Density Functional Theory Study on Spin States of LaCoO3 at Room Temperature

The electronic structure of the perovskite LaCoO3 at room temperature structure （293 K） was calculated by using PBE, PBE＋U and HSE. Different spin configurations have been considered. Our calculations showed that the choice of the Hubbard U parameter in DFT＋U and mixing factor α in HSE significantly influenced the band gap as well as relative energies. For the spin exited states, the optimal value for U and α were 3.0 eV and 0.05, respectively. Our calculation also emphasized that when U〉5.0 eV, PBE＋U would lead to unreasonable electronic structure and energy order.     

新型的双阴离子型镱(Ⅲ)胺化物{[Me_2Si(NPh)_2]_2Yb[(N~iPr)_2CN(SiMe_3)_2]}{Li(THF)_2}_2的合成及晶体结构

A new dianionic guanidinate bridged diamide ytterbium(Ⅲ) complex {[Me2Si(NPh)2]2Yb[(NiPr)2CN(SiMe3)2]}{Li(THF)2}2 was synthesized by the reaction of bisguanidinate ytterbium chloride [(SiMe3)2NC(NiPr)2]2Yb(μ-Cl)2Li(THF)2 with silylene-bridged diamide lithium PhLiNSiMe2NLiPh.The complex was characterized by elemental analysis and IR.The molecular structure was further determined by X-ray diffraction techniques.The crystals are monoclinic,space group p 21/c,a=14.0001(8),b=17.6808(9),c=24.9565(16),β=95.994(3)...     

Spectra and structure of some silicon containing compounds: VII. Microwave spectra of (ch3)3SiCN and (CH3)3SiNC

The microwave spectra of trimethylsilylcyanide and trimethylsilylisocyanide have been recorded between 26.5 and 40.0 GHz. The B values for (CH₃)₃SiCN and (CH₃)₃SiNC were found to be 1995.308 MHz and 2197.32 MHz, respectively. The centrifugal distortion constant was found to be 0.00027MHz for (CH₃)₃SiCN. These rotational constants are consistent with calculations based on structural parameters from related molecules. The reaction products from the standard method of preparation used in this study were found to contain 5.3 % (CH₃)₃SiNC at 25 °C.     

The change of the vibrational frequencies of a chemisorbed diatomic caused by the electrostatic interactions with the metal surface

Results of density functional calculations are used to discuss the change of the vibrational frequency of an adsorbed molecule caused by the electrostatic interaction between a chemisorbed molecule — simulated by two effective charges — and a metallic surface.     

12-钨磷酸钙与丁二酰亚胺加合物的制备和性质研究

本文研究了12-钨磷酸钙与丁二酰亚胺和邻苯二甲酰亚胺的加合反应,制备了12-钨磷酸钙的丁二酰亚胺加合物Ca_(3/2)PW_(12)O_(40)·4(CH_2CO)_2NH·7H_2O,测定了加合物的红外光谱、拉曼光谱和热重差热分析曲线,用X射线粉末衍射方法研究了加合物的结晶学特征.结果表明.配体丁二酰亚胺以一个羰基氧与金属阳离子配位,加合物的形成对杂阴离子的Kcggin结构没有明显影响.但WO_6八面体发生一定的畸变.其中W-O_d键减弱,W-O_c键增强.加合物属单斜晶系,晶胞参数为:a=25.839(6).b=13.223(2),c=18.438(2)(?),β=97.06(2)°,V=6251.88(?)~3,可能的空间群为C_2h~5-P2_1/c或C_2h~2-P2_1/m或C_2~2-P2_1,品质因子F_(30)=54(0.012,45).     

多齿配体改性的氧化锆色谱固定相表面吸附方式的研究

氧化锆微球的化学稳定性好且机械强度高,作为色谱固定相基质具有很好的应用前景,利用其表面存在的大量的Lewis酸性中心与Lewis碱性化合物的强烈的酸碱作用可对氧化锆进行吸附改性,用无机磷酸、烷基膦酸APA、硬脂酸SA及乙二胺-N,N′-四亚甲基膦酸(EDTPA)等改性的氧化锆固定相被成功地用于中性、碱性甚至酸性化合物的分离。     

Hydrothermal Synthesis and Crystal Structure of a New 2D Mn（Ⅱ） Coordination Polymer with 4,4′-Sulfonyldi Benzoic Acid and 1,4-Bis（imidazol-1-ylmethyl）benzene Ligands

A novel manganese coordination polymer [Mn2(sfdb)2(biyb)2(H2O)2]n (1, H2sfdb=4,4′-sulfonyldibenzoic acid, biyb=1,4-bis(imidazol-1-ylmethyl)benze) has been hydrothermally synthesized and structurally characterized by single-crystal X-ray determination, IR and thermogravimetric analysis (TGA). Complex 1 crystallizes in the triclinic system, space group P with a=10.138(4), b=11.187(5), c=13.582(6) γ, α=69.146(7), β=89.628(7), γ=77.076(7)°, Mn2C56H48N8O14S2, Mr=1231.02, V=1398.5(10) ·3, Dc=1.462 g/cm3, F(000)=634, μ=0.600 mm-1, S=1.088 and Z =1. The final refinement gave R=0.0570 and wR=0.1229 for 4889 observed reflections with I > 2σ(I). Interestingly, in complex 1, the sfdb2- and biyb ligands connect the Mn(II) ions into two-dimensional 2-fold interpenetrating layers, and such layers are further connected with each other to generate a 3D supramolecular structure through hydrogen bonding interaction.     

Studies on the Electronic Structures and Spectra of C78（CH2）3

The structures and spectra of 20 possible isomers of C78(CH2)3 have been studied by using AM1,INDO/CIS and DFT methods. The results show that the most stable isomer is 1,2,3,4,5,6-C78(CH2)3 (A) with annulene structures,where three -CH2 groups are added to the 6/6 bonds located at the same hexagon passed by the shortest axis of C78 (C2v). Compared with that of C78 (C2v),the first absorption in the electronic spectrum of C78(CH2)3 (A) is blue-shifted because of its wider LUMO-HOMO energy gap. While the IR frequencies of the C–C bonds on the carbon cage are red-shifted owing to the formation of annulene structures and the extension of the conjugated system. The chemical shifts of the carbon atoms in 13C NMR spectra are moved upfield upon the addition.     

芦丁修饰电极研究多巴胺的电化学响应

通过循环伏安法(CV)制备了芦丁修饰电极,研究多巴胺(DA)在修饰电极上的电化学行为.结果表明,芦丁修饰膜对DA的氧化有明显的催化作用,并且可以消除抗坏血酸(AA)对DA测定的干扰.DA的浓度在1.0×10-7～9.5×10-6 mol/L范围内与其氧化峰电流呈线性关系,相关系数为0.9996,检出限为1.0×10-8 mol/L.将该修饰电极用于注射液样品中DA的测定,结果表明该修饰电极可用于实际样品分析.