配位化合物分子内配体间的疏水缔合作用(Ⅱ)——镉(Ⅱ)、钴(Ⅱ)-邻二氮菲-氨基酸体系  

Intramolecular Ligand-Ligand Hydrophobic Interaction in Coordination Compounds (Ⅱ)--Systems of Cd^(2+)(Co^(2+))-Phenanthroline-Amino-Acids System

作　　者：高恩君[1] 朱宁[1] 刘祁涛[2] 

机构地区：[1]沈阳化工学院精细化工系,沈阳110021 [2]辽宁大学化学系

出　　处：《高等学校化学学报》1993年第6期755-759,共5页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金

摘　　要：pH电位法研究了镉(Ⅱ)、钴(Ⅱ)与邻二氮菲和甘氨酸、丙氨酸、缬氨酸、亮氨酸、苯丙氨酸和色氨酸等配体在37℃、离子强度I=0.02(NaCl)条件下形成12组混配配合物的稳定常数。lgK_(MAB)~M、△lgK和lgX值表明,亮氨酸、苯丙氨酸和色氨酸的混配配合物具有额外稳定性,并从配体间疏水缔合作用方面对该稳定性进行了重点讨论。The stabilities of binary complexes of type MB, MB2 and the mixed ligand complexes of type MAB have been studied by potentiometric pH titration technique at 37℃ and at ionic strength I= 0. 02(NaCI), where M = Cd(Ⅱ)orCo(Ⅱ); A = phenanthroline; B = glycine, alanine, valine, leucine, phenylalanine and tryptophan. The logarithm of stability constants IgKMABM, the logarithm of equilibrium constants △lgK of reaction MA+MB 5(?)MAB+M and the logarithm of equilibrium constants IgX of reaction M A2 + MB2(?)2MAB have been calculated. The results show that the six mixed ligand complexes containing leucine, phenylalanine or tryptophan as one of the ligands have an enhanced stability, because their △lgK and IgX are distinctly higher than the corresponding statistically expected values, even becoming positive values. The possible reasons that lead to these special results have been discussed from the viewpoints of π electronic back donation from the metal ions to the aromatic amine molecule and of the intramolecular ligand-ligand hydrophobic interactions presented in the mixed ligand complexes. After analysing the experimental data, we come to the conclusion that the major reason for the enhanced stability of above mentioned six mixed ligand complexes is the intramolecular hydrophobic interaction between the aromatical ring of phenanthroline and hydrophobic moieties of these amino-acids. The variation order of △lgK or IgX is Try>Phe>Leu, which is consistent with the size of hydrophobic moieties of amino-acids.The equilibrium constants, K1 of transfer between the opened species (absence of ligand-ligand interaction) and the closed species (hydrophobic interaction having occured) and the percentage of the. closed species have been calculated for each of the six mixed ligand complexes (Table 3).The results show that the closed species of the mixed ligand complexes containing amino-acid with aromatical ring moiety as a ligand have become the major components in solution.

关 键 词：配位化合物 镉 钴 氨基酸 疏水缔合 

分 类 号：O614.242[理学—无机化学]