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961.
烟酸对酸性硫酸盐体系铜电沉积的影响 总被引:2,自引:0,他引:2
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. 相似文献
962.
A kind of inorganic‐organic hybrid 18‐molybdodiphosphate nanoparticles ([(C4H9)4N]6P2Mo18Q62·4H2O) was firstly used as a bulk‐modifier to fabricate a three‐dimensional chemically modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior of the solid nanoparticles dispersed in the CPE in acidic aqueous solution was characterized by cyclic and square‐wave voltammetry. The hybrid 18‐molybdodiphosphate nanoparticles bulk‐modified CPE (MNP‐CPE) displayed a high electrocatalytic activity towards the reduction of nitrite, bromate and hydrogen peroxide. The remarkable advantages of the MNP‐CPE over the traditional polyoxometalates‐modified electrodes are their excellent reproducibility of surface‐renewal and high stability owing to the insolubility of the hybrid 18‐molybdodiphosphate nanoparticles. 相似文献
963.
TREN-Me-3,2-HOPO, TR322-Me-3,2-HOPO, TR332-Me-3,2-HOPO, and TRPN-Me-3,2-HOPO correspond to stepwise replacement of ethylene by propylene bridges. A series of tripodal, hexadentate hydroxypyridinone ligands are reported. These incorporate 1-methyl-3,2-hydroxypyridinone (Me-3,2-HOPO) bidentate chelating units for metal binding. They are varied by systematic enlargement of the capping scaffold which connects the binding units. The series of ligands and their iron complexes are reported. Single crystal X-ray structures are reported for the ferric complexes of all four tripodal ligands: FeTREN-Me-3,2-HOPO.0.375C(4)H(10)O.0.5CH(2)Cl(2) [P2(1)/n (No. 14), Z = 8, a = 20.478(3) A, b = 12.353(2) A, c = 27.360(3) A; beta = 91.60(1) degrees ]; FeTR322-Me-3,2-HOPO.CHCl(3).0.5C(6)H(14).CH(3)OH.0.5H(2)O [P2(1)/n (No. 14), Z = 4, a = 12.520(3) A, b = 22.577(5) A, c = 16.525(3) A; beta = 111.37(3) degrees ]; FeTR332-Me-3,2-HOPO.3.5CH(3)OH [C2/c (No. 15), Z = 8, a = 13.5294(3) A, b = 19.7831(4) A, c = 27.2439(4) A; beta = 101.15(3) degrees ]; FeTRPN-Me-3,2-HOPO.C(3)H(7)NO.2C(4)H(10)O [P1 (No. 2), Z = 2, a = 11.4891(2) A, b = 12.3583(2) A, c = 15.0473(2) A; alpha = 86.857(1) degrees, beta = 88.414(1) degrees, gamma = 70.124(1) degrees ]. The structures show the importance of intermolecular hydrogen bonds and the effect of cap enlargement to the stability and geometry of the metal complexes throughout the series. All protonation and iron complex formation constants have been determined from solution thermodynamic studies. The TREN-capped derivative is the most acidic, with a cumulative protonation constant, log beta(014), of 25.95. Corresponding values of 26.35, 26.93, and 27.53 were obtained for the TR322, TR332, and TRPN derivatives, respectively. The protonation constants and NMR spectroscopic data are interpreted as being due to the influence of specific hydrogen-bond interactions. The incremental enlargement of ligand size results in a decrease in iron-chelate stability, as reflected in the log beta(110) values of 26.8, 26.2, 26.42, and 24.48 for the TREN, TR322, TR332, and TRPN derivatives, respectively. The metal complex formation constants are also affected by the acidity of a proximal (non-metal-binding) amine in the complexes, a trend consistent with the effects of internal hydrogen bonding. The ferric complexes display reversible reduction potentials (measured relative to the normal hydrogen electrode (NHE)) between -0.170 and -0.223 V. 相似文献
964.
Anwar Usman Ibrahim Abdul Razak Suchada Chantrapromma Hoong‐Kun Fun Varughese Philip A. Sreekanth M. R. Prathapachandra Kurup 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(11):o652-o654
The title compound, C16H17N5S, is in the thione form and crystallizes with two independent molecules in the asymmetric unit. In both molecules, the pentamethyleneimine five‐membered ring adopts an envelope conformation, and in one of the molecules this ring shows positional disorder. The thione S and hydrazine N atoms are in the Z configuration with respect to the C—N bond. 相似文献
965.
报道了四种不同P/Pd摩尔比的膦化聚2,6-二甲基1,4-苯醚负载把催化剂的加氢和异构化性能;通过XPS、电镜和远红外对催化剂进行了表征;并考察了溶剂和温度对催化剂活性的影响. 相似文献
966.
Nanosize effect of ZrO2 in Au/ZrO2 catalyst was studied by deposition-precipitation of Au nanoparticles in similar sizes (4-5 nm) on ZrO2 nanoparticles of varying sizes. The catalysts were characterized with XRD, TEM, XPS, and nitrogen adsorption to understand the effect of ZrO2 particle size on the catalytic nanostructures. Nanocomposite Au/ZrO2 catalysts consisting of comparably sized Au-metal (4-5 nm) and ZrO2 (5-15 nm) nanoparticles are found advantageous over those containing similarly sized Au-metal but larger ZrO2 (40-200 nm) particles for CO oxidation. This finding may have important implications on the designed preparation of advanced nanostructured catalysts and other chemical materials. 相似文献
967.
In the presence of copper(I) iodide as catalyst, a variety of carbonyl compounds, such as aldehydes, ketones and acid anhydrous, could be trifluoromethylated with sodium trifluoroacetate to give the corresponding alcohols in moderate to high yields, and a possible mechanism was proposed to explain the roles of catalyst and solvent in the reaction system. 相似文献
968.
969.
Xiao-Bai Sun Pei-Hua Zhao Yang-Jun Xu Li-Mei Sun Mei-Ai Cao Cheng-Shan Yuan 《Chemistry of Natural Compounds》2007,43(5):563-566
Investigation of the roots of Polygonum bistorta L. afforded seven compounds including five triterpenoids, a coumarin, and a steroid, the structures of which were identified
by EIMS, 1H NMR, 13C NMR, DEPT, and HMBC experiments. All the compounds have been isolated from Polygonum genus for the first time.
Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 463–465, September–October, 2007. 相似文献
970.
酰胺是肽的基本结构单元, 而且在蛋白质的二级结构中与酰胺联系的氢键对蛋白质的稳定起着十分重要的作用. 作为蛋白质模型化合物热力学性质研究的一部分, 报道了甲酰胺在乙二醇水溶液中的稀释焓. 相似文献