopts a tetrahedral geometry.

Dichloro-bis(1-cinnamyl-benzimidazole)-cobalt(II) was prepared in one step using a cobalt precursor CoCl2 and corresponding substituted benzimidazole. The complex was fully characterized using IR, elemental analysis, and mass- and NMR spectroscopy. In the solid state, the cobalt atom displays a typical tetrahedral geometry and is coordinated to two chlorine atoms and two benzimidazole moieties.

<div><p>Practical MRI training is essential for bridging the gap between complex theoretical knowledge and clinical applications. Traditional phantoms used in MRI, such as ACR phantoms, are valuable for illustrating system characterization methods but often lack the anatomical complexity required for realistic training. This study presents the development of high-fidelity anatomical phantoms designed specifically for practical MRI training. These phantoms replicate key anatomical structures and tissue contrasts of the head, offering a more realistic training experience for healthcare students and medical imaging staff (radiologists, physicists, radiographers). Materials and Methods: We focused on the head region, creating phantoms from reference MRI T1-weighted slices and using computer-aided design (CAD) software to design detailed anatomical structures. These phantoms were 3D printed and filled with tissue-mimicking gels. MRI acquisitions were performed using a 1.5T clinical MRI system.</p><p>Results: The resulting images demonstrated high anatomical fidelity and realistic MRI tissue contrasts. The phantoms allow for effective demonstration of the impact of parameter modifications on MRI images and aid in anatomical structure recognition. Conclusion: While technical improvements are needed to ensure long-term stability and accurate relaxometric properties, these phantoms hold significant potential for enhancing MRI education and sequences evaluations. The approach can be extended to other anatomical regions, further supporting the training and optimization of MRI sequences.</p></div>

The prismatic and basal plane surfaces of carbon materials dictate most of their anisotropic physicochemical properties. For many applications where interfacial interactions are key, high-temperature treatments are performed to achieve their graphitization. Such treatment changes edge and basal plane configuration, impacting the energetical behavior of the carbon surfaces, particularly for carbon nanomaterials, with consequences for their properties. Therefore, efforts should be devoted to probing the prismatic and basal plane surfaces of such materials to understand their surface properties for the development of high-performance carbon materials. Herein, we investigate the effect of high-temperature graphitization (3073 K) on the structural, textural, chemical, and magnetic properties of graphitic carbon nanomaterials presenting different prismatic/basal surfaces. The evolution of the prismatic/basal surfaces has been probed by nitrogen adsorption, temperature-programmed desorption, and X-ray photoelectron spectroscopy (XPS). Although these three techniques are in agreement for the starting materials, they diverge in the case of materials that have undergone thermal annealing. This is linked in particular to the formation of loops following the heat treatment, which are identified as belonging to the prismatic surface by XPS and modified the N2 adsorptive potentials. Formed small vacancies on closed loops and nonperfect closure of certain loops can contribute to the accumulation of very reactive defects at the loop level. The thermal annealing also has a pronounced influence on the magnetic properties of these materials. Interestingly, we show that a positive correlation exists between the spin density of the annealed graphitic carbons and their prismatic and basal surfaces.

Glycine receptors (GlyR) are regulated by small-molecule binding at several allosteric sites. Cannabinoids like tetrahydrocannabinol (THC) and N-arachidonyl-ethanol-amide (AEA) potentiate the GlyR response but their mechanism of action is not fully established. By combining millisecond coarse-grained (CG) MD simulations powered by Martini 3 with backmapping to all-atom representations, we have characterized the cannabinoid-binding site(s) at the zebrafish GlyR-α1 active state with atomic resolution. Based on hundreds of thousand ligand-binding events, we find that cannabinoids bind to the transmembrane domain of the receptor at both intrasubunit and intersubunit sites. For THC, the intrasubunit binding mode predicted in simulation is in excellent agreement with recent cryo-EM structures, while intersubunit binding recapitulates in full previous mutagenesis experiments. Intriguingly, AEA is predicted to bind at the same intersubunit site despite the strikingly different chemistry. Statistical analyses of the ligand-receptor interactions highlight potentially relevant residues for GlyR potentiation, offering experimentally testable predictions. The predictions for AEA have been validated by electrophysiology recordings of rationally designed mutants. The results highlight the existence of multiple cannabinoid-binding sites for the allosteric regulation of GlyR and put forward an effective strategy for the identification and structural characterization of allosteric binding sites.

Bioinspired from cationic antimicrobial peptides, sequence-defined triazolium-grafted peptoid oligomers (6- to 12-mer) were designed to adopt an amphipathic helical polyproline I-type structure. Their evaluation on a panel of bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis), pathogenic fungi (Candida albicans, Cryptococcus neoformans, Aspergillus fumigatus) and human cells (hRBC, BEAS-2B, Caco-2, HaCaT, HepG2) enabled to identify two heptamers with improved activity to selectively fight Staphylococcus aureus pathogens. Modulation of parameters, such as the nature of the triazolium and hydrophobic/lipophilic side chains, the charge content and the sequence length, drastically potentiates activity and selectivity. Besides, the ability to block the pro-inflammatory effect induced by lipopolysaccharide or lipoteichoic acid was also explored. Finally, biophysical studies by circular dichroism and fluorescence spectroscopies strongly supported that the bactericidal effect of these triazolium-grafted oligomers was primarily due to the selective disruption of the bacterial membrane.

The electronic structure problem is one of the main problems in modern theoretical chemistry. While there are many already-established methods both for the problem itself and its applications like semi-classical or quantum dynamics, it remains a computationally demanding task, effectively limiting the size of solved problems. Fortunately, it seems, that offloading some parts of the computation to Quantum Processing Units may offer significant speed-up, often referred to as quantum supremacy or quantum advantage. Together with the potential advantage, this approach simultaneously presents several problems, most notably naturally occurring quantum decoherence, hereafter denoted as quantum noise and lack of large-scale quantum computers, making it necessary to focus on Noisy-Intermediate Scale Quantum computers when developing algorithms aspiring to near-term applications. SA-OO-VQE package aims to answer both these problems with its hybrid quantum-classical conception based on a typical Variational Quantum Eigensolver approach, as only a part of the algorithm utilizes offload to QPUs and the rest is performed on a classical computer, thus partially avoiding both quantum noise and the lack of quantum bits. The SA-OO-VQE has the ability to treat degenerate (or quasi-degenerate) states on the same footing, thus avoiding known numerical optimization problems arising in state-specific approaches around avoided crossings or conical intersections.

Analog to O-glycosides, C-glycosides are natural products exhibiting various bioactivities. Alkynyl C-glycosides represent important key intermediates towards more complex derivatives; however, a convenient access through a single catalytic and highly stereocontrolled step remains an important and only partially solved challenge. Here, a mechanistically designed gold(I)-catalyzed silyl-assisted efficient and highly alpha-stereoselective process is reported. The postulated mechanism has been ascertained by combining 1H, 31P and VT NMR and in situ MS experiments.

A seed recovered during archaeological excavations of a cave in the Judean desert was germinated, with radiocarbon analysis indicating an age of 993 CE– 1202 calCE. DNA sequencing and phylogenetic analysis identified the seedling as belonging to the angiosperm genus Commiphora Jacq., sister to three Southern African Commiphora species, but unique from all other species sampled to date. The germinated seedling was not closely related to Commiphora species commonly harvested for their fragrant oleoresins including Commiphora gileadensis (L.) C.Chr., candidate for the locally extinct “Judean Balsam” or “Balm of Gilead” of antiquity. GC-MS analysis revealed minimal fragrant compounds but abundance of those associated with multi-target bioactivity and a previously undescribed glycolipid compound series. Several hypotheses are offered to explain the origins, implications and ethnobotanical significance of this unknown Commiphora sp., to the best of our knowledge the first identified from an archaeological site in this region, including identification with a resin producing tree mentioned in Biblical sources and possible agricultural relationship with the historic Judean Balsam.

The Kumada‐Corriu hetero‐coupling between an halogeno‐arene and an arylmagnesiumbromide can be catalyzed with yields &gt; 80% by the new hydrotris(3,5‐diisopropylpyrazolyl)boratocobalt(III)diiodide, i.e. TpiPrCoI2. The catalysis, which is significantly improved upon exposure to light as compared to darkness, is determined by the coexistence of low and high spin states in a respective ratio of ~ 3:2 for the crucial “TpiPrCoAr2” intermediate. The pivotal cobalt(I) TpiPrCo(I)(thf)n intermediate is shown to be exclusively a triplet state in the ground state with a measured μeff value of 3.08μB at 293 K in C6D6. DFT investigations confirm the key role of triplet states for the bisaryl‐cobalt(III) intermediates in that they provide a reaction pathway with much lower activation barriers as compared to the singlet state. The low‐to‐high spin state transition in THF enhances the reactivity of the “TpiPrCoAr2” intermediate, which changes its coordination geometry from singlet spin state 18 electron OC‐6 TpiPrCoAr2(thf) to a triplet spin state 16 electron SPY‐5 TpiPrCoAr2 where the TpiPr ligand adopts a nearly κ2 bonding mode. The quantitative Independent Gradient Model analysis of the noncovalent interactions that prefigure the C‐C covalent bond in the key Co(Ar)2 intermediates informs of the peculiar importance of the singlet to triplet spin state transition.

La nature électrophile des halogènes et chalcogènes se caractérise par l’apparition à la surface de ces atomes d’une zone déficiente en électron, appelée « s-hole », qui leur permet d’interagir de façon non-covalente avec des zones riches en électrons (doublets non liants, électrons p). Si cette interaction implique un halogène électrophile, on parle de « liaison halogène », notée XB. De manière analogue, si c’est un chalcogène électrophile qui est concerné, cette interaction est définie par le terme de « liaison chalcogène », abrégée par ChB. Cet article décrit comment ces deux interactions ont été introduites en organocatalyse non-covalente et les avancées majeures dans la conception d’organocatalyseurs XB et ChB de plus en plus efficaces durant ces dix dernières années.

Objective: To understand possible reasons for poor durability of the Nellix (Endologix Inc., Irvine, USA) endovascular aneurysm sealing (EVAS) device. Materials and Methods: 21 Nellix endoprostheses explanted for endoleaks and migration underwent visual examinations of stent structures and instrumental examinations of the polymer endobags on 4 devices. We harvested 2.0-gram polymer slices out of each of them and tested the samples in an in vitro implantation replication that included wet and dry exposures. During the wet phase, we placed samples in a beaker with saline, mimicking the filling of the endobags during implantation. An exposure to a 37°C environment with 60% humidity during the dry phase replicated the postimplantation conditions inside the aneurysmal sac. Results: Iatrogenic defects affected 16 (76%) metal stents and 20 (95%) endobags. The polymer was disintegrated owing to degradation in 15 (71%) cases. The polymer could lose more than 70% of its initial weight when partially dehydrated and regain 80% when placed in saline. We observed volume decrease and polymer fragmentation during these study phases. Conclusions: The polymer can lose weight and volume while it dehydrates. This structural degradation of the polymer could lead to the development of endoleaks and/or migration of the device. Clinical Impact Based on the results of previous investigations, due to possible endovascular device degradation, patients with endografts should be offered life-long surveillance, and the Nellix device is no exception. Herein we suggest polymer degradation as one of the possible reasons for the device failure. Although Nellix has been withdrawn from the market, there are numerous patients with this type of endograft. Due to its unpredictable performance in the medium and long term, these patients should be recommended enhanced life-long surveillance every 6 months. Any suspicious conditions during the follow-up must be taken seriously and explantation should be considered.

Abstract Protonated and methylated bis‐acridinium tweezers built around a 2,6‐diphenylpyridyl and an electron enriched 2,6‐di(p‐anisyl)pyridyl spacer have been synthesized. These tweezers can self‐assemble in their corresponding homodimers and the associated thermodynamic parameters have been probed in organic solvents. The switching properties of the tweezers have been exploited in biphasic transfer experiments showing the shift of the equilibria towards the homodimers. Moreover, the thermodynamic parameters of the formation of the reduced methylated homodimers investigated by electrochemical experiments revealed the dissociation of the dimers. Thus, in addition to solvent and temperature, the pH and redox responsiveness of the acridinium units of the tweezers make it possible to modulate to a larger extent the monomer‐dimer equilibria.

Abstract We describe here an immobilization method of four Keggin‐type polyoxometalates (POMs) ([H 2 W 12 O 40 ] 6− , [BW 12 O 40 ] 5− [SiW 12 O 40 ] 4− , [PW 12 O 40 ] 3− ) by using the reaction with an ionic liquid, 1‐butyl‐3‐vinylimidazolium (BVIM) bromide. The reaction yields a hybrid material (BVIM‐POM) as a water‐insoluble salt. The chemical structure of both compounds is preserved, as indicated by infrared spectroscopy (FT‐IR), although with a reduced crystallinity (shown by X‐ray diffraction analysis) due to a decrease of water content (shown by thermogravimetric analysis). Cross polarization 1 H‐ 31 P NMR evidenced the presence of BVIM in the structure of (BVIM) 3 [PW 12 O 40 ]. The salt is mixed with carbon powder and Nafion to prepare an ink and casted on glassy carbon electrodes. The electrochemical behavior of immobilized POMs material is preserved. The electrochemical activity for nitrite reduction is measured by cyclic voltammetry and differential electrochemical mass spectrometry (DEMS). It was observed that the reduction current of 10 mM HNO 2 at pH 1 in 0.5 M Na 2 SO 4 is enhanced in the presence of these hybrid materials. DEMS has evidenced the formation of nitrous oxide (N 2 O) at potentials more positive compared to the use of parent POMs in solution.

The nicotinic acetylcholine receptor has served, since its biochemical identification in the 1970's, as a model of allosteric ligand-gated ion channel mediating signal transition at the synapse. In recent years, the application of X-ray crystallography and high-resolution cryo-electron microscopy together with molecular dynamic simulations to nicotinic receptors and homologs have opened a new era in the understanding of channel gating by the neurotransmitter. They reveal, at atomic resolution, the diversity and flexibility of the multiple ligand-binding sites including recently discovered allosteric modulatory sites distinct from the neurotransmitter orthosteric site and the conformational dynamics of the activation process as a molecular switch linking together these multiple sites. The model emerging from these studies paves the way to a new pharmacology based, first, upon the occurrence of an original mode of indirect allosteric modulation, distinct from a steric competition for a single and rigid binding site and, second, the design of drugs specifically interacting with privileged conformations of the receptor such as agonists, antagonists and desensitizers. The research on nicotinic receptor is still at the forefront in understanding the mode of action of drugs on the nervous system.

A method for the construction of trifluorinated-5-methylenepyrrolidinone is reported. This strategy combines an acid-catalyzed two-carbon homologation process between ynamides and aldehydes, providing CF3-substituted dienes followed by a metal-free domino hydroamination/isomerization/transamidation sequence, delivering trifluorinated-5-methylenepyrrolidinone stereoselectively.

Abstract Understanding the sequence-structure relationship in protein is of fundamental interest, but has practical applications such as the rational design of peptides and proteins. This relationship in the Type I left-handed β–helix containing proteins is updated and revisited in this study. Analysing the available structures in the Protein Data Base, we could describe further in details the structural features that are important for the stability of this fold, as well as its nucleation and termination. This study is meant to complete previous work, as it provides a separate analysis of the N-terminal and C-terminal rungs of the helix. Particular sequence motifs of these rungs are described along with the structural element they form.

From the second part of the 6th millennium BC onwards, pottery manufacture is attested throughout the western Mediterranean. The study of the functional and use of vessels has become a valuable source of information on the culinary patterns and subsistence practices of past societies. In the present study, we have analyzed the organic residues of a total of 37 ceramic vessels from the first Neolithic settlements in the Central Pyrenees. Results from lipid analysis using gas chromatography-mass spectrometry (GC-MS) and GC-stable carbon isotope ratio analyses (GC-IRMS) revealed that from the earliest phases, the use of pottery was related to the exploitation of dairy and meat products, as well as plant resources. The data obtained are contextualized within the general frame of the Pyrenees and the western Mediterranean.

Aminoglycosides are crucial antibiotics facing challenges from bacterial resistance. This study addresses the importance of aminoglycoside modifying enzymes in the context of escalating resistance. Drawing upon over two decades of structural data in the Protein Data Bank, we focused on two key antibiotics, neomycin B and kanamycin A, to explore how the aminoglycoside structure is exploited by this family of enzymes. A systematic comparison across diverse enzymes and the RNA A-site target identified common characteristics in the recognition mode, while assessing the adaptability of neomycin B and kanamycin A in various environments.

The ability of triaryltelluronium salts to interact with N‐halosuccinimides (NXS) through chalcogen bonding (ChB) in the solid state and in solution is demonstrated herein. Cocrystals of the triaryltelluronium bearing two CF3 electron‐withdrawing groups per aryl ring with N‐chloro‐, N‐bromo‐ and N‐iodosuccinimide (respectively NCS, NBS and NIS) were analyzed by X‐ray diffraction, evidencing a ChB between tellurium and the carbonyl group of NXS. This ChB was confirmed in solution by NMR spectroscopy, especially by 125Te NMR titration experiment, which allowed the determination of the association constant (Ka) between the telluronium and NBS. The so‐obtained Ka value of 17.3 ± 0.6 M‐1 indicated a moderate interaction in solution because of the competitive role of the solvent. The strength of the Te‐‐‐O ChB was however sufficient enough to promote the catalytic halofunctionalization of aromatics and of alkenes such as the intra‐ and intermolecular haloalkoxylation and haloesterification of alkenes.

<div><p>The pincer complexes [Ni II Br(CNC)]Br (4), [Cr III Br 3 (CNC)] (5 a) and [Cr III Br 2.3 Cl 0.7 (CNC)]</p><p>(5 b), where CNC = 3,3'-(pyridine-2,6diyl)bis (1-mesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene), were obtained from the novel ligand CNC, generated in situ from the precursor (CHNCH)Br 2 and [Ni II Br 2 (PPh 3 ) 2 ] or from [Cr II {N-(SiMe 3 ) 2 } 2 (THF) 2 ] and (CHNCH)Br 2 by aminolysis, respectively. The tetrahedrally distorted square planar (τ 4 ffi0.30) geometry and the singlet ground state of Ni in 4 were attributed to steric constraints of the CNC backbone. Computational methods highlighted the dependence of the coordination geometry and the singlet-triplet energy difference on the size of the N-substituent of the tetrahydropyrimidine wingtips and contrasted it to the situation in 5-membered imidazolin-2-ylidene pincer analogues. The octahedral Cr III metal center in 5 a and 5 b is presumably formed after one electron oxidation from CH 2 Cl 2 . 4/MAO and 5 a/MAO were catalysts of moderate activity for the oligomerization and polymerization of ethylene, respectively. The analogous (CH^N^CH)Br 2 precursor, where (CH^N^CH) = 3,3'-(pyridine-2,6-diylbis(methylene))bis(1-mesityl-3,4,5,6-tetrahydropyrimidin-1-ium), was also prepared, however its coordination chemistry was not studied due to the inherent instability of the resulting free C^N^C ligand.</p></div>

The chlorine radical is a strong HAT (Hydrogen Atom Transfer) agent that is very useful for the functionalization of C(sp 3 )−H bonds. Albeit highly attractive, its generation from the poorly oxidizable chloride ion mediated by an excited photoredox catalyst is a difficult task. We now report that 8R f8 ‐4CzIPN , an electron‐deficient fluorous derivative of the benchmark 4CzIPN photoredox catalyst belonging to the donor‐acceptor carbazole‐cyanoarene family, is not only a better photooxidant than 4CzIPN , but also becomes an excellent host for the chloride ion. Combining these two properties ultimately makes the self‐assembled 8R f8 ‐4CzIPN •Cl − dual catalyst highly reactive in redox‐neutral Giese‐type C(sp 3 )−H bond alkylation reactions promoted by the chlorine radical. Additionally, because of its fluorous character, the efficient separation/recovery of 8R f8 ‐4CzIPN could be envisioned.

Abstract This work presents an alternative, general, and in-principle exact extension of electronic Kohn–Sham density functional theory (KS-DFT) to the fully quantum-mechanical molecular problem. Unlike in existing multi-component or exact-factorization-based DFTs of electrons and nuclei, both nuclear and electronic densities are mapped onto a fictitious electronically non-interacting molecule (referred to as KS molecule), where the electrons still interact with the nuclei. Moreover, in the present molecular KS-DFT, no assumption is made about the mathematical form (exactly factorized or not) of the molecular wavefunction. By expanding the KS molecular wavefunction à la Born–Huang, we obtain a self-consistent set of ‘KS beyond Born–Oppenheimer’ electronic equations coupled to nuclear equations that describe nuclei interacting among themselves and with non-interacting electrons. An exact adiabatic connection formula is derived for the Hartree-exchange-correlation energy of the electrons within the molecule and, on that basis, a practical adiabatic density-functional approximation is proposed and discussed.

The Dziani Dzaha (Mayotte Islands, Indian Ocean) is a small, shallow, saline and hyperalkaline maar lake. Its surface waters are characterized by intense primary production, inducing the waters below 2 m depth to remain aphotic and anoxic all year round, at least until 2017, when a ~5 m-long core was taken from the center of the lake. The recovered sediments were described and sampled at high resolution. They consist of laminated microbial mats, mixed with carbonate lenses or nodular beds, and rare silty detrital facies. The inorganic and organic carbon contents of 160 samples were analyzed using the Rock-Eval® method, including the Rock-Eval® 7S device which quantifies both total organic sulfur and total sulfur content, in addition to conventional Rock-Eval parameters. The Dziani Dzaha sediments are characterized by high TOC content (8.5 wt.% on average and up to 27.9 wt.%) and variable inorganic carbon content. HI values average 630 mg HC/g TOC and reach up to 834 mg HC/g TOC. TS content varies from 0.3 to 3.6 wt.%, with TSorg/TOC ratios close to 0.01 at the top of the core and fluctuating downcore between 0.02 and 0.05. Interestingly, the pyrolysis thermal stability of sulfurized organic matter increases with depth, and the highest HI values are associated with highest Sorg content, sulfurization of organic matter being generally accompanied by reductive processes. The hydrogen- and organic-sulfur-rich sediments of Dziani Dzaha can be considered modern analogues of Type I and I-S petroleum source rock deposits, such as the Eocene Green River shales and Kimmeridgian Orbagnoux laminites, withremarkable facies and geochemical similarities.

Flavins and their alloxazine isomers are key chemical scaffolds for bioinspired electron transfer strategies. Their properties can be fine-tuned by functional groups, which must be introduced at an early stage of the synthesis as their aromatic ring is inert towards post-functionalization. We show that the introduction of a remote metal-binding redox site on alloxazine and flavin activates their aromatic ring towards direct C–H functionalization. Mechanistic studies are consistent with a synthetic sequence involving ground state single electron transfer (SET) with an electrophilic source followed by radical-radical coupling. This unprecedented reactivity opens new opportunities in molecular editing of flavins by direct aromatic post-functionalization and the utility of the method is demonstrated with the site-selective C6 functionalization of alloxazine and flavin with a CF3 group, Br or Cl, that can be further elaborated into OH and aryl for chemical diversification.

89Zr−immunoPET is a hot topic as 89Zr cumulates the advantages of 64Cu and 124I without their drawbacks. We report the synthesis of a model ligand of a chiral bioconjugable tetrahydroxamic chelator combining the desferriferrioxamine B siderophore and 1-hydroxy-2-piperidone ((PIPO)H), a chiral cyclic hydroxamic acid derivative, and the study by NMR spectroscopy of its zirconium complex. Nuclear Overhauser effect measurements (ROESY) indicated that the complex exists in the form of two diastereomers, in 77 : 23 ratio, resulting from the combination of the central chiralities at the 3-C of the (PIPO)H component and at the Zr4+ cation. The 44 lowest energy structures out of more than 1000 configurations/conformations returned by calculations based on density functional theory were examined. Comparison of the ROESY data and the calculated interatomic H⋅⋅⋅H distances allowed us to select the most probable configuration and conformations of the major complex.

Metal ion-catalyzed overproduction of reactive oxygen species (ROS) is believed to contribute significantly to oxidative stress and be involved in several biological processes, from immune defense to development of diseases. Among the essential metal ions, copper is one of the most efficient catalysts in ROS production in the presence of O2 and a physiological reducing agent such as ascorbate. To control this chemistry, Cu ions are tightly coordinated to biomolecules. Free or loosely bound Cu ions are generally avoided to prevent their toxicity. In the present report, we aim to find stable Cu-ligand complexes (Cu-L) that can efficiently catalyze the production of ROS in the presence of ascorbate under aerobic conditions. Thermodynamic stability would be needed to avoid dissociation in the biological environment, and high ROS catalysis is of interest for applications as antimicrobial or anticancer agents. A series of Cu complexes with the well-known tripodal and tetradentate ligands containing a central amine linked to three pyridyl-alkyl arms of different lengths were investigated. Two of them with mixed arm length showed a higher catalytic activity in the oxidation of ascorbate and subsequent ROS production than Cu salts in buffer, which is an unprecedented result. Despite these high catalytic activities, no increased antimicrobial activity toward Escherichia coli or cytotoxicity against eukaryotic AGS cells in culture related to Cu-L-based ROS production could be observed. The potential reasons for discrepancy between in vitro and in cell data are discussed.

The photocatalytic performance of Nb,N-codoped TiO 2 nanoparticles obtained via the sol-gel method was compared to that of N-doped TiO 2 . The study focused on investigating the effects of nitridation conditions on nitrogen insertion with a highlight on the nature of the doping sites in the photocatalyst depending on the initial presence of niobium in the TiO 2 . The photodegradation of methylene blue in solution under UV, visible, and simulated solar light was used to evaluate the photocatalytic activity of TiO 2 , Nb-or N-doped TiO 2 , and Nb,N-codoped TiO 2 nanoparticles. Codoped TiO 2 produced by mild thermal nitridation exhibits the best photocatalytic activity, with a strong contribution from visible light. On the contrary, the codoped TiO 2 produced by more intense thermal nitridation presents lower photocatalytic performances than TiO 2 despite a small improvement of activity in the visible range. In addition to material characterization (X-ray diffraction, UV-vis spectroscopy, and X-ray photoelectron spectroscopy), electron paramagnetic resonance and reversed double-beam photoacoustic spectroscopy measurements were used to identify the respective doping sites and ultimately propose the electronic band structure for each sample of Nb:TiO 2 , N:TiO 2 , and Nb,N:TiO 2 . Proper thermal nitridation conditions improve the charge compensation between Nb 5+ and N 3-, thereby enhancing the photocatalytic activity. However, too intense nitridation conditions led to the generation of oxygen vacancies and a large amount of Ti 3+ acting as charge recombination centers, resulting in significant deterioration of the photocatalytic performances. This study highlights the importance of understanding the intricate charge compensation process in codoped (M,N) TiO 2 materials, as the photocatalytic performance cannot be elucidated solely by the cation/anion ratio but also by considering the nature of the doping sites generated during synthesis.

A diradical with engineered g-asymmetry was synthesized by grafting a nitroxide radical onto the [Y(Pc)2]˙ radical platform. Various spectroscopic techniques and computational studies revealed that the electronic structures of the two spin systems remained minimally affected within the diradical system. Fluid-solution Electron Paramagnetic Resonance (EPR) experiments revealed a weak exchange coupling with |J| ~ 0.014 cm-1, subsequently rationalized by CAS-SCF calculations. Frozen solution continuous-wave (CW) EPR experiments showed a complicated and power-dependent spectrum that eluded analysis using the point-dipole model. Pulse EPR manipulations with varying microwave powers, or under varying magnetic fields, demonstrated that different resonances could be selectively enhanced or suppressed, based on their different tipping angles. In particular, Field-Swept Echo-Detected (FSED) spectra revealed absorptions of MW power-dependent intensities, while Field-Swept Spin Nutation (FSSN) experiments revealed two distinct Rabi frequencies. This study introduces a methodology to synthesize and characterize g-asymmetric two-spin systems, of interest in the implementation of spin-based CNOT gates.

The recently developed mRNA-based coronavirus SARS-CoV-2 vaccines highlighted the great therapeutic potential of the mRNA technology. Although the lipid nanoparticles used for the delivery of the mRNA are very efficient, they showed, in some cases, the induction of side effects as well as the production of antibodies directed against particle components. Thus, the development of alternative delivery systems is of great interest in the pursuit of more effective mRNA treatments. In the present work, we evaluated the mRNA transfection capacities of a series of cationic histidine-rich amphipathic peptides derived from LAH4. We found that while the LAH4-A1 peptide was an efficient carrier for mRNA, its activity was highly serum sensitive. Interestingly, modification of this cell penetrating peptide at the N-terminus with two tyrosines or with salicylic acid allowed to confer serum resistance to the carrier. Keywords: LAH4 peptide family; amphipathic peptide; cell penetrating peptide; gene delivery; mRNA transfection.

In this work diamino-porphyrin derivatives, in their free base or cobalt complex forms, have been used to construct SMJs. Porphyrin oligomers were covalently bonded to a bottom electrode by diazonium cation electroreduction and a STM tip was used to complete the junction. Conductance versus time (G(t)) measurements reveal stable SMJs with lifetimes as long as 70 s, attributable to the diazonium bonding procedure and the amino anchoring groups. SMJ conductance was studied statistically by three methods: the STM-bj G histo (d) histograms, STM G time (t) and voltage-dependent G volt (V) heat maps. Conductance and attenuation factors (b) for Co or free-base porphyrin SMJs, compared by the three methods, are fully consistent, length-dependent and show a strong molecular signature. Trends in the variation of the attenuation factors versus voltage indicate a voltage-driven b decrease for both types of SMJ.

ABSTRACT Fluorescent proteins have revolutionized science since their discovery in 1962. They have enabled imaging experiments to decipher the function of proteins, cells, and organisms, as well as gene regulation. Green fluorescent protein and all its derivatives are now standard tools in cell biology, immunology, molecular biology, and microbiology laboratories around the world. A common feature of these proteins is their dioxygen (O 2 )-dependent maturation allowing fluorescence, which precludes their use in anoxic contexts. In this work, we report the development and in cellulo characterization of genetic circuits encoding the O 2 -independent KOFP-7 protein, a flavin-binding fluorescent protein. We have optimized the genetic circuit for high bacterial fluorescence at population and single-cell level, implemented this circuit in various plasmids differing in host range, and quantified their fluorescence under both aerobic and anaerobic conditions. Finally, we showed that KOFP-7-based constructions can be used to produce fluorescing cells of Vibrio diazotrophicus , a facultative anaerobe, demonstrating the usefulness of the genetic circuits for various anaerobic bacteria. These genetic circuits can thus be modified at will, both to solve basic and applied research questions, opening a highway to shed light on the obscure anaerobic world. IMPORTANCE Fluorescent proteins are used for decades, and have allowed major discoveries in biology in a wide variety of fields, and are used in environmental as well as clinical contexts. Green fluorescent protein (GFP) and all its derivatives share a common feature: they rely on the presence of dioxygen (O 2 ) for protein maturation and fluorescence. This dependency precludes their use in anoxic environments. Here, we constructed a series of genetic circuits allowing production of KOFP-7, an O 2 -independant flavin-binding fluorescent protein. We demonstrated that Escherichia coli cells producing KOFP-7 are fluorescent, both at the population and single-cell levels. Importantly, we showed that, unlike cells producing GFP, cells producing KOFP-7 are fluorescent in anoxia. Finally, we demonstrated that Vibrio diazotrophicus NS1, a facultative anaerobe, is fluorescent in the absence of O 2 when KOFP-7 is produced. Altogether, the development of new genetic circuits allowing O 2 -independent fluorescence will open new perspective to study anaerobic processes.

The quantum mechanical definition of the mean square displacement proposed in a previous work (R. Marquardt, Mol. Phys. 119, e1971315 (2021)) is extended to the continuum of a free particle in the interval topology. Integrals are evaluated in the formalism of generalized functions (distributions). A comparison with the definition based on the quantum correlation function is carried out. It is found that the latter diverges, when evaluated in a ring topology with infinitely large rings.

PylB is a radical S-adenosyl-l-methionine (SAM) enzyme predicted to convert l-lysine into (3R)-3-methyl-d-ornithine, a precursor in the biosynthesis of the 22nd proteogenic amino acid pyrrolysine. This protein highly resembles that of the radical SAM tyrosine and tryptophan lyases, which activate their substrate by abstracting a H atom from the amino-nitrogen position. Here, combining in vitro assays, analytical methods, electron paramagnetic resonance spectroscopy, and theoretical methods, we demonstrated that instead, PylB activates its substrate by abstracting a H atom from the Cγ position of L-lysine to afford the radical-based β-scission. Strikingly, we also showed that PylB catalyzes the reverse reaction, converting (3R)-3-methyl-d-ornithine into L-lysine and using catalytic amounts of the 5'-deoxyadenosyl radical. Finally, we identified significant in vitro production of 5'-thioadenosine, an unexpected shunt product that we propose to result from the quenching of the 5'-deoxyadenosyl radical species by the nearby [Fe4S4] cluster.

Cu-thiosemicarbazones have been intensively investigated for their application in cancer therapy or as antimicrobials. Copper(II)-di-2-pyridylketone-4,4-dimethyl-thiosemicarbazone (CuII-Dp44mT) showed anticancer activity in the submicromolar concentration range in cell culture. The interaction of CuII-Dp44mT with thiols leading to their depletion or inhibition was proposed to be involved in this activity. Indeed, CuII-Dp44mT can catalyze the oxidation of thiols although with slow kinetics. The present work aims to obtain insights into the catalytic activity and selectivity of CuII-Dp44mT toward the oxidation of different biologically relevant thiols. Reduced glutathione (GSH), L-cysteine (Cys), N-acetylcysteine (NAC), D-penicillamine (D-Pen), and the two model proteins glutaredoxin (Grx) and thioredoxin (Trx) were investigated. CuII-Dp44mT catalyzed the oxidation of these thiols with different kinetics, with rates in the following order D-Pen>Cys≫NAC>GSH and Trx>Grx. CuII-Dp44mT was more efficient than CuII chloride for the oxidation of NAC and GSH, but not D-Pen and Cys. In mixtures of biologically relevant concentrations of GSH and either Cys, Trx, or Grx, the oxidation kinetics and spectral properties were similar to that of GSH alone, indicating that the interaction of these thiols with CuII-Dp44mT is dominated by GSH. Hence GSH could protect other thiols against potential deleterious oxidation by CuII-Dp44mT.

The aromatic Cope rearrangement is an elusive transformation that has been the subject of a limited number of investigations compared to those seemingly close analogues, namely the Cope and aromatic Claisen rearrangement. Herein we report our investigations inspired by moderate success observed in the course of pioneering works. By careful experimental and theoretical investigations, we demonstrate that key substitutions on 1,5‐hexadiene scaffold allow fruitful transformations. Especially, efficient functionalisation of the heteroaromatic rings results from the aromatic Cope rearrangement, while highly stereoselective interrupted aromatic Cope rearrangements highlight the formation of chiral compounds through a dearomative process.

Galvinoxyl, as one of the most extensively studied organic stable free radicals, exhibits a notable phase transition from a high-temperature (HT) phase with a ferromagnetic (FM) intermolecular interaction to a low-temperature (LT) phase with an antiferromagnetic (AFM) coupling at 85 K. Despite significant research efforts, the crystal structure of the AFM LT phase has remained elusive. This study successfully elucidates the crystal structure of the LT phase, which belongs to the P[1 with combining macron] space group. The crystal structure of the LT phase is found to consist of a distorted dimer, wherein the distortion arises from the formation of short intermolecular distances between anti-node carbons in the singly-occupied molecular orbital (SOMO). Starting from the structure of the LT phase, wave function calculations show that the AFM coupling 2J/kB varies significantly from −1069 K to −54 K due to a parallel shift of the molecular planes within the dimer.

ABSTRACT Graphene oxide (GO) and graphene-based materials (GBMs) have gained over the last two decades considerable attention due to their intrinsic physicochemical properties and their applications. Besides, a lot of concern regarding the potential toxicity of GBMs has emerged. One of the aspects of concern is the interactions between GBMs and different environmental compartments, especially indigenous microbial and, in particular, bacterial communities. Recent research showed that GO and GBMs impacted bacterial pure culture or bacterial communities; therefore, these interactions have to be further studied to better understand and assess the fate of these materials in the environment. Here, we present our opinion and hypotheses related to possible degradation mechanisms of GO that can be used by environmental bacteria. This work is the first attempt to deduce and summarize plausible degradation pathways of GO, from structurally similar recalcitrant and toxic compounds, such as polyaromatic hydrocarbons.

Abstract Nowadays, Al (dual) batteries are mainly based on graphite cathode materials. Besides this material, the limited life cycle and the rate performance of other possible cathode materials have hampered the development of practical and sustainable rechargeable aluminium batteries (RABs). Herein, we report an organic A 4 ‐metal‐free porphyrin system bearing diphenylamimo‐phenyl functional units as an Al‐storage cathode material, which is capable of delivering a reversible capacity of 83 mAh g −1 at 1 A g −1 after 200 cycles and displays a good cycling stability. Achieving such high rate performance opens a pathway to developing practical sustainable cathodes for aluminium batteries.

In an extended star with peripheral defects and a core occupied by a trap, it has been shown that exciton-mediated energy transport from the periphery to the core can be optimized [S. Yalouz et al. Phys. Rev. E 106, 064313 (2022)]. If the defects are judiciously chosen, the exciton dynamics is isomorphic to that of an asymmetric chain and a speedup of the excitonic propagation is observed. Here, we extend this previous work by considering that the exciton in both an extended star and an asymmetric chain, is perturbed by the presence of a dephasing environment. Simulating the dynamics using a Lindblad master equation, two questions are addressed: how does the environment affect the energy transport on these two networks? And, do the two systems still behave equivalently in the presence of dephasing? Our results reveal that the timescale for the exciton dynamics strongly depends on the nature of the network. But quite surprisingly, the two networks behave similarly regarding the survival of their optimization law. In both cases, the energy transport can be improved using the same original optimal tuning of energy defects as long as the dephasing remains weak. However, for moderate/strong dephasing, the optimization law is lost due to quantum Zeno effect.

Slightly different reaction conditions afforded two distinct cavity‐shaped cis‐chelating diphosphanes from the same starting materials, namely diphenyl(2‐phosphanylphenyl)phosphane and an α‐cyclodextrin‐derived dimesylate. Thanks to their metal confining properties, the two diphosphanes form only mononuclear [CuX(PP)] complexes (X = Cl, Br, or I) with the tricoordinated metal ion located just above the center of the cavity. The two series of CuI complexes display markedly different luminescence properties that are both influenced by the electronic properties of the ligand and the unique steric environment provided by the cyclodextrin (CD) cavity. The excited state lifetimes of all complexes are significantly longer than those of cavity‐free analogues suggesting peculiar electronic effects that affect radiative deactivation constants. The overall picture stemming from absorption and emission data suggests close lying charge‐transfer (MLCT, XLCT) and triplet ligand‐centered (LC) excited states.

Three new ligands based on the alloxazine core appended with pyridyl coordinating groups have been designed, synthesized, and characterized. The ligands are revealed to be redox-active in DMF solution, as attested to by CV and combined CV/EPR studies. The spin of the reduced species appears to be delocalized on the alloxazine core, as attested to by DFT calculations. The coordination abilities of one of the ligands toward Cu$^{2+}$ or Ni$^{2+}$ 3d cations revealed the formation of the first alloxazine-based 3D coordination polymers, presenting strong π–π stacking and substantial cavities. Preliminarily charge/discharge experiments in Li batteries evidence Li$^+$ insertion in such systems

The supramolecular interaction between lanthanide complexes and proteins is at the heart of numerous chemical and biological studies. Some of these complexes have demonstrated remarkable interaction properties with proteins or peptides in solution and in the crystalline state. Here we have used the paramagnetism of lanthanide ions to characterize the affinity of two lanthanide complexes for ubiquitin. As the interaction process is dynamic, the acquired NMR data only reflect the time average of the different steps. We have used molecular dynamics (MD) simulations to get a deeper insight into the detailed interaction scenario at the microsecond scale. This NMR/MD approach enabled us to establish that the tris-dipicolinate complex interacts specifically with arginines and lysines, while the crystallophore explores the protein surface through weak interactions with carboxylates. These observations shed new light on the dynamic interaction properties of these complexes, which will ultimately enable us to propose a crystallization mechanism.

Two different alkynyl-substituted C3-symmetric cyclotribenzylenes (CTB) were synthesized in racemic and enantiomerically pure forms, and six gold(I) phosphine complexes differring by the nature of the CTB and the phosphine were prepared and characterized, in particular by NMR spectroscopy, DOSY, electronic circular dichroism (ECD), and electrospray ionization mass spectrometry (ESI-MS). Their ECD patterns depended on the substitution of the starting CTBs and were shifted bathochromically by comparison with the latter. ESI-MS in the presence of HCO2H allowed us to detect the complexes as proton adducts. The intensities of the signals were stronger when the phosphine was more electron-rich. This technique was also used to investigate the exchange of phosphine betweeen pairs of CTB complexes. The scrambling reaction was demonstrated by the higher intensity of the signals of the complexes subjected to the exchange of a single phosphine ligand by comparison with the intensity of the signals of the starting complexes.

Myosin motors use the energy of ATP to produce force and directed movement on actin by a swing of the lever-arm. ATP is hydrolysed during the off-actin re-priming transition termed recovery stroke. To provide an understanding of chemo-mechanical transduction by myosin, it is critical to determine how the reverse swing of the lever-arm and ATP hydrolysis are coupled. Previous studies concluded that the recovery stroke of myosin II is initiated by closure of the Switch II loop in the nucleotide-binding site. Recently, we proposed that the recovery stroke of myosin VI starts with the spontaneous re-priming of the converter domain to a putative pre-transition state (PTS) intermediate that precedes Switch II closing and ATPase activation. Here, we investigate the transition from the pre-recovery, post-rigor (PR) state to PTS in myosin VI using geometric free energy simulations and the string method. First, our calculations rediscover the PTS state agnostically and show that it is accessible from PR via a low free energy transition path. Second, separate path calculations using the string method illuminate the mechanism of the PR to PTS transition with atomic resolution. In this mechanism, the initiating event is a large movement of the converter/ lever-arm region that triggers rearrangements in the Relay-SH1 region and the formation of the kink in the Relay helix with no coupling to the active site. Analysis of the free-energy barriers along the path suggests that the converter-initiated mechanism is much faster than the one initiated by Switch II closure, which supports the biological relevance of PTS as a major on-pathway intermediate of the recovery stroke in myosin VI. Our analysis suggests that lever-arm re-priming and ATP hydrolysis are only weakly coupled, so that the myosin recovery stroke is initiated by thermal fluctuations and stabilised by nucleotide consumption via a ratchet-like mechanism.

To deeply investigate the interaction between a tetrathiafulvalene (TTF) unit and a Ti(IV) center, a monomeric heteroleptic octahedral Ti(IV) complex containing a diimine ligand composed of a 1,10-phenanthroline core fused with a TTF fragment (ligand 2a) was prepared. The stable complex formulated as Ti(1)$_2$(2a), where 1 is a 2,2′-biphenolato derivative, was efficiently synthesized by following a one-step approach. This complex and its model species [Ti(1)$_2$(2b)] were fully characterized in solution, and their solid-state structures were established by single-crystal X-ray diffraction analysis. Density functional theory calculations allowed the assignment of the frontier orbitals involved in the electronic transitions characterized by ultraviolet–visible absorption spectroscopy. Electrochemical and spectroelectrochemical studies revealed that the TTF unit within Ti(1)$_2$(2a) can undergo two reversible one-electron oxidation processes; a reversible one-electron reduction of the Ti(IV) atom was highlighted. The photophysical measurements performed for this donor–acceptor molecular system indicated that an electron transfer process upon light excitation occurred within Ti(1)$_2$(2a).

Near infrared (NIR) emitting optoelectronic devices have great potential for applications in communication, encryption technologies, night-vision display and photodynamic biomedical devices. Nevertheless, their development is currently hampered by the lack of efficient NIR-emissive materials. Herein, a novel class of cationic binuclear Ir(III) emitters (Ir-D1 and Ir-D2) based on a ditopic coordinating scaffold featuring the π-deficient thiazolo[5,4-d]thiazole and π-accepting moiety (either pyridine or pyrazine), is described and fully characterized using photophysical and computational techniques. Comparison with the parental mononuclear derivatives Ir-M1 and Ir-M2 is provided as well. Remarkably, the binuclear complexes display NIR photoluminescence in solution with a maximum up to λem = ca. 840 nm, which represent some rare examples of metal complexes emitting in this spectral region. Interestingly, NIR photoluminescence is retained in polymer-matrix thin-film for the binuclear counterparts. These findings prompt the successful use of these NIR emitters as electroactive materials in light emitting electrochemical cells (LECs). Binuclear complexes Ir-D1 and Ir-D2 yield electroluminescence peaking at λEL = 750 and 800 nm, respectively, and device performances that are the highest reported for LECs in this spectral region to date for molecular (i.e. non-excimer) emitters. This work demonstrates the superior performances of the binuclear design strategy for achieving efficient NIR electroluminescence.

When aiming at the direct use of CO₂ for the preparation of advanced/valueadded materials, the synthesis of CO 2 /olefin copolymers is very appealing but challenging. The δ-lactone 3-ethylidene-6-vinyltetrahydro-2H-pyran-2-one (EVP), synthesized by telomerization of CO₂ with 1,3-butadiene, is a promising monomer. However, its chemoselective ring-opening polymerization (ROP) is hampered by unfavorable thermodynamics and the competitive polymerization of highly reactive C=C double bonds under usual conditions. Herein, we report the chemoselective ROP of EVP using a phosphazene/urea binary catalyst, affording exclusively a linear unsaturated polyester poly(EVP) ROP , with a molar mass (M n ) up to 16.1 kg•mol -1 and a narrow distribution (Ð &lt; 1.6), which can be fully recycled back to the pristine monomer, thus establishing a monomer-polymer-monomer closed-loop life cycle. In these polyesters, the CO₂ content reaches 33 mol% (29 wt%). The reasons for the unexpected chemoselectivity were investigated by Density-functional theory (DFT) calculations. The poly(EVP) ROP features two pendent C=C double bonds per repeating unit, which show distinct reactivity and thus can be properly engaged in sequential functionalizations towards the synthesis of bifunctional polyesters. We disclose here a methodology providing a facile access to bifunctional and recyclable polyesters from readily available feedstocks.

The present report describes the first use of unprotected and "free" N-heterocyclic carbenes (NHCs), such as IMes, IPr and air-stable Cl-IPr carbenes, as single component initiators for the alternating ringopening co-polymerization (ROCOP) of cyclic anhydrides ( phthalic anhydride, PA; succinic anhydride, SA) and various epoxides to efficiently and selectively access the corresponding polyesters in a well-defined manner and as metal-free materials. In the case of ROCOP runs with PA as the anhydride source, control experiments are in line with an initiation via ring-opening of PA by the NHC moiety, as established with the synthesis and structural characterization of the IMes-PA ring-opened product 1. The present NHC systems were further exploited as ROCOP initiators of PA and bio-sourced epoxides such as eugenyl glycidyl ether (EGE) and safrole glycidylether (SO) yielding the production of regioregular p(PA-alt-EGE) polyester, as well as p(PA-alt-SO), a novel polyester material.

Super bulky [(ITr)Zn(C 6 F 5 )] + cation is stable towards hydrolysis and reversibly coordinates water at room temperature. Despite its steric bulk, it is an effective imine hydrogenation and CO 2 hydrosilylation catalyst.

A series of tetraaza-expanded calix[4]arene analogues (2–4), in which two of the four aryl groups are ethylene-protected thiophenol components were prepared from tetraaldehyde 1. Two of these strapped macrocycles were characterized crystallographically, as well as the dipalladium complex of 4. The same tetraaldehyde had been previously used for the synthesis of a macrotricycle (5) and a macropentacycle (6), the coordination properties of which have been investigated. In particular, ligand 6 was shown to be able to encapsulate a Cu+ or a Ag+ ion in the tetrahedral coordination pocket offered by a bridgehead nitrogen atom and the three proximal thioether sulfur atoms.

Antimicrobial resistance (AMR) poses a serious threat to global health. The rapid emergence of resistance contrasts with the slow pace of antimicrobial development, emphasizing the urgent need for innovative drug discovery approaches. This study addresses a critical bottleneck in early drug development by introducing integral solvent-induced protein precipitation (iSPP) to rapidly assess the target-engagement of lead compounds in extracts of pathogenic microorganisms under close-to-physiological conditions. iSPP measures the change in protein stability against solvent-induced precipitation in the presence of ligands. The iSPP method for bacteria builds upon established SPP procedures and features optimized denaturation gradients and minimized sample input amounts. The effectiveness of the iSPP workflow was initially demonstrated through a multidrug target-engagement study. Using quantitative mass spectrometry (LC-MS/MS), we successfully identified known drug targets of seven different antibiotics in cell extracts of four AMR-related pathogens: the three Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and the Gram-positive bacterium Staphylococcus aureus. The iSPP method was ultimately applied to demonstrate targetengagement of compounds derived from target-based drug discovery. We employed five small molecules targeting three enzymes in the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway - a promising focus for anti-infective drug development. The study showcases iSPP adaptability and efficiency in identifying anti-infective drug targets, advancing early-stage drug discovery against AMR.

<div><p>Molecular triangles with competing Heisenberg interactions and significant Dzyaloshinskii-Moriya interactions (DMI) exhibit high environmental sensitivity, making them potential candidates for active elements for quantum sensing. Additionally, these triangles exhibit magnetoelectric coupling, allowing their properties to be controlled using electric fields. However, the manipulation and deposition of such complexes pose significant challenges. This work explores a solution by embedding iron-based molecular triangles in a polymer matrix, a strategy that offers various deposition methods. We investigate how the host matrix alters the magnetic properties of the molecular triangle, with specific focus on the magnetic anisotropy, aiming to advance its practical applications as quantum sensors.</p></div>

CPPs, or Cell-Penetrating Peptides, offer invaluable utility in disease treatment due to their ability to transport various therapeutic molecules across cellular membranes. Their unique characteristics, such as biocompatibility and low immunogenicity, make them ideal candidates for delivering drugs, genes, or imaging agents directly into cells. This targeted delivery enhances treatment efficacy while minimizing systemic side effects. CPPs exhibit versatility, crossing biological barriers and reaching intracellular targets that conventional drugs struggle to access. This capability holds promise in treating a wide array of diseases, including cancer, neurodegenerative disorders, and infectious diseases, offering a potent avenue for innovative and targeted therapies, yet their precise mechanism of cell entry is far from being fully understood. In order to correct Cu dysregulation found in various pathologies such as Alzheimer disease, we have recently conceived a peptide Cu(II) shuttle, based on the αR5W4 CPP, which, when bound to Cu(II), is able to readily enter a neurosecretory cell model, and release bioavailable Cu in cells. Furthermore, this shuttle has the capacity to protect cells in culture against oxidative stress-induced damage which occurs when Cu binds to the Aβ peptide. The aim of this study was therefore to characterize the cell entry route used by this shuttle and determine in which compartment Cu is released. Pharmacological treatments, siRNA silencing and colocalization experiments with GFP-Rab fusion proteins, indicate that the shuttle is internalized by an ATP-dependent endocytosis pathway involving both Rab5 and Rab14 endosomes route and suggest an early release of Cu from the shuttle.

Strigolactones exhibit dual functionality as regulators of plant architecture and signaling molecules in the rhizosphere. The important model crop rice exudes a blend of different strigolactones from its roots. Here, we identify the inaugural noncanonical strigolactone, 4-oxo-methyl carlactonoate (4-oxo-MeCLA), in rice root exudate. Comprehensive, cross-species coexpression analysis allowed us to identify a cytochrome P450, OsCYP706C2, and two methyl transferases as candidate enzymes for this noncanonical rice strigolactone biosynthetic pathway. Heterologous expression in yeast and Nicotiana benthamiana indeed demonstrated the role of these enzymes in the biosynthesis of 4-oxo-MeCLA, which, expectedly, is derived from carlactone as substrate. The oscyp706c2 mutants do not exhibit a tillering phenotype but do have delayed mycorrhizal colonization and altered root phenotype. This work sheds light onto the intricate complexity of strigolactone biosynthesis in rice and delineates its role in symbiosis and development.

Cancer cells are very diverse but mostly share a common metabolic property: they are strongly glycolytic even though oxygen is available. Herein, the metabolic abnormalities of cancer cells are interpreted as modifications of the electric currents in redox reactions. A lower current in the electron transport chain, an increase of the concentration of reduced cofactors and a partial reversal of the tricarboxylic acid cycle are physical characteristics of several forms of cancer. The existence of electric short-circuits between oxidative branches and reductive branches of the metabolic network argue in favor of an electronic approach of cancer in the nanoscopic scale. These changes of electron flows induce a pseudo-hypoxia and the Warburg effect through succinate production and divert electrons from oxygen to biosynthetic pathways. This new look at cancer may have potential therapeutic applications.

Creating specific noble metal/metal-organic framework (MOF) heterojunction nanostructures represents an effective strategy to promote water electrolysis but remains rather challenging. Herein, a heterojunction electrocatalyst is developed by growing Ir nanoparticles on ultrathin NiFe-MOF nanosheets supported by nickel foam (NF) via a readily accessible solvothermal approach and subsequent redox strategy. Because of the electronic interactions between Ir nanoparticles and NiFe-MOF nanosheets, the optimized Ir@NiFe-MOF/NF catalyst exhibits exceptional bifunctional performance for the hydrogen evolution reaction (HER) (η10 = 15 mV, η denotes the overpotential) and oxygen evolution reaction (OER) (η10 = 213 mV) in 1.0 m KOH solution, superior to commercial and recently reported electrocatalysts. Density functional theory calculations are used to further investigate the electronic interactions between Ir nanoparticles and NiFe-MOF nanosheets, shedding light on the mechanisms behind the enhanced HER and OER performance. This work details a promising approach for the design and development of efficient electrocatalysts for overall water splitting.

The following comment tries to answer why the reported removal of copper from buffer, cell culture medium and cell extract by a supported chelator called phenPS is so selective and efficient. It is further argued that the family of PSP (phosphine sulfide-stabilized phosphines) chelators, due to their unique properties, have various potential future application in biology and medicine, such es chelation therapy, copper-sensors, or tools to understand copper metabolism.

The cationic antimicrobial peptides PGLa and magainin 2 (Mag2) are known for their antimicrobial activity and synergistic enhancement in antimicrobial and membrane leakage assays. Further use of peptides in combinatory therapy requires knowledge of the mechanisms of action of both individual peptides and their mixtures. Here, electron paramagnetic resonance (EPR), double electron-electron resonance (DEER, also known as PELDOR) and electron spin echo envelope modulation (ESEEM) spectroscopies were applied to study self-assembly and localization of spin-labeled PGLa and Mag2 in POPE/POPG membranes with a wide range of peptide/lipid ratios (P/L) from ∼1/1500 to 1/50. EPR and DEER data showed that both peptides tend to organize in clusters, which occurs already at the lowest peptide/lipid molar ratio of 1/1500 (0.067 mol%). For individual peptides, these clusters are quite dense with intermolecular distances of the order of ∼2 nm. In the presence of a synergistic peptide partner, these homo-clusters are transformed into lipid-diluted hetero-clusters. These clusters are characterized by a local surface density that is several times higher than expected from a random distribution. ESEEM data indicate a slightly different insertion depth of peptides in hetero-clusters when compared to homo-clusters.

The pincer complexes [NiIIBr(CNC)]Br (4), [CrIIIBr3(CNC)] (5a) and [CrIIIBr2.3Cl0.7(CNC)] (5b), where CNC = 3,3'-(pyridine-2,6-diyl)bis(1-mesityl-3,4,5,6-tetrahydropyrimidin-2-ylidene), were obtained from the novel ligand CNC, generated in situ from the precursor (CHNCH)Br2 and [NiIIBr2(PPh3)2] or from [CrII{N(SiMe3)2}2(THF)2] and (CHNCH)Br2 by aminolysis, respectively. The tetrahedrally distorted square planar (τ4 ≅ 0.30) geometry and the singlet ground state of Ni in 4 were attributed to steric constraints of the CNC backbone. Computational methods highlighted the dependence of the coordination geometry and the singlet-triplet energy difference on the size of the N-substituent of the tetrahydropyrimidine wingtips and contrasted it to the situation in 5-membered imidazolin-2-ylidene pincer analogues. The octahedral CrIII metal center in 5a and 5b is presumably formed after one electron oxidation from CH2Cl2. 4/MAO and 5a/MAO were catalysts of moderate activity for the oligomerization and polymerization of ethylene, respectively. The analogous (CH^N^CH)Br2 precursor, where (CH^N^CH) = 3,3'-(pyridine-2,6-diylbis(methylene))bis(1-mesityl-3,4,5,6-tetrahydropyrimidin-1-ium), was also prepared, however its coordination chemistry was not studied due to the inherent instability of the resulting free C^N^C ligand.

This study addresses the chemoselectivity of the catalyzed reduction of a series of variously substituted γ-lactams by Et₃SiH mediated by a pentamethylcyclopentadienyl iridacyclic acetonitrilo salt derived from benzo[h]quinoline. Introduction of an unsaturation within the 5-membered ring of the γ-lactam annihilates the precedence of the amide function over the capture of the silylium cation, which results in a lower chemoselectivity. Monitoring over time the catalyzed reduction of a γ-lactam bearing a carboxylic ester appendage by 1H NMR spectroscopy revealed pseudo-zero-order kinetics for the prior hydrosilylation of the lactam’s amide. This primary hydrosilylation reaction is followed by the full conversion of the formed intermediate into a pyrrolidine following a pseudo-first-order rate law. Under anhydrous conditions, the hydrosilylation of the pendant ester function occurs only in a late stage once the γ-lactam’s amide function has underwent full reduction of the carbonyl function. DFT investigations show that chemoselectivity is governed (1) by the affinity of the organic substrate for the triethylsilylium cation produced by the electrophilic activation of Et3SiH by the Ir(III) catalyst and (2) by the ability of the in situ-formed hydrido-iridium(III) intermediate to transfer hydride to the activated substrate.

Background: In the first part of our study on possible contribution of dispersion forces in liquid-phase enantioseparations, the enantioseparation of the axially chiral 3,3′-dibromo-5,5′-bis-ferrocenylethynyl-4,4′-bipyridine with an amylose tris(3,5-dimethylphenylcarbamate)-based chiral column appeared reasonably consistent with a picture of the enantioselective recognition based on the interplay between hydrogen bond (HB), π-π stacking and dispersion interactions. Results: In the second part of this study, we evaluated the impact of analyte and chiral stationary phase (CSP) structure, mobile phase and temperature on the enantioseparations of planar chiral 1-(iodoethynyl)-3-arylferrocenes (3-aryl = phenyl, 2-naphthyl, 4-methylphenyl, 4-t-butylphenyl) with polysaccharide-based chiral columns. The main aim of the present study was to understand the molecular bases of the high affinity observed for the second eluted (Rp)-enantiomer of some of these analytes toward amylose phenylcarbamate-based selectors when methanol-containing mixtures were used as mobile phases. Significantly, higher affinity of the second eluted (Rp)-enantiomer toward the selector could be also observed for the sterically hindered 1-(iodoethynyl)-3-(4-t-butylphenyl)ferrocene (k2 = 6.21) compared to the smaller 1-(iodoethynyl)-3-(4-methylphenyl)ferrocenes (k2 = 4.07) as 2.5% methanol was added to the n-hexane-based mobile phase. Significance: This study reasonably showed that the contribution of dispersion forces may explain the unusually large retention of the second eluted enantiomers observed for the enantioseparation of some planar chiral 1-(iodoethynyl)-3-arylferrocenes with amylose-based selectors. Based on the obtained results, we can conclude that in liquid-phase enantioseparation steric repulsion can be turned into attraction depending on the features of analyte, selector, and mobile phase.

Here we present studies of the structure and membrane interactions of ecPis-4 s, a new antimicrobial peptide from the piscidin family, which shows a wide-range of potential biotechnological applications. In order to understand the mode of action ecPis-4 s, the peptide was chemically synthesized and structural investigations in the presence of anionic POPC:POPG (3:1, mol:mol) membrane and SDS micelles were performed. CD spectroscopy demonstrated that ecPis-4 s has a high content of helical structure in both membrane mimetic media, which is in line with solution NMR spectroscopy that revealed an amphipathic helical conformation throughout the entire peptide chain. Solid-state NMR experiments of ecPis-4 s selectively labeled with 15N/2H and reconstituted into uniaxially oriented POPC:POPG membranes revealed an ideal partition of hydrophilic and hydrophobic residues within the bilayer interface. The peptide aligns in parallel to the membrane surface, a topology stabilized by aromatic side-chain interactions of the Phe-1, Phe-2 and Trp-9 with the phospholipids. 2H NMR experiments using deuterated lipids revealed that anionic lipid accumulates in the vicinity of the cationic peptide upon peptide-membrane binding.

The widely used Laurdan probe has two conformers, resulting in different optical properties when embedded in a lipid bilayer membrane, as demonstrated by our previous simulations. Up to now, the two conformers’ optical responses have, however, not been investigated when the temperature and the phase of the membrane change. Since Laurdan is known to be both a molecular rotor and a solvatochromic probe, it is subject to a profound interaction with both neighboring lipids and water molecules. In the current study, molecular dynamics simulations and hybrid Quantum Mechanics/Molecular Mechanics calculations are performed for a DPPC membrane at eight temperatures between 270K and 320K, while the position, orientation, fluorescence lifetime and fluorescence anisotropy of the embedded probes are monitored. The importance of both conformers is proven through a stringent comparison with experiments, which corroborates the theoretical findings. It is seen that for Conf-I, the excited state lifetime is longer than the relaxation of the environment, while for Conf-II, the surroundings are not yet adapted when the probe returns to the ground state. Throughout the temperature range, the lifetime and anisotropy decay curves can be used to identify the different membrane phases. The current work might, therefore, be of importance for biomedical studies on diseases, which are associated with cell membrane transformations.

New iron and cobalt bis(dithiolene) complexes [M(3cbdt)$_2$] (3cbdt = 3-cyanobenzene-1,2-dithiolate) were prepared as tetraphenylphosphonium (Ph4P+) salts for Fe in the monoanionic state and for Co in both the dianionic and monoanionic states: (Ph$_4$P)$_2$[Fe(III)(3cbdt)$_2$]$_2$ (1); (Ph$_4$P)$_2$[Co(III)(3cbdt)$_2$]$_2$ (2); (Ph$_4$P)$_2$[Co(II)(3cbdt)$_2$] (3). These compounds were characterized by single-crystal X-ray diffraction, cyclic voltammetry, EPR, and static magnetic susceptibility. Their properties are discussed in comparison with the corresponding complexes based on the isomer ligand 4-cyanobenzene-1,2-dithiolate (4cbdt) and 4,5-cyanobenzene-1,2-dithiolate (dcbdt), previously described by us. The Fe(III) and the Co(III) compounds (1 and 2) are isostructural, crystallizing in the triclinic P1¯ space group, with cis [M(III)(3cbdt)2] complexes dimerized in a trans fashion, and the transition metal (M = Fe, Co) has a distorted 4+1 square pyramidal coordination geometry. The Co(II) compound (3) crystallizes in the triclinic P1¯ space group, with the unit cell containing one cis and three trans inequivalent [Co(II)(3cbdt)$_2$] complexes with the transition metal (Co) and having a square planar coordination geometry. The Fe(III) complex (1) is EPR-silent, and the static magnetic susceptibility shows a temperature dependence typical of dimers of antiferromagnetically coupled S = 3/2 spins with −J/kB = 233.6 K and g = 1.8. Static magnetic susceptibility measurements of compound (3) show that this Co(II) complex is paramagnetic, corresponding to an S = ½ state with g = 2, in agreement with EPR spectra showing in solid state a hyperfine structure typical of the I(59Co) = 7/2. Static susceptibility measurements of Co(III) complex (2) showed an increase in the paramagnetic susceptibility upon warming above 100 K, which is consistent with strong AFM coupling between dimerized S = 1 units with a constant −J/kB ~1286 K.

The heptad repeat 1 and 2 (HR1, HR2) regions in the spike protein of SARS-CoV 2 play a key role in the fusogenic mechanism of the virus with the host cell. During the fusion process they are thought to rearrange into an interdomain multimer. Functional fragments of the heptad repeat 1 and 2 regions in the spike protein of SARS-CoV 2 were chemically synthesized, labeled with nitrofurazone (NBD) and their interactions investigated by fluorescence spectroscopy. Steady state emission, fluorescence quenching, anisotropy and lifetime measurements in combination with a fluorophore dilution scheme were used to dissect multimer formation of HR1 and HR2 in quantitative detail. In addition, the investigation of the multimers by homo-FRET (via anisotropy) and lifetime measurements reveals new insights into the mechanism of fluorophore-fluorophore interactions in biological samples.

In this work, the dynamics of a quantum walker on glued trees is revisited to understand the influence of the architecture of the graph on the efficiency of the transfer between the two roots. Instead of considering regular binary trees, we focus our attention on leafier structures where each parent node could give rise to a larger number of children. Through extensive numerical simulations, we uncover a significant dependence of the transfer on the underlying graph architecture, particularly influenced by the branching rate (M) relative to the root degree (N). Our study reveals that the behavior of the walker is isomorphic to that of a particle moving on a finite-size chain. This chain exhibits defects that originate in the specific nature of both the roots and the leaves. Therefore, the energy spectrum of the chain showcases rich features, which lead to diverse regimes for the quantum-state transfer. Notably, the formation of quasi-degenerate localized states due to significant disparities between M and N triggers a localization process on the roots. Through analytical development, we demonstrate that these states play a crucial role in facilitating almost perfect quantum beats between the roots, thereby enhancing the transfer efficiency. Our findings offer valuable insights into the mechanisms governing quantum-state transfer on trees, with potential applications for the transfer of quantum information.

In the last decade, biological processes involving halogen bond (HaB) as a leading interaction attracted great interest. However, although bound iodine atoms are considered powerful HaB donors, few iodinated new drugs were reported so far. Recently, iodinated 4,4’‐bipyridines showed interesting properties as HaB donors in solution and in the solid state. In this paper, a study on the inhibition activity of seven halogenated 4,4’‐bipyridines against malignant melanoma (MM) cell proliferation is described. Explorative dose/response proliferation assays were first performed with three 4,4’‐bipyridines by using four MM cell lines and the normal BJ fibroblast cell line as control. Among them, the A375 MM cell line was the most sensitive, as determined by MTT assays, which was selected to evaluate the antiproliferative activity of all 4,4’‐bipyridines. Significantly, the presence of an electrophilic iodine impacted the biological activity of the corresponding compounds. The 3,3’,5,5’‐tetrachloro‐2‐iodo‐4,4’‐bipyridine showed significant antiproliferation activity against the A375 cell line, and lower toxicity on BJ fibroblasts. Through in silico studies, the stereoelectronic features of possible sites determining the bioactivity were explored. These results pave the way for the utilization of iodinated 4,4’‐bipyridines as templates to design new promising HaB‐enabled inhibitors of MM cell proliferation.

While particle therapy has been used for decades for cancer treatment, there is still a lack of information on the molecular mechanisms of biomolecules radiolysis by accelerated ions. Here, we examine the effects of accelerated protons on highly concentrated native myoglobin, by means of Fourier transform infrared and UV–Visible spectroscopies. Upon irradiation, the secondary structure of the protein is drastically modified, from mostly alpha helices conformation to mostly beta elements at highest fluence. These changes are accompanied by significant production of carbon monoxide, which was shown to come from heme degradation under irradiation. The radiolytic yields of formation of denatured protein, carbon monoxide, and of heme degradation were determined, and found very close to each other: G+denatured Mb ≈ G+CO ≈ G-heme = 1.6 × 10–8 ± 0.1 × 10–8 mol/J = 0.16 ± 0.01 species/100 eV. The denaturation of the protein to a beta structure and the production of carbon monoxide under ion irradiation are phenomena that may play an important role in the biological effects of ionizing radiation.

The controlled growth of self-assembled networks on surfaces based on viologen salts is a major scientific challenge due to their unique electronic properties. The combination of solid-state NMR spectroscopy and atomic force microscopy at ambient conditions can unravel the fine organization of the supramolecular network on a graphitic surface by positioning the counter-ions relative to the viologen cation.

The synthesis as well as the structural, optical and computational characterization of seven new highly hindered homoleptic copper(I) phenanthroline complexes (namely C1-C7) is reported along with the comparison with the benchmark derivatives. Despite limited steric hindrance in direct proximity of the copper(I) coordination site, X-ray structures show that the higher hindered derivatives of the series display a more optimal tetrahedral geometry with minimal D2 symmetry distortion. A novel remote control of the geometry, with steric hindrance away from the coordination site, leads to a favorable arrangement as demonstrated by structural and computational data. In addition, electrochemical and steady-state and time-resolved photophysical studies are presented which further support the beneficial effects on the ground-state redox and excited-state properties when both remote and close steric effects are exploited. Indeed, both an increase of the photoluminescence quantum yield and a prolongation of the excited state lifetime is observed for the highly-substituted derivative C6 compared to benchmark counterparts on account of the reduced excited-state flattening distortions imparted by the additional steric constraints.Seven copper(I) phenanthroline complexes have been synthesized with steric hindrance present at and away from the coordination site, coined as remote control. This technique allowed for the synthesis of highly hindered stable homoleptic complexes which presented interesting ground and excited state properties that were corroborated by DFT calculations. image

An atom-economic and diazo-free strategy for the construction of novel pseudo anomeric C-1 alkenyl spirocyclopropyl sugars is described. Leveraging the 1,2-migration pathway of propargyl esters under gold(I) catalysis, easily available exo-glycals undergo β-selective alkenylcarbenoid insertion in moderate to excellent yields. Preferential activation of pro-pargyl moieties and concerted [2+1] insertion are both favored through ligand choice and electron enrichment of esters. Stereocontrol using conformational bias and rearrangement are also demonstrated.

A chemoselective metal-free 1,2-and 2,3-semireduction of CF 3 -substituted N -allenamides was developed. The enamide moiety could be reduced by Et 3 SiH/BF 3 ·OEt 2 , while DBU promoted the stereoselective isomerization of the resulting allyl amides.

Les ions métalliques offrent une diversité chimique tout à fait distincte de celle des molécules organiques et sont largement utilisés par la nature. La chimie bioinorganique est la discipline qui vise à comprendre le rôle des métaux dans les processus vitaux, à concevoir des complexes métalliques bioinspirés et à utiliser ces connaissances dans divers contextes tels que l'énergie, la santé ou l'environnement. La communauté scientifique française de chimie bioinorganique est structurée dans un groupe d'intérêt scientifique dépendant du CNRS, le FrenchBIC,et dans un groupe thématique de la Société Chimique de France, le Groupe thématique de Chimie bioinorganique. Elle expose toutes les facettes de ses recherches dans ce dossier spécial qui vous est présenté par L'Actualité Chimique.

NK-2 is an antimicrobial peptide derived from helices 3 and 4 of the pore-forming protein of natural killer cells, NK-lysin. It has potent activities against Gram-negative and Gram-positive bacteria, fungi and protozoan parasites without being toxic to healthy human cells. In biophysical assays its membrane activities were found to require phosphatidylglycerol (PG) and phosphatidylethanolamine (PE), lipids which dominate the composition of bacterial membranes. Here the structure and activities of NK-2 in binary mixtures of different PE/PG composition were investigated. CD spectroscopy reveals that a threshold concentration of 50 % PG is needed for efficient membrane association of NK-2 concomitant with a random coil – helix transition. Association with PE occurs but is qualitatively different when compared to PG membranes. Oriented solid-state NMR spectroscopy of NK-2 specifically labelled with 15N indicates that the NK-2 helices are oriented parallel to the PG bilayer surface. Upon reduction of the PG content to 20 mol% interactions are weaker and/or an in average more tilted orientation is observed. Fluorescence spectroscopy of differently labelled lipids is in agreement of an interfacial localisation of both helices where the C-terminal end is in a less hydrophobic environment. By inserting into the membrane interface and interacting differently with PE and PG the peptides probably induce high curvature strain which result in membrane openings and rupture.

Organofluorines have a broad range of industrial applications, such as pharmaceuticals, liquid crystal displays (LCDs), solar cells, textiles, and construction coatings, and are used in peptidomimetics, surfactants, refrigerants, anesthetics, and agrochemicals. Among them are versatile monofluoroalkenes that play a crucial role in medicinal and synthetic chemistry. The synthetic strategies for this class of molecules are limited, and prior efforts frequently suffered from poor atom- and step-economies. As a surrogate pathway for traditional cross-coupling transformations, transition metal (TM)-catalyzed C–H direct α-fluoroalkenylation overcomes these obstacles and provides straightforward techniques to access monofluoroalkenes. Nevertheless, substrate scope is still a challenge for catalysis, where gem-bromofluoroalkene synthons are applicable with electronically biased substrates such as azoles, while gem-difluoroalkene-based strategies are limited to substrates containing N-based directing groups. Herein, we review the cutting-edge fluoroalkenylation research for direct synthesis of monofluoroalkenes achieved during the last decade (2013–2023). This review is divided into two main parts: the first part discusses TM-catalyzed direct α-fluoroalkenylation via the merging of C–H activation and C(sp2)–Br cleavage strategies using gem-bromofluoroalkenes, and the second part describes the same reaction, albeit with C(sp2)–F cleavage of highly explored gem-difluoroolefins. Our review surveys all previously reported monofluoroalkenes in this research area, including their preparation techniques, stereoselectivity, and yield percentages. Furthermore, optimal conditions, reactant scope, mechanistic investigations, synthetic applications, benefits, and drawbacks of each presented methodology are critically discussed.

The mechanism of isomerization of the known 2-phenyl,pyridine (phpy) derivatives [Ru(phpy-$K$C,N) (MeCN-trans-N)(terpy)]PF₆ , 2, to [Ru(phpy-$K$C,N)( MeCN-trans-C)(terpy)]PF₆ (terpy = 2,2';6',2"-terpyridine), 3, at temperatures &gt; 50°C has been investigated both by $^1$H NMR spectroscopy and by DFT calculations. The photoisomerization of 2 to 3 by UV light occurred also quantitatively in MeCN after 20h at room temperature. A similar behavior to that of 2, could be established for the related compound [Ru(3-acridine-2′-C₅H₄N-$K$C,N)( MeCN-trans-N)( 2,2';6',2"-terpyridine)]PF₆ , 6, (acridine = dibenzo[b,e]pyridine or 2,3-benzoquinoline) that was obtained from the reaction between [Ru(3-acridine-2′-C₅H₄N-$K$C,N) (MeCN) 4 ]PF₆ , 4, and terpy in MeOH/MeCN at 60°C during 24 hours. Likewise to 2, the isomerization of 6 to [Ru(3-acridine-2′-C₅H₄ N-$K$C,N)(MeCN-trans-C) (terpy)]PF₆ , 7, could be induced thermally (48 h at 60 °C in pure MeOH) or photochemically under UV radiations in MeCN at room temperature. A compound closely related to 7 but in which MeCN was replaced by H₂O, was described earlier (Tanaka et al. Inorg. Chem. 2012, 51, 5386-539). The presence of water on this compound had a dramatic effect as far as the coordination of terpy was concerned as its isomerisation to a compound related to 6 (in which H₂O instead of MeCN is coordinated to Ru) occurred indeed photochemically via irradiation with visible light.

Imaging extracellular Cu²⁺ in vivo is of paramount interest due to its biological importance in both physiological and pathological states. Magnetic resonance imaging (MRI) is a powerful technique to do so. However, the development of efficient MRI contrast agents selective for Cu²⁺, particularly versus the more abundant Zn²⁺ ions, is highly challenging. We present here an innovative Cu²⁺ -responsive MRI contrast agent that contains a bioinspired Cu²⁺ binding site. This sensor shows a remarkable increase in relaxivity of nearly 400% in the presence of Cu²⁺, which could be rationalized in terms of an increase in the hydration number of the Ln³⁺ ion, as demonstrated by spectroscopic and relaxometric studies and supported by density functional theory calculations. Importantly, the system also shows an unprecedented selectivity for Cu²⁺, in particular over Zn²⁺. Phantom MRI images were recorded at 9.4 T to highlight the potential of such probes, which lies directly in their bioinspired design.

Perturbative methods are attractive to describe the electronic structure of molecular systems because of their low-computational cost and systematically improvable character. In this work, a two-step perturbative approach is introduced combining multi-state Rayleigh-Schrödinger (effective Hamiltonian theory) and state-specific Brillouin-Wigner schemes to treat degenerate configurations and yield an efficient evaluation of multiple energies. The first step produces model functions and an updated definition of the perturbative partitioning of the Hamiltonian. The second step inherits the improved starting point provided in the first step, enabling then faster processing of the perturbative corrections for each individual state. The here-proposed two-step method is exemplified on a model-Hamiltonian of increasing complexity.

An efficient and simple approach has been developed for the synthesis of eight dialkyl/aryl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(aryl)methyl]phosphonates through the Pudovik-type reaction of dialkyl/arylphosphite with imines, obtained from 5-phenyl-1,3,4-oxadiazol-2-amine and aromatic aldehydes, under microwave irradiation. Five of them were hydrolyzed to lead to the corresponding phosphonic acids. Selected synthesized compounds were screened for their in vitro antiviral activity against the avian bronchitis virus (IBV). In the MTT cytotoxicity assay, the dose-response curve showed that all test compounds were safe in the range concentration of 540–1599 µM. The direct contact of novel synthesized compounds with IBV showed that the diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethoxyphenyl)methyl]phosphonate (5f) (at 33 µM) and the [(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl] phosphonic acid (6a) (at 1.23 µM) strongly inhibited the IBV infectivity, indicating their high virucidal activity. However, virus titers from IBV-infected Vero cells remained unchanged in response to treatment with the lowest non-cytotoxic concentrations of synthesized compounds suggesting their incapacity to inhibit the virus replication inside the host cell. Lack of antiviral activity might presumably be ascribed to their polarity that hampers their diffusion across the lipophilic cytoplasmic membrane. Therefore, the interactions of 5f and 6a were analyzed against the main coronavirus protease, papain-like protease, and nucleocapsid protein by molecular docking methods. Nevertheless, the novel 1,3,4-oxadiazole-based α-aminophosphonic acids and α-amino-phosphonates hold potential for developing new hygienic virucidal products for domestic, chemical, and medical uses.

Our previous research revealed that (E)-4-amino-3-methylbut-2-en-1-yl diphosphate (AMBPP) is one of the best inhibitors of IspH, a [4Fe-4S]-dependent enzyme involved in the methylerythritol phosphate pathway that is a valuable target for the discovery of new antibacterial and antiparasitic drugs as it is absent in humans. AMBPP has substantial limitations for drug development due to its poor metabolic stability. Here, we investigate the replacement of the diphosphate moiety of AMBPP by more stable mimics: sulfonate, phosphonate or phosphinophosphonate. After synthesis of the derivatives, enzymatic assays demonstrated that none of these AMBPP analogs is an efficient IspH inhibitor.

The structure, bonding, and properties of a series of atypical pentanuclear nickel hydride clusters supported by electron-rich iPr3P of the type [(iPr3P)Ni]5Hn (n = 4, 6, 8; H4, H6, H8) and their anionic models where iPr3P are substituted by H– (H4′, H6′, H8′) were investigated by density functional theory (DFT) calculations. All clusters were calculated to adopt a similar square pyramidal core geometry. Calculations indicate singlet ground states with small singlet–triplet gaps for H4 and H6, similar to previously reported experimental values. Molecular orbital theory description clusters were investigated using the simplified model complexes [HNi]5Hn5– (n = 4, 6, 8; H4′, H6′, H8′). The results show that there are three skeletal electron pairs (SEPs) in H4′. The addition of two molecules of H2 to form H6′ and H8′ results in the partial or full occupation of two degenerate MOs (e* set) that give two SEPs and one SEP, respectively. Indeed, the occupation of these low-lying weakly antibonding orbitals governs the multielectron chemistry available for these clusters and plays a role in their unique reactivity.

Telluronium salts [Ar2MeTe]X were synthesized and their Lewis acidic properties towards a number of Lewis bases were addressed in solution by physical and theoretical means. The structural X‐ray diffraction analysis of 21 different salts revealed the electrophilicity of the Te centers in their interactions with anions. Telluroniums’ propensity to form Lewis pairs was investigated with OPPh3. Diffusion‐ordered NMR spectroscopy suggests that telluroniums may bind up to three OPPh3 molecules. Isotherm titration calorimetry showed that the related heats of association in 1,2‐dichloroethane depend on the electronic properties of the substituents of the aryl moiety and on the nature of the counterion. The enthalpies of first association of OPPh3 span ‐0.5 to ‐5 kcal/mol. The study of the affinity of telluroniums for OPPh3 by state‐of‐the‐art DFT and ab initio methods reveals the dominant Coulombic and dispersion interactions as well as an entropic effect favoring association in solution. Intermolecular orbital interactions between [Ar2MeTe]+ cations and OPPh3 are deemed insufficient to ensure alone the cohesion of [Ar2MeTe•Bn]+ complexes in solution (B= Lewis base). Comparison of Grimme’s and Tkatchenko’s DFT‐D4 / MBD‐vdW thermodynamics of formation of higher [Ar2MeTe•Bn]+ complexes reveals significant molecular size‐dependent divergence of the two methodologies, with MBD yielding better agreement with experiment.

The design of enantiomerically pure circularly polarized luminescent (CPL) emitters would enormously benefit from the accurate and in-depth interpretation of the chiroptical properties by means of jointly (chiroptical) photophysical measurements and state-of-the-art theoretical investigation. Herein, computed and experimental (chiro-)optical properties of a series of eight enantiopure phosphorescent rhenium(I) tricarbonyl complexes are systematically compared in terms of electronic circular dichroism (ECD) and CPL. The compounds have general formula fac-[ReX(CO)(3)(N

Trifluoromethyl analogues of methylerythritol phosphate (MEP) and 2-C-methyl-erythritol 2,4-cyclodiphosphate (MEcPP), natural substrates of key enzymes from the MEP pathway, were prepared starting from d-glucose as the chiral template to secure absolute configurations. The obligate trifluoromethyl group was inserted with complete diastereoselectivity using the Ruppert–Prakash nucleophile. Target compounds were assayed against the corresponding enzymes showing that trifluoro-MEP did not disrupt IspD activity, whereas trifluoro-MEcPP induced 40% inhibition of IspG at 1 mM.

Abstract We herein report the first use of thiosquaramides as polymerization catalysts, which are shown to be effective for the controlled ROP of lactide in the presence of an alcohol source and NEt 3 . Comparison of their catalytic performances with the less acidic squaramides are also discussed. The observed catalytic activity of variously N ‐substituted thiosquaramides suggest that a balanced NH Brønsted acidity is required for optimal performance. Most interestingly and rather unexpectedly, DFT‐supported calculations on thiosquaramide‐mediated lactide ROP catalysis suggest that secondary interactions between the thiosquaramide N ‐substituents and the incoming lactide (presently of type C‐H⋅⋅⋅ π ‐arene) are crucial for catalytic activity. Though this type of interactions is quite common in organo‐catalysis, it has rarely been evidenced to play a key role in the area of organo‐catalyzed polymerizations. Such catalyst substituents/substrate interactions may well play a significant role in the catalytic performances of various other systems.

Cancer treatment is a crucial area of research and development, as current chemotherapeutic treatments can have severe side effects or poor outcomes. In the constant search for new strategies that are localized and minimally invasive and produce minimal side effects, photodynamic therapy (PDT) is an exciting therapeutic modality that has been gaining attention. The use of theranostics, which combine diagnostic and therapeutic capabilities, can further improve treatment monitoring through image guidance. This study explores the potential of a theranostic agent consisting of four Gd(III) DTTA complexes (DTTA: diethylenetriamine-N,N,N″,N″-tetraacetate) grafted to a meso-tetraphenylporphyrin core for PDT, fluorescence, and magnetic resonance imaging (MRI). The agent was first tested in vitro on both nonmalignant TIB-75 and MRC-5 and tumoral CT26 and HT-29 cell lines and subsequently evaluated in vivo in a preclinical colorectal tumor model. Advanced MRI and optical imaging techniques were employed with engineered quantitative in vivo molecular imaging based on dynamic acquisition sequences to track the biodistribution of agents in the body. With 3D quantitative volume computed by MRI and tumoral cell function assessed by bioluminescence imaging, we could demonstrate a significant impact of the molecular agent on tumor growth following light application. Further exhaustive histological analysis confirmed these promising results, making this theranostic agent a potential drug candidate for cancer.

The chelator diacetyl-bis(N4-methylthiosemicarbazone) (ATSM) and its complexes with Cu II and Zn II are becoming increasingly investigated for medical applications such as PET imaging for anti-tumour therapy and the treatment of amyotrophic lateral sclerosis. However, the solubility in water of both the ligand and the complexes presents certain limitations for in vitro studies. Moreover, the stability of the Cu II and Zn II complexes and their metal exchange reaction against the potential biological competitor human serum albumin (HSA) has not been studied in depth. In this work it was observed that the ATSM with an added carboxylic group into the structure increases its solubility in aqueous solutions without altering the coordination mode and the conjugated system of the ligand. The poorly water-soluble Cu II-and Zn II-ATSM complexes were prevented from precipitating due to the binding to HSA. Both HSA and ATSM show a similar thermodynamic affinity for Zn II. Finally, the Cu II-competition experiments with EDTA and the water-soluble ATSM ligands yielded an apparent log Kd at pH 7.4 of about-19. When ATSM was added to Cu II-and Zn II-loaded HSA, withdrawing of Zn II was kinetically 2 favoured, but this metal is slowly substituted by the Cu II afterwards taken from HSA so that this protein could be considered as a source of Cu II for ATSM.

We report on a concept that some of us first described a decade ago for pure electron transfer [V. Balland, C. Hureau and J.-M. Savéant, Proc. Natl. Acad. Sci. U. S. A., 2010, 107, 17113]. In the present viewpoint, based on more recent results, we refine and extend this “in-between state” concept to explain the formation of reactive oxygen species by copper ions bound to the amyloid-β (Aβ) peptide involved in Alzheimer's disease. In such intrinsically disordered peptides, the Cu coordination is versatile due to the lack of stable folding and the presence of multiple possible binding anchors. Hence, the Cu(I) and Cu(II) ions do impose their favoured sites, with Cu(I) bound in a linear fashion between two His residues and Cu(II) in a square-based pyramid bound to Asp1 amine and carbonyl groups and two His residues in the equatorial plane. Hence a direct electron transfer is prevented and alternatively an in-between state (IBS) mechanism applies, whose description and analysis with respect to other electron transfer processes is the topic of the present viewpoint.

Background: Highly ordered chiral secondary structures as well as multiple (tunable) recognition sites are the keys to success of polysaccharide carbamate-based chiral selectors in enantioseparation science. Hydrogen bonds (HBs), dipole-dipole, and π-π interactions are classically considered the most frequent noncovalent interactions underlying enantioselective recognition with these chiral selectors. Very recently, halogen, chalcogen and π-hole bonds were also identified as interactions working in polysaccharide carbamate-based selectors to promote enantiomer distinction. On the contrary, the function of dispersion interactions in this field was not explored so far. Results: The enantioseparation of chiral ferrocenes featuring chiral axis or chiral plane as stereogenic elements was performed by comparing five polysaccharide carbamate-based chiral columns, with the aim to identify enantioseparation outcomes that could be reasonably determined by dispersion forces, making available a reliable experimental data set for future theoretical studies to confirm the heuristic hypothesis. The effects of mobile phase polarity and temperature on the enantioseparation were considered, and potential recognition sites on analytes and selectors were evaluated by electrostatic potential (V) analysis and molecular dynamics (MD). In this first part, the enantioseparation of 3,3′-dibromo-5,5′-bis-ferrocenylethynyl-4,4′-bipyridine bearing two ferrocenylethynyl units linked to an axially chiral core was performed and compared to that of the analyte featuring the same structural motif with two phenyl groups in place of the ferrocenyl moieties. The results of this study showed the superiority of the ferrocenyl compared to the phenyl group, as a structural element favouring enantiodifferentiation. Significance and novelty: Even if dispersion (London) forces have been envisaged acting in liquid-phase enantioseparations, focused studies to explore possible contributions of dispersion forces with polysaccharide carbamate-based selectors are practically missing. This study allowed us to collect experimental information that support the involvement of dispersion forces as contributors to liquid-phase enantioseparation, paving the way to a new picture in this field.

In this work, we introduce a self-consistent scheme based on the one-body reduced density matrix (γ) formalism. A significant feature of this methodology is the utilization of an optimal unitary transformation of the Hamiltonian, determined through a self-consistently determined, unitary reflection R[γ]. This enables the extraction of all reduced properties of the system from a smaller, accurately solved embedding cluster, and the systematic reconstruction of the reduced density matrix of the system. This process ensures that both extended and embedded systems satisfy the local virial-like relation, providing quantitative insight into the correspondence between the fragment in the extended system and its embedded analog. The performance and convergence of the method, as well as the N-representability of the resulting correlated density matrix, are evaluated and discussed within the context of the one-dimensional Hubbard model, which provides exact results for a comprehensive comparison.

The weak intramolecular magnetic interactions within a series of CuII3 complexes based on the trinucleating 2,4,6-tris(di-2-pyridylamino)-1,3,5-triazine (dipyatriz) ligand were investigated via Electron Paramagnetic Resonance (EPR) spectroscopy. X- and Q-band EPR spectroscopy in powders and frozen solutions were recorded and the Q-band spectra were interpreted by a multispin Hamiltonian model comprising exchange, dipolar and hyperfine interactions. The described methodology is suitable for the elucidation of weak intramolecular interactions which are not amenable to analysis via magnetic susceptibility studies.

New nickel and copper cyanobenzene-functionalised bisdithiolene transition metal complexes reveal a rich polymorphism and pave the way for analogous compounds with other transition metals as building blocks for molecular materials.

Chiral molecule-based organic thin films are of increasing interest in optoelectronics and light technologies, where the development of isotropic neat films of chiral molecules is important for practical applications. Understanding the chiroptical responses of dense molecular aggregates often becomes challenging due to the reflection or scattering of light arising from significant reflectivity changes at the excitonic transition. Furthermore, the combination of linear birefringence (LB) and linear dichroism (LD) from micro- to mesoscopic ordering is a potential source of artifacts. Here, we report the circular dichroism (CD) of optically isotropic neat films of a new BODIPY–BINOL conjugate (O-BODIPY), which reveals a negligible LD-LB contribution as measured with both conventional methods and Mueller polarimetry. A 5-fold increase in the anisotropy factor in the neat film relative to the solution is explained by intermolecular exciton coupling. Time-dependent density functional theory calculations of possible intermolecular geometries induced in the film indicate the formation of short-ordered structures in the isotropic film with the help of combined chiral units. These results provide insight into chiral light–matter interactions, which are currently at the core of many fundamental discussions and promising chiroptical applications.

Two binuclear heteroleptic Cu I complexes, namely Cu−NIR1 and Cu−NIR2, bearing rigid chelating diphosphines and π‐conjugated 2,5‐di(pyridin‐2‐yl)thiazolo[5,4‐ d ]thiazole as the bis ‐bidentate ligand are presented. The proposed dinuclearization strategy yields a large bathochromic shift of the emission when compared to the mononuclear counterparts (M1–M2) and enables shifting luminescence into the near‐infrared (NIR) region in both solution and solid state, showing emission maximum at ca. 750 and 712 nm, respectively. The radiative process is assigned to an excited state with triplet metal‐to‐ligand charge transfer ( 3 MLCT) character as demonstrated by in‐depth photophysical and computational investigation. Noteworthy, X‐ray analysis of the binuclear complexes unravels two interligand π–π‐stacking interactions yielding a doubly locked structure that disfavours flattening of the tetrahedral coordination around the Cu I centre in the excited state and maintain enhanced NIR luminescence. No such interaction is present in M1–M2. These findings prompt the successful use of Cu−NIR1 and Cu−NIR2 in NIR light‐emitting electrochemical cells (LECs), which display electroluminescence maximum up to 756 nm and peak external quantum efficiency (EQE) of 0.43 %. Their suitability for the fabrication of white‐emitting LECs is also demonstrated. To the best of our knowledge, these are the first examples of NIR electroluminescent devices based on earth‐abundant Cu I emitters.

Cyclotribenzylenes (CTBs) combining carbonitrile (−CN) and alkyne (−C 2 H) substituents were synthesized as racemic mixtures and resolved by HPLC on chiral stationary phases. Two of these compounds were used to prepare platinum‐bridged CTB dimers, in which Pt II is bound to the CTBs via Pt−alkynyl bonds in cis configuration. The organometallic complexes were examined by mass spectrometry and NMR spectroscopy, which indicated that they were obtained as mixtures of diastereoisomers (a meso or syn form and a pair of chiral or anti forms) when racemic CTBs were used. Enantiomerically pure complexes were prepared from resolved CTBs, which allowed us to distinguish the NMR signals of the chiral and meso forms in the diastereoisomeric mixtures. In certain conditions, the platinum complexes played the role of a pincer π‐alkynyl ligand for Cu(I) coming from the copper iodide used as a synthetic auxiliary. The Cu + cations could be easily removed by treatment with NaCN, affording the mononuclear bis‐cyclotribenzylene complexes. These compounds failed to lead to metallo‐cryptophanes by coordination of two [M(dppp)] 2+ complex subunits (M=Pd, Pt; dppp=1,3‐bis(diphenylphosphino)propane), each to two carbonitrile substituents belonging to different CTBs, pointing to the superiority of the one pot self‐assembly processes for the preparation of metallo‐cryptophanes.

In this work, we present a computational study that is able to predict the optical absorption and photoluminescent properties of the chiral Re(I) family of complexes [fac-ReX(CO)3L], where X is either Cl or I and L is N-heterocyclic carbene extended with π-conjugated [5]-helicenic unit. The computational strategy is based on carefully calibrated time dependent density functional theory calculations and operates in conjunction with an excited state dynamics approach to treat in addition to absorption (ABS) and photoluminescence (PL), electronic circular dichroism (ECD), and circularly polarized luminescence (CPL) spectroscopies, respectively. The employed computational approach provides, an addition, access to the computation of phosphorescence rates in terms of radiative and non-radiative relaxation processes. The chosen molecules consist of representative examples of non-helicenic (NHC) and helicenic diastereomers. The agreement between theoretical and experimental spectra, including absorption (ABS, ECD) and emission (PL, CPL), is excellent, validating a quantitative interpretation of the spectral features on the basis of natural transition orbitals and TheoDore analyses. It is demonstrated that across the set of studied Re(I) diastereomers, the emission process in the case of NHC diastereomers is metal to ligand charge transfer in nature and is dominated by the easy-axis anisotropy of the emissive excited multiplet. On the contrary, in the cases of the helicenic diastereomers, the emission process is intra ligand charge transfer in nature and is dominated by the respective easy-plane anisotropy of the emissive excited multiplet. This affects remarkably the photoluminescent properties of the molecules in terms of PL and CPL spectral band shapes, spin-vibronic coupling, relaxation times, and the respective quantum yields. Spin-vibronic coupling effects are investigated at the level of the state-average complete active space self-consistent field in conjunction with quasi-degenerate second order perturbation theory. It is in fact demonstrated that a spin-vibronic coupling mechanism controls the observed photophysics of this class of Re(I) complexes.

Taking advantage of tungsten oxide inherent Brønsted–Lewis acidity, the first series of WO3–SiO2(HIPE) monolithic (MUB-104(x) series) catalysts bearing multiscale porosity have been designed through integrative chemistry. At the microscopic length scale, beyond X-ray diffraction (XRD) revealing the WO3 monoclinic structure, local electron spin resonance (ESR) spectroscopy addresses g values clearly located at the frontier between extended WO3 phases and polyanion clusters, in agreement with scanning transmission electron microscopy high-angle annular dark field (STEM-HAADF) investigations. NH3-TPD shows that when the tungsten loading is increased from 10 wt % for MUB-104(1) to 24 wt % for MUB-104(3), the amount of acidic sites significantly decreases from 0.35 to 0.08 mmol of NH3 g–1, respectively, in agreement with the particle sizes. The MUB-104(x) series offers efficient cosolvent-less heterogeneous cycling catalysis toward both Friedel–Crafts alkylation and acylation syntheses. MUB-104(1) carries the highest turnover number (TON) of 121 and turnover frequency (TOF) of 20 h–1, while for acylation, MUB-104(1) carries the highest TON of 117 and TOF of 26 h–1. Besides, we find out that the catalysts offer good selectivity, where 30/70% of ortho- and para-substituted alkylated products are obtained. Considering the acylation reaction, the selectivity is even higher, reaching 100% toward the para-substituted acylated product. The catalyst, due to its intrinsic monolithic character, can be easily extracted from the reactive media, recycled, and re-employed further.

Abstract The performance of six newly synthesized benzo[ h ]quinoline‐derived acetonitrilo pentamethylcyclopentadienyl iridium(III) tetrakis(3,5‐bis‐trifluoromethylphenyl)borate salts bearing different substituents −X (−OMe, −H, −Cl, −Br, −NO 2 and −(NO 2 ) 2 ) on the heterochelating ligand were evaluated in the dehydro‐ O ‐silylation of benzyl alcohol and the monohydrosilylation of 4‐methoxybenzonitrile by Et 3 SiH, two reactions involving the electrophilic activation of the Si−H bond. The benchmark shows a direct dependence of the catalytic efficiency with the electronic effect of −X, which is confirmed by theoretical assessment of the intrinsic silylicities Π of hydridoiridium(III)‐silylium adducts and by the theoretical evaluation of the propensity of hydridospecies to transfer the hydrido ligand to the activated substrate. The revisited analysis of the Ir−Si−H interactions shows that the most cohesive bond in hydridoiridium(III)‐silylium adducts is the Ir−H one, while the Ir−Si is a weak donor‐acceptor dative bond. The Si…H interaction in all the cases is noncovalent in nature and dominated by electrostatics confirming the heterolytic cleavage of the hydrosilane's Si−H bond in this key catalytically relevant species.

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In this work, several exact and approximate analytical solutions to the quantum master equation are derived using both classical and non-classical coupling models to describe the kinetics of Hartmann-Hahn cross-polarization (HHCP) and multiple-contact CP (MC-CP). Moreover, the analytical solution originally obtained by Naito and McDowell [J. Chem. Phys. 84 (1986) 4181.] is shown to be incorrect and the different regimes of spin diffusion and relaxation are characterized by the amplitude of the second stage of the HHCP dynamics and the HHCP/MC-CP crossing time. The analysis of the 1H-13C HHCP and MC-CP dynamics together with (Lee-Goldburg) 1H relaxation experimental data provides a consistent picture of spin dynamics in solid alanine and explains the apparent discrepancies previously observed between and relaxation measurements. The CH and CH3 protons relax as expected via spin diffusion towards the NH3 protons but the assumption of common proton spin temperature, in which the bottleneck of relaxation is at the NH3 sites, generally valid for relaxation breaks down for relaxation. A diffusion-limited situation in which nuclear Zeeman energy is transferred to the lattice faster than can be supplied by spin diffusion is observed instead.

The equivalence in one-electron quantum baths between the practical implementation of density matrix embedding theory (DMET) and the more recent Householder-transformed density matrix functional embedding theory has been shown previously in the standard but special case where the reference full-size (one-electron reduced) density matrix, from which the bath is constructed, is idempotent [S. Yalouz et al., J. Chem. Phys. 157, 214112 (2022)]. We prove mathematically that the equivalence remains valid when the density matrix is not idempotent anymore, thus allowing for the construction of correlated (one-electron) quantum baths. A density-matrix functional exactification of DMET is derived within the present unified quantum embedding formalism. Numerical examples reveal that the embedding cluster can be quite sensitive to the level of density-matrix functional approximation used for computing the reference density matrix.

This paper presents the characterization of a novel solid-phase sorbent for iron(III) and zirconium(IV) obtained by the functionalization of a commercial epoxy methacrylate resin (Purolites ECR8209) with desferrioxamine B (DFO). The sorption properties of the solid material, named DFO@Purolite, towards Fe(III) and Zr(IV) were investigated in detail. In particular, the sorption kinetics, isotherms and sorption profiles as a function of the solution’s pH were studied. The stoichiometry and the complexation constants of both cations with the active sites of the sorbent were determined by applying the Gibbs– Donnan model, i.e., the model used to explain the protonation and the metal sorption on ion exchange resins. While the chelating properties of the solid material investigated herein are in good agreement with those of Fe(III)/DFO and Zr(IV)/DFO previously determined in homogeneous aqueous solutions, the solid/liquid extraction studies further allow to ascertain the speciation model for the latter system that is still subjected to controversy in the literature.

Upon treatment with TBAF, CF3-substituted N-allenamides were transformed into γ-sultams. Cyclic sulfonamides bearing an ene-gem-difluorinated tether could be obtained by addition of acetic acid to the ammonium salt whereas TBAF alone provided the correspondingtrifluorinated ethyl sultams. A combined experimental and computationnal mechanistic study suggested that this transformation involves a 5-endo-dig cyclization on the ene-ynamide generated in situ.

An easy-to-handle, highly reusable and efficient [Ru(bpy)3] 2+-based heterogeneous photocatalyst was obtained by post-functionalization of a polydopamine-coated open cell polyurethane foam (PDA@PUF) via a silanization process of the mussel-inspired adhesive layer with 3-(triethoxysilyl)propan-1-amine (APTES), followed by an EDC-mediated coupling with [2,2'-bipyridine]-4-carboxylic acid and further complexation with [Ru(bpy)2Cl2] (bpy = 2,2'-bypyridine). The successful covalent grafting of APTES on the PDA layer of PUF and functionalization all over the foam surface with [Ru(bpy)3] 2+ was suggested by 29Si CP-MAS NMR, XPS, ICP-AES and SEM-EDX. The macroscopic photocatalyst proved effective in model benzylic amine homocouplings and cross dehydrogenative couplings under visible-light irradiation and molecular oxygen, showing good functional group tolerance and excellent reusability in an easy-to-carry "dip-and-play" mode for at least six runs. Impressively, an improvement of the catalytic performances was even observed in both reactions, which most likely results from a modification of the uppermost layer of polydopamine throughout the successive cycles that renders the photocatalyst more accessible.

Liposome-based nanoparticles able to release, via a photolytic reaction, a payload anchored at the surface of the phospholipid bilayer were prepared. The liposome formulation strategy uses an original drug-conjugated blue light-sensitive photoactivatable coumarinyl linker. This is based on an efficient blue light-sensitive photolabile protecting group modified by a lipid anchor, which enables its incorporation into liposomes, leading to blue to green light-sensitive nanoparticles. In addition, the formulated liposomes were doped with triplet–triplet annihilation upconverting organic chromophores (red to blue light) in order to prepare red light sensitive liposomes able to release a payload, by upconversion-assisted photolysis. Those light-activatable liposomes were used to demonstrate that direct blue or green light photolysis or red light TTA-UC-assisted drug photolysis can effectively photorelease a drug payload (Melphalan) and kill tumor cells in vitro after photoactivation.

Lipid biomarkers, such as the various bacteriohopanetetrol (BHT) isomers studied here, are useful tools in tracing bacterially mediated nitrogen and carbon cycle processes affecting greenhouse gas emissions, including the anaerobic oxidation of ammonia. Three BHT isomers occur commonly in the environment. By gas chromatography, BHT-34S elutes first; it is produced by numerous bacteria. The two later eluting isomers are more constrained in their origin. The marine anammox bacteria ‘Ca. Scalindua’ is the only known producer of a BHT isomer of unknown stereochemistry (BHT-x), making BHT-x a diagnostic biomarker in anoxic marine settings. The BHT-34R isomer is produced by three freshwater aerobic heterotrophic producers (Frankia spp., Acetobacter pasteurianus, and Komagataeibacter xylinus), a freshwater serine-cycle (Type II) methanotroph (Methylocella palustris), and the freshwater anammox ‘Ca. Brocadia’, which makes the detection of freshwater anammox using BHT-34R more complicated. We investigated whether the source of BHT-34R in freshwater environments could be ascertained via its δ13C value. We used conventional on-column gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) (as opposed to high temperature GC-C-IRMS) to determine the δ13C composition of acetylated BHT isomers in cultured bacteria and bacterial enrichments. We combined these with bulk biomass and substrate δ13C compositions to establish carbon isotopic fractionation factors. The two anammox genera had large fractionation factors from dissolved inorganic carbon (DIC) to biomass (Δ13Cbiomass – DIC = –43.8 to –26.4 ‰) and to BHTs (Δ13CBHT – DIC = –53.8 to –38.2 ‰), which clearly distinguished them from the freshwater aerobic heterotrophic producers (Δ13Cbiomass – substrate = –2.3 to –0.1 ‰; Δ13CBHT – substrate = –12.8 to 5.2 ‰). Methylocella assimilated mainly carbon from DIC, rather than from methane, into its biomass and BHT, and previous work suggested this assimilation comes with relatively small fractionation. Thus, in peatlands, the BHT δ13C values of Methylocella would not reflect the low δ13C values of biogenic methane. Consequently, the presence of BHT-34R with low δ13C values relates to ‘Ca. Brocadia’ and presents a novel tool to trace anammox in freshwater environments.

Eukaryotic life appears to have flourished surprisingly late in the history of our planet. This view is based on the low diversity of diagnostic eukaryotic fossils in marine sediments of mid-Proterozoic age (~1,600 to 800 million years (Ma) ago) and an absence of steranes, the molecular fossils of eukaryotic membrane sterols 1,2. This scarcity of eukaryotic remains is difficult to reconcile with molecular clocks that suggest that the last eukaryotic common ancestor (LECA) already emerged ~1200 to >1,800 Ma ago. LECA, in turn, must have been preceded by stem-group eukaryotic forms by several hundred million years. We report the discovery of abundant protosteroids in sedimentary rocks of mid-Proterozoic age. These primordial compounds remained unnoticed because their structures represent early intermediates of the modern sterol biosynthetic pathway, as famously predicted by Konrad Bloch4. The protosteroids reveal an ecologically prominent ‘Protosterol Biota’ that was widespread and abundant in aquatic environments from at least 1,640 to ~800 Ma ago and that likely comprised ancient protosterol-producing bacteria and deep-branching stem group eukaryotes. Modern eukaryotes started to rise in the Tonian period (1,000 to 720 Ma), fuelled by the proliferation of red algae (rhodophytes) by ~800 Ma. This ‘Tonian Transformation’ emerges as one of the most profound ecological turning points in our planet’s history.

Abstract A series of four homoleptic cationic Zn II complexes ( Zn1 – Zn4 ) coordinated by two substituted bis ‐imidazo[1,2‐ a ]pyridine (ImPy) ligands ( L1 – L4 ) is herein presented. The ligands are functionalized with either electron acceptor or donor functional groups at the C6 positions of the two ImPy moieties. In DMF solution, all of the complexes display intense near‐UV to blue emission (λ em =379–450 nm) with high photoluminescence quantum yields (PLQY) up to 0.50 and short‐lived excited states. Additionally, complex Zn4 , containing the ‐NPh 2 functionalized ligand, displays an interesting solvatochromic behavior. The absorption spectrum is characterized by electronic transitions with mainly ligand‐centered ( 1 LC) and intraligand charge‐transfer ( 1 ILCT) character, which involves a symmetric electron density redistribution at Franck‐Condon (FC). In stark contrast, the subsequent excited‐state dynamics relaxes the molecular symmetry and allows symmetry‐breaking hole‐electron pair redistribution on the bichromophoric system. As a consequence, an efficient radiative de‐excitation process takes place that is ascribed to a singlet‐manifold excited state with symmetry‐broken charge transfer ( 1 SBCT) character, as supported by an in‐depth photophysical, electrochemical and time‐dependent density functional theory (TD‐DFT) investigation. Remarkably, the 1 SBCT nature provides structureless green photoluminescence in the solid state (λ em up to 520 nm for Zn4 ), which is rather uncommon for Zn II complexes.

In the field of noncovalent interactions, chalcogen bonding (ChB) involving the tellurium atom is currently attracting much attention in supramolecular chemistry and in catalysis. However, as a prerequisite for its application, the ChB should be studied in solution to assess its formation and, if possible, to evaluate its strength. In this context, new tellurium derivatives bearing CH 2 F and CF 3 groups were designed to exhibit Te•••F ChB and were synthesized in good to high yields. In both types of compounds, Te•••F interactions were characterized in solution by combining 19 F, 125 Te and HOESY NMR techniques. These Te•••F ChBs were shown to contribute to the overall J Te-F coupling constants (94-170 Hz) measured in the CH 2 F-and CF 3based tellurium derivatives. Finally, a variable temperature NMR study allowed us to approximate the energy of the Te•••F ChB, from 3 kJ/mol for the compounds for weak Te -holes to 11 kJ/mol for Te -holes activated by the presence of strong electron withdrawing substituents. .

A series of nickel(II) porphyrins bearing one or two bulky nitrogen donors at the meso positions were prepared by using Ullmann methodology or more classical Buchwald–Hartwig amination reactions to create the new C-N bonds. For several new compounds, single crystals were obtained, and the X-ray structures were solved. The electrochemical data of these compounds are reported. For a few representative examples, spectroelectrochemical measurements were used to clarify the electron exchange process. In addition, a detailed electron paramagnetic resonance (EPR) study was performed to estimate the extent of delocalization of the generated radical cations. In particular, electron nuclear double resonance spectroscopy (ENDOR) was used to determine the coupling constants. DFT calculations were conducted to corroborate the EPR spectroscopic data.

Th is a promising radioisotope for targeted a-particle therapy. It produces 5 a-particles through its decay, with the clinically approved 223 Ra as its first daughter. There is an ample supply of 227 Th, allowing for clinical use; however, the chemical challenges of chelating this large tetravalent f-block cation are considerable. Using the CD20-targeting antibody ofatumumab, we evaluated chelation of 227 Th 41 for a-particle-emitting and radiotheranostic applications. Methods: We compared 4 bifunctional chelators for thorium radiopharmaceutical preparation: S-2-(4-Isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid (p-SCN-Bn-DOTA), 2-(4-isothicyanatobenzyl)-1,2,7,10,13-hexaazacyclooctadecane-1,4,7,10,13,16-hexaacetic acid (p-SCN-Bn-HEHA), p-isothiacyanatophenyl-1-hydroxy-2-oxopiperidine-desferrioxamine (DFOcyclo*-p-Phe-NCS), and macrocyclic 1,2-HOPO N-hydroxysuccinimide (L804-NHS). Immunoconstructs were evaluated for yield, purity, and stability in vitro and in vivo. Tumor targeting of the lead 227 Thlabeled compound in vivo was performed in CD20-expressing models and compared with a companion 89 Zr-labeled PET agent. Results: 227 Th-labeled ofatumumab-chelator constructs were synthesized to a radiochemical purity of more than 95%, excepting HEHA. 227 Th-HEHAofatumumab showed moderate in vitro stability. 227 Th-DFOcyclo*-ofatumumab presented excellent 227 Th labeling efficiency; however, high liver and spleen uptake was revealed in vivo, indicative of aggregation. 227 Th-DOTA-ofatumumab labeled poorly, yielding no more than 5%, with low specific activity (0.08 GBq/g) and modest long-term in vitro stability (,80%). 227 Th-L804-ofatumumab coordinated 227 Th rapidly and efficiently at high yields, purity, and specific activity (8 GBq/g) and demonstrated extended stability. In vivo tumor targeting confirmed the utility of this chelator, and the diagnostic analog, 89 Zr-L804-ofatumumab, showed organ distribution matching that of 227 Th to delineate SU-DHL-6 tumors. Conclusion: Commercially available and novel chelators for 227 Th showed a range of performances. The L804 chelator can be used with potent radiotheranostic capabilities for 89 Zr/ 227 Th quantitative imaging and a-particle therapy.

3,3',3''-(Benzene-1,3,5-triyl)tris(1-phenyl-1H-benzo[e][1,2,4]triazin-4-yl) (1) is a C 3-symmetrical triradical comprised of three Blatter radical units connected at the 1, 3, 5 positions of a central trimethylenebenzene core. This triradical has an excellent air, moisture, and thermal stability. Single-crystal XRD indicates that triradical 1 adopts a propeller-like geometry with the benzotriazinyl moieties twisted by 174.1(2)° and packs in 1D chains along the c axis to form an extensive network of weak intermolecular interactions. Frozen solution continuous wave (CW) EPR spectra and variable-temperature field-sweep echo-detected (FSED) spectra revealed an intramolecular ferromagnetic exchange within the spin system, supporting a quartet S = 3/2 ground state. DFT calculations further supported these experimental findings.

Quantum entanglement between the spin states of a metal center and radical ligands is suggested in an iron(II) [Fe(dipyvd) 2 ] 2+ compound (dipyvd = 1-isopropyl-3,5-dipyridil-6-oxoverdazyl). Wave function ab initio (Difference Dedicated Configuration Interaction, DDCI) inspections were carried out to stress the versatility of local spin states. We named this phenomenon excited state spinmerism, in reference to our previous work (see Roseiro et al., ChemPhysChem 2022, e202200478) where we introduced the concept of spinmerism as an extension of mesomerism to spin degrees of freedom. The construction of localized molecular orbitals allows for a reading of the wave functions and projections onto the local spin states. The low-energy spectrum is well-depicted by a Heisenberg picture. A 60 cm −1 ferromagnetic interaction is calculated between the radical ligands with the S total = 0 and 1 states largely dominated by a local low-spin S Fe = 0. In contrast, the higher-lying S total = 2 states are superpositions of the local S Fe = 1 (17%, 62%) and S Fe = 2 (72%, 21%) spin states. Such mixing extends the traditional picture of a high-field d 6 Tanabe-Sugano diagram. Even in the absence of spin−orbit coupling, the avoided crossing between different local spin states is triggered by the field generated by radical ligands. This puzzling scenario emerges from versatile local spin states in compounds which extend the traditional views in molecular magnetism.

Fouillé en 2018 dans le cadre du contournement ouest de Strasbourg, le gisement de Berstett Langenberg (site n° 5.6 du projet) a livré sur près de deux hectares plusieurs occupations successives du Néolithique récent à La Tène finale. L’occupation de l’âge du Bronze se caractérise par 43 structures se répartissant quasiment sur toute l’emprise, tandis que les 31 faits du plein Bronze moyen correspondent à une dizaine de fosses, des silos (sept) et des fonds de silos probables (quatre), deux possibles bâtiments excavés, trois fentes et cinq chablis. Aucun plan de bâtiment n’a été repéré, mais des espaces vides entourés de fosses ou silos suggèrent l’emplacement de bâtiments, tout comme les restes de torchis (architecture de terre et de bois). La quantité importante de vestiges céramiques mise au jour (160 récipients), tout comme plusieurs datations radiocarbones ont permis de mieux caractériser la typochronologie des ensembles pour le Bronze D et la transition Bronze C-D. Certains fonds de silos ont livré des vases vraisemblablement déposés entiers. Une série d’analyses biogéochimiques sur les parois internes d’une dizaine de vases ont permis d’identifier des graisses animales, tout comme des restes d’huile végétale (Brassicacées) ou de résine (Pinacée) pour des usages divers. Au-delà de la quantité importante de mobilier céramique exhumée, qui en fait un site de référence pour la fin du Bronze moyen, les autres types de mobiliers exhumés (lithique, faune) permettent de mieux caractériser ce type de site d’habitat encore peu connu dans l’est de la France.

A series of ten cationic complexes of the general formula [(C^C)Au(P^P)]X, where C^C = 4,4′-di-tert-butyl-1,1′-biphenyl, P^P is a diphosphine ligand, and X is a noncoordinating counteranion, have been synthesized and fully characterized by means of chemical and X-ray structural methods. All the complexes display a remarkable switch-on of the emission properties when going from a fluid solution to a solid state. In the latter, long-lived emission with lifetime τ = 1.8–83.0 μs and maximum in the green-yellow region is achieved with moderate to high photoluminescence quantum yield (PLQY). This emission is ascribed to an excited state with a mainly triplet ligand-centered (3LC) nature. This effect strongly indicates that rigidification of the environment helps to suppress nonradiative decay, which is mainly attributed to the large molecular distortion in the excited state, as supported by density functional theory (DFT) and time-dependent DFT (TD-DFT) computation. In addition, quenching intermolecular interactions of the emitter are avoided thanks to the steric hindrance of the substituents. Emissive properties are therefore restored efficiently. The influence of both diphosphine and anion has been investigated and rationalized as well. Using two complexes as examples and owing to their enhanced optical properties in the solid state, the first proof-of-concept of the use of gold(III) complexes as electroactive materials for the fabrication of light-emitting electrochemical cell (LEC) devices is herein demonstrated. The LECs achieve peak external quantum efficiency, current efficiency, and power efficiency up to ca. 1%, 2.6 cd A–1, and 1.1 lm W–1 for complex 1PF6 and 0.9%, 2.5 cd A–1, and 0.7 lm W–1 for complex 3, showing the potential use of these novel emitters as electroactive compounds in LEC devices.

The magnetic properties of noble‐metal nanoparticles are a puzzling phenomenon, tentatively often explained as a size effect or a ligand effect. Many experimental studies performed to date have attempted to vary these readily available parameters without reaching a definitive conclusion. In an attempt at better understanding the role of core crystallinity on these magnetic properties, we have compared the behavior of silver nanoparticles, which were either single‐crystalline or multi‐twinned, of almost identical sizes and with the same ligand coating. Our results indicate that single‐crystalline nanoparticles tend to behave as classical paramagnetic materials, whereas multi‐twinned ones exhibit a combination of para‐ and ferro‐magnetic behaviors. Our hypothesis is that lattice defects within the core bear magnetic moments which couple through conduction electrons, with dipolar interactions also playing a local and macroscopic role.

Pentameric ligand-gated ion channel mediate signal transduction at chemical synapses by transiting between resting and open states upon neurotransmitter binding. Here, we investigate the gating mechanism of the glycine receptor fluorescently labeled at the extracellulartransmembrane interface by voltage-clamp fluorimetry (VCF). Fluorescence reports a glycineelicited conformational change that precedes pore opening. Low concentrations of glycine, partial agonists or specific mixtures of glycine and strychnine trigger the full fluorescence signal while weakly activating the channel. Molecular dynamic simulations of a partial agonist boundclosed Cryo-EM structure show a highly dynamic nature: a marked structural flexibility at both the extracellular-transmembrane interface and the orthosteric site, generating docking properties that recapitulate VCF data. This work thus illuminates a progressive propagating transition towards channel opening, displaying structural plasticity with novel implications concerning the mechanism of action of allosteric effectors.

A molecular conjugate made of a free-base diphenyl porphyrin chromophore (DPP) translinked to two N-acridinium units has been synthesized and photophysically characterized in acetonitrile. Interestingly, the emission of both fluorophores is quenched in the array at room temperature. Steadystate and time-resolved optical analysis proved that an ultrafast electron transfer from the porphyrin to the acridinium units occurs upon excitation of either the porphyrin or the acridinium moiety. On the other hand, at low temperature (77 K) the emission of the porphyrin is completely recovered, thanks to the inhibition of the electron transfer, and a photoinduced energy transfer from the acridinium to the porphyrin component is observed.

Two novel compounds isolated from an amber sample from the Santonian of Piolenc (Vaucluse, SE France) were identified using nuclear magnetic resonance and high-resolution mass spectrometry as sulfurized analogues of diterpenic acids from the isopimaric series originating from ancient conifers possibly related to the Cupressaceae family. These two compounds are members of a diterpenoid series corresponding to early diagenetic transformation products of resin diterpenoids. They were likely formed once plant resin comes into contact with reduced sulfur species originating from bacterial sulfate reduction occurring in anaerobic settings such as mangroves or marshes. They represent the first evidence of sulfurization processes affecting plant resin prior to diagenetic transformation into amber. Given their mode of formation, these compounds may be used as indicators of sulfate-reducing processes in past depositional environments.

In this work, the mechanisms of radical generation on different functionalized graphene oxide (GO) conjugates under near-infrared (NIR) light irradiation are investigated. The GO conjugates are designed to understand how chemical functionalization can influence the generation of radicals. Both pristine and functionalized GO are irradiated by a NIR laser, and the production of different reactive oxygen species (ROS) is investigated using fluorimetry and electron paramagnetic resonance to describe the type of radicals present on the surface of GO. The mechanism of ROS formation involves a charge transfer from the material to the oxygen present in the media, via the production of superoxide and singlet oxygen. Cytotoxicity and effects of ROS generation are then evaluated using breast cancer cells, evidencing a concentration dependent cell death associated to the heat and ROS. The study provides new hints to understand the photogeneration of radicals on the surface of GO upon near infrared irradiation, as well as, to assess the impact on these radicals in the context of a combined drug delivery system and phototherapeutic approach. These discoveries open the way for a better control of phototherapy-based treatments employing graphene-based materials.

Studies on a series of tetracyanoquinodimethanes (TCNQs) fused with [1,2,5]chalcogenadiazole rings reveals that chalcogen bonds (ChBs), through E•••N≡C (E = S or Se) contacts, are a decisive factor in determining their crystal structures, with the formation of one- or two-dimensional networks in a lateral direction. For anion-radical salts generated by one-electron reduction, electron conduction occurs in the direction of the network due to intermolecular electronic interactions involving ChBs. Based on the reliable synthon E•••N≡C for crystal engineering, molecular recognition occurs so that solid-state molecular complexes are selectively formed with certain donors, such as xylenes, among their isomers by charge-transfer-type clathrate formation. The inclusion cavity of the clathrate might provide a reaction environment for photoinduced electron transfer in the solid state. The accommodation of multiple conformers of overcrowded ethylene exhibiting thermo/mechanochromism is another example of a novel function that can be realized by ChBs through E•••N≡C contacts. Therefore, these chalcogenadiazolo-TCNQs endowed with the ability to form ChBs are promising materials for the development of novel solid-state functions.

We report the major highlights of the School of Cheminformatics in Latin America, Mexico City, November 24-25, 2022. Six lectures, one workshop, and one roundtable with four editors were presented during an online public event with speakers from academia, big pharma, and public research institutions. One thousand one hundred eighty-one students and academics from seventy-nine countries registered for the meeting. As part of the meeting, advances in enumeration and visualization of chemical space, applications in natural product-based drug discovery, drug discovery for neglected diseases, toxicity prediction, and general guidelines for data analysis were discussed. Experts from ChEMBL presented a workshop on how to use the resources of this major compounds database used in cheminformatics. The school also included a round table with editors of cheminformatics journals. The full program of the meeting and the recordings of the sessions are publicly available at https:// www. youtu be. com/@ Schoo lChem InfLA/ featu red.

Cu chelation in biological systems is of interest as a tool to study the metabolism of this essential metal or for applications in the case of diseases with a systemic or local Cu overload, such as Wilson’s or Alzheimer’s disease. The choice of the chelating agent must meet several criteria. Among others, affinities and kinetics of metal binding and related metal selectivity are important parameters of the chelators to consider. Here, we report on the synthesis and characterization of Cu-binding properties of two ligands, L1 and L2, derivatives of the well-known peptidic CuII-binding motif Xxx-Zzz-His (also called ATCUN), where CuII is bound to the N-terminal amine, two amidates, and the imidazole. In either L, the N-terminal amine was replaced with a pyridine, and for L2, one amide was replaced with an amine compared to Xxx-Zzz-His. In particular, L2 showed several interesting features, including a CuII-binding affinity with a log KDapp = −16.0 similar to that of EDTA and stronger than all reported ATCUN peptides. L2 showed high selectivity for CuII over ZnII and other essential metal ions, even under the challenging conditions of the presence of human serum albumin. Further, L2 showed fast and efficient CuII redox silencing qualities and CuII-L2 was stable in the presence of mM GSH concentrations. Benefitting the fact that L2 can be easily elongated on its peptide part by standard SPPS to add other functions, L2 has attractive properties as a CuII chelator for application in biological systems.

Geraniol derived from essential oils of various plant species is widely used in the cosmetic and perfume industries. It is also an essential trait of the pleasant smell of rose flowers. In contrast to other monoterpenes which are produced in plastids via the methyl erythritol phosphate pathway, geraniol biosynthesis in roses relies on cytosolic NUDX1 hydrolase which dephosphorylates geranyl diphosphate (GPP). However, the metabolic origin of cytosolic GPP remains unknown. By feeding Rosa chinensis “Old Blush” flowers with pathway-specific precursors and inhibitors, combined with metabolic profiling and functional characterization of enzymes in vitro and in planta, we show that geraniol is synthesized through the cytosolic mevalonate (MVA) pathway by a bifunctional geranyl/farnesyl diphosphate synthase, RcG/FPPS1, producing both GPP and farnesyl diphosphate (FPP). The downregulation and overexpression of RcG/FPPS1 in rose petals affected not only geraniol and germacrene D emissions but also dihydro-β-ionol, the latter due to metabolic cross talk of RcG/FPPS1-dependent isoprenoid intermediates trafficking from the cytosol to plastids. Phylogenetic analysis together with functional characterization of G/FPPS orthologs revealed that the G/FPPS activity is conserved among Rosaceae species. Site-directed mutagenesis and molecular dynamic simulations enabled to identify two conserved amino acids that evolved from ancestral FPPSs and contribute to GPP/FPP product specificity. Overall, this study elucidates the origin of the cytosolic GPP for NUDX1-dependent geraniol production, provides insights into the emergence of the RcG/FPPS1 GPPS activity from the ancestral FPPSs, and shows that RcG/FPPS1 plays a key role in the biosynthesis of volatile terpenoid compounds in rose flowers.

A series of four binuclear complexes of general formula [(C^C)Au(Cl)(L^L)(Cl)Au(C^C)], where C^C is 4,4'-diterbutylbiphenyl and L^L is either a bridging diphosphine or 4,4'bipyridine, are synthetized with 52 to 72 % yield and structurally characterized by X-ray diffraction. The use of the chelating 1,2diphenylphosphinoethane ligand in a 1 : 2 (P^P):Au stoichiometry leads to the near quantitative formation of a gold doublecomplex salt of general formula [(C^C)Au(P^P)][(C^C^)AuCl 2 ]. The compounds display long-lived yellow-green phosphorescence with λ em in the range of 525 to 585 nm in the solid state with photoluminescence quantum yields (PLQY) up to 10 %. These Au III complexes are tested for their antiproliferative activity against lung adenocarcinoma cells A549 and results show that compounds 2 and 5 are the most promising candidates. The digold salt 5 shows anticancer activity between 66 and 200 nM on the tested cancer cell lines, whereas derivative 2 displays concentration values required to reduce by 50 % the cell viability (IC 50) between 7 and 11 μM. Reactivity studies of compound 5 reveal that the [(C^C)Au(P^P)] + cation is stable in the presence of relevant biomolecules including glutathione suggesting a structural mechanism of action.

Background: Acetophenone azine (CAS no. 729-43-1) present in sport equipment (shoes, socks and shin pads) has been suspected to induce skin allergies. Twelve case reports of allergy in children and adults from Europe and North America were published between 2016 and 2021.Objectives: The objective of this study was to confirm that acetophenone azine is indeed a skin sensitizer based on in vitro/ in vivo testings derived from the Adverse Outcome Pathway (AOP) built for skin sensitization by OECD in 2012.Methods: acetophenone azine was tested in vitro according to the human Cell Line Activation Test (h-CLAT) and the ARE-Nrf2 Luciferase Test (Keratinosens®) and in vivo using the Local Lymph Nodes Assay (LLNA).Results: Both the h-CLAT and the Keratinosens® were positive whereas the LLNA performed at 5, 2.5 and 1% (w/v) of acetophenone azine, was negative.Conclusion: Based on these results, acetophenone azine was considered as a skin sensitizer. This was recently confirmed by its classification under the CLP regulation.

α-Pyridyl thiosemicarbazones (TSC) such as Triapine (3AP) and Dp44mT are a promising class of anticancer agents. Contrary to Triapine, Dp44mT showed a pronounced synergism with CuII, which may be due to the generation of reactive oxygen species (ROS) by Dp44mT-bound CuII ions. However, in the intracellular environment, CuII complexes have to cope with glutathione (GSH), a relevant CuII reductant and CuI-chelator. Here, aiming at rationalizing the different biological activity of Triapine and Dp44mT, we first evaluated the ROS production by their CuII-complexes in the presence of GSH, showing that CuII-Dp44mT is a better catalyst than CuII-3AP. Furthermore, we performed density functional theory (DFT) calculations, which suggest that a different hard/soft character of the complexes could account for their different reactivity with GSH.

A bipyridine-strapped porphyrin was prepared using a remote template effect of alkali or transition metal cations in the bipyridine subunit to enhance the yield 10-fold. The flexibility of the bipyridine-strap also allowed the synthesis of a doubly strapped porphyrin.

In the last decade, the availability of new and versatile synthetic strategies for the preparation of substituted 4,4'bipyridyl derivatives based on chemo-and regioselective functionalization of the 4,4'-bipyridine core has encouraged studies for exploring the bioactivity of these compounds in the fields of drug discovery and medicinal chemistry. In substituted 4,4'-bipyridines, chirality may emerge from restricted rotation induced by sterically hindered atoms or functional groups located around the 4,4'-biaryl bond (chiral axis). The first atropisomeric substituted 4,4'-bipyridine was prepared in 2008, and no asymmetric synthesis to produce pure atropisomers of chiral 4,4'-bipyridine derivatives has been available so far. Thus, in the last few years, our groups developed methods to separate atropisomers of a wide series of 4,4'-derivatives by high-performance liquid chromatography (HPLC) using polysaccharide-based chiral stationary phases (CSPs). In the frame of our interest in this field, we reported herein the synthesis of two new chiral carboxylic acids containing an axially chiral 4,4'bipyridyl unit as source of chirality, and their HPLC enantioseparation on polysaccharide-based CSPs. In particular, the impact of analyte and CSP structures on the enantioseparation outcomes as well as mechanisms and noncovalent interactions underlying the enantioseparation were explored by using electrostatic potential analysis and molecular dynamics (MD) simulations.

The conformational preference of a cavity-based biaryl phosphine, namely 5-(2-diphenylphosphinyl-phenyl)-25,26,27,28-tetrapropyloxycalix[4]arene (L) has been investigated by density functional theory calculations. The analysis showed that the barrier to rotation about the C–C axle of the biaryl unit is only 10.7 kcal mol−1, this rendering possible access to conformers of two types, those in which the P lone pair sits at the cavity entrance and points to the calixarene interior, others with a more open structure where the P atom is located outside the cavity. As revealed by a single crystal X-ray diffraction study, the biaryl phosphine appears virtually as an atropisomer in the solid state in which the phosphorus atom lies totally out of the cavity defined by the four phenoxy rings.

: Chalcogen bonding (ChB) is the non‐covalent interaction occurring between chalcogen atoms as Lewis acid sites and atoms or groups of atoms able to behave as Lewis bases through their lone pair or p electrons. Analogously to its sister halogen bonding, the high directionality of this interaction was implemented for the precise structural organization in the solid state and in solution. Regarding catalysis, ChB is now accepted as a new mode of activation as demonstrated by the increased number of examples in the last five years. In the family of ChB catalysts, those based on tellurium rapidly appeared to overcome their lighter sulfur and selenium counterparts. In this review, we highlight the Lewis acid properties of tellurium‐based derivatives in solution and summarize the start‐of‐the‐art of their applications in catalysis.

Six- and seven-membered cyclic hydroxamic acids are found as terminal binding units in different families of siderophores, including exochelins and mycobactins. The simplest models of these preorganized chelating ligands were known, but their coordination chemistry with Fe3+, the target metal ion of siderophores, had never been reported. Four complexes were synthesized and studied: two Fe3+ complexes, one with the six-membered ring hydroxamate PIPO− and one with the seven-membered ring hydroxamate AZEPO−, and the two corresponding Ga3+ complexes. X-ray diffraction studies showed that the interligand repulsion energies were better minimized in the case of the AZEPO− complexes whatever the metal cation considered, and that the Fe−O bond distances were shorter in [Fe(AZEPO)3] by comparison with [Fe(PIPO)3].

The synthesis of several new compounds containing a chromophore and a helicenic moiety is reported. The preparation, characterisation and some physico-chemical studies are detailed. In particular, the two enantiomers of several chiral molecules of this type were separated by chiral HPLC (both analytically and in a preparative way) and their racemisation rates were determined for short-lived species. Electronic circular dichroism (ECD) and circular polarised luminescence (CPL) measurements were performed for the compounds with a very long racemisation half-life. Chiral porphyrins and Bodipys both gave ECD and CPL responses over a large area of the visible spectrum. The syntheses of several porphyrin and bodipy helicene conjugates are reported. Chiral HPLC separations of the enantiomers were performed and ECD and CPL spectra determined.

During the last fifteen years, the reduction of electrically insulating graphene oxide (GO) through the elimination of oxygen containing functional groups and the restoration of sp2 conjugation yielding its conducting form, known as reduced graphene oxide (rGO), has been widely investigated as a scalable and low-cost method to produce materials featuring graphene-like characteristics. Among various protocols, thermal annealing represents an attractive green approach compatible with industrial processes. However, the high temperatures typically required to accomplish this process are energetically demanding and are incompatible with the use of plastic substrates often desired for flexible electronics applications. Here, we report a systematic study on the low-temperature annealing of GO by optimizing different annealing conditions, i.e., temperature, time, and reduction atmosphere. We show that the reduction is accompanied by structural changes of GO, which affect its electrochemical performance when used as an electrode material in supercapacitors. We demonstrate that thermally-reduced GO (TrGO) obtained under air or inert atmosphere at relatively low temperatures (<300 °C) exhibits low film resistivities (10−2–10−4 Ω m) combined with unaltered resistance after 2000 bending cycles when supported on plastic substrates. Moreover, it exhibits enhanced electrochemical characteristics with a specific capacitance of 208 F g−1 and a capacitance retention of >99% after 2000 cycles. The reported strategy is an important step forward toward the development of environmentally friendly TrGO for future electrical or electrochemical applications.

Thiosemicarbazones (TSCs) are a class of biologically active compounds with promising anticancer activity. Their typical mechanism, especially of the clinically far developed representative Triapine, is chelation of iron (Fe), with the Fe-containing enzyme ribonucleotide reductase as primary intracellular target. However, for the subclass of terminally disubstituted, nanomolar-active derivatives like Dp44mT and Me2NNMe2, recent findings suggest that the chelation, stability, and reduction properties of the copper(II) (Cu) complexes are essential for their modes of action. Consequently, it is important to elucidate whether blood serum Cu(II) is a potential metal source for these TSCs. To gain more insights, the interaction of Triapine, Dp44mT or Me2NNMe2 with purified human serum albumin (HSA) as the main pool of labile Cu(II) was investigated by UV-vis and electron paramagnetic resonance measurements. Subsequently, a size-exclusion chromatography inductively coupled plasma mass spectrometry method for the differentiation of Cu species in serum was developed, especially separating the non-labile Cu enzyme ceruloplasmin from HSA. The results indicate that the TSCs specifically chelate copper from the N-terminal Cu-binding site of HSA. Furthermore, the Cu(II)-TSC complexes were shown to form ternary HSA conjugates, most likely via histidine. Noteworthy, Fe-chelation from transferrin was not overserved, even not for Triapine. In summary, the labile Cu pool of HSA is a potential source for Cu-TSC complex formation and, consequently, distinctly influences the anticancer activity and pharmacological behavior of TSCs.

We report the synthesis of new vanadylporphyrins bearing peripheral coordination sites. By using palladium(II) or platinum(II) as connecting ions, porphyrin dimers were isolated and characterized by X-ray crystallography. These paramagnetic species were studied by electronic spectroscopy and Continuous Wave Electron Paramagnetic Resonance (CW EPR). Large bathochromic shifts were observed by comparing porphyrin monomers and dimers showing that electronic delocalization was present as demonstrated earlier for diamagnetic compounds. Despite the large distance (&gt; 14 Å) between the two vanadyl centers in these dimers, small dipolar interactions between the two paramagnetic ions could be determined.

In the chalcogen series, tellurium species exhibit the strongest chalcogen bonding (ChB) interaction with electron-rich atom. This property explains the renewed interested toward tellurium-based derivatives and their use in different applications, such as organocatalysis. In this context, the catalytic activity of telluronium salts in the Povarov reaction is presented herein. Different dienophiles, as well as imines of variable electronic nature, efficiently react in the presence of catalytic amount of either diarylmethyltelluronium or triaryltelluronium salts. Both catalysts could also readily perform the three-component Povarov reaction starting from aldehyde, aniline and dihydrofuran. The reactivity of telluroniums towards imines and aldehydes was confirmed in the solid state by the ability of Te atom to interact through ChB with the oxygen carbonyl of acetone, and in solution with significant shift variations of the imine proton and of the tellurium atom in 1 H and 125 Te NMR spectroscopy. For the most active telluronium catalysts bearing CF 3 groups, association constants (K) with N-phenyl phenylmethanimine in the range 22-38 M À 1 were measured in dichloromethane.

Potential inversion refers to the situation where a protein cofactor or a synthetic molecule can be oxidized or reduced twice in a cooperative manner, that is the second electron transfer (ET) is easier than the first. This property is very important regarding the catalytic mechanism of enzymes that bifurcate electrons and the properties of bidirectional redox molecular catalysts that function in either direction of the reaction with no overpotential. Cyclic voltammetry is the most common technique for characterizing the thermodynamics and kinetics of ET to or from these molecules. However, a gap in the literature is the absence of analytical predictions to help interpret the values of the voltammetric peak potentials when potential inversion occurs ; the cyclic voltammograms are therefore often analyzed by simulating the data, with no discussion of the possibility of overfitting and often no estimation of the error on the determined parameters. Here we formulate the theory for the voltammetry of freely-diffusing or surface-confined two-electron redox species in the experimentally relevant irreversible limit where the peak separation depends on scan rate. We explain why the model is intrinsically underdetermined, and we illustrate this conclusion by the analysis of the voltammetry of a Ni complex with redox-active iminosemiquinone ligands. Being able to characterize the thermodynamics of two-electron transfer reactions will be crucial for designing more efficient catalysts.

Water electrolysis is a promising and environmentally friendly means for renewable energy storage. Recent progress in the development of anion exchange membranes (AEMs) has provided new perspectives for high-performance anode catalysts based on transition metal oxides (TMOs) for the sluggish anodic oxygen evolution reaction (OER). Here, we report on core–shell nanoparticles (Fe3O4@CoFe2O4) which allow combining an electrocatalytic shell (CoFe2O4) with a conductive core (Fe3O4). Such an original approach significantly minimizes critical Co content in the catalyst and avoids addition of unstable conductive carbon black. The core–shell nanoparticles outperform Co(1−x)Fe(2+x)O4 nanoparticles and show an exceptional OER activity per Co unit mass (2800 A gcobalt−1 at 1.65 V vs. RHE) suggesting synergistic interaction between the core and the shell. Along with the core–shell structure, the size of the Fe3O4 core is a critical parameter, with a large conductive Fe3O4 core being beneficial for OER enhancement

An easy-to-handle eosin Y-based heterogeneous photocatalyst was prepared by postfunctionalization of a polydopamine-coated open cell polyurethane foam (PDA@PUF) via the silanization of the adhesive layer with 3-(triethoxysilyl)propan-1-amine (APTES) and the subsequent EDC-mediated coupling of the resulting amino-functionalized foam with eosin Y. The obtained macroscopic material, EY-APTES@PDA@PUF, showed good efficiency and excellent reusability, in an easy-to-carry "dip-and-play" mode for at least six runs as photocatalyst for the aerobic oxidation of 2-methyl-5-nitroisoquinolin-2-ium iodide to the corresponding isoquinolone. Subsequent investigation of the catalytic efficiency of EY-APTES@PDA@PUF for the oxidation of sulfides to sulfoxides, however, evidenced non-negligible eosin Y leaching, leading to a progressive deactivation of the catalytic foam in this case. Two alternative synthetic protocols for the preparation of the macroscopic photocatalyst were next explored to avoid eosin Y leaching. In both cases however, cycling tests also highlighted a progressive deactivation of the catalytic foams in sulfide-to-sulfoxide oxidation reactions.

Using highly sensitive and selective in situ techniques to investigate the dynamics of intermediates formation is key to better understand reaction mechanisms. However, investigating the early stages of solid-state reactions/transformations is still challenging. Here we introduce in situ fluorescence spectroscopy to observe the evolution of intermediates during a two-step [2 + 2] photocycloaddition process in a coordination polymer platform. The structural changes and kinetics of each step under ultraviolet light irradiation versus time are accompanied by the gradual increase-decrease of intensity and blue-shift of the fluorescence spectra from the crystals. Monitoring the fluorescence behavior using a laser scanning confocal microscope can directly visualize the inhomogeneity of the photocycloaddition reaction in a single crystal. Theoretical calculations allow us to rationalize the fluorescence behavior of these compounds. We provide a convenient strategy for visualizing the solid-state photocycloaddition dynamics using fluorescence spectroscopy and open an avenue for kinetic studies of a variety of fast reactions.

Quantum Chemistry and Physics have been pinpointed as killer applications for quantum computers, and quantum algorithms have been designed to solve the Schrödinger equation with the wavefunction formalism. It is yet limited to small systems, as their size is limited by the number of qubits available. Computations on large systems rely mainly on meanfield-type approaches such as density functional theory, for which no quantum advantage has been envisioned so far. In this work, we question this a priori by proposing a counterintuitive mapping from the non-interacting to an auxiliary interacting Hamiltonian that may provide the desired advantage. Contents

Specialized metabolite (SM) diversification is a core process to plants’ adaptation to diverse ecological niches. Here, we implemented a computational mass spectrometry–based metabolomics approach to exploring SM diversification in tissues of 20 species covering Nicotiana phylogenetics sections. To markedly increase metabolite annotation, we created a large in silico fragmentation database, comprising >1 million structures, and scripts for connecting class prediction to consensus substructures. Together, the approach provides an unprecedented cartography of SM diversity and section-specific innovations in this genus. As a case study and in combination with nuclear magnetic resonance and mass spectrometry imaging, we explored the distribution of N-acylnornicotines, alkaloids predicted to be specific to Repandae allopolyploids, and revealed their prevalence in the genus, albeit at much lower magnitude, as well as a greater structural diversity than previously thought. Together, the data integration approaches provided here should act as a resource for future research in plant SM evolution.

The direct CO2 conversion to liquid fuels by catalytic hydrogenation (CO2-based Fischer-Tropsch synthesis, FTS), is a sustainable approach to reduce CO2 emissions. This challenging reaction proceeds through tandem catalysis involving reverse water gas shift reaction to produce CO and subsequent traditional CO-FTS. Unmodified Co-based catalysts allow performing the reaction at low temperatures (&lt; 250 °C), albeit producing mainly methane. In this study, we modified a commercial TiO2-P25 support by NaBH4 reduction so as to introduce controlled amounts of promoters and oxygen vacancies (Ov). The modified and unmodified supports were used to prepare Co-based catalysts, which were evaluated for CO2-based FTS at 220-250 °C and 20 bar. The promoted catalysts outperform the one prepared on commercial TiO2 in terms of activity and selectivity towards C5+. Detailed characterizations of the catalysts were performed to decipher the role of promoters. We show that, besides improving CO2 activation and limiting H2 activation, the presence of alkali on the support allows a modulation of hydrogen spillover in the system. The best catalyst in terms of activity and selectivity is the one for which sodium is deposited in sufficient amount to modulate the hydrogen spillover, which allows an optimal surface C/H ratio on cobalt.

Background: SAAP-148 is an antimicrobial peptide derived from LL-37. It exhibits excellent activity against drug-resistant bacteria and biofilms while resisting degradation in physiological conditions. Despite its optimal pharmacological properties, its mechanism of action at the molecular level has not been explored. Methods: The structural properties of SAAP-148 and its interaction with phospholipid membranes mimicking mammalian and bacterial cells were studied using liquid and solid-state NMR spectroscopy as well as molecular dynamics simulations. Results: SAAP-148 is partially structured in solution and stabilizes its helical conformation when interacting with DPC micelles. The orientation of the helix within the micelles was defined by paramagnetic relaxation enhancements and found similar to that obtained using solid-state NMR, where the tilt and pitch angles were determined based on 15N chemical shift in oriented models of bacterial membranes (POPE/POPG). Molecular dynamic simulations revealed that SAAP-148 approaches the bacterial membrane by forming salt bridges between lysine and arginine residues and lipid phosphate groups while interacting minimally with mammalian models containing POPC and cholesterol. Conclusions: SAAP-148 stabilizes its helical fold onto bacterial-like membranes, placing its helix axis almost perpendicular to the surface normal, thus probably acting by a carpet-like mechanism on the bacterial membrane rather than forming well-defined pores.

Carbonylmetallates [m]-, such as [MoCp(CO)3]-, [Mn(CO)5]-, [Co(CO)4]-, have long been successfully used in the preparation of hundreds of metal carbonyl complexes and clusters, in particular of the heterometallic type. We focus here on situations where [m]- can be viewed as a terminal, doubly- or even triply-bridging metalloligand, developing metal-metal interactions with one, two or three metal centres M, respectively. With metals M from the groups 10-12, is not straightforward or even impossible to rationalize the structure of the resulting clusters by applying the well-known Wade-Mingos rules. A very simple but global approach is presented to rationalize structures not obeying usual electron-counting rules by considering the anionic building blocks [m]- as metalloligands behaving formally as potential 2, 4 or 6 electron donors, similarly to what is typically encountered with e.g. halido ligands. Qualitative and theoretical arguments using DFT calculations highlight similarities between seemingly unrelated metal complexes and clusters and also entails a predicting power with high synthetic potential.

A multi-responsive receptor consisting of two (acridinium-Zn(II) porphyrin) conjugates has been designed. The binding constant between this receptor and a ditopic guest has been modulated (i) upon addition of nucleophiles converting acridinium moieties into the non-aromatic acridane derivatives and (ii) upon oxidation of the porphyrin units. A total of eight states has been probed for this receptor resulting from the cascade of the recognition and responsive events. Moreover, the acridinium/ acridane conversion leads to a significant change of the photophysical properties, switching from electron to energy transfer processes. Interestingly, for the bis(acridinium-Zn(II) porphyrin) receptor, charge-transfer luminescence in the nearinfrared has been observed.

In aiming to identify an interfacial agent for polyethylene (PE)/poly(ethylene-co-vinyl alcohol) (EVOH) blends, which are the main components found in flexible food packaging, triallyl isocyanurate and a molecule bearing two (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) groups were initially investigated with model molecules of targeted polymers, but the results were only moderate. The design of a suitable interfacial agent led to 4-glycidyl-2,2,6,6-tetramethylpiperidin-1-oxyl, which demonstrated covalent coupling of the TEMPO group with the model molecule of PE and the glycidyl group with the hydroxyl group of the model molecule of EVOH. This approach with model molecules could be a way to screen molecules that could have potential as interfacial agents to compatibilize polymers from materials that need to be upcycled.

Two series of bis(1-alkylbenzimidazole)silver(I) nitrate and bis(1-alkyl-5,6-dimethylbenzimidazole)silver(I) nitrate complexes, in which the alkyl substituent is either an allyl, a 2-methylallyl, an isopropyl or a 3-methyloxetan-3-yl-methyl chain, were synthesized and fully characterized. The eight N-coordinated silver(I) complexes were screened for both antimicrobial activities against Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii) and Gram-positive (Staphylococcus aureus, Staphylococcus aureus MRSA, and Enterococcus faecalis) bacteria and antifungal activities against Candida albicans and Candida glabrata strains. Moderate minimal inhibitory concentrations (MIC) of 0.087 μmol/mL were found when the Gram-negative and Gram-positive bacteria were treated with the silver complexes. Nevertheless, MIC values of 0.011 μmol/mL, twice lower than for the well-known fluconazole, against the two fungi were measured. In addition, molecular docking was carried out with the structure of Escherichia coli DNA gyrase and CYP51 from the pathogen Candida glabrata with the eight organometallic complexes, and molecular reactivity descriptors were calculated with the density functional theory-based calculation methods.

Eugenol and isoeugenol are well acknowledged to possess antioxidant and thus cytoprotective activities. Yet both compounds are also important skin sensitizers, compelling the cosmetics and fragrance industries to notify their presence in manufactured products. While being structurally very similar, they show significant differences in their sensitization properties. Consequently, eugenol and isoeugenol have been the subject of many mechanistic studies where final oxidation forms, electrophilic ortho-quinone and quinone methide, are blamed as the reactive species forming the antigenic complex with nucleophilic residues of skin proteins inducing skin sensitization. However, radical mechanisms could compete with such electrophilic-nucleophilic pathway. The antioxidant activity results from neutralising reactive oxygen radicals by release of the phenolic hydrogen atom. The so-formed phenoxyl radicals can then fully delocalize upon the structure becoming potentially reactive towards skin proteins at several positions. To obtain in-depth insights of such reactivity we investigated in situ the formation of radicals from eugenol and isoeugenol using electron paramagnetic resonance combined with spin trapping in reconstructed human epidermis (RHE), mimicking human skin and closer to what may happen in vivo. Two modes of radical initiation were used, exposing RHE to (i) horseradish peroxidase (HRP), complementing RHE metabolic capacities and mimicking peroxidases present in vivo or (ii) solar light using a AM 1.5 solar simulator. In both experimental approaches, where the antioxidant character of both compounds is revealed, oxygen- and carbon-centred radicals were formed in RHE. Our hypothesis is that such carbon radicals are relevant candidates to form antigenic entities prior to conversion into electrophilic quinones. On this basis, these studies suggest that pro- or prehapten fingerprints could be advanced depending of the radical initiation method. The introduction of HRP suggested eugenol and isoeugenol behave as prohaptens, while exposed to light a prehapten nature could be highlighted.

Copper (Cu) is essential for most organisms, but it can be poisonous in excess, through mechanisms such as protein aggregation, trans-metallation, and oxidative stress. The latter could implicate the formation of potentially harmful reactive oxygen species (O2•−, H2O2, and HO•) via the redox cycling between Cu(II)/Cu(I) states in the presence of dioxygen and physiological reducing agents such as ascorbate (AscH), cysteine (Cys), and the tripeptide glutathione (GSH). Although the reactivity of Cu with these reductants has been previously investigated, the reactions taking place in a more physiologically relevant mixture of these biomolecules are not known. Hence, we report here on the reactivity of Cu with binary and ternary mixtures of AscH, Cys, and GSH. By measuring AscH and thiol oxidation, as well as HO• formation, we show that Cu reacts preferentially with GSH and Cys, halting AscH oxidation and also HO• release. This could be explained by the formation of Cu-thiolate clusters with both GSH and, as we first demonstrate here, Cys. Moreover, we observed a remarkable acceleration of Cu-catalyzed GSH oxidation in the presence of Cys. We provide evidence that both thiol-disulfide exchange and the generated H2O2 contribute to this effect. Based on these findings, we speculate that Cu-induced oxidative stress may be mainly driven by GSH depletion and/or protein disulfide formation rather than by HO• and envision a synergistic effect of Cys on Cu toxicity.

A β-cyclodextrin-based diphosphane with metal-confining properties was efficiently synthesized thanks to an unprecedented Smiles-like rearrangement of diphenyl-(2-phosphanylphenyl)phosphane in the presence of excess n-BuLi. The cis-chelating bidentate ligand is capable of forming very stable heteroleptic [Cu(NN)(PP)]+ complexes in which a metal-bound diimine ligand (bpy, phen, or mmp) is located within the cyclodextrin cavity. As a result of ligand encapsulation, flattening of the metal tetrahedral geometry in the excited state is disfavored, thereby resulting in enhanced luminescent properties.

A [2]rotaxane built around a multi-responsive bisacridinium macrocycle has been synthesized. Structural investigation has confirmed the interlocked nature of the molecule and MD simulations illuminated its conformational dynamics with atomic resolution. Both halochromic and redox switching properties were explored to shed light on the mechanical responses and electronic changes that occur in the bis-acridinium [2]rotaxane. The topology of the rotaxane led to different mechanical behaviors, upon addition of hydroxide ions or reduction, easily detected by UV/Vis spectroscopy and electrochemistry.

Recently, some of the authors introduced the use of the Householder transformation as a simple and intuitive method for embedding local molecular fragments [see Sekaran et al., Phys. Rev. B 104, 035121 (2021) and Sekaran et al., Computation 10, 45 (2022)]. In this work, we present an extension of this approach to the more general case of multi-orbital fragments using the block version of the Householder transformation applied to the one-body reduced density matrix, unlocking the applicability to general quantum chemistry/condensed matter physics Hamiltonians. A step-by-step construction of the block Householder transformation is presented. Both physical and numerical areas of interest of the approach are highlighted. The specific mean-field (noninteracting) case is thoroughly detailed as it is shown that the embedding of a given N spin–orbital fragment leads to the generation of two separated sub-systems: (1) a 2 N spin–orbitals “fragment+bath” cluster that exactly contains N electrons and (2) a remaining cluster’s “environment” described by so-called core electrons. We illustrate the use of this transformation in different cases of embedding scheme for practical applications. We particularly focus on the extension of the previously introduced Local Potential Functional Embedding Theory and Householder-transformed Density Matrix Functional Embedding Theory to the case of multi-orbital fragments. These calculations are realized on different types of systems, such as model Hamiltonians (Hubbard rings) and ab initio molecular systems (hydrogen rings).

The metastable trilacunary heteropolyoxomolybdate [PMo9O31(py)3]3− – {PMo9}; py = pyridine) and the ditopic pyridyl bearing diarylethene (DAE) (C25H16N2F6S2) self-assemble via a facile ligand replacement methodology to yield the photo-active molecular capsule [(PMo9O31)2(DAE)3]6−. The spatial arrangement and conformation of the three DAE ligands are directed by the surface chemistry of the molecular metal oxide precursor with exclusive ligation of the photo-active antiparallel rotamer to the polyoxometalate (POM) while the integrity of the assembly in solution has been verified by a suite of spectroscopic techniques. Electrocyclisation of the three DAEs occurs sequentially and has been investigated using a combination of steady-state and time-resolved spectroscopies with the discovery of a photochemical cascade whereby rapid photoinduced ring closure is followed by electron transfer from the ring-closed DAE to the POM in the latent donor–acceptor system on subsequent excitation. This interpretation is also supported by computational and detailed spectroelectrochemical analysis. Ring-closing quantum yields were also determined using a custom quantum yield determination setup (QYDS), providing insight into the impact of POM coordination on these processes.

We study the quantum dynamics of a photo-excitation uniformly distributed at the periphery of an extended star network (with NB branches of length LB). More specifically, we address here the question of the energy absorption at the core of the network and how this process can be improved (or not) by the inclusion of peripheral defects with a tunable energy amplitude ∆. Our numerical simulations reveal the existence of optimal value of energy defect ∆ * which depends on the network architecture. Around this value, the absorption process presents a strong speedup (i.e. reduction of the absorption time) provided that LB ≤ L * B with L * B ≈ 12.5/ ln(NB). Analytical/numerical developments are then conducted to interpret this feature. We show that the origin of this speedup takes place in the hybridization of two upper-band excitonic eigenstates. This hybridization is important when LB ≤ L * B and vanishes almost totally when LB > L * B. These structural rules we draw here could represent a potential guide for the practical design of molecular nano-network dedicated to the realisation of efficient photo-excitation absorption.

Underwater operations conducted along the southern French coast have unveiled two large, isolated anchors of iron. The largest ever found in the ancient Mediterranean, they reveal that Roman merchantmen moored in Aigues-Mortes Bay. A combination of analyses focusing on the ring, which belonged to one of the two anchors, offered the opportunity to collect data from isolated anchors and to document their production. Radiocarbon analysis, conducted for the first time on this type of object, determined that they were manufactured in the early imperial period. Another key discovery was a layer of fibers found in a concretion from the ring, which revealed rare remnants of ropes impregnated with pitch that could correspond to puddening. The replication of similar analyses on rings belonging to other anchors would provide a better understanding of this crucial component for ancient mooring.

Nitrogen (N2) fixation, or diazotrophy, supports a large part of primary production in oceans. Culture-independent approaches highlighted the presence in abundance of marine non-cyanobacterial diazotrophs (NCD), but their ecophysiology remains elusive, mostly because of the low number of isolated NCD and because of the lack of available genetic tools for these isolates. Here, a dual genetic and functional approach allowed unveiling the ecophysiology of a marine NCD affiliated to the species Vibrio diazotrophicus. Physiological characterization of the first marine NCD mutant obtained so far was performed using a soft-gellan assay, demonstrating that a ΔnifH mutant is not able to grow in nitrogen-free media. Furthermore, we demonstrated that V. diazotrophicus produces a thick biofilm under diazotrophic conditions, suggesting biofilm production as an adaptive response of this NCD to cope with the inhibition of nitrogen fixation by molecular oxygen. Finally, the genomic signature of V. diazotrophicus is essentially absent from metagenomic data of Tara Ocean expeditions, despite having been isolated from various marine environments. We think that the genetically tractable V. diazotrophicus strain used in this study may serve as an ideal model to study the ecophysiology of these overlooked procaryotic group.

Three chiral diphosphites, (S,S)-5,17-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)-25,26,27,28-tetrapropyloxycalix[4]arene (1), (S,S)-5,11,17,23-tetra-tert-butyl-25,27-dipropoxy-26,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)calix[4]arene (2) and (S,S)-5,11,17,23-tetra-tert-butyl-25,26-dipropoxy-27,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)calix[4]arene (3), based on conical calix[4]arene were investigated in the rhodium-catalyzed asymmetric hydrogenation of α-dehydroamino esters. High conversions were observed after 24 h under 5 bar of hydrogen whatever the employed diphosphite, and the chiral induction increases in the order 1 &lt; 3 &lt; 2. This may be due to the presence of the calix[4]arene moiety, which by its presence modifies the second coordination sphere of the catalytic center. The larger steric hindrance around the rhodium atom leads to the higher enantiomeric excess.

The replacement of the imine functionality in the ubiquitous phenoxy-imine (FI) ligands by a more robust and do-nor N,N,N’-trisubstituted amidine function was examined and gave rise to the synthesis of five new phenoxy-amidine (FA) ligands (L1-L5). The solid-state structure of four proligands has been determined by X-ray diffraction analysis and showed that the amidine moiety is in trans-configuration. The reaction of the phenol-amidine proligands with AlMe3 afforded mon-onuclear (L1-L5)AlMe2 (1a-5a). A similar alkane elimination route was used from ZnEt2 and led to dinuclear [(L1-L5)ZnEt]2 complexes (1b-5b) or to homoleptic (L2/L4)2Zn complexes (2b’, 4b’) depending on the metal:ligand ratio used. The structure of these complexes has been determined by NMR spectroscopy (1H, 13C, HMBC, HSQC, DOSY, and NOESY experiments) and X-Ray diffraction study for seven of them. The crystal structure of the Al complexes showed FA ligands coordinated in a chelate fashion via the O atom of the aryloxy group and the imino-N atom indicating that the amidine function has undergone trans-cis isomerization upon coordination. A similar chelating coordination mode was observed for the FA ligands with Zn metal ions. These complexes were used as initiators for the ring-opening polymerization (ROP) of rac-lactide. FA-Zn complexes gave the best performance affording polylactic acid (PLA) with narrow molecular weight distribu-tion and heterotactic bias (Pr up to 0.75). Remarkably, some of these complexes were able to tolerate the presence of a large amount of lactic acid to the point of using it as a co-initiator during the polymerization reaction

Elaboration of new engine oil specifications and growing level of environmental awareness have been calling for better fuel efficiency and reduction of carbon emissions. In this context, molybdenum dithiocarbamates (MoDTC) are important lubricant additives used to reduce friction coefficients and hence to improve fuel economy. It has been recently shown that under engine test conditions, the combined use of MoDTC and methylene-bis(dithiocarbamates) (MBDTC) leads to the prolonged existence of MoDTC complexes at useful levels in formulated engine oil due to ligand transfer reactions, resulting in the synergistic enhancement of tribological performances. In order to investigate the process of this ligand transfer at the molecular level in detail, laboratory ageing experiments involving MoDTC, MBDTC and zinc dithiophosphates (ZnDTP) – a combination of additives frequently used in formulated lubricants – in solution in hydrocarbon base oils were performed under thermal and thermo-oxidative conditions. The evolution of the concentrations of the substrates and of their transformation products were followed using HPLC-MS, Probe-MS analyses and NMR spectroscopy. It could be shown that Zn(II) complexes such as ZnDTP are able to induce dithiocarbamate (DTC) transfer reactions from MBDTC to MoDTC through a mechanism involving activation of carbon-sulfur bonds on MBDTC. Zn(II) ions act as a Lewis acid inducing the release of DTC from MBDTC. Oxidative conditions (NO2 in air) were also shown to induce the release of DTC from MBDTC, even in the absence of Zn(II) ions, which then become available for ligand exchange with MoDTC or for re-complexation of the metal core of Mo complexes (Mo2O2S2 or Mo oxysulfides) after partial oxidative degradation of the genuine MoDTC ligands.

Recent theory and experiments have showcased how to harness quantum mechanics to assemble heat/information engines with efficiencies that surpass the classical Carnot limit. So far, this has required atomic engines that are driven by cumbersome external electromagnetic sources. Here, using molecular spintronics, an implementation that is both electronic and autonomous is proposed. The spintronic quantum engine heuristically deploys several known quantum assets by having a chain of spin qubits formed by the paramagnetic Co center of phthalocyanine (Pc) molecules electronically interact with electron-spin-selecting Fe/C60 interfaces. Density functional calculations reveal that transport fluctuations across the interface can stabilize spin coherence on the Co paramagnetic centers, which host spin flip processes. Across vertical molecular nanodevices, enduring dc current generation, output power above room temperature, two quantum thermodynamical signatures of the engine's processes, and a record 89% spin polarization of current across the Fe/C60 interface are measured. It is crucially this electron spin selection that forces, through demonic feedback and control, charge current to flow against the built-in potential barrier. Further research into spintronic quantum engines, insight into the quantum information processes within spintronic technologies, and retooling the spintronic-based information technology chain, can help accelerate the transition to clean energy.

In the last few years, chiral 4,4 ′-bipyridine derivatives have been developed for different applications in catalysis, enantioseparation science, supramolecular and theoretical chemistry by modulating the activity of the molecular system through the introduction of specific substituents in the heteroaromatic scaffold. More recently, the biological activity of 2 ′-substituted-3,3 ′ ,5,5 ′-tetrachloro-2-iodo-4,4 ′-bipyridines has been explored in the field of transthyretin (TTR) fibrillogenesis inhibition, and the anticancer cytotoxicity of some derivatives is currently under systematic investigation. In this frame, the high-performance liquid chromatography (HPLC) enantioseparation of four atropisomeric 2,2 ′-disubstituted-4,4 ′-bipyridines (R, R' = Ar, I), which contain multiple interaction sites, such as hydrogen bonding (HB) donors and acceptors, halogen bond (XB) donors, and-extended electronic clouds, was explored by using n-hexane (Hex)/2-propanol (2-PrOH) 90:10 v/v as a mobile phase (MP), and eight chiral columns with coated and immobilized amylose-and cellulose-based selectors. The impact of subtle structural variations of analytes and selectors on their mutual intermolecular interactivity was evaluated in terms of retention (k) and selectivity () factors. On this basis, chromatographic analysis based on systematic screening of analytes and selectors was integrated with electrostatic potential (V) analysis and molecular dynamics (MD) simulations as computational techniques. The effect of temperature on retention, selectivity, and enantiomer elution order (EEO) of the analytes with coated and immobilized amylose tris (3,5-dimethylphenylcarbamate) was also considered by comparing the variation of the thermodynamic profile associated with each enantioseparation. Chromatographic responses proved to be strictly dependent on specific regions within the analyte, and functions of different interactions sites of the analytes as the structure of the chiral selector changes were significantly disclosed.

The chemistry of chiral NHC-oxazoline bidentate ligands was investigated in silver(I) and gold(I) chemistries yielding stable dinuclear cationic complexes with good yields via coordination of the oxazoline heterocycle. Upon full characterization, the reactivity of the gold(I) complexes was assessed in homogeneous catalysis and under oxidative conditions.

The neutral complex dichloro‐{diethyl[(5‐phenyl‐1,3,4‐oxadiazol‐2‐ylamino)‐(4‐trifluoro‐methylphenyl)methyl]phosphonate} ( p ‐cymene)‐ruthenium(II) was encapsulated inside a self‐assembled hexameric host obtained upon reaction of 2,8,14,20‐tetra‐undecyl‐resorcin[4]arene and water. The formation of an inclusion complex was inferred from a combination of spectral measurements (MS, UV/Vis spectroscopy, 1 H and DOSY NMR). The 31 P and 19 F NMR spectra are consistent with motions of the ruthenium complex inside the self‐assembled capsule. Molecular dynamics simulations carried out on the inclusion complex confirmed these intra‐cavity movements and highlighted possible supramolecular interactions between the ruthenium first coordination sphere ligands and the inner part (aromatic rings) of the capsule. The embedded ruthenium complex was assessed in the catalytic oxidation (using NaIO 4 as oxidant) of mixtures of three arylmethyl alcohols into the corresponding aldehydes. The reaction kinetics were shown to vary as a function of the substrates’ size, with the oxidation rate varying in the order benzylalcohol &gt;4‐phenyl‐benzylalcohol &gt;9‐anthracenemethanol. Control experiments realized in the absence of hexameric capsule did not allow any discrimination between the substrates.

In this article, we explore the dissipation dynamics of a strongly coupled multidimensional system in contact with a Markovian bath following a system-bath approach. We use in this endeavour the recently developed stochastic Multi-Configuration Time-Dependent Hartree approach within the Monte Carlo wave packet formalism [J. Chem. Phys. 156, 094109 (2022)]. The method proved to yield thermalized ensembles of wave packets when intramolecular coupling is weak. To treat strongly coupled systems, new Lindblad dissipative operators are constructed as linear combinations of the system coordinates and associated momenta. These are obtained by an unitary transformation to a normal mode representation, which reduces intermode coupling up to second order. Additionally, we use combinations of generalized raising/lowering operators to enforce the Boltzmann distribution in the dissipation operators, which yield perfect thermalization in the harmonic limit. The two ansatz are tested using a model two-dimensional hamiltonian parameterized to disentangle the effects of intramolecular potential coupling, of strong mode mixing observed in Fermi resonances, and of anharmonicity.

Glycine receptors (GlyR) are ligand-gated ion channels mediating signal transduction at chemical synapses. Since the early patch-clamp electrophysiology studies, the details of the ion permeation mechanism have remained elusive. Here, we combine molecular dynamics simulations of a zebrafish GlyR-⍺1 model devoid of the intracellular domain with mutagenesis and single-channel electrophysiology of the full-length human GlyR-⍺1. We show that lateral fenestrations between subunits in the extracellular domain provide the main translocation pathway for chloride ions to enter/exit a central water-filled vestibule at the entrance of the transmembrane channel. In addition, we provide evidence that these fenestrations are at the origin of current rectification in known anomalous mutants and design de novo two inward-rectifying channels by introducing mutations within them. These results demonstrate the central role of lateral fenestrations on synaptic neurotransmission. Teaser Extracellular chloride ions access the glycine receptor pore via lateral fenestrations outdating the standard apical model.

Photolytic reactions allow the optical control of the liberation of biological effectors by photolabile protecting groups. The development of versatile technologies enabling the use of deep-red or NIR light excitation still represents a challenging issue, in particular for light-induced drug release (eg; light induced prodrug activation). Here, we present light-sensitive biocompatible lipid nanocapsules able to liberate an antitumoral drug through photolysis. We demonstrate that original photon upconverting nanoparticles (LNC-UCs) chemically conjugated to a coumarin-based photocleavable linker can quantitatively and efficiently release a drug by upconversion luminescence-assisted photolysis using a deep-red excitation wavelength. In addition, we were also able to demonstrate that such nanoparticles are stable in the dark, without any drug leakage in the absence of light. These findings open new avenues to specifically liberate diverse drugs using deep- red or NIR excitations for future therapeutic applications in nanomedicine.

Biphenol-based ligands have proven their ability to bind titanium(IV) centers and generate sophisticated self-assembled structures in which auxiliary nitrogen ligands often complete the coordination sphere of the metal and improve stability. Here, a central 4,4'bipyridine, which acts both as a spacer and a source of monodentate nitrogen to complete the coordination sphere of the Ti(IV) complex, was incorporated within two bis-2,2'-biphenol strands, 3H4 and 4H4. Both proligands possess structural features that are well adapted to form selfassembled structures built from titanium-oxygen-nitrogen units; however, their different degrees 2 of torsional freedom highly influenced the nuclearity of the complexes formed. The presence of a phenyl spacer between the bipyridine and the biphenol moieties of 3H4 provided enough flexibility for the ligand to wrap around one titanium(IV) center to form a mononuclear complex Ti(3)(DMF)2 in the presence of DMF. Assembly of the more rigid ligand 4H4 with Ti(OiPr)4 afforded a tetranuclear complex Ti4(4)2(4H)2(OEt)2 containing four stacked 4,4'-bipyridine units as shown by the X-ray structure of the complex. DFT studies suggested that the assembly of this tetrametallic complex involves a dimetallic intermediate with TiO6 nodes that is converted to the thermodynamically stable tetranuclear complex with two TiO6 nodes and two TiO5N units with enhanced covalent character.

The progressive, neurodegenerative Alzheimer’s disease (AD) is the most widespread dementia. Due to the ageing of the population and the current lack of molecules able to prevent or stop the disease, AD will be even more impactful for society in the future. AD is a multifactorial disease, and, among other factors, metal ions have been regarded as potential therapeutic targets. This is the case for the redox-competent Cu ions involved in the production of reactive oxygen species (ROS) when bound to the Alzheimer-related Aβ peptide, a process that contributes to the overall oxidative stress and inflammation observed in AD. Here, we made use of peptide ligands to stop the Cu(Aβ)-induced ROS production and we showed why the AHH sequence is fully appropriate, while the two parents, AH and AAH, are not. The AHH peptide keeps its beneficial ability against Cu(Aβ)-induced ROS, even in the presence of ZnII-competing ions and other biologically relevant ions. The detailed kinetic mechanism by which AHH could exert its action against Cu(Aβ)-induced ROS is also proposed.

Upon gold catalysis, the 2,3-dihydropyrrolo[1,2-a]indole motif, encountered in few but interesting bioactive natural products, was efficiently obtained from N-aryl 2-alkynylazetidine derivatives. In an attempt to apply this methodology to the synthesis of harmalidine, isolated from the seeds of Peganum harmala, advanced amino 2,3-hydropyrrolo[1,2-a]indol(one) derivatives were readily obtained in only 11 steps from but-3-yn-1-ol. While the reported structure of harmalidine could not be reached from these intermediates, a surprising 12-membered diimino dimer was isolated. Extensive comparison of the reported harmalidine NMR data to the experimental and calculated data of our synthetic molecules, harmaline or the synthetised N-methylharmaline show discrepancies with the proposed natural product structure.

In this joint theoretical and experimental study, the analysis of weak interligand noncovalent interactions within Co(IV) [Cp*Co(phpy)X]+ cobaltacycles (phpy = 2-phenylenepyridine, κC,N) was carried out using the the Independent Gradient Model/Intrinsic Bond Strength Index (IGM/IBSI) method to evaluate the dependency of the catalytically desired reductive elimination pathway (RE) on the nature of the -X ligand. It is shown that the barrier of activation of the RE pathway correlates directly with the IBSI of the X-to-carbanionic chelate’s carbon. This correlation suggests that the in silico prediction of which -X ligand is more prone to operate an efficient Cp*Co-catalyzed directed X-functionalization of aromatic C-H bond is at reach. A set of experiments staging various sources of -X ligands supports the theoretical conclusions.

Despite their clinical importance, saving numerous human lifes, over-and misuses of antibiotics has created a strong selective pressure on bacteria, which induces the emergence of (multi)resistant strains. Antibioresistance is becoming so pregnant that since 2017, WHO lists bacteria threatening most human health (AWaRe, ESKAPE lists), and those for which new antibiotics are urgently needed. Since the century turn, this context is leading to a burst in the chemical synthesis of new antibiotics, mostly derived from natural antibiotics. Among them, aminoglycosides, and especially the neomycin family, exhibit broad spectrum of activity and remain clinically useful drugs. Therefore, numerous endeavours have been undertaken to modify aminoglycosides with the aim of overcoming bacterial resistances. After having replaced antibiotic discovery into an historical perspective, briefly surveyed the aminoglycoside mode of action and the associated resistance mechanisms, this review emphasized the chemical syntheses performed on the neomycin family and the corresponding structure activity relationships in order to reveal the really efficient modifications able to convert neomycin and its analogues into future drugs. This review would help researchers to strategically design novel aminoglycoside derivatives for the development of clinically viable drug candidates.

The zinc complex Zn(C6F5)2(toluene) (1) behaves as a very active and selective catalyst in cyclohexene oxide (CHO) polymerization to produce poly(cyclohexene oxide) (PCHO) by the trans-ring-opening of CHO with remarkable TOF values at room temperature. The ring-opening copolymerization (ROCOP) of CO2 with CHO catalysed by 1 yields poly(cyclohexene carbonate) (PCHC) when using benzyl alcohol (BnOH) as an initiator at 120 °C. The 1H NMR monitoring of the in situ reaction of 1 with BnOH highlighted the formation of the dinuclear species [(C6F5)2Zn2(BnO)2 (2) that was isolated and found an active catalyst in the ROCOP of CO2 with CHO in the absence of initiators. Interestingly, PCHCs by 2 in solventless conditions show polydispersity index (Mw/Mn) values close to 2, corresponding to those expected for a single-site catalyst; on the contrary, a broader polydispersity index of the polymer products was found in toluene solution, suggesting the formation of new zinc catalysts during the polymerization reaction.

Strigolactones (SLs) are plant hormones exuded in the rhizosphere with a signaling role for the development of arbuscular mycorrhizal (AM) fungi and as stimulants of seed germination of the parasitic weeds Orobanche, Phelipanche, and Striga, the most threatening weeds of major crops worldwide. Phelipanche ramosa is present mainly on rape, hemp, and tobacco in France. P. ramosa 2a preferentially attacks hemp, while P. ramosa 1 attacks rapeseed. The recently isolated cannalactone (14) from hemp root exudates has been characterized as a noncanonical SL that selectively stimulates the germination of P. ramosa 2a seeds in comparison with P. ramosa 1. In the present work, (−)-solanacol (5), a canonical orobanchol-type SL exuded by tobacco and tomato, was established to possess a remarkable selective germination stimulant activity for P. ramosa 2a seeds. Two cannalactone analogues, named (±)-SdL19 and (±)-SdL118, have been synthesized. They have an unsaturated acyclic carbon chain with a tertiary hydroxy group and a methyl or a cyclopropyl group instead of a cyclohexane A-ring, respectively. (±)-SdL analogues are able to selectively stimulate P. ramosa 2a, revealing that these minimal structural elements are key for this selective bioactivity. In addition, (±)-SdL19 is able to inhibit shoot branching in Pisum sativum and Arabidopsis thaliana and induces hyphal branching in the AM fungus Rhizophagus irregularis, like SLs

The rhazinilam family of natural products exhibits a main structure with a stereogenic quaternary carbon and a tetrahydroindolizine core imbedded within a 9-membered macrocycle, imposing axial chirality. This unique architecture combined with their taxol-like antimitotic activities have attracted various attentions, expecially from synthetic chemists, notably in the past decade. The present review describes the known total and formal syntheses of the members of the rhazinilam family (rhazinilam, rhazinal, leuconolam and kopsiyunnanines), according to the strategy developed.

The solid-state 1 H, 31 P NMR spectra and cross-polarization (CP MAS) kinetics in the series of samples containing amorphous phosphate phase (AMP), composite of AMP + nanostructured calcium hydroxyapatite (nano-CaHA) and high-crystalline nano-CaHA were studied under moderate spinning rates (5-30 kHz). The combined analysis of the solid-state 1 H and 31 P NMR spectra provides the possibility to determine the hydration numbers of the components and the phase composition index. A broad set of spin dynamics models (isotropic/anisotropic, relaxing/non-relaxing, secular/semi-non-secular) were applied and fitted to the experimental CP MAS data. The anisotropic model with the angular averaging of dipolar coupling was applied for AMP and nano-CaHA for the first time. It was deduced that the spin diffusion in AMP is close to isotropic, whereas it is highly anisotropic in nano

Citronellol, one of the most used fragrance compounds worldwide, is one ingredient of Fragrance Mix II used to assess skin allergy to fragrances in dermatitis patients. Pure citronellol is nonallergenic. Main issue is it autoxidizes when exposed to air becoming then allergenic. The increased skin sensitizing potency of air-exposed citronellol has been attributed to the hydroperoxides detected at high concentrations in the oxidation mixtures. It has been postulated that such hydroperoxides can give rise to specific antigens, although chemical mechanisms involved and the pathogenesis are far from being unraveled. Hydroperoxides are believed to react with skin proteins through mechanisms involving radical intermediates. Here, insights on the potential radicals involved in skin sensitization to citronellol hydroperoxides are given. The employed tool is a multispectroscopic approach based on (i) electron paramagnetic resonance and spin trapping, that confirmed the formation of oxygenand carbon-radicals when exposing reconstructed human epidermis to concentrations of hydroperoxides close to those used for patch testing patients with air-oxidized citronellol; (ii) liquid chromatography-mass spectrometry, that proved the reaction with amino acids such as cysteine and histidine, known to be involved in radical processes and (iii) density functional theory calculations, that gave an overview on the preferential paths for radical degradation.

The electronic and structural alterations induced by the functionalization of the 1,10-phenanthroline (phen) ligand in [Cu(I) (phen-R2)2]+ complexes (R=H, CH3, tertio-butyl, alkyl-linkers) and their consequences on the luminescence properties and thermally activated delay fluorescence (TADF) activity are investigated using the density functional theory (DFT) and its time-dependent (TD) extension. It is shown that highly symmetric molecules with several potentially emissive nearly-degenerate conformers are not promising because of low S1/S0 oscillator strengths together with limited or no S1/T1 spin–orbit coupling (SOC). Furthermore, steric hindrance, which prevents the flattening of the complex upon irradiation, is a factor of instability. Alternatively, linking the phenanthroline ligands offers the possibility to block the flattening while maintaining remarkable photophysical properties. We propose here two promising complexes, with appropriate symmetry and enough rigidity to warrant stability in standard solvents. This original study paves the way for the supramolecular design of new emissive devices.

The σ-hole interaction represents a noncovalent interaction between atoms with σ-hole(s) on their surface (such as halogens and chalcogens) and negative sites. Over the last decade, significant developments have emerged in applications where the σ-hole interaction was demonstrated to play a key role in the control over chirality. The aim of this review is to give a comprehensive overview of the current advancements in the use of σ-hole interactions in stereoselective processes, such as formation of chiral supramolecular assemblies, separation of enantiomers, enantioselective complexation and asymmetric catalysis. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Mechanisms combining organic radicals and metallic intermediates hold strong potential in homogeneous catalysis. Such activation modes require careful optimization of two interconnected processes: one for the generation of radicals and one for their productive integration towards the final product. We report that a bioinspired polymetallic nickel complex can combine ligand- and metal-centered reactivities to perform fast hydrosilylation of alkenes under mild conditions through an unusual dual radical- and metal-based mechanism. This earth-abundant polymetallic complex incorporating a catechol-alloxazine motif as redox-active ligand operates at low catalyst loading (0.25 mol%) and generates silyl radicals and a nickel-hydride intermediate through a hydrogen atom transfer (HAT) step. Evidence of an isomerization sequence enabling terminal hydrosilylation of internal alkenes points towards the involvement of the nickel-hydride species in chain walking. This single catalyst promotes a hybrid pathway by combining synergistically ligand and metal participation in both inner- and outer- sphere processes.

A synthesis of new-to-nature aza-iridoids via ynamides is presented. ZrCl 4 proved to be the best acid to perform this transformation. Various ynamides were accommodated, and seco-iridoids could be obtained as well. Aza-iridoids were infiltrated into leaves of Scrophularia Nodosa, an iridoid-producing plant species. High-resolution mass spectrometry coupled to computational metabolomics approaches was employed for the detection of aza-iridoid bioconversion products.

IspG (also called GcpE) is an oxygen-sensitive [4Fe-4S] enzyme catalyzing the penultimate step of the methylerythritol phosphate (MEP) pathway, a validated target for drug development. It converts 2-C-methyl-d-erythritol-2,4-cyclo-diphosphate (MEcPP) into (E)-4-hydroxy-3-methyl-but-2-enyl-1-diphosphate (HMBPP). The reaction, assimilated to a reductive dehydration, involves redox partners responsible for the formal transfer of two electrons to substrate MEcPP. The 2-vinyl analogue of MEcPP was designed to generate conjugated species during enzyme catalysis, with the aim of providing new reactive centers to be covalently trapped by neighboring amino acid residues. The synthesized substrate analogue displayed irreversible inhibition towards IspG. Furthermore, we have shown that electron transfer occurs prior to inhibition; this might designate conjugated intermediates as probable affinity tags through covalent interaction at the catalytic site. This is the first report of an irreversible inhibitor of the IspG metalloenzyme.

The steric strain around copper(I) in typical [Cu(NNR)2] + complexes, where NNR is a diimine ligand substituted in α of the nitrogen atoms by R, is known to strongly impact the excited-state properties. Generally speaking, the larger R, the longer the emission lifetime and higher quantum yield. However, the stability of the coordination scaffold can be at stake if the steric strain imposed by R is too large. In this work, we explore a way of fine-tuning the steric strain around Cu(I) to reach a balance between high emission quantum yield and stability in a highly bulky copper(I) complex. Taking stable [Cu(dipp)2] + and unstable [Cu(dtbp)2] + (where dipp and dtbp are respectively 2,9-diisopropyl-1,10-phenanthroline and 2,9-ditert-butyl-1,10phenanthroline) as boundary of two least and most sterically strained structures, we designed and characterized non-symmetrical ligand 2-isopropyl-9-tert-butyl-1,10-phenanthroline (L1) and corresponding complex [Cu(L1)2] + (Cu1). The key experimental findings are that Cu1 exhibits a rigid tetrahedral geometry in the ground state, close to that of [Cu(dtbp)2] + and with an intermediate stability between that of [Cu(dipp)2] + and [Cu(dtbp)2] +. Conversely, the non-symmetrical nature of ligand L1 leads to a shorter emission lifetime and smaller quantum yield than either [Cu(dipp)2] + or [Cu(dtbp)2] +. This peculiar behavior is rationalized through the in depth analysis of the ultrafast dynamics of the excited state measured with optical transient absorption spectroscopy and theoretical calculations performed on the ground and excited state of Cu1. Our main findings are that the obtained complex is significantly more stable than [Cu(dtbp)2] + despite the sterically strained coordination sphere. The non-symmetrical nature of the ligand translates into a strongly distorted structure in the excited state. The distortion can be described as a rocking motion of one ligand, entailing the premature extinction of the excited state via several deactivation channels.

Well-defined π-conjugated thiophene donor–acceptor molecules play an important role in different fields ranging from synthetic chemistry to materials science. Their chemical structure provides specific electronic and physicochemical properties, which can be further tuned by the introduction of functional groups. Herein, we design and synthesize two novel thiophene-based π-conjugated donor–acceptor molecules TDA-1 and TDA-2 through Aldol and Knoevenagel condensations. In our proof-of-concept study we report for the first time on the use of small organic molecules employed in aqueous zinc-ion hybrid supercapacitors (Zn-HSCs),which exhibit capacitance as high as 206.7 and 235.2 F g−1 for TDA-1, and TDA-2, respectively.

In the frame of palaeobotanical studies aimed at identifying reliable molecular markers for the determination of the botanical origins of Cretaceous ambers, four diterpenoids from the amber from Archingeay (Charente-Maritime, South western France) were identified after chromatographic isolation and detailed nuclear magnetic resonance studies as 13-hydroxy-and 8,13 epoxy-nor-labdanoids. These compounds are structurally related to cupressic acid and torulosol, which are C-13 oxygenated labdanoids sometimes occurring as predominant constituents in resins from Cupressaceae s.l. and Araucariaceae. A diagenetic pathway leading from cupressic acid and torulosol to the fossil terpenoids is proposed. It involves incorporation of the parent diterpenoids into macromolecular constituents of amber during burial followed by the progressive release of the identified nor-labdanoids during maturation. The newly identified Version acceptée pour publication 2 nor-labdanoids might thus be considered as potential biomarker for amber originating from Cupressaceae s.l and/or Araucariaceae. Nevertheless, detailed investigation of the other terpenoid assemblages from the Archingeay amber points to an origin from Cupressaceae s.l.. However, since biomarkers exclusive to this botanical family have not been identified, the possibility that the amber originates from Cheirolepidiaceae is also considered.

N-Allenamides, substituted by an ester at the γ-position, were obtained through addition of terminal ynamides with ethyl diazoacetate under copper catalysis for the first time. Regio-and stereoselective hydroamination of those activated Nallenamides provided exclusively E-configured captodative enamimes through a one-pot anti-Michael addition. Numerous ynamides as well as various secondary amines were adapted in this process.

Direct borohydride fuel cells (DBFC) oxidize an easily-stored energy-dense borohydride fuel (sodium borohydride: NaBH4), that in theory reacts ca. 400 mV below H2 and produce 8 electrons per BH4anion. However, the borohydride oxidation reaction (BOR) does not fully meet these promises in practice: the electrocatalyst nature, structure and state-of-surface, and the operating conditions (pH, BH4concentration, temperature, fluxes) noticeably influence the BOR kinetics and mechanism. Nickel and platinum-based catalysts both have assets for the BOR. DBFCs can only yield decent performance if their separator combines high ionconductivity and efficient separation of the reactants; cation-exchange membranes, anionexchange membranes, bipolar membranes and porous separators all have their own advantages and drawbacks. Besides the anode, the choice of separator must consider the DBFC cathode reaction, where oxygen (air) or hydrogen peroxide are reduced, provided adapted catalysts are used. All these aspects drive the DBFC performance and stability/durability.

In contrast to p ‐quinodimethane tetraesters, which undergo facile polymerization due to their diradical character, newly synthesized 1 and 2 consisting of a chalcogenadiazole fused to a p ‐naphthoquinodimethane tetraester are thermodynamically stable due to butterfly‐shaped deformation. Such a folded molecular structure is also favorable for chalcogen bond (ChB) formation through intermolecular close contacts between a chalcogen atom (E: Se or S) and the oxygen atoms of ester groups in a crystal. The less‐explored chelating‐ChB through a C=O⋅⋅⋅E⋅⋅⋅O=C contact [Se⋅⋅⋅O: 2.94–3.37 Å] is the key supramolecular synthon for the formation of a one‐dimensional rod‐like assembly in a crystal, which is commonly observed in selenadiazole‐tetraesters ( 1 ) with OMe, OEt, and O i Pr groups. The formation of inclusion cavities between the rods shows that 1 could serve as solid‐state host molecules for clathrate formation, as found in a hexane‐solvated crystal. In contrast, thiadiazole‐tetraesters ( 2 ) are less suitable for the formation of a rod‐like assembly since the ChB involving S is less effective, and thus is overwhelmed by weak hydrogen bonds through C−H⋅⋅⋅O contacts.

We show that dipyridylamine-acetamide (Dpaa), can be cleaved under mild acidic conditions (30% formic acid in dichloromethane). The release of the amine function is orthogonal to other acid-labile protecting groups. Calculations suggest that the ease of Dpaa cleavage relies on activation of the carbonyl function by the protonated dipyridylamine nitrogen and activation of a water molecule by a hydrogen-bond network.

We propose an extension and further development of the Monod-Wyman-Changeux model for allosteric transi- tions of regulatory proteins to brain communications and specifically to neurotransmitters receptors, with the nicotinic acetylcholine receptor (nAChR) as a model of ligand-gated ion channels. The present development of- fers an expression of the change of the gating isomerization constant caused by pharmacological ligand binding in terms of its value in the absence of ligands and several “modulation factors”, which vary with orthosteric lig- and binding (agonists/antagonists), allosteric ligand binding (positive allosteric modulators/negative allosteric modulators) and receptor desensitization. The new – explicit – formulation of such “modulation factors”, pro- vides expressions for the pharmacological attributes of potency, efficacy, and selectivity for the modulatory lig- ands (including endogenous neurotransmitters) in terms of their binding affinity for the active, resting, and de- sensitized states of the receptor. The current formulation provides ways to design neuroactive compounds with a controlled pharmacological profile, opening the field of computational neuro-pharmacology.

Due to a high conductivity of about 0.1 S·cm−1, Li-Na-K carbonate eutectic and Sm-doped ceria composite material is a good electrolyte candidate for hybrid fuel cells operating between 500 °C and 600 °C. The present paper aims at a deeper understanding of the species and mechanisms involved in the ionic transport through impedance spectroscopy and thermal analyses, in oxidizing and reducing atmospheres, wet and dry, and during two heating/cooling cycles. Complementary structural analyses of post-mortem phases allowed us to evidence the irreversible partial transformation of molten carbonates into hydrogenated species, when water and/or hydrogen are added in the surrounding atmospheres. Furthermore, this modification was avoided by adding CO2 in anodic and/or cathodic compartments. Finally, a mechanistic model of such composite electrical behavior is suggested, according to the surrounding atmospheres used. It leads to the conclusions that cells based on this kind of electrolyte would preferably operate in molten carbonate fuel cell conditions, than in solid oxide fuel cell conditions, and confirms the name of “Hybrid Fuel Cells” instead of Intermediate Temperature (or even Low Temperature) Solid Oxide Fuel Cells.

Rationale: Multiple Reaction Monitoring (MRM) is a sensitive and selective detection mode for target trace-level analysis. However, it requires the fragmentation of labile bonds which are not present in molecules such as Polycyclic Aromatic Hydrocarbons (PAHs) and their heterocyclic derivatives (PANHs, PASHs). Methods: We present the application of an alternative tandem mass spectrometry (MS/MS) mode called "pseudo-MRM" for the GCMS/MS analysis of Polycyclic Aromatic Compounds (PACs). This mode is based on the monitoring of transitions with no mass loss between the precursor and the product ion. Pseudo-MRM peak areas were compared with those of classic MRM on three different mass spectrometers: two triple quadrupoles and an ion trap. Results: For all non-polar PACs studied here (PAHs, PANHs and PASHs), the pseudo-MRM transition was always the most intense. The classic MRM transitions exhibited peak areas 2 to 5 times lower. On the contrary, for the functionalized PACs (oxygenated and nitrated PAHs), classic MRM was favored over pseudo-MRM. These observations were confirmed on two triple quadrupoles (QqQs), and the real-world applicability of pseudo-MRM on QqQs was validated by the successful analysis of Diesel PM. However, a comparison with an ion trap showed that pseudo-MRM was never favored on that instrument, which caused fragmentation of non-polar PACs in MS/MS. Conclusions: The results of this study show an important gain in sensitivity when using pseudo-MRM instead of MRM for non-polar PACs on QqQ instruments. The selectivity of MRM is preserved in pseudo-MRM by applying non-zero collision energies to which only these non-polar PACs are resistant, not the isobaric interferences. No interference issue was observed when analyzing Diesel PM, a complex matrix, with our pseudo-MRM method. Therefore, we advise for a broader use of this MS/MS mode for trace-level determination of non-polar PAHs.

A photoinduced arylation of N-substituted acridinium salts has been developed and has exhibited a high functional group tolerance (e.g., halogen, nitrile, ketone, ester, and nitro). A broad range of well-decorated C9-arylated acridinium-based catalysts with fine-tuned photophysical and photochemical properties, namely, excited-state lifetimes and redox potentials have been synthetized in a one-step procedure. These functionalized acridinium salts were later evaluated in the photoredox-catalyzed fragmentation of 1,2-diol derivatives (lignin models). Among them, 2-bromophenyl substituted N-methyl acridinium has outperformed all photoredox catalysts, including commercial Fukuzumi’s catalyst, for the selective C(β)O-Ar bond cleavage of diol monoarylethers to afford 1,2-diols in good yields.

Abstract The presence of phosphate from different origins (inorganic, bioorganic) is found more and more in calcium carbonate-based biominerals. Phosphate is often described as being responsible for the stabilization of the transient amorphous calcium carbonate phase. In order to specify the composition of the mineral phase deposited at the onset of carbonated shell formation, the present study investigates, down to the nanoscale, the growing shell from the European abalone Haliotis tuberculata , using a combination of solid state nuclear magnetic resonance, scanning transmission electron microscope and spatially-resolved electron energy loss spectroscopy techniques. We show the co-occurrence of inorganic phosphate with calcium and carbonate throughout the early stages of abalone shell formation. One possible hypothesis is that this first-formed mixed mineral phase represents the vestige of a shared ancestral mineral precursor that appeared early during Evolution. In addition, our findings strengthen the idea that the final crystalline phase (calcium carbonate or phosphate) depends strongly on the nature of the mineral-associated proteins in vivo.

Copper is well known for its antimicrobial and antiviral properties. Under aerobic conditions, copper toxicity relies in part on the production of reactive oxygen species (ROS), especially in the periplasmic compartment. However, copper is significantly more toxic under anaerobic conditions, in which ROS cannot be produced. This toxicity has been proposed to arise from the inactivation of proteins through mismetallations. Here, using the bacterium Escherichia coli, we discovered that copper treatment under anaerobic conditions leads to a significant increase in protein aggregation. In vitro experiments using E. coli lysates and tightly controlled redox conditions confirmed that treatment with Cu$^+$ under anaerobic conditions leads to severe ROS-independent protein aggregation. Proteomic analysis of aggregated proteins revealed an enrichment of cysteine- and histidine-containing proteins in the Cu$^+$-treated samples, suggesting that nonspecific interactions of Cu$^+$ with these residues are likely responsible for the observed protein aggregation. In addition, E. coli strains lacking the cytosolic chaperone DnaK or trigger factor are highly sensitive to copper stress. These results reveal that bacteria rely on these chaperone systems to protect themselves against Cu-mediated protein aggregation and further support our finding that Cu toxicity is related to Cu-induced protein aggregation. Overall, our work provides new insights into the mechanism of Cu toxicity and the defense mechanisms that bacteria employ to survive.

In this paper, multidimensional dissipative quantum dynamics is studied within a system–bath approach in the Markovian regime using a model Lindblad operator. We report on the implementation of a Monte Carlo wave packet algorithm in the Heidelberg version of the Multi-Configuration Time-Dependent Hartree (MCTDH) program package, which is henceforth extended to treat stochastic dissipative dynamics. The Lindblad operator is represented as a sum of products of one-dimensional operators. The new form of the operator is not restricted to the MCTDH formalism and could be used with other multidimensional quantum dynamical methods. As a benchmark system, a two-dimensional coupled oscillators model representing the internal stretch and the surface–molecule distance in the O 2 /Pt(111) system coupled to a Markovian bath of electron–hole-pairs is used. The simulations reveal the interplay between coherent intramolecular coupling due to anharmonic terms in the potential and incoherent relaxation due to coupling to an environment. It is found that thermalization of the system can be approximately achieved when the intramolecular coupling is weak.

We herein report on the synthesis, structure, and use in alkyne hydroboration catalysis of [(IPrCl)Zn−R]+ and [(ItBu)Zn−R]+ cations bearing IPrCl (IPrCl=1,3-bis[2,6-bis(1-methylethyl)phenyl]-4,5-dichloro-1,3-dihydro-imidazol-2-ylidene) and the sterically demanding ItBu carbene (ItBu=1,3-bis(1,1-dimethylethyl)−1,3-dihydro-imidazol-2-ylidene). Ionization of neutral precursors [(IPrCl)ZnR2] (1 a, R=Et; 1 b, R=Me) and [(ItBu)ZnEt2] (2) with one equivalent of [Ph3C][B(C6F5)4] led to with robust and stable two-coordinate ZnII cations [(IPrCl)Zn−R]+ (3 a, R=Et; 3 b, R=Me) and [(ItBu)Zn−Et]+ (4), respectively, all isolated as [B(C6F5)4]− salts. Further derivatization of alkyl cations 3 b and 4 by reaction with one equivalent of [B(C6F5)3] afforded cations [(IPrCl)Zn−C6F5]+ (5) and [(ItBu)Zn−C6F5]+ (6) as [B(C6F5)4]− salts, with cation 6 displaying a limited stability in solution. The molecular structures of cations 3 b, 4 and 5 were confirmed through X-ray diffraction studies. Among stable cations, Fluoride ion affinity (FIA) estimations agree with cation 5 being the most Lewis acidic in thus far reported [(IPrCl)Zn−R]+ cations. In the presence of pinacol borane and 1-octyne, cations 3 a–b, 5 and [(IPrCl)Zn−C6F5]+ (5 mol%) slowly catalyze the selective cis-hydroboration of 1-octyne to the vinylborane product A. Cation 5 also mediates 2-hexyne hydroboration to afford a mixture of hydroboration products B and C. In the case of hydroboration catalysis mediated by cations 5 and [(IPrCl)Zn−C6F5]+, experimental data and preliminary DFT calculations are consistent a Lewis-acid-type catalysis.

A class of four bright heterobimetallic emitters is presented, which features both a chromophoric [Ir(C^N)2] center and a positively charged, linear bis-NHC M(I) ancillary moiety bridged through a Janus-type ligand. An in-depth investigation of their optical and electrochemical properties is also reported, which are further elucidated by means of time-dependent density functional theory including spin–orbital coupling effects. All complexes display efficient, vibrant red phosphorescence with a higher quantum yield and a faster radiative rate constant compared to the mononuclear parental complexes. This effect was elucidated in terms of better S–T excited-state mixing as well as increased rigidity favored by the multimetallic architecture. Finally, their electroluminescence performances are investigated by using these bimetallic complexes as electroactive materials in light-emitting electrochemical cells, achieving external quantum efficiency values up to 6% and resulting in among the most efficient ones for red emitters. This result is also attributable to the charge-neutral nature of an emitting Ir complex bearing a charged, wider energy gap, metal complex as an ancillary moiety.

Exchange bias is a physical effect that is used in many spintronic devices like magnetic read heads, MRAMS, and most kinds of magnetic sensors. For the next generation of fully organic devices, molecular exchange bias, if existing, could have a huge impact for developing mechanically soft and environment friendly devices. The observation of molecular exchange bias has been reported recently in hybrid systems where a metallic ferromagnet is exchanged biased by an organic film, and it is considered to be a spinterface effect. To understand this effect, we investigate if the molecular exchange bias exists in Co/metal tetra-phenyl porphyrin hybrid bilayer systems. Molecular exchange bias is never observed when the samples are properly encapsulated, and when exchange bias is eventually observed, it is not a spinterface effect, but it results from air-driven partial oxidation of the cobalt film transforming part of the metallic cobalt into a cobalt oxide that is well known to induce exchange bias effects. Surprisingly, oxidation is very difficult to prevent even by using very thick metallic encapsulating layers. A similar effect is observed in the Co/metal-phthalocyanine bilayer system showing that molecular exchange bias is not a spinterface effect also in the hybrid system in which this effect was originally discovered.

The theory developed in an accompanying paper [Déjardin, Phys. Rev. E 105, 024109 (2022)] is used to compute the Kirkwood correlation factor of simple polar fluids of different nature. From this calculation, the theoretical static permittivity is readily obtained, which is compared with experimental values. This is accomplished by fitting only one parameter accounting for induction or dispersion forces and torques, which is necessarily connected with the individual molecular polarizability but not explicitly related to the physical properties due to the nonadditivity of such energies. Excellent agreement between theoretical and experimental static permittivities is obtained over a very broad temperature range for a number of associated and nonassociated liquids. Finally, limitations of the present theory are given.

Microbes preserve membrane functionality under fluctuating environmental conditions by modulating their membrane lipid composition. Although several studies have documented membrane adaptations in Archaea, the influence of most biotic and abiotic factors on archaeal lipid compositions remains underexplored. Here, we studied the influence of temperature, pH, salinity, the presence/absence of elemental sulfur, the carbon source, and the genetic background on the lipid core composition of the hyperthermophilic neutrophilic marine archaeon Pyrococcus furiosus. Every growth parameter tested affected the lipid core composition to some extent, the carbon source and the genetic background having the greatest influence. Surprisingly, P. furiosus appeared to only marginally rely on the two major responses implemented by Archaea, i.e., the regulation of the ratio of diether to tetraether lipids and that of the number of cyclopentane rings in tetraethers. Instead, this species increased the ratio of glycerol monoalkyl glycerol tetraethers (GMGT, aka. H-shaped tetraethers) to glycerol dialkyl glycerol tetrathers (GDGT) in response to decreasing temperature and pH and increasing salinity, thus providing for the first time evidence of adaptive functions for GMGT. Besides P. furiosus, numerous other species synthesize significant proportions of GMGT, which suggests that this unprecedented adaptive strategy might be common in Archaea.

The present study aimed at investigating the extent to which Captains' risky decisions influence young and inexperienced First Officers. Participants (i.e., student pilots who had almost completed their training) had to decide, alone or in a crew configuration, whether to continue or abort the landing according to four risk levels (safe, moderately risky, highly risky and extremely risky). In the lone pilot configuration, they made their decisions by themselves, while in the crew configuration they were paired with a Captain who acted as a risk taker and almost always chose to land (except in extremely risky situations). The Captain's mere presence led participants to increase their risk-taking in moderately risky situations (before they even knew the Captain's decision), supposedly in an attempt to look competent and impress their superior. In reaction to the Captain's decision to land, participants also increased their risk-taking in highly risky situations. This tendency was positively correlated to the perceived authority of the Captain. Surprisingly, some participants sometimes insisted on continuing the landing in extremely risky situations after the Captain asked for a go-around, suggesting that some pilot students may greatly overestimate their piloting skills (i.e., Dunning Kruger effect). Some applications of the present experimental protocol as training for student pilots are proposed.

The ability of [Ru(bpy)2(bpym)]2+ (bpy = 2,2′-bipyridine; bpym = 2,2′-bipyrimidine) to probe specifically heavy cations has been investigated by means of density functional theory for transition metals, group 12 elements and Pb2+. On the basis of the calculated Gibbs free energies of complexation in water it is shown that all reactions are favorable with negative enthalpies except for Hg2+, with the transition metal cations forming stable bi-metallic complexes by coordination to the bpym ligand. Comparison between the optical and photophysical properties of the Ru2+ probe and those of the coordination compounds does not demonstrate a high selectivity due to very similar characteristics of the absorption and emission spectra. Whereas by complexation the lowest metal-to-ligand-charge-transfer (MLCT) shoulder of [Ru(bpy)2(bpym)]2+ at 462 nm is more or less shifted to the red as a function of the cation, the second MLCT band at 415 nm, less sensitive to the complexation, gains in intensity and is slightly blue-shifted. The visible MLCT emission of [Ru(bpy)2(bpym)]2+ at 706 nm is altered by complexation leading to near IR (800–900 nm) emission in most of the coordination compounds. Complexation to some transition metal cations (Fe, Co, Rh and Pd) generates low-lying metal-centered (MC) excited states that quench luminescence. In contrast to the conclusion of experimental findings by Kumar et al. (Chem. Commun. 2014, 50, 8488–8490), [Ru(bpy)2(bpym)]2+ cannot be proposed as a fast and selective probe for monitoring Pd2+ in aqueous media. Indeed, it does not possess the optical and photophysical characteristics necessary to discriminate Pd2+ ions over a variety of other cations.

The non-mevalonate or also called MEP pathway is an essential route for the biosynthesis of isoprenoid precursors in most bacteria and in microorganisms belonging to the Apicomplexa phylum, such as the parasite responsible for malaria. The absence of this pathway in mammalians makes it an interesting target for the discovery of novel anti-infectives. As last enzyme of this pathway, IspH is an oxygen sensitive [4Fe-4S] metalloenzyme that catalyzes 2H+/2e- reductions and a water elimination by involving non-conventional bioinorganic and bioorganometallic intermediates. After a detailed description of the discovery of the [4Fe-4S] cluster of IspH, this review focuses on the IspH mechanism discussing the results that have been obtained in the last decades using an approach combining chemistry, enzymology, crystallography, spectroscopies, and docking calculations. Considering the interesting druggability of this enzyme, a section about the inhibitors of IspH discovered up to now is reported as well. The presented results constitute a useful and rational help to inaugurate the design and development of new potential chemotherapeutics against pathogenic organisms.

The synthesis and in vitro anti-HIV activity of a novel series of pronucleotides are reported. These prodrugs were characterized by a phosphorodithiolate structure, incorporating two O-pivaloyl-2-oxyethyl substituents as biolabile phosphate protections. The compounds were obtained following an original one-pot three-step procedure, involving the formation of a phosphorodithioite intermediate which is in situ oxidized. In vitro, comparative anti-HIV evaluations demonstrate that such original prodrugs are able to allow the efficient intracellular release of the corresponding 5 0-mononucleotide. The pronucleotide of 2 0 ,3 0-dideoxyadenosine (ddA) 3 exhibited a very potent antiretroviral effect with 50% effective concentration (EC 50) values in nanomolar concentration range in various cell lines. In primary monocytes/ macrophages, this derivative was 500 times more potent in inhibiting HIV replication (EC 50 0.23 pM) than ddA and the selectivity index of the prodrug is fifty times higher than the one of the parent nucleoside.

Using a pincer platform based on a bridgehead NHC donor with functional side arms, the combined effect of increased flexibility in six-membered pyrimidine-type heterocycles compared to the more often studied five-membered imidazole, and rigidity of phosphane side arms was examined. The unique features observed include: 1) the reaction of the azolium Csp2 -H bond with [Ni(cod)2 ] affording a carbanionic ligand in [NiCl(PCsp3 H P)] (8) rather than a carbene; 2) its transformation into the NHC, hydrido complex [NiH(PCNHC P)]PF6 (9) upon halide abstraction; 3) ethylene insertion into the Ni-H bond of the latter and ethyl migration to the N-C-N carbon atom of the heterocycle in [Ni(PCEt P)]PF6 (10); and 4) an unprecedented C-P bond activation transforming the P-CNHC -P pincer ligand of 8 in a C-CNHC -P pincer and a terminal phosphanido ligand in [Ni(PPh2 )(CCNHC P)] (15). The data are supported by nine crystal structure determinations and theoretical calculations provided insights into the mechanisms of these transformations, which are relevant to stoichiometric and catalytic steps of general interest.

A combined experimental and theoretical study is reported on the new dibenzo-1,5-ditellurocine 2-Te in order to get an overview on the parameters controlling conformational change and to explain the differences with sulfur and selenium analogues. The boat to chair conformer preference is revealed by DFT calculations. For 2-Te, a G value of about 3 kJ/mol was calculated, close to the value measured by NMR (5 kJ/mol). However, DFT calculations with implicit solvation effects could not clearly establish the presence of an intramolecular Te---HC noncovalent interaction (NCI), as observed in the solid state. The Independent Gradient Model (IGM) methodology discloses an existent but probably not sufficiently discriminating Te---HC NCI. It also confirms that van der Waals interactions between phenyl rings is a source of stabilization of the boat conformer. Furthermore, electrostatic potential analysis suggests that chalcogen bonds between Te -holes and solvent might play an important role.

We discuss the quantum chemical nature of the Lead(II) valence basins, sometime called the Lead “lone pair”. Using various chemical interpretation tools such as the molecular orbital analysis, Natural Bond Orbitals (NBO), Natural Population Analysis (NPA) and Electron Localization Function (ELF) topological analysis, we study a variety of Lead(II) complexes. A careful analysis of the results show that the optimal structures of the lead complexes are only govern by the 6s and 6p subshells whereas no involvement of the 5d orbitals is found. Similarly, we do not find any significant contribution of the 6d. Therefore, the Pb(II) complexation with its ligand can be explained through the interaction of the 6s2 electrons and the accepting 6p orbitals. We detail the potential structural and dynamical consequences of such electronic structure organization of the Pb (II) valence domain.

In this study, the enantioseparation of fourteen planar chiral ferrocenes containing halogen atoms, and methyl, iodoethynyl, phenyl and 2-naphthyl groups, as substituents, was explored with a cellulose tris(4-methylbenzoate) (CMB)-based chiral column under multimodal elution conditions. n-Hexane/2-propanol (2-PrOH) 95:5 v/v, pure methanol (MeOH), and MeOH/water 90:10 v/v were used as mobile phases (MPs). With CMB, baseline enantioseparations were achieved for nine analytes with separation factors (α) ranging from 1.24 to 1.77, whereas only three analytes could be enantioseparated with 1.14 ≤ α ≤ 1.51 on a cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC)-based column, used as a reference for comparison, under the same elution conditions. Pendant group-dependent reversal of the enantiomer elution order (EEO) was observed in several cases by changing CMB to CDMPC. The impact of analyte and CSP structure, and MP polarity on the enantioseparation was evaluated. The two cellulose-based CSPs featured by different pendant groups were also compared in terms of thermodynamics. For this purpose, enthalpy (ΔΔH°), entropy (ΔΔS°) and free energy (ΔΔG°) differences, isoenantioselective temperatures (Tiso) and enthalpy/entropy ratios (Q), associated with the enantioseparations, were derived from van ’t Hoff plots by using n-hexane/2-propanol 95:5 v/v and methanol/water 90:10 v/v as MPs. With the aim to disclose the functions of the different substituents in mechanisms and noncovalent interactions underlying analyte-selector complex formation at molecular level, electrostatic potential (V) analysis and molecular dynamics (MD) simulations were used as computational techniques. On this basis, enantioseparations and related mechanisms were investigated by integrating theoretical and experimental data

High-performance liquid chromatography (HPLC) enantioseparations of ten 1,2and 1,3-disubstituted planar chiral ferrocenes on five polysaccharide-based chiral stationary phases (CSPs) were comparatively explored under multimodal elution conditions. The presence of π-extended systems in the analyte structure was shown to impact affinity of the most retained enantiomer toward amylose-based selectors, observing retention times higher than 80 min with methanol-containing mobile phases (MPs).

A sustainable approach for the synthesis of substituted quinazolines by a sequential acceptorless dehydrogenative coupling of 2-aminobenzyl alcohol with alcohols using new Pd(II)-NNO pincer type complexes as catalysts. The airstable palladium(II) complexes with the general formula [Pd(L)(PPh3)] (where L = 4-substituted methyl 2pyrrolylbenzhydrazone ligands) have been synthesized and their compositions were recognized by analytical and spectral methods (FT-IR, NMR and HR-MS). Single crystal X-ray crystallography confirms the tridentate coordination of the ligands and the existence of square planar geometry around the metal ion. A wide range of substituted quinazoline derivatives has been synthesized from double dehydrogenation of benzyl alcohols by using 1.5 mol % of the catalyst loading with a maximum of 93% yield. The formation of an amino-benzaldehyde and benzaldehyde intermediates via double dehydrogenative coupling reaction was confirmed by control experiments.

Designing and building unique cage assemblies attract increasing interest from supramolecular chemists but remain synthetically challenging. Herein, we propose the use of a flexible vertex with adjustable angles to selectively form highly distorted tetrahedral and octahedral cages, for the first time, in which the flexible vertex forms from the synergistic effect of coordination and covalent interactions. The inherent interligand angle of the vertex can be modulated by guest anions present, which allows for the finetuning of different cage geometries. Furthermore, the reversible structural transformation between tetrahedral and octahedral cages was achieved by anion exchange monitored by mass spectrometric technique, the smaller anions favoring tetrahedral cages, while the larger anions supporting octahedral cages. Additionally, the KBr-based cage thin films exhibited prominent enhancement of their third-order NLO responses in two or three orders of magnitude compared to those obtained for their corresponding solutions. This work not only provides a new methodology to build irregular polyhedral structures in a controlled and tunable way but also provides access to new kinds of promising functional optical materials.

The first synthesis of gem-difluorinated ene–ynamides is presented via deprotonation of trifluoromethylated N-allenamides and δ extrusion of fluorine. These highly reactive building blocks, owing to their dual functional groups, offer a unique entry to difluorinated dienes and to stereodefined, monofluoro-substituted dienes. Stereoselective addition to the ynamide moiety led to difluorinated dienes. A stereocontrolled domino δ elimination reaction followed by an addition/elimination sequence from trifluoromethylated N-allenamides provided exclusively stereodefined monofluorinated ene–ynamides

Molybdenum dithiocarbamates (MoDTC) are widely used in automotive industries as lubricant additives to reduce friction and to enhance fuel economy. Sulfur-containing additives such as zinc dithiophosphates (ZnDTP) are proposed to play a key role in the improvement of friction reducing properties of MoDTC in formulated lubricants by facilitating the formation of MoS2 tribofilm at the rubbing contacts. This study focuses on the interactions between MoDTC and ZnDTP under conditions comparable with those prevailing in operating engines. The capacity of ZnDTP to sulfurize MoDTC in solution in a hydrocarbon base oil could be demonstrated. Sulfurized Mo complexes bearing one or two additional sulfur atoms (1S-MoDTC and 2S-MoDTC, respectively) which have replaced the genuine oxygen atom(s) from the MoDTC core were detected and quantified using a specifically developed HPLC-MS analytical method. A possible sulfurization mechanism relying on the higher affinity of phosphorus from ZnDTP for oxygen could be proposed. In parallel, the evolution and molecular transformation of the prepared 2S-MoDTC in hydrocarbon base oil under thermal and thermo-oxidative conditions were followed using HPLC-MS and compared with the evolution of their friction coefficients. 2S-MoDTC complexes were shown to exhibit a better retention of friction reducing capability under oxidative conditions than the "classical" MoDTC, although they did not seem to significantly reduce the friction coefficients of lubricants as compared to the "classical" MoDTC. Therefore, sulfurization of MoDTC by ZnDTP might contribute to delay the progressive consumption of MoDTC and the loss of their friction-reducing efficiency in lubricants under thermo-oxidative conditions.

The syntheses and properties of expanded 4-tert-butyl-mercapto-calix[4]arenes, in which the methylene linkers are replaced by -CH2NRCH2- or -CH2NRCH2- and CH2NRCH2CH2CH2NRCH2- units, are described. The new macrocycles were obtained in a step-wise manner, utilizing fully protected, i.e. S-alkylated, derivatives of the oxidation-sensitive thiophenols in the cyclisation steps. Reductive cleavage of the macrobicyclic or macrotricyclic intermediates (6, 7, 11) afforded the free thiophenols (H48, H49, and H412) in preparative yields as their hydrochloride salts. The protected proligands can exist in two conformations, resembling the “cone” and “1,3-alternate” conformations found for the parent calix[4]arenes. The free macro-cycles do not show conformational isomerism, but are readily oxidized forming intramolecular disulfide linkages. Preliminary complexation experiments show that these expanded mercaptocalixarenes can serve as supporting ligands for tetranuclear thiolato clusters.

The chalcogen bonding (ChB) ability of Te is studied in symmetrical diaryl ditellurides ArTeTeAr. Among the two Te σ-holes, the one along the less polarized Te-Te bond was calculated as the more electropositive. This counter-intuitive situation is due to the hyperconjugation contribution from Te lone pair to the σ* of the adjacent Te which coincides with σ-hole along the more polarized Te-Ar bond. ArTeTeAr showed notable structural features in the solid state as a result of intermolecular Te···Te ChB, such as a Te 4 rectangle through dimer aggregation or a triangular Te 3 motif, where one Te interacts with both Te atoms of a neighboring molecule through both its σ-hole and lone pair, in a slightly frustrated geometry. Lewis acidity of ArTeTeAr was also evaluated by NMR with R 3 PO as σ-hole acceptors in different solvents. Thus, 125 Te NMR allowed monitoring Te···O interaction and delivering association constants ( K a ) for 1:1 adducts. The highest value of K a = 90 M -1 was measured for the adduct between ArTeTeAr bearing CF 3 groups and Et 3 PO in cyclohexane. Notably, by using n Bu 3 PO, Te···O interaction was revealed by 19 F- 1 H HOESY showing spatial proximity between CF 3 and CH 3 of n Bu 3 PO.

Planar chiral halogenated ferrocenes have come in useful as synthetic intermediates over the years, allowing for the preparation of functionalized derivatives for catalysis, material science, optoelectronics, and medicinal chemistry. Despite their chemical interest, few halogenated planar chiral ferrocenes have been prepared in enantiopure form by asymmetric synthesis so far. Enantioselective HPLC on polysaccharide-based chiral stationary phases (CSPs) has been used for resolving planar chiral ferrocenes making both enantiomers available. However, the enantioseparation of derivatives containing halogens or alkyl groups exclusively remains rather challenging. Given this context, in this study the enantioseparation of eleven dihalogenated planar chiral ferrocenes was systematically explored by using five polysaccharide-based CSPs under multimodal elution conditions. Baseline enantioseparations were achieved for nine analytes with separation factors (α) ranging from 1.15 to 1.66. Thermodynamic quantities associated with the enantioseparations were derived from van't Hoff plots, and for 1-halo-2-(iodoethynyl)ferrocenes (1-halogen = F, Cl, Br) halogen-dependent thermodynamic profiles were identified on a cellulose tris(3,5-dimethylphenylcarbamate)-based column. The impact of CSP structure and mobile phase (MP) polarity on the enantioseparation was evaluated. In addition, with the aim to unravel the functions of halogen substituents in mechanisms and noncovalent interactions underlying selector-selectand complex formation at molecular level, local electron charge density of specific molecular regions of the interacting partners were evaluated in terms of calculated electrostatic potential (V) and related source function (SF) contributions. On this basis, the impact of halogen type and position on the enantioseparation was investigated by correlating theoretical and experimental data.