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71.
单核铁(Ⅲ)双卟啉配合物在溶液中的构象平衡及其对环己烷羟化反应的催化活性的影响 总被引:1,自引:0,他引:1
合成及表征了一系列以柔韧碳氢链相连不同长度的p/p型单核铁(Ⅲ)双卟啉配合物,以可见光谱首次观察到该系列配合物在氯仿溶液中开放式及闭合式构象的平衡,发现680nm处吸收峰强度与这种构象平衡有关,烷氧链越长,该吸收峰强度越大.利用该类配合物模拟了细胞色素P450单加氧酶对环己烷的羟化作用,催化结果表明,在以分子氧为氧源及还原剂存在的温和条件下,该类配合物的催化活性显著高于单核铁卟啉(FeTPPCl),随着柔韧碳氢链长度的增加,双卟啉的催化活性依次增加.高的催化活性与双卟啉配合物在溶液中的构象平衡,即闭合式构象引起的立体位阻及电子转移有关. 相似文献
72.
金属络合物的相转移催化分析与分离 总被引:2,自引:0,他引:2
以可简单分离回收、可反复使用为目标,详细介绍了相转移催化的变化发展过 程.通过对溶剂的选择,使得催化剂选择性地溶解在某一液相中,而使产物溶解在 另一液相中,如水-有机两相催化体系;通过温度的变化,简单地实现了在较高温 度下反应为均相体系以提高催化剂的活性,而在较低温度下实现了催化剂与产物不 相溶使得催化剂得以简单分离,如温控型水-有机两相催化体系、氟-有机两相催化 体系、温控型含氟催化剂、温控型有机金属催化剂等. 相似文献
73.
The action of a series of lanthanide chelate complexes LnL3, where Lu=La, Pr, Nd, Sm, Eu, Dy, Ho, Er and Yb; L= dbm (dibenzoylmethanato), dpm (dipivaloylmethanato), and acac acetylactonato), on nmr spectra of 2-butanol has been studied. The origin of shifting abilities and shifting sign of various lanthanide ions are explained by means of Bleaney's theory. 相似文献
74.
肝素化聚甲基硅氧烷-聚氧乙烯接枝物的合成及其体外抗凝血性能评价 总被引:5,自引:0,他引:5
以二甲基硅油接枝端羟基聚氧乙烯(PDMS g PEO OH)为基材,用二环己基碳二亚胺(DCCI)作脱剂,研究了羟基(OH)与肝素上的羧基(—COOH)之间的脱水缩合反应,制备出肝素化的抗血栓材料PDMS g PEO Hep,并对其涂覆表面的肝素含量和体外抗凝血性能进行了初步评价.实验结果表明,肝素接枝的共聚物具有优良的抗凝血性能和一定的应用前景. 相似文献
75.
以硫醇为螯合剂, 在溶剂热条件下合成了两种层状硫代亚碲酸盐KAgTeS3 (1)和RbAgTeS3 (2). X射线单晶解析表明, 1和2是类质同晶化合物. 在晶体结构中, 银硫四面体通过共用顶点形成无限的平行链, 在相邻链中银硫四面体取向相反, 这些链与链由三角锥配位的碲互相连接形成阴离子层状结构, 阳离子在阴离子层间. 1的结晶学数据为: Mr=370.75, P21/c, a=0.73639(6) nm, b=1.06468(8) nm, c=0.85203(6) nm, β=106.4640(10)°, V=0.64062(8) nm3, Z=4, R(F)=4.44%, wR(F2)=11.66%. 2的结晶学数据: Mr=417.12, P21/c, a=0.75531(12) nm, b=1.07076(7) nm, c=0.8583(2) nm, β=106.497(6)°, V=0.66558(19) nm3, Z=4, R(F)=6.00%, wR(F2)=15.43%. DSC及紫外-可见漫反射光谱研究表明, 这两种化合物为半导体, 并具有很好的热稳定性. 相似文献
76.
77.
D. S. Hwang W. M. Choung Y. K. Kim J. H. Park S. J. Park 《Journal of Radioanalytical and Nuclear Chemistry》2002,254(2):255-262
The formation property of Mo precipitate was investigated and improved the existing process was using H2O2 that acts as an interfering compound in a subsequent alumina adsorption process. The property of the Mo precipitate was investigated by using SEM, FTIR, TG-DTA, and XRD. The simulated solution consisted of 1M nitric acid containing seven elements (Mo, I, Ru, Zr, Ce, Nd, Sr) and their radioactive tracers. As a result, the precipitate was composed of the Mo precipitate and re-precipitated a-benzoinoxime which was added excessively for increasing the precipitation efficiency. It was confirmed that the Mo precipitate was formed by the reaction of two a-benzoinoxime molecules and one MoO2
2+. Molybdenum precipitate was dissolved in 0.4M NaOH solution within 5 minutes without H2O2. Hydrogen peroxide induced only the rapid dissolution of the a-benzoinoxime re-precipitate. Also, the dissolution method without H2O2 was favorable in the purification aspect because Zr and Ru were contained as a small fraction of 1.3% and 7.7%, respectively, in the dissolving solution. 相似文献
78.
N-(α-Alkoxyalkyl)benzotriazoles were synthesized via the condensation of benzotriazole with various aldehydes and alcohols catalyzed by acidic ionic liquid [hmim]HSO4 at room temperature. The yield was up to 99%. This novel method was effective when triethoxymethane was utilized instead of alcohols. Moreover, acidic ionic liquid could be reused easily with no significant degradation of its catalytic activity. 相似文献
79.
Simultaneous anodic oxidation and cathodic reduction of aldoses in a divided flow cell were studied. The stream of the anolyte was an aqueous solution containing D-glucose, sodium bromide, and sodium bicarbonate. The stream of the catholyte was also an aqueous solution containing xylose and sodium sulfite. The factors which affected both the anodic and cathodic reactions were studied. The results indicate that the flow rates and temperatures of the anolyte and the catholyte, concentrations of the aldoses, pH values and the material of electrodes significantly affect both anodic and cathodic yields. The selectivities of gluconic acid in the anode and xylitol in the cathode were very high. The power consumption of paired electrolysis in the flow system was less than paired electrolysis in a batch system. 相似文献
80.
Gregory M. Anstead Kathryn E. Carlson Philip R. Kym Kwang-Jin Hwang John A. Katzenellenbogen 《Photochemistry and photobiology》1993,58(6):785-794
Abstract The absorption and emission characteristics of five hydroxytetrahydrochrysenes substituted with acceptor groups (nitro, cyano, methylketone, 1° amide and methyl ester) (THC-NO2, THC-CN, THC-COCH3, THC-CONH2 and THC-CO2CH3, respectively) were investigated in an extensive set of solvents. The order of absorption and fluorescence bathochromicity are: THC-NO2 > THC-COCH3 > THC-CN ≥ THC-CO2CH3 > THC-CONH2 and THC-NO2 >> THC-COCH3 > THC-CO2CH3 > THC-CN > THC-CONH2, respectively. The emission spectra of these compounds are sensitive to the solvent polarity (ET[30] scale) in the order: THC-NO2 > THC-COCH3 > THC-CO2CH3 > THC-CONH2 > THC-CN. The response of the emission maxima of these compounds to the solvent polarity and hydrogen-bond donor/acceptor properties (π*/α/β and acity/basity scales) was also determined. The emission energies of THC-NO2 were most sensitive to π*, β, acity, and basity of the solvent; those of the amide were least sensitive to the solvent π*, β, and basity. The ground- and excited-state dipole moments were determined by semiempirical molecular orbital calculations and the absorption/fluorescence solvent-shift method, respectively. THC-NO2 had the largest ground- and excitedstate moments. The ester and amide had the smallest ground- and excited-state moments, respectively. In general, unsatisfactory results were obtained for correlations of the emission and absorption energies, fluorescence solvatochromism and the ground- and excited-state dipole moments with the Hammett substituent constants of the five acceptor groups. Acceptable correlations were obtained for the absorption and emission energies and the fluorescence solvatochromism with the substituent constants if the cyano compound was excluded. 相似文献