N,N′-二羧甲基大环醚双内酯配合性能的研究

Study on the coordinate properties of N,N′—Dicarboxymethyl Macrocyclic Ether\|bis\|Lactone

用电位滴定法，在（２５．０ ±０．１）℃， Ｉ＝ ０．１０ ｍ ｏｌ·ｄｍ ３（ＮＭｅ４ＮＯ３） 条件下测定了Ｎ，Ｎ′—二羧甲基大环醚双内酯（Ⅰ，Ⅱ，Ⅲ） 的质子化平衡常数，及其与Ｍｇ２＋ ，Ｃａ２＋ ，Ｓｒ２＋ ，Ｂａ２＋ ，Ｃｕ２＋ ，Ｚｎ２＋ ，Ｃｄ２＋ ，Ｐｂ２＋ 金属离子配合的平衡常数，讨论了醚环大小对平衡常数、配位方式以及配体稳定性的影响． 配体Ⅰ与上述金属离子形成配合物的稳定常数，对于同一种金属与配体Ⅱ，Ⅲ相比为最小． 配体Ⅰ与较大的金属离子如Ｓｒ２＋ ，Ｂａ２＋ ，Ｃｄ２＋ 生成配合物时，这种差异更加显著． 配体Ⅰ与Ｐｂ２＋ 配合的稳定常数，比预料的高出很多． 与碱土金属离子Ｃａ２＋ ，Ｓｒ２＋ ，Ｂａ２＋ 形成配合物的稳定常数，随金属离子半径增大而减小． 与过渡金属离子Ｃｕ２＋ ，Ｚｎ２＋ ，Ｃｄ２＋ 形成配合物的稳定常数，呈相似的规律． 配体Ⅱ与Ｍｇ２＋ 形成的配合物，其稳定性最差．而与Ｃａ２＋ ，Ｓｒ２＋ ，Ｂａ２＋ 形成配合物的稳定常数比与Ｍｇ２＋ 形成的配合物的稳定常数高出很多且相互间很相近，故配体Ⅱ可用于从碱土金属离子中分离出Ｍｇ２＋ 离子． 用ＮＭＲ

The protonation equilibrium constants of N,N′—Dicarboxymethyl Macrocyclic Ether\|bis\|Lactone (Ⅰ, Ⅱ,Ⅲ) and the stability constants of their complexes coordinating with Mg\+\{2+\}, Ca\+\{2+\}, Sr\+\{2+\}, Ba\+\{2+\}, Cu\+\{2+\}, Zn\+\{2+\}, Cd\+\{2+\}, Pb\+\{2+\} metal ions in aqueous solution I = 0.10 mol·dm\+\{-3\} (NMe\-4NO\-3) at 25 ℃ had been determined by potentiometric titration method, which has been reported in this paper. The ring size of ether cycle effect on the equilibrium constants, the coordinate form and stability of the macrocyclic ether bis-lactone(Ⅰ, Ⅱ,Ⅲ) as ligand has been discussed. For ligand Ⅰ, as compared with ligand Ⅱ & Ⅲ, coordinating with above metal ions to form complexes, their stability constants are the smallest. These differences are more significant, when the ligand Ⅰ coordinate with larger metal ions such as Sr\+\{2+\}, Ba\+\{2+\}, Cd\+\{2+\}. However, the stability constant of complex of ligand Ⅰ coordinate with Pb\+\{2+\} is more high than anticipant value. The stability constant of complex for the ligands coordinating with earth alkali metal ions such as Ca\+\{2+\}, Sr\+\{2+\}, Ba\+\{2+\},decrese with increasing the ion radius of metal except Mg\+\{2+\}. The stability of complex formed by ligand Ⅱ coordinating with Mg\+\{2+\} is the lowest compared with other earth alkali metal ions. So , the ligand Ⅱ could be used for separating Mg\+\{2+\} from earth alkali metal ions. The stability of the complexes of these ligands coordinating with earth alkali metal ions is lower 5 order than with Cu\+\{2+\}, Zn\+\{2+\}, Cd\+\{2+\}, Pb\+\{2+\} ions. The stability of ligand Ⅰ has studied by NMR. The mechanism of the ligands coordinating with metal ions had been discussed in this paper.