Synthesis of new 1,3-bis（phenylethynyl）disilazanes

Three new 1,3-bis(phenylethynyl)disilazanes were synthesized from the reaction of 1,3-dichlorodisilazanes with (phenylethy- nyl)lithium,and characterized by infrared (IR) spectra,nuclear magnetic resonance (NMR) and mass spectrometry (MS).     

对酞内酰胺苯甲酰氯柱前衍生反应HPLC分析痕量多胺

本文提出了一种快速、简便、灵敏检测痕量多胺的新方法。用对酞内酰胺苯甲酰氯同多胺进行柱前衍生反应,以反相高效液相色谱定量测定多胺含量。在4～500 pmol范围内有良好的定量线性关系,腐胺、精脒和精胺的检测限均为0.1 pmol。     

吸附式增湿饱和器

本文介绍了美国GE公司DPG—300分流湿度发生器的工作原理。针对该发生器的增湿饱和度不够的缺陷,提出了改进措施。改进的方法是通过在增湿饱和器内放置能够吸附水的吸附材料而实现的。     

Probing the kinetic landscape of transient peptide-protein interactions by use of peptide (15)n NMR relaxation dispersion spectroscopy: binding of an antithrombin peptide to human prothrombin

Protein-ligand interactions may lead to the formation of multiple molecular complexes in dynamic exchange, affecting the kinetic and thermodynamic characteristics of the binding equilibrium. We followed the dissociation kinetics of the transient and specific complex of an antithrombotic peptide N-acetyl-Asp(55)-Phe-Glu-Glu-Ile-Pro(60)-Glu-Glu-Tyr-Leu-Gln(65) with human prothrombin by use of (15)N NMR relaxation dispersion spectroscopy of the peptide. Every one of the five (15)N-labeled adjacent residues of the peptide exhibited apparently different kinetic exchange and relaxation behaviors, which were especially evident at different concentrations of prothrombin. Binding-induced (15)N relaxation dispersion of residues Phe(56), Glu(57), Glu(58), and Ile(59) can be fitted phenomenologically to a two-site on-and-off exchange mechanism with physically feasible relaxation and kinetic parameters obtained for residues Phe(56), Glu(58), and Ile(59), independent of the prothrombin concentration. The apparent kinetic parameters of Glu(57) show some dependence on the concentration of prothrombin and the extracted transverse relaxation rate for Glu(57) in the bound state was severalfold higher than that expected for a protein-peptide complex with a size of approximately 72 kDa. In addition, the equilibrium population of the bound peptide obtained for Glu(57) was inconsistent with those for Phe(56), Glu(58), and Ile(59) and with the prothrombin/peptide ratios used in the experiments. These discrepancies can be explained by the presence of two conformations for the peptide-protein complex exchanging at a rate of approximately 100 s(-)(1). In all, our study shows that fast dissociation of protein-peptide complexes can be studied quantitatively using peptide (15)N NMR relaxation dispersion measurements without a precise knowledge of the peptide and protein concentrations. In addition, protein titration was found to improve the accuracy of quantitative analysis and may make it possible to determine the rate of conformational changes within the protein-peptide complex.     

FABRICATION OF SELF-ASSEMBLY DNA-C_(60) MULTILAYER FILMS

Electrostatic layer-by-layer self-assembly multilayer films were successfully fabricated from C_(60)-ethylenediamineadduct (C_(60)-EDA) and DNA. Under visible light irradiation, DNA is ready to be cleaved and the films are destroyed.     

PNPP Hydrolysis Catalyzed by Manganese(III) Complexes with Crowned Salicylaldimine Schiff Base Ligand

Four manganese(III) complexes (MnL¹Cl, MnL²Cl, MnL⁴₂Cl, MnL⁵₂Cl) with a crowned salicylaldimine Schiff base ligand have been synthesized and employed as models to mimic hydrolase in the hydrolysis of p-nitrophenyl picolinate (PNPP). The kinetics and mechanism of catalytic PNPP hydrolysis have been investigated. The kinetic mathematical model of PNPP cleavage catalyzed by these complexes has been proposed. The effects of the ligand structure and crown ether ring in complexes, and the reactive temperature on the rate of catalytic PNPP hydrolysis have been also examined. The results show that compared with the crown-free analogous MnL³Cl and MnL⁶₂Cl, the crowned Schiff base manganese(III) complexes, MnL¹Cl, MnL²Cl, MnL⁴₂Cl and MnL⁵₂Cl, exhibit more high catalytic activity, which follow the order: MnL¹Cl >MnL²Cl >MnL⁴₂Cl >MnL⁵₂Cl >MnL³Cl >MnL⁶₂Cl; the pseudo-first-order-rate (k_obs) for the PNPP hydrolysis catalyzed by the complex MnL¹Cl containing three crown ether rings is highest among six complexes and is 1.81 times that of MnL³Cl, 1.49 × 10³ times that of spontaneous hydrolysis of PNPP, respectively, at pH = 7.00, [S] = 2.0 × 10⁻⁴ mol dm⁻³.     

Synthesis,crystal structure and spectroscopic characterization of a hydrogen-bonded 1D copper(II) complex

Novel 1:2 and 1:1 (M:L) copper(II) complexes have been prepared from the tridentate ligand 2-(1-methyl-2-aza-5-oxapentyl)phenol (H₂L¹). The crystal structure of [Cu(HL¹)₂] (1) exhibits a noncentrosymmetric square-planar geometry with a slightly tetrahedral distortion. The Cu^II atom is coordinated by two amino N and two phenoxo O atoms of two (HL¹)^– ligands. The phenoxo and the alkoxy groups are involved in two strong intramolecular hydrogen bonds. The coordination moieties are further connected to a 1D linear structure by the action of intermolecular hydrogen bonds between the alkoxyl and the amino groups. The importance of steric hindrance introduced by the methyl group in the molecular structure and the packing of the complex molecules has been demonstrated. The e.p.r. parameters of (1) have been obtained: g = 2.231, g = 2.005, g _iso = 2.080, A = 185.0 G, A _iso = 86.5 G, A = (3A _iso – A )/2 = 37.3 G. These results confirm a distorted square planar stereochemistry with a ( )¹ ground state.     

Bitumen-clay interactions in aqueous media studied by zeta potential distribution measurement

A new method of measuring the amount of coalescence that occurs between drops during the emulsification process is proposed. The method uses a hydrophobic fluorescent probe, which is introduced into a fraction of the oil phase that is to be homogenized. The ratio of the intensity of the excimer peak to the intensity of the monomer peak in the fluorescent emission spectrum is sensitive to the concentration of the probe in the oil phase. Random coalescence events between oil drops lead to redistribution of the probe and its effective dilution in the oil phase. Coalescence results in a decrease in the intensity ratio in the fluorescence spectrum obtained from the ensemble of drops. Monte Carlo simulation is used to relate the change in intensity ratio to the coalescence rate. It is experimentally verified that the signal change is only due to coalescence and is not affected by the drop size of the distribution.     

PAMAM体型缩聚物的制备及其性能研究

以分子末端带有多官能度活泼端基的PAMAM等为原料 ,通过缩聚反应制备了一类新型体型缩聚物 .借助X射线光电子能谱仪 (XPS)对制备的体型缩聚物进行分析 ,利用其化学分析电子光谱 (ESCA)中碳元素价态的拟合数据判断体型缩聚反应进行的程度 ,数据表明酯基碳 (—COO)拟合峰已基本消失 ,说明其与氨基缩合反应转化为酰胺基 (—CON) ,且反应进行的比较彻底 .通过体型缩聚物在乙醇、正己烷、甲苯、氯仿、异丙醇、乙酸、甲酸、去离子水中进行溶胀试验 ,发现其在甲酸作为溶剂体系中的溶胀比出现最大值 ,根据溶度参数的意义估测体型缩聚物的溶度参数约为δ2 =2 7 6 (MJ m3) 1 2 (即甲酸的溶度参数 ) .对原料PAMAM以及制备的体型缩聚物进行DSC分析 ,发现制备体型缩聚物的玻璃化转变温度 (Tg)有了较大提高 ,从初始原料PAMAM的负值提高到 4 8℃左右 .     

自交联型丙烯酸酯共聚物乳液的研究

以羟甲基丙烯酰胺、丙烯酸作为活性单体，采用种子乳液聚合法制得四元体系自交联型丙烯酸酯共聚物乳液。用透射电镜观察了乳胶粒的微观形态，并对共聚物乳液的流变性，稳定性等进行了测试，考察了羟甲基丙烯酰胺和丙烯酸的含量、聚合方式对共聚物乳液性能的影响。