On the magnetic properties of Lithium Vanadium Bronzes LixV2O5

Magnetic susceptibility of V₂O₅ and of the α-, ?-, δ- and γ-Li_xV₂O₅ bronzes prepared either at high or at room temperature has been measured between liquid helium and ambient temperature. The results are representative of the localized character of the V⁴⁺ ion d-electron and, for high enough x-values, of the existence of antiferromagnetic interactions in a low dimensional system. The intrachain exchange integral J has been determined using the Bonner/Fischer model for Heisenberg chains with S = 1/2 spin. It is larger for the γ- than for the δ-phase. This result as well as the occurrence of long range ordering below T_N ≈ 130 K in the γ-phase may be ascribed to ordering of V⁴⁺ and V⁵⁺ ions in the former bronze and to the random distribution of V⁴⁺ ions in the latter one.     

层状LiMnO_2正极材料的研究进展

层状LiMnO2 化合物的研究是目前锂离子电池正极材料锂锰氧化物研究工作的新热点 ,本文综述了近年来国内外LiMnO2 化合物的研究进展 ,主要阐述了具有层状和扭曲层状结构的m LiMnO2和o LiMnO2 的结构、电性能、合成和改性方法等方面的研究状况 ,重点介绍了离子交换法合成层状LiMnO2 的原因和机理。探索新的合成方法和掺杂其它金属离子改性以提高循环性能是今后LiMnO2 的研究趋势。     

Application of symplectic algorithms to QCT calculation:H+H_2 system

The basic theory of symplectic algorithm was introduced. A comparison between Runge-Kutta method and symplectic integration method was preformed in the simulation of the long time behavior of H + H2 system on BKMP potential energy surface. Our results reveal a dis-sipative behavior in the integral of ordinary differential equation by the fourth order Runge-Kutta method, which causes incorrect simulation results in QCT calculations. However, when the symplectic integration method is applied, the dissipative behavior is not found in the same system. When the initial state is the same, the energy deviation of fourth order symplectic integral method is almost one percent of that of fourth order Runge-Kutta method in a 60000-step simulation, and that of sixth order symplectic integral method is much less. These results show that the symplectic integral methods are always the better choice in the integral calculation of the long time behavior in maintaining energy conservation.     

N-heterocyclic carbenes as ligands in high-valent molybdenum and tungsten complexes

Oxometal complexes of molybdenum and tungsten in high oxidation states from stable adducts with 1,3-dimethylimidazoline-2-ylidene (L) 1. The first ‘carbene’ complexes of molybdenum(VI) [MoO₂Cl(L)₃]Cl (3a) and tungsten(VI) WO₂Cl₂(L)₂ (4b) are reported.     

B2O3/TiO2-ZrO2催化环己酮肟气相Beckmann重排反应研究Ⅱ.焙烧温度的影响

采用XRD、FT-IR和NH3-TPD等方法，研究了载体预焙烧温度和催化剂活化焙烧温度对B2O3/TIO2-ZRO2催化剂的结构、酸性和催化环己酮肟气相Beckmann重排反应性能的影响。结果表明，在383-773K范围内，载体预烧温度对催化剂性能的影响不大，但经973K高温预焙烧后，由于生成了ZrTiO4晶相，使其与H3BO3的相互作用减弱，从而导致催化剂的酸性和反应性能降低，提高催化剂活化焙烧温度，有利于B2O3与TiO2-ZrO2的相互作用，生成更多的Beckmann重排反应所需的中等强度酸中心，使催化剂的活性和选择性提高；但活化焙烧温度过高，会使催化剂中大量的B2O3晶粒析出，引起酸中心数量和催化活性的明显下降。     

[Co(amp)2Cl2]2[ZnCl4]体系中两对称异构体的2D NMR研究

The two symmetrical isomers in [Co(amp)₂Cl₂]₂[ZnCl₄](amp=2-(Aminomethyl)pyridine) system were syn-thesized by general oxidation method and were separated by chromatography and recrystallization method. Their configurations were assigned by using 2D NMR techniques, particularly the NOESY NMR spectra. Solvent used was Me₂SO-d₆ with the central peak of the CD₃ septet as the reference ( ₁₃C,δ 39.37; ₁H,δ 2.49 relative to SiMe₄). Cation exchange media used was Dowex 50Wx 2(H⁺ form, 200～400mesh; Biorad).     

复合Fe2O3纳米粒子的高分子微球的结构表征

近年来，复合有机、无机粒子的高分子微球及其特殊性质越来越引起人们的兴趣与关注［1］．获得有机、无机复合微球的方法很多，如在无机粒子存在下的乳液或无皂乳液聚会[2，3]，通过可聚合的表面活性剂在粒子表面形成胶囊化层[4]以及共沉淀法等[5]．这些无机粒子包括氧化钛、氧化铁、氧化铝及氧化硅等．Haga等[6]增发现包覆在聚合物粒子中的CdS与其本体的光电性质不同；单分散的聚合物微球可以在基片上被组装成二维乃至三维有序的结构[7]．这为信息存储、立体印刷等领域提供了新途径．因此，将无机粒子与聚合物复合成为功能化粒子是一项有…     

2-(N'-乙基咔唑-3'-烯基)-8-羟基喹啉的合成及理论研究

设计合成了2-(N'-乙基咔唑-3'-烯基)-8-羟基喹啉. 以UV-Vis, ¹H NMR, FT-IR, 元素分析和MS进行了结构表征, 并测定了产物的光致发光(PL)性质. 运用Gaussian98量子化学程序包, 采用B3LYP密度泛函(DFT)的方法, 在6-31G(d,p)水平上对分子的几何构型进行结构优化; 预测目标产物的振动光谱, 结果表明与实验值相符.     

Complete assignments of 1H and 13C NMR data for 10 phenylethanoid glycosides

Ten phenylethanoid glycosides, including two new ones, isolated from the aerial parts of the mangrove plant Acanthus ilicifolius were identified. The first complete assignments of the 1H and 13C NMR chemical shifts for these glycosides were achieved by means of 2D NMR techniques, including 1H-1H COSY, TOCSY, HSQC and HMBC spectra.