oxidation catalysis employing bromine has remained largely unexplored. We herein show that the combination of a tetraalkylammonium bromide and meta‐chloroperbenzoic acid offers a unique catalyst system for the convenient and selective oxidation of saturated C(sp3)−H bonds upon photochemical initiation with day light. This approach enables remote, intramolecular, position‐selective C−H amination as demonstrated
Synthesis, characterization and use of highly stable trimethyl sulfonium tin(IV) halide defect perovskites in dye sensitized solar cells
作者:Mohamed M. Elsenety、Andreas Kaltzoglou、Maria Antoniadou、Ioannis Koutselas、Athanassios G. Kontos、Polycarpos Falaras
DOI:10.1016/j.poly.2018.05.001
日期:2018.8
We report here on the crystal structure and physical properties of ((CH3)(3)S)(2)SnX6 (X = Cl, Br, I) compounds as well as the application of ((CH3)3S)(2)SnI6 in dye-sensitized solar cells. Powder X-ray diffraction and Rietveld analysis show that the materials form a cubic structure with a OD network of [SnX6] octahedra, which can be considered as a defect variant (AB(0.5)X(3)) of the perovskite archetype (ABX(3)). The electronic band gaps of ((CH3)(3)S)(2)SnX6 were determined by UV-Vis reflectance spectroscopy at 4.1, 2.9 and 1.4 eV for X = Cl, Br, and I, respectively. The direct bandgap and its relative decrease in the order of light to heavy halide was independently verified by density-of-states calculations. According to Raman spectroscopy, the lattice vibrations also depend largely on the halogen atom. The air-stable and non-toxic ((CH3)(3)S)(2)SnI6 compound was incorporated in electrolyte-free, dye -sensitized solar cells based on the Z907 chromophore chemisorbed onto mesoporous titania electrodes. A power conversion efficiency of 5% is achieved for these photovoltaic devices, confirming efficient charge transport in the bulk ((CH3)(3)S)(2)SnI6 and hole extraction at the perovskite-Pt interface. (C) 2018 Elsevier Ltd. All rights reserved.
BORREDON, E.;CLAVELLINAS, F.;DELMAS, M.;GASET, A.;SINISTERRA, J. V., J. ORG. CHEM., 55,(1990) N, C. 501-504
作者:BORREDON, E.、CLAVELLINAS, F.、DELMAS, M.、GASET, A.、SINISTERRA, J. V.