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在303.0 K维持离子强度为0.16 mol.L-1,体积比为0.0～60.0%的1,4二氧六环-水混合体系中用pH滴定法研究了CoⅡ,NiⅡ和CuⅢ离子与L-组氨酸和L-谷氨酸混合配体配合物的生成平衡。对不同的金属(M)与L-组氨酸(L)、L-谷氨酸(X)比(cM∶cL∶cX=1∶2.5∶2.5,1∶2.5∶5.0,1∶5.0∶2.5)的体系进行了碱量滴定。计算了三元配合物的稳定常数并用MINIQUAD75对各种模型进行了优化。根据统计数据和残差分析结果选取了最合适的化学模型。检测到的物种:对CoII而言为MLX2H2-和MLX23-,对NiⅡ和CuⅡ而言为MLXH,MLX2H2-和MLX23-。就有关浓度和稳定性对三元物种与二元物种进行了比较。三元物种的额外稳定性可归因于电荷中和,鳌合效应,堆叠作用和氢键等。
In the 1,4-dioxane-water mixed system with the ionic strength of 0.16 mol·L-1 and the volume ratio of 0.0-60.0% at 303.0 K, the effects of CoⅡ, NiⅡ and CuⅢ ions and L-group Balanced formation of a mixture of L-glutamic acid and L-glutamic acid ligands. The ratios of different metals (M) to L-histidine (L) and L-glutamic acid (X) (cM:cL:cX = 1: 2.5: 2.5, 1: 2.5: 5.0, 1: 5.0: 2.5 ) System was alkalimetric titration. The stability constants of ternary complexes were calculated and the various models were optimized with MINIQUAD75. The most suitable chemical model was chosen based on the statistics and the results of the residual analysis. Species detected: MLX2H2- and MLX23- for CoII, MLXH, MLX2H2- and MLX23- for NiII and CuII. Three-species and two-species species were compared for concentration and stability. The extra stability of ternary species can be attributed to charge neutralization, chelation effects, stacking and hydrogen bonding.