稀土与L-苯丙氨酸配合物的pH电位法及量热滴定法研究

Study on Complexes of Rare Earth with L-Phenylalanine by Potentiometry and Calorimetry

本文在25℃和0.15mol·dm^(-3)(NaCl)离子强度下,用pH电位法和量热滴定法测定了十五个稀土元素(Y和除Pm外的镧系元素)与L-苯丙氨酸1∶1配合物的稳定常数及热力学函数。L-苯丙氨酸通过—CO_2^-和—NH_2与稀土离子配位,生成较稳定的1∶1配合物。配合物稳定性呈“四分组效应”。配合物稳定性顺序中Y的位置向轻稀土方向移动。体系的熵变是配位反应驱动力。离子的去水化在配位反应中超重要作用。

The stability constants and thermodynamic functions for complexes of rare earth with L-phenylalanine have been determined by potentiometry and calorimetry at 25℃ and ionic strength of 0.15mol·dm^(-3)(NaCl). Stability of the complexes shows the 'Tetrad effect'. The entropy change makes a predominant contribution to the stability of these complexes. The ligand is coordinated to rare earth ions through its —CO_2^- and—NH_2 group, and dehydration of ions plays an important role in coordination reaction.