Experimental evidence of charge transfer in a functionalized hexavanadate: a high resolution X-ray diffraction study

International audienceA high resolution X-ray diffraction study has been carried out on [(C4H9)4N]2 [V6O13{(OCH2)3CCH2OCCH2CH3}2] (V6–C3) at 100 K. The V6 core possesses a negative charge, leading to a strong polarization of the anion. A nucleophilic region localized near the organic moiety and an electrophilic region in the vicinity of the V6 core provide an overall description of charge-transfer behavior

Liaisons chimiques dans les complexes métal-hétérocumuléniques. Partie 3. Etude vibrationnelle du ligande cyanamide NCNR2 et des complexes (CO)5MNCNR2 (M est Cr ou W, R est C2H5 ou CH3) et détermination du champ de force du complexe (CO)5CrNCN(C2H5)2

International audienceA vibrational spectroscopic study of the four complexes (CO)5MNCNR2 (M is Cr or W, and R is C2H5 or CH3) and of the two ligands diethyl- and dimethyl-cyanamide has been carried out at 295 and 77 K and an attribution of the infrared and Raman frequencies of the two free ligands and of the four complexes is proposed. A simplified generalized valence force field for the complex (CO)5CrNCN(C2H5)2 has been calculated; it is in good agreement with these attributions.L'étude par spectroscopies d'absorption infrarouge et de diffusion Raman des quatre complexes (CO)5MNCNR2 (M est Cr ou W; R est C2H5 ou CH3) et des deux ligandes libres diéthyl- et diméthyl-cyanamide, à 295 et 77 K, nous a permis d'attribuer les fréquences vibrationnelles observées pour ces complexes métallo-cyanamide et pour les deux ligandes libres correspondants. Le champ de force de valence général simplifié du complexe (CO)5CrNCN(C2H5)2 a été calculé et est en bon accord avec ces attributions

NPLIN (Non-Photochemical Laser-Induced nucleation) of caffeine-gallic acid co-crystals in water, methanol and mixture of water methanol

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Thermodynamics of Oiling-Out in Antisolvent Crystallization. II. Diffusion toward Spinodal Decomposition

International audienceThe extensive use of antisolvent crystallization for poorly soluble chemicals is hindered by oiling-out. This study delves into solute diffusion kinetics upon antisolvent addition. We conducted time-dependent simulations on a hypothetical micrometric diffusion couple, utilizing chemical potential gradients as driving forces within the Maxwell–Stefan model. Our computations compared two types of interflux coupling: drags and thermodynamics. The thermodynamic force dominates solute diffusion behavior. Antisolvent influx elevates solute chemical potential. This energy wave drives the solute to focus toward the good solvent and leads to the competition between crystallization and oiling-out. Through microfluidics and simulations, characteristic times of oiling-out and two sites of antisolvent-induced spinodal decomposition were identified. Diffusion trajectories on the phase diagram unveiled local thermodynamic conditions and impacts of mixing parameters. Initial antisolvent gradient dominates the strength of the focusing effect. Initial solute concentration acts as an offset in diffusion trajectories. Faster agitation in antisolvent and smaller droplets of solution both effectively enhance solute focusing. These findings are general, allowing mixing processes to be designed into metastable phase regions, with local compositions staying above the designed concentrations for prolonged durations. Elevated supersaturations and extended diffusion times offer favorable conditions for nucleation of metastable phases

Experimental and theoretical insights of functionalized hexavanadates on Na+/K+-ATPase activity; molecular interaction field, ab initio calculations and in vitro assays

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Reactivity of 12-tungstophosphoric acid and its inhibitor potency toward Na + /K + -ATPase: A combined 31 P NMR study, ab initio calculations and crystallographic analysis

International audienceInfluence of 12-tungstophosphoric acid (WPA) on conversion of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) in the presence of Na + /K +-ATPase was monitored by 31 P NMR spectroscopy. It was shown that WPA exhibits inhibitory effect on Na + /K +-ATPase activity. In order to study WPA reactivity and inter-molecular interactions between WPA oxygen atoms and different proton donor types (D = O, N, C), we have considered data for WPA based compounds from the Cambridge Structural Database (CSD), the Crystallographic Open Database (COD) and the Inorganic Crystal Structure Database (ICSD). Binding properties of Keggin's anion in biological systems are illustrated using Protein Data Bank (PDB). This work constitutes the first determination of theoretical Bader charges on polyoxotungstate compound via the Atom In Molecule theory. An analysis of electrostatic potential maps at the molecular surface and charge of WPA, resulting from DFT calculations, suggests that the preferred protonation site corresponds to WPA bridging oxygen. These results enlightened WPA chemical reactivity and its potential biological applications such as the inhibition of the ATPase activity

A combined crystallographic analysis and ab initio calculations to interpret the reactivity of functionalized hexavanadates and their inhibitor potency toward Na+/K+-ATPase

International audienceIn vitro influence of five synthesized functionalized hexavanadates (V 6) on commercial porcine cerebral cortex Na + /K +-ATPase activity has been studied. Dose dependent Na + /K +-ATPase inhibition was obtained for all investigated compounds. Calculated half maximal inhibitory concentration IC 50 values, in mol/L, for Na + /K +-ATPase were 7.6 × 10 −5 , 1.8 × 10 −5 , 2.9 × 10 −5 , 5.5 × 10 −5 for functionalized hexavanadates (V 6) with tetrabutylammonium (TBA) [V 6 –CH 3 ][TBA] 2, [V 6 –NO 2 ][TBA] 2 , [V 6 –OH][TBA] 2 and [V 6 –C 3 ][TBA] 2 respectively. [V 6 –OH][Na] 2 inhibited Na + /K +-ATPase activity up to 30% at maximal investigated concentration 1 × 10 −3 mol/L. This reactivity has been interpreted using a study of the non-covalent interactions of function-alized hexavanadate hybrids through Cambridge Structural Database (CSD) analysis. Bibliographic searching has led to 18 different structures and 99 contacts. We have observed that C–H⋯O contacts consolidate the structures. We have also performed density functional theory (DFT) calculations and have determined electrostatic potential values at the molecular surface on a series of functionalized V 6. These results enlightened their chemical reactivity and their potential biological applications such as the inhibition of the ATPase

New Cocrystallization Method: Non-photochemical Laser-Induced Nucleation of a Cocrystal of Caffeine–Gallic Acid in Water

International audienceThis paper reports for the first time the crystallization of cocrystals (caffeine–gallic acid) in water using the non-photochemical laser-induced nucleation (NPLIN) technique. The nucleation temporal control of NPLIN and the induction time reduction (70 times shorter than spontaneous nucleation) allow the obtention of cocrystals on demand, with excellent repeatability. Prior to NPLIN experiments, solubility measurements, metastable zone limit determination, and spontaneous nucleation (SN) are carried out. Supersaturated solutions at three different molarities of caffeine (0.0158, 0.0167, and 0.0179 M) are prepared and dissolved at 338 K. Supersaturated solutions are exposed to a 532 nm-wavelength nanosecond pulsed laser at 296 K. Some hours later, crystals can be filtered. The impact of supersaturation on probability of nucleation has been studied, and the result shows a higher supersaturation, which implies a higher probability of nucleation. Crystalline form characterization has employed a combination of Raman scattering, high-performance liquid chromatography, thermogravimetry, differential scanning calorimetry, and powder X-ray diffraction; the sizes of the cocrystals are too small for a single-crystal X-ray diffraction experiment. Two different cocrystal forms are obtained: a new polymorph of hemihydrate CAFGAL.0.5H2O from spontaneous nucleation by precipitation and a new hydrate form CAFGAL.1.5H2O from NPLIN and from spontaneous nucleation of a supersaturated solution without evaporation. These results open a promising way to crystallize cocrystals in the context of the pharmaceutical industry

Experimental Demonstration of the Carbamazepine Crystallization from Non-photochemical Laser-Induced Nucleation in Acetonitrile and Methanol

International audienceThis paper reports for the first time the crystallization of the carbamazepine (CBZ) molecule in two solvents (methanol and acetonitrile) using the non-photochemical laser-induced nucleation (NPLIN) technique. The metastable zone of CBZ is first determined experimentally for different temperatures in both solvents. Then, the prepared solutions are irradiated by a 532 nm wavelength nanosecond pulsed laser and permitted to obtain CBZ crystals of phases I and III. The impact of laser power and polarization (circularly (CP) and linearly (LP)) on the CBZ crystallization efficiency in both solvents is determined through experiments. According to the results, the crystallization efficiency is significantly higher in methanol than in acetonitrile, and it is higher in solutions irradiated by CP laser than those by LP laser. Moreover, the irradiation of an acetonitrile solution by a LP laser results in CBZ phases I and III, whereas irradiation by the CP laser leads to CBZ phase III crystals. An ab initio determination of the interaction energy of different pairs of CBZ has been carried-out that enables the explanation of the nucleation in acetonitrile for both polarizations. In methanol, only CBZ phase III is obtained, which is in agreement with the ability of methanol to create noncovalent interactions preventing the CBZ phase I and II nucleation