稀土元素与天冬氨酸及天冬酰胺的配位作用

Coordination of Rare Earths with l-Aspartic Acid and d.l-Asparagine

本文利用pH电位法在μ=0.10及不同温度下测定l-天冬氨酸和d.l-天冬酰胺的质子化常数、钇和其它十四个稀土元素与上述配体生成配合物的稳定常数,并研究了水-有机溶剂对天冬氨酸钇稳定性的影响,探讨了钇的位置与“四分组效应”等问题。

In this paper protonation constants of the title ligands at various temperatures as well as stability constants(K_(1),K_(2))of its chelates with rare earth elements in H_(2)O and in mixed solvents were determined potentiometrically at 30℃ and at ionic strength of 0.10.The calculations of these constants were carried out by different methods on DJS-131 electronic computer,the data have been also treated by a least-squares method.Two important facts can be observed from the results obtained.First,there is an apparent"tetrad effect"in both systems.The second fact to observe is the shift of the y position from its usual Ho-Er region to the vicinity of Gd(for aspartic)and Nd(for asparagine system).It can be reasonably explained by the different polarizability between the lanthanides and yttrium ion.