超(近)临界水中的有机合成反应

作为一种环境友好的化学工艺过程,以超(近)临界水作有机合成反应介质越来越受到人们的关注。人们考察了在超(近)临界水中的许多有机反应,并获得了预期的结果。综述了近年来超(近)临界水中的有机合成反应的研究进展。     

景洪哥纳香化学成分研究

景洪哥纳香为蕃荔枝科哥纳香属植物,主要分布在我国云南省。为了从该属植物中寻长新类型的抗肿瘤化合物,我们通过药理筛选,发现哥纳香根的醇提取物对人肿瘤细胞培养系有较强的素毒性。以生物活性跟踪为手段,指导分离景洪哥纳香根的醇提取物,得到38个化合物,通过光谱学及化学方法,确定其中两个化合物是新化合物,分别命名为哥纳香醌及哥纳香呋喃并呋喃酮丙亚基化物。     

纳米碳管电子结构和键合特性的第一原理研究

利用第一原理方法对一系列尺寸变化的单层纳米碳管电子结构进行了研究,得到了总态密度和态密度随碳管半径R的变化情况与实验结果完全一致,Fermi能级处态密度值随着管径R的增大而减小,说明纳米管的化学活性随着管径的增大而增强。碳管中C-C之间的键合为2s和2p价电子混合而成的弯曲的σ,π键,随着管径R的增大,化学键的弯曲度逐渐减小,C-C之间的键合作用和结合能逐渐增强,电荷密度和对应的势场也逐渐减弱。这些结果表明管径较小的纳米碳管在复合材料的合成中具有一定的优势。     

Pt及其修饰电极上乙醇吸附和氧化的CV和EQCM研究

运用电化学循环伏安和石英晶体微天平研究了乙醇在Pt电极和以Sb,S吸附原子修饰的Pt(Pt/Sbad和Pt/Sad)电极上的吸附和氧化过程。结果表明乙醇的氧化与电极表面氧物种有着极其密切的关系。Pt电极表面Sb吸附原子能在较低的电位下吸附氧,可显著提高乙醇电催化氧化活性。相反,Pt电极表面S吸附原子的氧化会消耗表面氧物种,抑制了乙醇的电氧化。本文从表面质量变化提供了吸附原子电催化作用的新数据。     

一种锰的超分子化合物的制备、结构及非线性光学 性质研究

用MnSO4·H2O,KSCN,六次甲基四胺(HMTA)制备出超分子化合物[Mn(NCS)2(H2O)2(HMTA)2][Mn(NCS)2(H2O)4](H2O)2,并测定了其晶体结构。该化合物由[Mn(NCS)2(H2O)2(HMTA)2],[Mn(NCS)2(H2O)4]和H2O三部分组成,每一个HMTA配体中仅有一个N原子与Mn原子配位,剩余的3个N分别与[Mn(NCS)2(H2O)4]中的H2O及结晶H2O之间形成氢键。[Mn(NCS)2(H2O)2(HMTA)2]和[Mn(NCS)2(H2O)4]之间通过N…H—O氢键边接成无限延伸的线性长链,链与链、以及链和结晶H2O之间通过七种形式的氢键构成三维结构的超分子。用Z-扫描法测定该化合物在DMF溶液中的三阶非线性光学性质,发现它具有自聚焦效应,三阶非线性折射系数n2=9.52×10^-9m^2·W^-1,非线性极化率χ^(3)=3.41×10^-12esu.     

Carbon nanotube-polymer nanocomposites: The role of interfaces

Research aimed at producing new nanocomposites with improved properties has dramatically increased in the last decade, especially on materials tailored at a nanometric level, such as fullerenes and carbon nanotubes. The use of nanoforms as reinforcement of organic polymers has opened the possibility of developing novel ultra-strong and conductive nanocomposites. Nevertheless, the challenge of manufacturing multifunctional composite materials based on nanostructures is still open, in particular in the details of the corresponding interfacial properties, which are particularly relevant in these systems. This paper reviews the main technical activities in this field, focusing on the most important parameters that influence the behavior of their interface, discussing recent advances, as well as current and future trends in research.     

Stabilization of solvent-impregnated resins (SIRs) by coating with water-soluble polymer and chemical cross-linking and its application in mercury removal

Stabilization of solvent impregnated resins was achieved by the formation of a surface coating with the absorptive layer of poly(vinyl alcohol) and cross-linking with the protective layer of vinyl sulphone (VS). Amberlite XAD-4 and vinyl sulphone proved to be effective matrix and cross-linking agents, respectively, in the preparation of a protective layer of SIRs containing Cyanex 923 as extractant. The stabilized SIRs were characterized by the amount of vinyl sulphone contributing to the N and S content in the stabilized resin as well as to its operational stability. Optical and single electron microscope pictures were used to examine the appearance and the morphology, respectively, of the external protective barrier of SIR. Batch and column mode of sorption/elution studies for the removal of mercury from aqueous solution at pH 4 were carried out with Cyanex 923 containing SIR coated with PVA cross-linked with VS. Stabilized SIR was found to be effective for the mercury removal and showed great stability during the batch recycle runs. Elution of mercury from SIR was quantitatively achieved with 3M HNO₃. Kinetic and column performances were influenced by the degree of cross-linking of resin coating. Chemical stability and sorption capacity of stabilized SIR remained almost constant after several recycle runs whilst uncoated SIRs lose extractant with time as confirmed by efficiency studies.     

含Cu咪唑桥联异多核配合物的合成、表征及ESR研究

用具有低自旋d^6构型的[(NH3)5MIm]^2^+, [(en)2Co(Im)2]^+(M=Co, Rh; Im^-为咪唑基)为配体与配位未饱和的含Cu单核配合物作用, 定向合成了八种新的咪唑桥联含Cu异双核、异三核和异五核配合物。对它们进行了元素分析、差热失重分析、摩尔电导测定及反射光谱研究, 确证了配合物的组成及分子中咪唑桥的存在, 通过对各配合物的ESR谱测定, 得到了它们的自旋Hamilton参数和键参数, 讨论了配合物的成键性质。     

绣毛野桐化学成分的研究I:野桐酮的化学结构

从海南岛产大戟科植物特有种绣毛野桐(Mallotus anomalusMeer et Chun)中, 分得两个结晶, 其一为ent-Kaurenc型新二萜野桐酮(anomaluone,1)。另一结晶为已知物橙酰胺乙酸酯(aurantiamideacetate)。     

抗坏血酸在普鲁士蓝薄膜修饰电极上的电催化氧化

本文详细研究了普鲁士蓝(PB)薄膜本身电荷传输过程的动力学及PB 薄膜催化抗坏血酸(AH2)电氧化的动力学。 用电位阶跃计时电流法和计时电量法, 恒电流计时电位法测得PB膜中电荷传输表观扩散系数Dct平均为2.62×10ˉ10cm2·sˉ1; 用RDE法测得AH2在PB薄膜上催化氧化的速率常数为1.23×10^8cm3·molˉ1·sˉ1。催化反应对AH2为一级。 只发生在PB薄膜与溶液的界面上。 整个催化过程受到溶液中的传质、膜内部的电荷传输及膜与溶液界面上交叉反应三种因素单独或联合控制, 实际出现四种动力学情况。