杂环型稳定硅烯插入HF、H_2O和NH_3反应

硅烯为卡宾的硅类似物,在有机光和热化学中作为一类重要的反应活性中间体引起了化学界的广泛兴趣.杂环型硅烯是实验合成的稳定硅烯,因其在有机硅化学中的重要作用,十几年来在实验和理论上均有研究报道.本文基于单重态杂环型硅烯的特殊电子性质和丰富的化学反应性,系统探讨了几种杂环型硅烯的插入反应.使用密度泛函理论(DFT),在B3LYP/6-311++G(d,p)水平上研究了三种氮杂环型不饱和硅烯(1,3,4)和两种氮杂环型饱和硅烯(2,5)分别与H—X(X=F,OH,NH2)键的插入反应,阐明了插入反应的机理并对各反应的结果进行了比较.杂环型硅烯与H—X的插入反应机理类似于简单硅烯,体现了硅烯的亲电亲核的双重反应性.由反应势垒和反应热看,五种硅烯与H—X键的插入反应均为HF最容易,H2O次之,NH3最难.饱和硅烯的反应性比不饱和硅烯的反应活性高,这也间接验证了杂环型饱和硅烯在实验中较难合成.     

Fixation of CO_2 by electrocatalytic reduction to synthesis of dimethyl carbonate in ionic liquid using effective silver-coated nanoporous copper composites

<正>With high surface area,open porosity and high efficiency,a catalyst was prepared and firstly employed in electrocatalytic reduction of CO_2 and electrosynthesis of dimethyl carbonate(DMC).The electrochemical property for electrocatalytic reduction of CO_2 in ionic liquid was studied by cyclic voltammogram(CV).The effects of various reaction variables like temperature,working potential and cathode materials on the electrocatalytic performance were also investigated.80%yield of DMC was obtained under the optimal reaction conditions.     

Pattern and feature designed growth of ZnO nanowire arrays for vertical devices

An approach is demonstrated for growing aligned ZnO nanowire/nanorod arrays following a predesigned pattern and feature with controlled site, shape, distribution, and orientation. The technique relies on an integration of atomic force microscopy (AFM) nanomachining with catalytically activated vapor-liquid-solid (VLS) growth. The pattern and growth locations are defined by the catalyst distribution created by AFM, and the orientation is determined by the epitaxial growth on a single-crystal substrate. The technique opens a variety of possibilities of using nanowire arrays as sensor arrays, piezoelectric antenna arrays, nanolasers, photonic band gap crystal, biosensors, and field emitters with controlled density, location, shape, and distribution according to a designed pattern and feature.     

Determination of Ba, Fe, Sr, and Zr in silicate materials with ED-XRF using241Am excitation source

The possibilities of ED-XRF with²⁴¹Am excitation source are evaluated in the analysis of geological materials: rocks, clays, soils, and sediments. The calibration curves are made using different SRM's. Data from the analysis of various SRM's are presented.     

Evolution of quasi-stationary states of an electron in an open spherical quantum dot

Physics of the Solid State - A theory of the evolution of spectral parameters of quasi-stationary states of an electron in an open spherical quantum dot is proposed in terms of the effective-mass...     

A mononuclear manganese(III) complex of an asymmetric macrocyclic ligand with a ring contraction [MnHL2(ClO4)](ClO4) · 2.5H2O

The template reaction of sodium 2,6-diformyl-4-chlorophenolate and N,N-bis(2-aminoethyl)–hydroxyethylamine followed by in situ transmetallation of Mn(ClO₄)₂ results in a mononuclear manganese(III) complex of one 21-membered asymmetric 2:2 Schiff base macrocycle, in which a hydroxyethyl group of the amine has been eliminated and ring contraction at one chamber of the macrocycle has occurred to form an imidazolidine ring. An X-ray study indicates that the geometry about the manganese(III) ion is distorted octahedral. The electrochemical behavior of this complex in MeCN has been studied by cyclic voltammetry.     

Synthesis and nonlinear optical properties of novel Y‐type polyurethane containing tricyanovinylthiazole with enhanced thermal stability of second harmonic generation

A novel Y‐type poly[iminocarbonyloxyethyl‐5‐methyl‐4‐{2‐thiazolylazo‐4‐(1,2,2‐tricyanovinyl)}resorcinoxyethyloxycarbonylimino‐(3,3′‐dimethoxy‐4,4′‐biphenylene)] 4 containing 5‐methyl‐4‐{5‐(1,2,2‐tricyanovinyl)‐2‐thiazolylazo}resorcinoxy groups as nonlinear optical (NLO) chromophores, which constitute part of the polymer backbone, was prepared and characterized. Polyurethane 4 is soluble in common organic solvents such as acetone and N,N‐dimethylformamide. It showed a thermal stability up to 250 °C in thermogravimetric analysis thermogram and the glass‐transition temperature (T_g) obtained from differential scanning calorimetry thermogram was around 118 °C. The second harmonic generation coefficient (d₃₃) of poled polymer films at 1560 nm fundamental wavelength was around 8.43 × 10^?9 esu. The dipole alignment exhibited a thermal stability even at 12 °C higher than T_g, and there was no SHG decay below 130 °C due to the partial main‐chain character of the polymer structure, which is acceptable for NLO device applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1166–1172, 2010     

Labdane Diterpenes and Flavonoids from Leonurus japonicus

Chemical investigation of the aerial part of Leonurus japonicus led to the isolation and characterization of a new labdane‐type diterpene, named 3α‐acetoxy‐15‐O‐methylleopersin C ( 3 ), and a new acylated rutin derivative, named 2′′′‐syringylrutin ( 9 ), along with seven known compounds, including a labdane‐type diterpene and six flavonoids. The structures of the new compounds were established by spectroscopic methods.