A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constant...A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.展开更多
对M髤[M=Co,Ni and Cu]与L-多巴（L）和1,10-菲咯啉（X）在的1,4-二氧杂环己烷（DOX）-水混合物【0~60%（V/V）】三元配合物体系在（303.0±0.1）K和离子强度为0.16 mol.L-1情况下进行pH滴定。结果表明：对Co髤和Cu髤而言,三元物种...对M髤[M=Co,Ni and Cu]与L-多巴（L）和1,10-菲咯啉（X）在的1,4-二氧杂环己烷（DOX）-水混合物【0~60%（V/V）】三元配合物体系在（303.0±0.1）K和离子强度为0.16 mol.L-1情况下进行pH滴定。结果表明：对Co髤和Cu髤而言,三元物种为MLX2H,MLXH,ML2X和MLX,但对Ni髤而言,三元物种为MLX2H,MLXH和MLX。三元物种的稳定性和浓度随介质的介电常数的变化趋势根据静电和非静电力作出解释。同时还给出了物种在不同pH值的DOX-水混合物中的分布图。根据滴定曲线推论了各种二元和三元配合物的生成。用两种方法解释了三元配合物比对应的二元配合物稳定的原因。展开更多
A novel Schiff base N＇-[1-（3-aminophenyl）ethylidine]isonicotinohydrazide was prepared and its complexation behavior towards some selected lanthanides had been studied employing pH-metric and calorimetric titration ...A novel Schiff base N＇-[1-（3-aminophenyl）ethylidine]isonicotinohydrazide was prepared and its complexation behavior towards some selected lanthanides had been studied employing pH-metric and calorimetric titration and spectral techniques, pH-metric studies were carried out for the trivalent La, Pr, Nd, Sm, Eu, and Gd complexes in 30% aqueous-dioxane medium at constant ionic strength of 0.05 mol/L NaClO4 and at different temperatures of 293, 303 and 313 K. The proton-ligand formation constants of the ligand indicated the presence of only one dissociable proton while the metal-ligand formation constants were compatible with the formation of 1：1 Ln（III） complexes. The stability of the complexes followed the order： La3＋〈pr3＋〈Nd3＋〈Sm3＋〈Eu3-〉Gd3＋, showing a break at gadolinium. The thermodynamic parameters, AG, AH and AS associated with protonation and complexation reactions were negative which suggested that all reactions were exothermic and enthalpy-driven. Isothermal calorimetric studies of Gd3＋-aeINH systems at 303 K also showed exothermic nature of the complexation reaction and formation of 1：1 complex in agreement with the pH-metric data. Formation of 1：1 complexes was confirmed by the characterization of Nd（III） complex. A seven coordinated geometry was assigned for the complex based on its elemental and spectral data.展开更多
文摘A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.
文摘对M髤[M=Co,Ni and Cu]与L-多巴（L）和1,10-菲咯啉（X）在的1,4-二氧杂环己烷（DOX）-水混合物【0~60%（V/V）】三元配合物体系在（303.0±0.1）K和离子强度为0.16 mol.L-1情况下进行pH滴定。结果表明：对Co髤和Cu髤而言,三元物种为MLX2H,MLXH,ML2X和MLX,但对Ni髤而言,三元物种为MLX2H,MLXH和MLX。三元物种的稳定性和浓度随介质的介电常数的变化趋势根据静电和非静电力作出解释。同时还给出了物种在不同pH值的DOX-水混合物中的分布图。根据滴定曲线推论了各种二元和三元配合物的生成。用两种方法解释了三元配合物比对应的二元配合物稳定的原因。
基金Department of Science & Technology, New Delhi (SR/SI/PC-39/2003)
文摘A novel Schiff base N＇-[1-（3-aminophenyl）ethylidine]isonicotinohydrazide was prepared and its complexation behavior towards some selected lanthanides had been studied employing pH-metric and calorimetric titration and spectral techniques, pH-metric studies were carried out for the trivalent La, Pr, Nd, Sm, Eu, and Gd complexes in 30% aqueous-dioxane medium at constant ionic strength of 0.05 mol/L NaClO4 and at different temperatures of 293, 303 and 313 K. The proton-ligand formation constants of the ligand indicated the presence of only one dissociable proton while the metal-ligand formation constants were compatible with the formation of 1：1 Ln（III） complexes. The stability of the complexes followed the order： La3＋〈pr3＋〈Nd3＋〈Sm3＋〈Eu3-〉Gd3＋, showing a break at gadolinium. The thermodynamic parameters, AG, AH and AS associated with protonation and complexation reactions were negative which suggested that all reactions were exothermic and enthalpy-driven. Isothermal calorimetric studies of Gd3＋-aeINH systems at 303 K also showed exothermic nature of the complexation reaction and formation of 1：1 complex in agreement with the pH-metric data. Formation of 1：1 complexes was confirmed by the characterization of Nd（III） complex. A seven coordinated geometry was assigned for the complex based on its elemental and spectral data.
