铜(Ⅱ)-杂环碱-赖氨酸配合物的稳定性研究

Study on stability of coordination compounds formed from L-lysine,heterocyclic bases with Cu(Ⅱ)

用pH电位滴定法研究了在乙醇 水介质(φ(乙醇)=30%;I(NaClO4)=0.1mol/L,t=(25±1)℃)中Cu(Ⅱ)与杂环碱(2,2′ 联吡啶(Bpy)或邻菲咯啉(Phen),配体A)和赖氨酸(Lys,配体B)形成配合物的行为;测定了Cu(Ⅱ) Lys二元配合物和Cu(Ⅱ) 杂环碱 Lys三元配合物的稳定常数.三元配合物相对于二元配合物的稳定性用ΔlgKM(ΔlgKM=lgKMAMAB-lgKMMB)表示.结果表明,二元配合物的稳定常数较大且ΔlgKM值均大于理论统计值.这可能与Lys分子侧基的推电子效应及三元配合物中存在的π\-A←M←πB电子效应等因素有关.

The stability constants of ternary mixed ligand coordination compounds Cu(Ⅱ)-heterocyclic bases-L-lysine(heterocyclic bases=2,2′-bipyridyl(Bpy),1,10-phenanthroline(Phen)) were determined by potentiometric pH titration at 25 ℃ in ethanol solution(φ(CH-3CH-2OH)=30%) in the presence of 0.1 mol/L NaClO-4.The values are lgK~{Cu(Bpy)}--{Cu(Bpy)(Lys)}=11.15,lgK~{Cu(Phen)}--{Cu(Phen)(Lys)}=11.42.The binary {Cu(Ⅱ)-}Lys system were also investigated under identical conditions as those of the ternary systems in order to have a comparative complexation behaviour in both such types of systems.And the stability constant of Cu(Ⅱ)-Lys binary complex and protonation constant of L-lysine were determined.