Synthesis of novel tri-podal mesogenic alkenes and side-chain polysiloxanes

Low molecular weight tri-podal biphenyl- and benzoate-type mesogens [C₆H₅C₆H₄O(CH₂)₅SiMe₂CH₂CH₂SiMe₂]₃CH (4), [C₁₁H₂₃O(C₆H₄)₂O(CH₂)₅SiMe₂]₃CH (5) and [MeOC₆H₄OC(O)C₆H₄O(CH₂)₅SiMe₂]₃CH (6) (C₆H₄ = 1,4-phenylene) were obtained, from branched silyl substituted methane precursors [CH₂CH(Me)₂Si]₃CH (1) and (HMe₂Si)₃CH (2). The biphenyl-containing ones (4) and (5) were converted into terminal alkenes, which were subsequently hydrosilylated with poly(methylsiloxanes). The polymer derived from (5) exhibited mesomorphic properties. Such systems have the potential to significantly increase the density of liquid crystal rod-like structures in side chains of linear polymers (or dendritic liquid crystal polymers).     

烟酸对酸性硫酸盐体系铜电沉积的影响

对溶液A: 0.8 mol•L－1硫酸铜,0.6 mol•L－1硫酸,5.0×10－5 mol•L－1氯离子,1.0×10－4 mol•L－1聚乙二醇的溶液,溶液B:在溶液A中加入2.0×10－2 mol•L－1烟酸,pH为0.5,运用循环伏安和计时安培法研究玻碳电极上铜的电沉积行为.结果表明,铜的电沉积过程经历了晶核形成过程,其电结晶按瞬时成核和三维生长方式进行.烟酸的加入对铜的电沉积具有阻化作用,但不改变铜的电结晶机理.沉积层的X射线衍射表明Cu为面心立方结构,在烟酸存在下沉积层出现(220)高择优取向,这可能是烟酸在Cu(220)晶面上发生强烈吸附作用的结果.     

Unicyclic Graphs with Minimal Energy

If G is a graph and ₁,₂,..., _n are its eigenvalues, then the energy of G is defined as E(G)=|₁|+|₂|++| _n |. Let S _n ³ be the graph obtained from the star graph with n vertices by adding an edge. In this paper we prove that S _n ³ is the unique minimal energy graph among all unicyclic graphs with n vertices (n6).     

钯催化下有机锡化合物的偶联反应在碳-碳键形成过程中的应用

本文述评了最近几年来钯催化的有机锡化合物与有机亲电试剂的交叉偶联反应在有机合成中用于碳-碳键形成的主要研究成果。主要讨论了直接交叉偶联反应,CO或烯键插入的交叉偶联反应和机理。     

A thermodynamic analysis on the coincidence of extrema conditions in the sorption equilibrium for ternary polymer systems

Flory-Huggins theory of polymer solutions has been used to express the condition of extrema values in the total sorption, as well as the inversion point in the preferential adsorption parameters for termary polymer systems. Two approaches have been followed, the first considers the binary and ternary interaction parameters independent of polymer concentration and solvent composition. In the second one, this dependence has been introduced. Our attention is focused on the volume fraction of solvent mixture dependence of the above parameters, in order to confirm or not the coincidence between the extrema values and the inversion point. Several cosolvent and cononsolvent ternary polymer systems, have been used to test the validity of the equations obtained. Also, it has been verified, from an experimental point of view, that in cosolvent ternary polymer systems there is coincidence in both compositions while in cononsolvent ternary polymer systems, such coincidence does not appear.     

Enhancing chemical analysis with signal derivatization using simple available software packages

Derivative techniques for analytical signal processing are useful for solving some noise and signal resolution problems in various fields of study such as titrimetry, spectrophotometry, chromatography and electrochemistry. The broad use of these techniques, however, is often limited by costly inflexible built-in software packages in commercial analytical instruments. We propose here the application of commercial simple software packages such as Microsoft® Excel and Microcal Origin for signal smoothing and fitting, and for obtaining derivative analytical signals in batch and flow-based analyses, including potentiometric titration, spectrophotometry, chromatography, voltammetry and sequential injection analysis (SIA). The worldwide (especially Excel) software packages are easy-to-use for less experienced users and have also capabilities for advanced users, and therefore employing such packages can result in expansion of useful derivative techniques. We demonstrate application of the available package-aided derivative capabilities for enhancing some chemical analyses, including potentiometric acid–base titration, Bradford assay of protein, chromatographic separation of ajmaline and reserpine and anodic stripping voltammetry of copper. The derivative signals from smoothed and fitted curves offer better accuracy and precision, even for non-resolving peaks and tailing peaks. In some cases, the optimization of experimental conditions is not further required, which can lead to fast method development.     

SYNTHESIS, CHARACTERIZATION, METAL-UPTAKE BEHAVIOR OF BIS（BENZIMIDAZOLE） RESIN SUPPORTED ON EPOXIDE POLYMER

The new chelate resins, abbreviated as PNBMZs and PBBMZs based on epoxide polymer, were synthesized by polycondensation of N,N-diglycidyl-4-glycidyloxyaniline or 1,4-bis（2,3-epoxypropyl）benzene with the primary amine group of 1,3-bis（benzimidazol-2yl）propylamine （BBPAH）. The ion exchangers contain 2.71-3.23 mmol of the ligand contents per gram of the resin. Batch extraction capacities were determined for the metal chloride salts in buffer solutions in the pH range from -1 to 6.0. The chelate resins were very selective for Cu^2＋, Zn^2＋, Cd^2＋ in the presence of other divalent transition metal ions. The maximum uptake capacities of PNBMZ （synthetic molar ratio = 1：1.5） under non-competitive condition were found to be 0.94 mmol/g for Cu^2＋ at pH = 2, 1.3 mmol/g for Cd^2＋ at pH = 1 and 1.75 mmol/g for Zn^2＋ at pH = -1 respectively. While in the case of PBBMZ, it was 1.39 mmol/g for Cd〉 at pH = 1. The metal-uptake behaviors for both of them showed strong pH dependence, and their extraction capacities increase with decreasing pH. The uptake of Cu^2＋ by the resin PNBMZs at pH = 1 was found to be rather fast with t1/2 = 18 min. Metal-uptake experiments under competitive conditions also confirm that the chelate resins have a high selectivity for Cu^2＋, Zn^2＋, Cd^2＋ and the contrary pH dependence.     

Synthesis and X-ray structural study of octa-coordinated hexafluoroacetylacetone hafnium(IV) complex

Hexafluoroacetylacetonate hafnium(IV) complex has been synthesized and studied by X-ray structural analysis. Crystal data for C₃₀H₈F₃₆Hf₂O₁₄ are: a = 12.957(3) Å, b = 16.687(3) Å, c = 12.398(3) Å, β = 108.97°, space group P2₁/c, Z = 2, d _calc = 2.137 g/cm³, R = 0.047. The molecular structure is built from discrete binuclear molecules of Hf₂(OH)₂(hfac)₆ composition; the Hf...Hf distance in dimer is 3.533 Å. The structural units are connected by van der Waals interactions in the crystal.     

（H2O）^＋n（n=1,2）的几何结构优化和振动光谱分析

采用Ｈａｒｔｒｅｅ－Ｆｏｃｋ和ＭＰ２方法在多种水平下优化了（Ｈ２Ｏ）＾＋ｎ（ｎ ＝１，２）的几何结构，并进行了振动光谱分析。结果表明：对（Ｈ２Ｏ）＾＋采用ＭＰ２／６－３１１＋＋Ｇ（ｄ，ｐ）可得出最满意的结论。     

Die multikomponenten Formen von Cellulase (EC 3.2.1.4) ausAspergillus oryzae

The enzyme cellulase fromAspergillus oryzae was resolved into four multiple forms, using anion exchange chromatography on DEAE Sephadex A-50 and gel filtration on Sephadex G-75. The stages of fractionation were followed by electrophoresis on cellulose acetate strips. These enzyme forms are characterized by different enzyme activities and isoelectric points.

Herrn Univ.-Prof. Dr.Hans Tuppy zum 65. Geburtstag herzlichst gewidmet.