配合物的稳定性与配体碱性之间的直线自由能关系——锌(Ⅱ)—芬布芬—α—氨基酸三元体系

LINEAR FREE ENERGY RELATIONSHIPS BETWEEN STABILITY CONSTANT OF COMPLEX COMPOUNDS AND BASICITY OF LIGANDS Zn(Ⅱ)-FENBUFEN-α-AMINO ACID TERNARY SYSTEM

在25±0.1℃,1=0.1 mol·L^(-1) KNO_3条件下,在80％(V/V)DMSO—H_2O混合溶剂中,应用pH法测定了甘氨酸,L—缬氨酸,L—丙氨酸,L—脯氨酸,L—丝氨酸和DL—笨丙氨酸等α—氨基酸(缩写为α—AA,记为B配体)的酸离解常数,Zn(Ⅱ)—α—AA二元配合物和锌(Ⅱ)—芬布芬—α—氨基酸三元配合物(芬布芬缩写为Fen记为A配体)的稳定常数。实验发现在logβ_(102)与pK_2~B,logβ_(111)与pK_2~B及logβ_(111)与logβ_(102)三对参数之间均存在良好的直线自由能关系,用△logK_M和△logβ_(111)二个参数描述了三元配合物相对于二元母体配合物的稳定性,讨论了溶剂的性质、配体分子间的疏水作用、堆积作用对配合物稳定性的影响。

The dissociation constants of glycine, valine, alanine, proline, phenylalanine and serine and stability constants of Zn (Ⅱ ) —α—amino acid binary complex compounds and Zn (Ⅱ)—a—Amino acid—Fenbufen ternary complex compounds have been determined by pH method at 25±0. 1℃ ,1=0. 1 mol · L^(-1)KNO_3 in 80% (V/V) DMSO—H_2O mixed solvent. These results show that the Linear Free Energy Relationships exist nicely between three pair parameters of logβ_(102) and pK_2~B, logβ_(111) and pK_2~B and logβ_(111) and logβ_(102). △logk_M and △logβ_(111) are used to characterize stability of ternary complexes related to stability of binary parent complexes. The factors contributing to the stability of the binary and ternary complexes are discussed.