三元混配配合物分子内的芳环堆积作用(Ⅴ)Ca(Ⅱ)/核苷酸/杂环碱体系

The Intramolecular Aromatic-Ring Stacking Interaction of the Ternary Mixed-Ligand Complexes (Ⅴ)Calcium(Ⅱ)/Nucleotide/Heterocycilic Ring Base System

用ｐＨ电位滴定法测定了Ｃａ（Ⅱ）与腺苷５’－三磷酸（ＡＴＰ）和芳香杂环碱Ａ（Ｐｈｅｎ，Ｂｐｙ和Ｔｒｐ）形成的三元混配配合物Ｃａ（Ａ）（ＡＴＰ）ｎ－（ｎ＝２或３）的稳定常数（Ｉ＝０．１，ＫＮＯ３，２５℃）．比较了三元混配配合物与三元配合物的稳定性大小，其差值ΔｌｇＫＣａ要比预期的统计值ΔｌｇＫｓｔ来得大．

The stability constants of the ternary mixed-ligand complexes Ca(A)(ATP) n- (A=Phen,Bpy,and Trp;ATP=adenosine 5′-triphosphate;n=2 or 3)have been determined by potentiometric pH titration in aqueous solution(I=0.1,KNO 3;25℃).The difference of stability between the ternary complexes and the binary complexes has been compared and discussed,which is greater than the expected value of ΔlgK st .This increasing stability is due to the cooperative effect of π-acid-π-base and the intramolecular aromatic-ring stacking interaction in the ternary mixed-ligand complexes.