分子内芳环堆积效应研究(Ⅵ)混配配合物Ca(Ⅱ)-UTP-HRB体系

Study on the Intramolecular Aromatic-Ring Stacking Interaction in the Ternary Mixed-Ligand Complexes(Ⅵ) Ca(Ⅱ)-UTP-HRB System

用pH电位滴定法测定了Ca(Ⅱ )与尿苷 5′ 三磷酸 (UTP)和芳香杂环碱HRB形成的三元混配配合物Ca(HRB) (UTP) n - (HRB =Phen ,Bpy和Trp ;n =2或 3)的稳定常数 (I =0 .1mol/L ,KNO3;2 5℃ ) .用ΔlgKCa比较了二元和三元混配配合物的稳定性差异 ,认为三元混配配合物稳定性的增加可归因于π -酸和π -碱之间的合作效应和分子内配体 配体间的芳环堆积作用 ,分子内芳环堆积效应的大小和参与堆积的芳环大小顺序一致 .

The stability constants of the ternary mixed ligand complexes Ca(HRB)(UTP) n- (HRB=Phen, Bpy and Trp;UTP=uridine 5′ triphosphate; n= 2 or 3)have been determined by potentiometric pH titration in aqueous solution (I=0.1 mol/L, 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 Δlg K 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.