【摘要】 用PH-电势法研究了锌(Ⅱ)-芳香氮碱(Ar)-氨基酸(Aa)三元配合物在溶液中的稳定性,其中Ar为2,2′-联吡啶或1,10-邻菲咯啉;Aa为甘氨酸,丙氨酸,缬氨酸,亮氨酸,苯丙氨酸和色氨酸.以稳定性数据为探针,结合~1H NMR谱的研究,讨论了在上述某些三元配合物中可能发生的分子内配体间疏水缔合作用.计算了这些配合物分子的异构化平衡常数及平衡时闭式分子的百分率.结果表明,在含有芳香侧基的氨基酸配体的三元配合物溶液中,闭式异构体已成为配合物的主要存在形式.初步研究了溶剂对配体间疏水缔合作用的影响.更多还原

【Abstract】 The stability constants of the ternary complexes of type MAB and of the corresponding binary complexes MA, MA2, MB and MB2 have been determined by potentiometric pH titration technique at 25+0.1℃ and at 0.10 ionic strength (NaNO3), where M = Zn2+; A = bipyridyl (bipy), phenanthroline (phen); B = glycinate (gly), alaninate (ala), valinate (val), leucinate (leu), phenylalaninate (phe) and tryptophanate (trp). The results combining with those of 1H NMR research confirmed that the intramolecular hydrophobic interaction between ligands of the abovementioned ternary complexes, except those with gly or ala as one of the ligands, obviously presented. The interaction strengthens in the aminoacid ligand order.- val < leu 《phe < trp, which corresponds with the order of hydrophobic qualities of the noncoordinating hydrophobic moieties in these aminoacid ligands. The equilibrium constants of transfer between open species (absence of ligand-ligand interaction) and close species (hydrophobic interaction having occurred) have also been calculated. The results show that the close species of the ternary complexes with phe or trp as one of ligands have become the major components presented in solution. The solvent influence on the hydrophobic interaction between ligands has also been studied initially.更多还原