氯化1-乙基-3-甲基烷基咪唑分子结构及其氢键作用能的密度泛函研究

采用量子化学密度范函方法计算研究了氯化1-乙基-3-甲基咪唑盐（[EMIM]C1）正负离子间相互作用的平衡构型和Cl^-离子从不同方位与咪唑阳离子的结合能．计算发现Cl^-可在咪唑环平面上结合形成离子键，其结合能为．368．97kJ／mol，还可与环上的三个H原子形成氢键，其氢键键长和结合能分别为0．2000nm／-378．03kJ／mol、0．2339nm／-344，69kJ／mol和0．2301nm／-346，01kJ／mol．结合能包括氢键作用能和正负离子的静电作用能，后者为主要贡献．从理论上展示了该离子液体的氢键结构．     

Fine characterization of the ethylene and ethane sorption in poly(amide 12-block-tetramethylenoxide) copolymer/AgBF4 membranes

Ethylene/ethane sorption characteristics were determined for dry Pebax™ (poly(amide 12-block-tetramethylenoxide) copolymer)/AgBF₄ membranes by using an electronic microbalance. The membranes containing 0.7 and 22 wt.% AgBF₄ showed a dual-mode sorption isotherm. The ethane isotherms for all the membranes were of the Henry-type, which is the normal sorption for gases in rubbery polymers. The abnormal presence of Langmuir sorption sites only for ethylene in the rubbery copolymer, never reported sofar, is attributed to the silver-based specific complexation sites. The silver salt which dissolved in limited amounts in the rubbery copolymer had a much smaller Langmuir sorption capacity than the salt that crystallized in the copolymer. The sorption kinetics indicate that the crystallized salt did adsorb slowly ethylene according to a zeroth-order kinetics, but not ethane. The gas uptake kinetics resulting from a step of the pressure surrounding the copolymer exhibited one stage for ethane but two stages for ethylene. For the latter, there was first a fast Fickian sorption stage, then a drift of the zeroth-order sorption of ethylene on salt crystals, which contributes for a large part to the total uptake. The zeroth-order sorption suggests that the sorbed ethylene amount in the second-stage is independent of the crystal-surface coverage. The value of the Fickian diffusion coefficient calculated by fitting the kinetics with a solution of the second Fick’s law was 5 × 10⁻¹² m²/s for both ethylene (the first stage) and ethane, and is typical for small organic compounds in a rubbery material.     

Structure of Low Temperature Phase b-Ba_3Y(BO_3)_3 Crystal

1 INTRODUCTION Recently the series of compounds M3Ln(BO3)3 (M = Sr, Ba and Ln = LaLu, Sc, Y) with space group P63cm or -3R have been reported[1～5], and some of them exhibit interesting optical properties when doped with the active Cr3+ or Yb3+ ions as laser materials. For example, Yb3+-doped Sr3Y- (BO3)3 crystal is a promising laser material for both tunable and femtosecond laser applications[6～8]. The Ba3Y(BO3)3 crystal melts congruently at 1256 ℃ and has a phase transitio…     

PREPARATION OF POLY（METHYL METHACRYLATE）/LAYERED DOUBLE HYDROXIDES NANOCOMPOSITES via in situ SOLUTION POLYMERIZATION

An exfoliated layered double hydroxides/poly(methyl methacrylate)(LDHs/PMMA)nanocomposite was prepared by in situ solution polymerization of methyl methacrylate(MMA)in the presence of 4-vinylbenzenesulfonate intercalated LDHs(MgAl-VBS LDHs).MgAl-VBS LDHs was prepared by the ion exchange method,and the structure and composition of the MgA1-VBS LDHs were determined by X-ray diffraction(XRD),infrared spectroscopy and elemental analysis.XRD and transmission electron microscopy(TEM)were employed to examine the structure of LDHs/PMMA nanocomposite.It was indicated that the LDHs layers were well exfoliated and dispersed in the PMMA matrix.The grafting of PMMA onto LDHs was confirmed by the extraction result and the weight fraction of grafted PMMA increased as the weight fraction of LDHs in the nanocomposites increased.     

环氧丙烯酸酯的紫外光固化

制备了适于配制紫外光固化涂料的环氧丙烯酸酯，研究了反应温度、阻聚剂、催化剂等因素对环氧树脂与丙烯酸反应的影响；讨论了反应机理和动力学；并利用红外光谱观察了产物的紫外光固化行为。季铵盐能有效地催化环氧树脂和丙烯酸的反应，当其用量为０．６％～１．２％时，在９０～１１０℃反应４．５～８小时后，环氧基转化率大于９７％。由此配制的光固化涂料经紫外光辐照能快速固化。     

Potential distribution around a charged spherical colloidal particle in a medium containing its counterions and a small amount of added salts

A theory is developed for the potential distribution around a charged spherical colloidal particle carrying ionized groups on the particle surface in a medium containing its counterions (i.e., counterions produced from dissociation of the particle surface groups) and a small amount of added salts on the basis of the theory of Imai and Oosawa. Numerical solutions to the Poisson–Boltzmann equation for the potential distribution are obtained for the case of dilute (but not infinitely dilute) particle suspensions of volume fraction 1 for a1 (where is the Debye–Hückel parameter and a is the particle radius). Here we have taken into account the effects of (i) counterions from the particle surface groups, and (ii) the finite particle volume fraction. These effects, which are usually neglected in the conventional Poisson–Boltzmann equation, are found to be important. It is found that, as in the case of completely salt-free media, there is a certain critical value of the particle charge (which is the same as that for the completely salt-free case). When the particle charge is lower than the critical value, the potential is given by a Coulomb potential. If the particle charge is higher than the critical value, then counterions are accumulated in the vicinity of the particle surface (counterion condensation) and the potential becomes less dependent on the particle charge. The above behaviors can be observed even for the case where the electrolyte concentration is higher than the concentration of counterions from the particle surface groups, if the conditions 1 and a1are both satisfied.     

A novel measurement method of Donnan potential at an interface between a charged membrane and mixed salt solution

We developed a novel measurement method of the Donnan potential difference at a charged membrane/salt solution interface. The method can measure the potential under the condition that the membrane charge density is much lower than the KCl concentration of the salt bridge. This method is very useful for obtaining the effective charge density of each layer of a bipolar membrane. The present experiments in a system of a negatively charged poly(vinyl alcohol) membrane and a single salt solution of KCl, NaCl, LiCl, CaCl₂ and LaC₃ revealed that the membrane effective charged density has the same value for all the ions. The experiments in mixed KCl and CaCl₂ solution revealed that the potential in the system is governed mainly by the concentration of the counterion having the highest valence in the system.     

Calculation of affinities of peptides for proteins

Several methodologies were employed to calculate the Gibbs standard free energy of binding for a collection of protein-ligand complexes, where the ligand is a peptide and the protein is representative for various protein families. Almost 40 protein-ligand complexes were employed for a continuum approach, which considers the protein and the peptide at the atomic level, but includes solvent as a polarizable continuum. Five protein-ligand complexes were employed for an all-atom approach that relies on a combination of the double decoupling method with thermodynamic integration and molecular dynamics. These affinities were also computed by means of the linear interaction energy method. Although it generally proved rather difficult to predict the absolute free energies correctly, for some protein families the experimental ranking order was correctly reproduced by the continuum and all-atom approach. Considerable attention has also been given to correctly analyze the affinities of charged peptides, where it is required to judge the effect of one or more ions that are being decoupled in an all-atom approach to preserve electroneutrality. The various methods are further judged upon their merits.     

相转移催化合成增塑剂BBP和水杨醛的研究

相转移催化合成增塑剂ＢＢＰ和水杨醛的研究郭锡坤，高文华，曾东宇（汕头大学化学系，汕头５１５０６３）关键词相转移催化，季铵盐，聚乙二醇，邻苯二甲酸丁苄酯，水杨醛，增塑剂邻苯二甲酸丁苄酯（增塑剂ＢＢＰ）是一种优良的增塑剂．邻羟基苯甲醛（水杨醛）不仅是重要...     

基于天然氨基酸的双环手性季铵盐相转移催化剂的合成及催化性能研究

以L－脯氨酸及L－羟基脯氨酸为原料合成了4个新型手性季铵盐磁相转移催化 剂，并用于催化不对称查耳酮环氧化反应，高产率得到相应环氧化合物，ee最高达 9％。