EPR studies on H-abstractions/spin-trapping reactions of new 'magic blue' reagents with alcohols

The H-abstractions/spin-trapping reactions with primary, secondary and tertiary alcohols of new 'magic blue' reagents, namely, the blue F113 (CClF₂CCl₂F) solution containing bis{perfluoro[1-(2-fluorosulfonyl)ethoxy]ethyl} nitroxide (2) and perfluoro[1-nitroso-1-(2-fluorosulfonyl)ethoxy]ethane (3) both generated in the reaction of perfluoro[2-(2-fluorosulfonyl)ethoxy]propionyl peroxide (1) with sodium nitrite in F113 at room temperature, were studied by EPR. Based on the interpretation of the EPR spectra of the spin adducts, nitroxides, the region-selectivity of H-abstraction has been disclosed and the possible mechanistic paths of H-abstraction have also been discussed. EPR of H-abstraction by using 'magic blue' reagents can also be used for producing various hydroxyalkyl radicals from common alcohols.     

A New Hydroxo‐bridged Chromium(III) Dimer [Cr(saltn)OH]2·4H2O: Synthesis,Crystal Structure and Magnetic Properties

A new hydroxo‐bridged dimeric Cr(III) complex [Cr(saltn)OH]₂·4H₂O [H₂saltn=N,N′‐bis(salicylidene)trimethylenediamine] has been synthesized and its structural and magnetic properties have been investigated. The complex crystallizes in the triclinic space group P‐1 with one dimeric formula unit in a cell of dimensions a=0.95828(19) nm, b=0.95926(19) nm, c=1.0437(2) nm, α=86.77(3)°, β=82.48(3)°, and γ=64.93(3)°. The geometry around each chromium(III) center is six‐coordinate, distorted‐octahedral. The bridging Cr₂O₂ unit is strictly planar, as required by the crystallographic symmetry. The Cr? O? Cr′ bridging angle is 99.94(16)°, and the distance between Cr…Cr′ is 0.3019 nm. The magnetic susceptibility of the complex has been examined in the range of 2‐300 K. By using the spin‐spin coupled model for an S₁=S₂=3/2 dimeric system , the magnetic data were fitted to give the parameters of g=2.01(1), J=‐0.85(2) cm^‐1, and zJ' =0.18(3)cm^‐1, indicating the presence of a weak antiferromagnetic spin‐exchange interaction between the Cr(III) ions in the binuclear complex.     

丙烷直接氨氧化制丙烯腈催化剂的研究进展

丙烷直接氨氧化制丙烯腈是一条潜在的具有巨大经济效益的丙烯腈生产路线。本文概述了丙烷直接氨氧化制丙烯腈的催化反应机理，对丙烷直接氨氧化制丙烯腈的催化反应路径进行了归纳，同时对丙烷直接氨氧化制丙烯腈催化剂设计的思想以及日前所开发的几类丙烷直接氨氧化制丙烯腈催化剂体系加以了总结，重点介绍了锑酸盐和钼酸盐催化剂，对锑酸盐和钼酸盐催化剂活性相的结构、影响活性相形成的因素以及催化剂的结构与催化反应性能的关系等问题作了阐述。     

超微粒La-Co氧化物催化剂对柴油机尾气碳黑催化燃烧性能的研究

用有机酸络合法制备了Co3O4，NiCo2O4和LaCo2O43种催化剂。通过程序升温氧化反应(TPO)技术对这3种催化剂进行模拟柴油碳黑催化燃烧反应的活性评价。研究发现以Co3O4为活性成分的催化剂能显著降低碳黑燃烧的温度。以Ni和La部分取代Co3O4后形成的复合氧化物NiCo2O4和混合氧化物LaCo2O4能改进Co3O4的氧化活性。但是NiCo2O4不能改进碳黑在松散接触时的燃烧活性；而混合氧化物LaCo2O4由于形成了超微粒含缺陷的LaCoO3钙钛矿型结构，它具有良好的低温氧化活性和表面原子移动性，因而能显著改进碳黑在松散接触时的燃烧活性。     

水分子团簇结构的改变及其生物效应

概述了近30年来从水分子团簇结构的发现到水分子簇的稳定结构及相关理论计算的研究进展;总结了改变水分子团簇结构的四种方法．包括外加磁场、外加电场、激光辐射以及直接加热法．分别讨论了这四种方法的作用机理;最后简要介绍了改变水分子团簇结构所诱发的生物效应,并对该领域的研究前景作了展望。     

钡A-偶氮氯膦Ⅲ络合物探针分光光度法测定蛋白质

在pH 1.0～ 1.5的酸性介质中 ,蛋白质与Ba 偶氮氯膦Ⅲ络合物发生作用 ,导致络合物溶液褪色 ,其最大吸收波长处吸光度的降低值与蛋白质的浓度成正比。基于此建立了以Ba 偶氮氯膦Ⅲ络合物为光谱探针 ,分光光度测定蛋白质含量的新方法。该法灵敏度高 ,选择性好。蛋白质 (以牛血清白蛋白为例 )的浓度在 0～ 4 0mg/L范围内服从比尔定律 ,表观摩尔吸光系数ε656=6 .4 7× 10 5L·mol-1·cm-1。生物体内常见物质均不产生干扰 ,直接应用于人血清样品中蛋白质总量的测定 ,结果满意     

SYNTHESIS AND THERMAL PROPERTIES OF POLYBENZOXAZOLE FROM SOLUBLE PRECURSOR WITH HYDROXY-SUBSTITUTED POLYENAMINONITRILE

Aromatic polybenzoxazole (PBO) precursor, hydroxy-substituted polyenaminonitrile, was prepared by direct polycondensation of 1,4-bis(l-chloro-2,2-dicyanovinyl)benzene (CCB) and 4,6-diaminoresorcinol dihydrochloride (DAR) using pyridine and N,N-dimethylacetamide as condensing agent and solvent. The precursor has good solubility in polar aprotic solvent which is due to the strong dipolar nature of the main chain. The soluble precursor was subjected to thermal cyclization in an inert atmosphere to convert it into the corresponding PBO, which has its 5% weight loss temperature at 540℃ The fully cyclized PBO were characterized by FT-IR and TGA. The introduction of 10% mol 1,3,5-benzenetricarboxylic chloride (BTC) into the main chain not only has little effect on the solubility of PBO precursor but also raises its 5% weight loss temperature to 552℃ and char yield at 700℃ for the cyclized PBO with BTC.     

Synthesis of á-aminonitrile through Anodic Cyanation of N-benzylpiperidine

Electrochemistry behaviors including linear sweep voltammetry and cyclic voltammetry of tertiary cyclic amines with different substituted group were studied. The effect of different substituted group of the nitrogen on the oxidation potential was analyzed. The most suited potential used in α-aminonitrile synthesis through potentiostatic anodic cyanation of cyclic teritary amines was found. The anodic cyanation of N-alkyl-substituted cyclic six-membered amines including N-benzylpiperidine and…     

新型咪唑啉酮类Schiff碱的合成及其生物活性

新型咪唑啉酮类Schiff碱的合成及其生物活性;串联aza-Witing反应     

碳纳米管原子力显微镜针尖在结构生物学研究中的应用

碳纳米管以其较小的半径、较高的纵横比和高的柔韧性成为原子力显微镜对结构生物学进行研究的理想针尖。新的制备方法获得了亚纳米级半径的碳纳米管针尖,运用它们得到了生物大分子及其复合物的生物结构,并获得了新的生物信息,这用传统的原子力显微镜针尖是无法实现的。