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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 研究了配体Ⅰ的水解产物的结构
Potentiometric titration of N, N’-dicarboxymethyl macrocyclic ether bis-lactone was carried out at (25.0 ± 0.1) ℃ and I = 0.10 m ol · dm 3 (NMe4NO3) (I, II, III) and their equilibrium constants with the metal ions Mg2 +, Ca2 +, Sr2 +, Ba2 +, Cu2 +, Zn2 +, Cd2 + and Pb2 + were studied. The effects of ether ring size on the equilibrium constants, As well as the influence of ligand stability. The stability constant of the complex formed by the ligand I and the above metal ions is the minimum for the same metal and the ligands II and III. This difference was more pronounced when ligand I was complexed with larger metal ions such as Sr2 +, Ba2 +, Cd2 +. The stability constant of ligand I and Pb2 + is much higher than expected. With the alkaline earth metal ions Ca2 +, Sr2 +, Ba2 + complex formation stability constant, with the metal ion radius decreases. With the transition metal ions Cu2 +, Zn2 +, Cd2 + form a stable constant, showed a similar pattern. The complexes formed by ligand II and Mg2 + have the poorest stability. However, the stability constants of complexes formed with Ca2 +, Sr2 + and Ba2 + are much higher than those of Mg2 + complexes and close to each other. Therefore, ligand Ⅱ can be used to separate Mg2 + from alkaline earth metal ions. The structure of the hydrolyzate of ligand I was investigated by NMR