有机溶剂对三元混配物芳环堆积作用的影响

Influence of Organic Solvents on Intramolecular Aromatic-Ring Stacking in Ternary Mixed-Ligand Complexes

用pH电位滴定法测定了含 1 ,1 0 -邻菲绕啉 (Phen)和羧酸 (CA)配体的三元混配物Pd(Phen) (CA) +体系在不同浓度乙醇 -水溶液 ( 30 %～ 90 % ,V/V)中的稳定常数 ,比较和讨论了各种配合物之间的稳定性差异 ,并计算了三元混配物Pd(Phen) (PCA) +(PCA为 2 -苯乙酸和 3-苯丙酸 )中堆积异构体的百分数。实验结果表明 :三元混配物Pd(Phen) (PCA) +分子内的芳环堆积作用与溶液极性有关。溶液极性愈弱 ,分子内芳环堆积作用愈强 ,堆积异构体的百分数愈大 。

The stability constants of the ternary mixed-ligand complexes Pd(Phen)(CA) +(Phen=1,10-Phenanthroline and CA=carboxylate ligands)have been determined by potentiometric pH titration in aqueous ethanol solution with 30%～90%(V/V)concentration(I=0 1,KNO 3,25℃).The difference of stability among the different complexes has been compared and discussed,and the percentages of the stacked isomers in the ternary mixed-ligand complexes Pd(Phen)(PCA) +(PCA=2-phenylacetate and 3-phenylpropionate)was calculated.The experimental results indicate that the extent of the intramolecular aromatic-ring stacking interaction in the ternary mixed-ligand Pd(Phen)(PCA) +complexes depends on the polarity of the solution.The weaker the polarity of the solution,the more notable the intramolecular aromatic-ring stacking interaction,the larger the percentage of the stacked isomers in the ternary complexes,and the more stable the ternary mixed-ligand complexes.