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Dr. Ram Kumar Dr. Yang Song Anissa Ghoridi Dr. Philippe Boullay Prof. Gwenaelle Rousse Prof. Christel Gervais Dr. Cristina Coelho Diogo Dr. Houria Kabbour Dr. Capucine Sassoye Patricia Beaunier Dr. Victor Castaing Dr. Bruno Viana Dr. Maria Luisa Ruiz Gonzalez Prof. José Gonzalez Calbet Prof. Christel Laberty-Robert Dr. David Portehault 《Angewandte Chemie (International ed. in English)》2023,62(26):e202303487
Mixed-anion compounds widen the chemical space of attainable materials compared to single anionic compounds, but the exploration of their structural diversity is limited by common synthetic paths. Especially, oxychlorides rely mainly on layered structures, which suffer from low stability during photo(electro)catalytic processes. Herein we report a strategy to design a new polar 3D tetrahedral framework with composition Zn4Si2O7Cl2. We use a molten salt medium to enable low temperature crystallization of nanowires of this new compound, by relying on tetrahedral building units present in the melt to build the connectivity of the oxychloride. These units are combined with silicon-based connectors from a non-oxidic Zintl phase to enable precise tuning of the oxygen content. This structure brings high chemical and thermal stability, as well as strongly anisotropic hole mobility along the polar axis. These features, associated with the ability to adjust the transport properties by doping, enable to tune water splitting properties for photoelectrocatalytic H2 evolution and water oxidation. This work then paves the way to a new family of mixed-anion solids 相似文献
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Albeiro A. Restrepo-Cossio Hermisul Cano Frank Marí Carlos A. Gonzalez 《Heteroatom Chemistry》1997,8(6):557-569
In this study, we describe the results of ab initio (HF and MP2) and MNDO-PM3 calculations on the model reactions of unstabilized (Me3P=CH–CH3), semi-stabilized (Me3P=CH–C≡CH), and stabilized (Me3P=CH–C≡N) ylides with acetaldehyde to form their respective Z and E olefins and trimethylphosphine oxide. These reactions occur in three stages: oxaphosphetane formation, oxaphosphetane pseudorotation, and oxaphosphetane decomposition. The calculated barriers for these processes vary considerably depending on the level of theory employed (ab initio vs. MNDO-PM3 or HF vs. MP2 at the ab initio level). However, self-consistent geometries of reactants, intermediates, transition states and products are obtained at all levels. Oxaphosphetane formation is best described as very asynchronous cycloaddition (borderline two-step mechanisms). The geometries of the transition states are near planar with respect to P, C, C, and O atoms. Analysis of the bond indices of these reactions shows that the C–C bonds are between 44% (unstabilized case) and 60% (stabilized case) formed, whereas the corresponding P–O bonds have not been formed to any significant degree. Oxaphosphetane decomposition can be described as a very asynchronous retrocycloaddition where P–C bond breakage runs ahead of C–O bond breakage. These results are compared with experimental findings for the Wittig reaction, and its relevance to the overall mechanism of the olefination is discussed. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 557–569, 1997 相似文献
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