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971.
In this article, equilibrium and kinetics of the ligand exchange reaction between a series of N,N-disubstituted dithiocarhamate chelates of Nickel (Ⅱ) have been studied by means of high-performance liquid chromatography in various solvents such as chloroform, dichloromethane, methylbenzene, ethyl acetate and DMF (dimethyl formamide) etc. at 30 ℃. The activation parameters of two selected reactions with different disubstituted alkyl groups have been determined in toluene. The experimental results indicate that steric effect of the alkyl groups may influence to some extent the rate of ligand exchange. The reactions of ligand exchange conform to an S_N2 mechanism. Statistical factor seems to enter the evaluation of the equilibrium constants. Solvation effect may contribute to the influence of solvents on reaction rate. 相似文献
972.
Chuan-xiang Chen Shao-lin Mu Department of Chemistry School of Sciences Yangzhou University Yangzhou China 《高分子科学》2002,(4):309-316
Polyphenol film deposited on platinum foil can continuously grow with time during the electrolysis of a phenolsolution consisting of 0. 1 mol L~(-1) phenol, 3 mol L~(-1) NaOH and 0.5 mol L~(-1) Na_2SO_4, as has been proved by the methods ofsweep potential, constant potential and constant current, and visible spectra during the electrolysis of phenol. A polyphenolfilm with thickness of 0.11 mm was obtained by the electrolysis of phenol at a constant potential of 0.70 V (versus Ag/AClwith saturated KCl solution). Polyphenol film is inactive and stable in 2 mol L~(-1) H_2SO_4 solution, neutral solution and3 mol L~(-1) NaOH solution and in the potential range between -0.95 and 1.35 V. The usable potential range is dependent onthe pH value. Polyphenol has an ESR signal with a g factor of 2.0049. The conductivity of polyphenol is 1.2×10~(-4) S cm~(-1). Inthe solution of polyphenol dissolved in DMSO, the mobility of polyphenol anions is 8×10~(-9) m~2 s~(-1) V~(-1) at 20℃. 相似文献
973.
Pérez-Morales M Muñoz E Martín-Romero MT Camacho L 《Langmuir : the ACS journal of surfaces and colloids》2005,21(12):5468-5474
The oxidative electrodeposition of NiTSPP (tetrakis(4-sulfonatophenyl) Ni porphyrin) on ITO electrode from 0.1 M NaOH aqueous solution has been studied, and UV-visible and reflection FTIR spectroscopies have been used to analyze the composition of such film. By use of UV-vis spectroscopy, small absorbance of the film and an almost nulling effect on the Soret band of the porphyrin along the Ni(III)/Ni(II) redox process were observed. The reflection FTIR spectroscopy detected the presence of Ni-OH groups in the reduced film and as well the state of the porphyrin molecules as radical cation. Moreover, the porphyrin has been quantified by means of the area of the vibration bands assigned to the sulfonate groups by using as reference a Langmuir-Blodgett film containing a known surface concentration of NiTSPP. These results lead us propose the formation of a conductor salt by electrocrystallization, with stoichiometries TSPP/Ni(II)(OH)2 and TSPP/Ni(III)OOH, for its reduced and oxidized forms, respectively. In these two forms, the porphyrin rings will be present as radical cation, which may be stabilized through its dimerization or polymerization. 相似文献
974.
新显色剂AsA-TB直接光度法测定球墨铸铁中铈组稀土 总被引:3,自引:0,他引:3
研究显色剂三溴偶氮胂 (AsA TB)与Ce4 + 的显色反应。在HCl和H2 C2 O4 介质中AsA TB与Ce4 + 生成蓝色的络合物。最大吸收波长位于 644nm ,试剂的最大吸收波长位于 5 2 7nm ,摩尔吸收系数为 1.2× 10 5L·mol-1·cm-1,铈含量在 4~ 30 μg 2 5ml范围内 ,符合比耳定律 ,测定了球墨铸铁中稀土含量 ,结果满意 相似文献
975.
聚丙烯加热改性制备大孔吸附树脂的工艺及其应用 总被引:4,自引:0,他引:4
This article reported the preparation of macro porous resin by heating polyproplyene and improving its property. The result showed that macro porous resin with good quality and big soil adsorption rote can be prepared when the ration of polypmplyene to soybean salad oil is 1 : 2, the highest heating temperture is 250℃, time of homothermal agitation is 20min and the rote of cooling is 2℃/min.The resin can effectively adsorb waste grease in restaurant wastewater. After removing grease, wastewater is treated with cogulant deposition. CODcr descend to 83mg/l from 790mg/l, which can reach the national discharge standards. 相似文献
976.
977.
Jean-Jacques Aaron Belkacem Laassis M. Carmen Mahedro Arsenio Muñoz de la Peña F. Salinas 《Journal of inclusion phenomena and macrocyclic chemistry》1994,18(1):69-79
The photo-oxidation reaction of phenothiazine has been studied in the presence of-cyclodextrin (-CD) and 2-hydroxypropyl-cyclodextrin (HP -CD). The influence of these organized media on the formation of the oxidation photoproduct upon UV irradiation has been investigated. Phenothiazine forms an inclusion complex with the cyclodextrins. The stoichiometry and formation constant of the complex formed with 2-hydroxypropyl -CD have been calculated using the changes of the fluorescence emission signal and of the absorbance of the drug upon inclusion. An increase of the fluorescence intensity of the photogenerated product is attained when it becomes included inside the cyclodextrin cavity. 相似文献
978.
979.
Garcia-Kirchner O. Muñoz-Aguilar M. Pérez-Villalva R. Huitrón-Vargas C. 《Applied biochemistry and biotechnology》2002,98(1-9):1105-1114
The efficient saccharification of lignocellulosic materials requires the cooperative actions of different cellulase enzyme
activities: exoglucanase, endoglucanase, β-glucosidase, and xylanase. Previous studies with the fungi strains Aureobasidium sp. CHTE-18, Penicillium sp. CH-TE-001, and Aspergillus terreus CH-TE-013, selected mainly because of their different cellulolytic and xylanolytic activities, have demonstrated the capacity
of culture filtrates of cross-synergistic action in the saccharification of native sugarcane bagasse pith. In an attempt to
improve the enzymatic hydrolysis of different cellulosic materials, we investigated a coculture fermentation with two of these
strains to enhance the production of cellulases and xylanases. The 48-h batch experimental results showed that the mixed culture
of Penicillium sp. CH-TE-001 and A. terreus CH-TE-013 produced culture filtrates with high protein content, cellulase (mainly β-glucosidase), and xylanase activities
compared with the individual culture of each strain. The same culture conditions were used in a simple medium with mineral
salts, corn syrup liquor, and sugarcane bagasse pith as the sole carbon source with moderate shaking at 29°C. Finally, we
compared the effect of the cell-free culture filtrates obtained from the mixed and single fermentations on the saccharification
of different kinds of cellulosic materials. 相似文献
980.
Ye K Wang J Sun H Liu Y Mu Z Li F Jiang S Zhang J Zhang H Wang Y Che CM 《The journal of physical chemistry. B》2005,109(16):8008-8016
The synthesis and single-crystal X-ray structures of two quinacridone derivatives, N,N'-di(n-butyl)quinacridone (1) and N,N'-di(n-butyl)-1,3,8,10-tetramethylquinacridone (2), are reported, and the 1H NMR, absorption, photoluminescent (PL), and electroluminescent (EL) characteristics are presented. Both these crystal structures are characterized by intermolecular pi...pi and hydrogen bonding interactions. The intermolecular pi...pi interactions lead to the formation of molecular columns in the solids of 1 and 2, and the interplanar contact distances between two adjacent molecules are 3.48 and 3.55 angstroms, respectively. Crystals of 1 display shorter intermolecular pi...pi contacts and higher density than 2. These results suggest that tighter intermolecular interactions exist in 1. The 1H NMR, absorption, and PL spectra of 1 and 2 in solutions exhibit concentration-dependent properties. The PL quantum yields of 1 in solutions decrease more quickly with the increase of concentration compared to that of 2 in solutions. For solid thin films of Alq3:1 (Alq3 = tris(8-hydroxyquinolinato)aluminum), emission intensities dramatically decrease and obvious red shifts are observed when the dopant concentration is above 4.2%, while for films of Alq3:2, a similar phenomenon occurs when the concentration is above 6.7%. EL devices with Alq3:1 as emitting layer only show high efficiencies (20.3-14.5 cd/A) within the narrow dopant concentration range of 0.5-1.0%. In contrast, high efficiencies (21.5-12.0 cd/A) are achieved for a wider dopant concentration range of 0.5-5.0% when Alq3:2 films are employed as emitting layer. The different PL and EL concentration-dependent properties of the solid thin films Alq3:1 and Alq3:2 are attributed to their different molecular packing characteristics in the solid state. 相似文献