Clarification and Application of Selectivity for Metal Ion of Ternary System of Aldonic Acid, Boric Acid, and Metal (II) Ion

以Ni （II）、Zn （II）、Cd （II）和Pb （II）为金属（II）离子，用电位法研究了氨基葡萄糖酸（2-氨基-2-脱氧-d -葡萄糖酸）与硼酸二元体系、氨基葡萄糖酸与金属（II）离子三元体系和氨基葡萄糖酸与硼酸与金属（II）离子的络合平衡。该配合物的结构用^<13>C和^<11>B NMR进行了表征。形成三元体系的附加稳定化作用在Cd （II）体系中最大。认为氨基葡萄糖在其硼酸二元体系中的构象可以区分离子大小的差异。另一方面，用锗酸代替硼酸的三元体系对金属（II）离子没有选择性，这可能是由于五坐标锗酸的几何结构调整所致。结果表明，Cd （II）配合物在硼酸三元体系中比Pb （II）配合物更稳定，而在葡萄糖-酸二元体系中则相反。在三元体系中发展这种新的选择性是本研究的主要目的。由于三元配合物很容易通过提高溶液的pH值来解离金属（II）离子，因此本体系广泛适用于分析化学领域中金属离子的分离或浓缩。

The complexation equilibria for the binary system of glucosaminic acid (2-amino-2-deoxy-D-gluconic acid) and boric acid and that of glucosaminic acid and metal (II) ion and the ternary system of glucosaminic acid, boric acid, and metal (II) ion have been investigated by potentiometric measurements using Ni (II), Zn (II), Cd (II), and Pb (II) as the metal (II) ions. The structures of the present complexes have been characterized by ^<13>C and ^<11>B NMR.The additional stabilization by forming the ternary systems is the greatest in the Cd (II) system. It is considered that the conformation of the glucosaminic acid in its boric-acid binary systems can distinguish the difference in the ion size. On the other hand, the ternary system with germanic acid instead of boric acid exhibits no selectivity for the metal (II) ions probably due to the adjustment of the geometry of the five-coordinate germanic acid. It is revealed that the Cd (II) complex is more stable than the Pb (II) complex in the ternary system with boric acid while the stability in the glucosaminic-acid binary system is reversed. The development of such a new selectivity arising from the ternary system is the major purpose for the present study. Because it is easy for the ternary complex to dissociate the metal (II) ion by raising the pH value of the solution, the present system is extensively applicable for the separation or concentration of the metal ion in the field of analytical chemistry.