Nickel‐Catalyzed C?H Alkylations: Direct Secondary Alkylations and Trifluoroethylations of Arenes

A versatile nickel catalyst allowed for C H alkylations of unactivated arenes with challenging secondary alkyl bromides and chlorides. The high catalytic efficacy also set the stage for direct secondary alkylations of indoles as well as C H trifluoroethylations with ample substrate scope.     

Cycloadditions of 1H-1,3-Benzazaphospholes with o-Chloranil

NH-Functional 1H-1,3-benzazaphospholes 1a–1c and o-chloranil (tetrachloro-o-benzoquinone - TCBQ) undergo rapid [1+4]-cycloaddition in a 1:2 molar ratio to give 2a – 2c as high-melting zwitterionic σ⁶λ⁵-phosphorus compounds. In the case of 2a the yield is high (rel. to TCBQ) even if the reactants were used in a 1:0.5 molar ratio. For the 2-tert-butyl-substituted compounds 2b and 2c the yields were significantly lower, in part by unidentified byproducts. Addition of excess TCBQ to crude 2c containing unconverted 1c did not increase but strongly decrease the amount of 2c . Crystallization and XRD analysis led to detection of a minor side or consecutive product 3c , formally corresponding to P=C bond cleavage and [1+4] cycloaddition of three equivalents TCBQ, two at the phosphinidene and one at the carbene end. NMR spectroscopic data of 2a – 2c including conclusive ¹³C data for 2a give evidence of the structures of the new compounds.     

A time-dependent density functional study on optical response in all-inorganic lead-halide perovskite nanostructures

Recently, all-inorganic perovskite nanostructures have become a hot research topic due to their unique optical response and novel properties. Here, we theoretically study the optical response in Cs₂PbX₄ and CsPb₂X₅ (X = Cl, Br, and I) nanostructures. First, to study the ground state, we calculate the band structures of the periodic system using the HSE06 method, which shows that all those periodic perovskites possess the direct band gaps, with distribution from 2.225 to 3.536 eV. Their valence band maximum are mainly contributed from both halogen and lead atoms, while the conduction band minimum are mainly contributed from lead atoms. Then, we study the excited state using the time-dependent density functional theory method and find that, with the increase of halogen atom radius, the photogenerated carrier concentrations in perovskite nanostructures become larger, while the surface plasmon resonance becomes localized rather than long-range. Moreover, through the analysis of photocurrent and local field enhancement, Cs₂PbX₄ and CsPb₂X₅ nanostructures exhibit nearly 40 μA photocurrent along the direction of optical polarization. Besides, by regulating the different anions, we predict that field enhancement in Cs₂PbI₄ and CsPb₂I₅ share a much stronger distribution at both the center and border parts of Pb-I planes due to localized plasmon resonance, while other perovskites are distributed at the edge parts of Pb-I planes, caused by long-range plasmon resonance. Our research shows that all-inorganic perovskite nanostructures are great candidate materials for developing optoelectronic devices working in high-frequency and high-energy regions and improving their application in sensitive detection and sensors.     

Theoretical studies on the infrared spectrum of the tetrahedral molecules R<Subscript>2</Subscript>MH<Subscript>2</Subscript> (R = D(H), CH<Subscript>3</Subscript>, OH; M = Ti,Zr, Hf)

Using Stuttgart/Dresden effective core potentials MWB28, MWB60, and GTO valence basis sets (8s7p6d)/[6s5p3d], (8s7p6d)/[6s5p3d] for Zr and Hf atoms and 6-311++G(3df,3pd) basis set for C, H, O, and Ti atoms, tight convergence criteria geometry optimizations and harmonic frequency calculations are performed at B3LYP and B3LYP/IEF-PCM levels of theory so as to model the gas phase and argon matrix infrared spectra of the tetrahedral molecules R₂MH₂ (R = D(H), CH₃, OH; M = Ti, Zr, Hf). Influence of the transition metal and/or substituent group on the symmetric and asymmetric stretching frequencies of the MH₂ fragment of the R₂MH₂ molecules is investigated at both the levels of theory. The modelling of the argon matrix effect improves the agreement between the calculated frequencies and the experimental ones. The calculated argon matrix to gas phase frequency shifts is compared reasonably to the experimental argon to neon matrix shifts.     

Photocatalytic Activities for Water Splitting of RuO_2-loaded MGa_2O_4（M=Zn,Ni） with d~（10） Configuration

MGa2O4(M=Zn,Ni) rods with similar crystallinity and BET surface area were prepared via a facile template-engaged reaction.The photocatalytic activities for water splitting of RuO2-loaded MGa2O4(M=Zn,Ni) were investigated under high-pressure Hg lamp.RuO2-loaded ZnGa2O4 catalyst exhibited much higher photocatalytic activity than RuO2-loaded NiGa2O4.Factors affecting the photocatalytic activities of RuO2-loaded MGa2O4(M=Zn,Ni) were discussed.It was suggested that the electronic structure of oxide semiconductor was a predominant factor of the photocatalytic behavior for RuO2-loaded MGa2O4(M=Zn,Ni).     

ANiN(A=Li,Na,Mg,Ca)的结构、热力学、弹性和电子性质的第一性原理研究

三元过渡金属氮化物ANiN(A=Li,Na,Mg,Ca)是潜在的可充放电池的电极材料.物理性质,比如热稳定性、电子能隙以及弹性稳定性等,对于这些材料的电池应用都是非常重要的.本文使用第一原理方法,对比研究了 ANiN这些材料的结构、动力学、弹性和电子结构性质.对状态方程和声子谱的计算被用来确定体系的稳定结构.对最稳定结...