Defect calculations with quasiparticle correction: A revisited study of iodine defects in CH3NH3PbI3

Defect levels in semiconductor band gaps play a crucial role in functionalized semiconductors for practical applications in optoelectronics;however,first-principle defect calculations based on exchange-correlation functionals,such as local density approximation,grand gradient approximation(GGA),and hybrid functionals,either underestimate band gaps or misplace defect levels.In this study,we revisited iodine defects in CH₃NH₃PbI₃ by combining the accuracy of total energy calculations of GGA and single-electron level calculation of the GW method.The combined approach predicted neutral Im_i to be unstable and the transition level of Im_i(+1/-1)to be close to the valence band maximum.Therefore,Im_i may not be as detrimental as previously reported.Moreover,Vm I may be unstable in the-1 charged state but could still be detrimental owing to the deep transition level of Vm I(+1/0).These results could facilitate the further understanding of the intrinsic point defect and defect passivation observed in CH₃NH₃PbI₃.     

盐酸甲胺三化铬对快肟的氧化反应

本文报导利用盐酸甲胺三化铬氧化列解肟基的研究结果。在二甲基醛胺溶液中,盐酸甲胺三化铬能够有效地将肟氧化成相应羟化合物,而不氧化分子内的酚羟基和双键。     

Ethylenebis(<Emphasis Type="Italic">N</Emphasis>-methylimidazolium) Chlorochromate (<Emphasis Type="Italic">EBMICC</Emphasis>): An Efficient and Selective Reagent for the Oxidation of Thiols to Disulfides

Summary. Ethylenebis(N-methylimidazolium) chlorochromate was prepared by addition of N-methylimidazole to 1,2-dibromoethane to form the corresponding dibromide salt and subsequent treatment of this salt with CrO₃ in 6N HCl solution. It is a stable yellow-orange solid, which oxidized thiols to the corresponding disulfides at room temperature. Selective oxidation of thiols in the presence of sulfides and hydroxyl groups was also achieved with this reagent.     

Short‐Range Order of Methylammonium and Persistence of Distortion at the Local Scale in MAPbBr3 Hybrid Perovskite

Short‐range investigation by means of variable‐temperature neutron total scattering and pair distribution function analysis revealed that the local environment around the methylammonium (MA) cation in MAPbBr₃ hybrid perovskite is maintained through the different phase transitions observed as a function of temperature. In addition, the orthorhombic distortion of the lattice is present at any temperature. Local structure around MA changes from static to configurationally averaged or dynamic with temperature but the local structure of the low‐temperature orthorhombic phase is preserved.     

Pyridinium chlorochromate oxidation route to polyaniline

In this work, for the first time, pyridinium chlorochromate is used as an oxidizing agent inorder to oxidize aniline to polyaniline salts via an aqueous polymerization pathway in the presence of protic acids such as sulfuric, nitric, hydrochloric and phosphoric acid. The polymer samples were characterized by infrared, electronic absorption spectral, elemental analysis, conductivity, density and water absorption measurements. The results of the polyaniline salts prepared by pyridinium chlorochromate as an oxidizing agent were compared with that of the polyaniline salt prepared by ammonium persulfate. Generally, aniline is oxidized using ammonium persulfate as an oxidizing agent, which is unstable. In this work, pyridinium chlorochromate is used to oxidize aniline to polyaniline salt and the polymerization reaction could be completed in 30 min. Copyright © 2003 John Wiley & Sons, Ltd.     

N-Methyl Morpholine Chlorochromate: An Efficient Reagent for Oxidation of Primary and Secondary Alcohols to Carbonyl Compounds

Instantaneous generation of N-methyl morpholine chlorochromate (NMMCC) is an efficient reagent for oxidation of primary and secondary alcohols to the corresponding carbonyl compounds. The comparison of reaction time and product yield was studied with novel NMMCC and other chlorochromate reagents and shows that the presented method requires less reaction time with good yield at laboratory temperature. The synthesis of reagent, formation of toxic and hazardous chromylchloride have been avoided, and also use of NMMCC under microwave irradiation for oxidation leads to fast reaction time and success of the strategy.     

AlCl3/PCC-SiO2-Promoted Oxidation of Azaindoles and Indoles

Abstract

A simple and efficient method is described for the oxidation of 7-azaindoles and indoles to 7-azaisatins and isatins using pyridinium chlorochromate–silica gel (PCC-SiO₂) with the aid of Lewis acid catalyst aluminium chloride (AlCl₃) in dichloroethane. Simplicity of the reaction conditions, easy workup procedure, and good yields are the key features of this protocol.     

三氧化铬二吡啶、三氧化铬吡啶盐酸盐——两种有效的专用氧化剂

近年来,文献[1]陆续报道了多种能选择地将伯、仲醇氧化为醛和酮的专一氧化剂,例如四醋酸铅吡啶,铬酸叔丁酯,Ｎ氯代丁二烯亚胺,二甲硫醚,硝酸氨铈,三氧化铬的吡啶溶液,其中有些氧化剂制备较复杂,或是制备成本较高,使之应用范围较窄。而三氧化铬的吡啶溶液由于氧化醇时条件温和,产物分离方便,在近年来得到了广泛的应用,例在合成前列腺素和甾体的醛的中间体时,得到了几乎定量的产物。我们对三氧化铬吡啶溶液中最具代表性的氧化剂三氧化铬二吡啶及三氧化铬吡啶盐酸盐的合成、应用及氧化机理作了一些探讨。1　实验部分11　试剂和仪器文中所用试剂…