物理化学学报 >> 1991, Vol. 7 >> Issue (03): 276-280.doi: 10.3866/PKU.WHXB19910304

研究论文 上一篇    下一篇

稀土-蛋氨酸配合物的热力学

高峰; 牛春吉; 倪嘉缵   

  1. 中国科学院长春应用化学研究所,长春 130022
  • 收稿日期:1990-02-20 修回日期:1990-08-08 发布日期:1991-06-15
  • 通讯作者: 牛春吉

Thermodynamics of Complexation of Rare Earths by L-Methionine

Gao Feng; Niu Chun-Ji; Ni Jia-Zuan   

  1. Changchun Institute of Applied Chemistry, Academia Sinica, Changchun 130022
  • Received:1990-02-20 Revised:1990-08-08 Published:1991-06-15
  • Contact: Niu Chun-Ji

摘要: 在25 ℃和μ=0.15 mol·L~(-1)[NaCl]条件下, 用pH电位法测定了L-蛋氨酸的质子化常数、15个稀土元素与该配体生成配合物的稳定常数。表明稀土与L-蛋氨酸可生成1:1配合物。讨论了“四分组效应”及钇的位置。用量热滴定法直接测定了稀土与L-蛋氨酸生成1:1配合物的△H_(101)值, 计算了△S_(101)和△G_(101)值。

关键词: 稀土, 蛋氨酸, 配合物, 热力学参数

Abstract: The protonation constant of the ligand and stability constants of its complexes with rare earths have been determined by poteatiometric titration at 25 ℃ and ionic strength μ=0.15 mol·L~(-1)(NaCl). The results indicate that rare earth elements can form 1:1 complexes with L-methionine. There is an apparent "tetrad effect" in this system. Shift of the yttrium position to the vicinity of Gd can be explained by the different polarization between the Ln~(3+) and the ligand. The enthalpy ehanges(△H_(101)) of the coordination reaction as represented by the reaction (M+L<=>ML) have been measured by calorimetric titration, where M and I denote rare earths and L-Met respectively. The ΔG_(101) and ΔS_(101) of these reaction have been calculated by using Gibbs' equation. Furthermore, the stability of rare earth complexes with L-Met has been compared with that of Cu~(2+), Zn~(2+), Fe~(2+), Fe~(3+) complexes with L-Met.

Key words: Rare earth, Methionine, Coordination compounds, Thermodynamic parameters