镧、镨及钐与氨基酸配合物的滴定量热研究

Study on Complexes of La^(3+) ,Pr^(3+) ,Sm^(3+) with Amino Acids by Titration Calorimeter

用滴定量热法测定了 2 98.15 K下稀土镧 ( )、镨 ( )及钐 ( )离子与 8种氨基酸配合物的稳定常数及反应焓变 ,并由此推出反应的吉布斯自由能变化和熵变 .实验结果表明 :焓变是配合反应的主要驱动力 ;氨基酸侧链 R基极性的增加对配合反应有阻碍作用 。

The stability constants and thermodynamic functions for complexes of La 3+ ,Pr 3+ ,Sm 3+ with some amino acids have been determined by titration calorimeter at 298.15 K. The optimum condition of forming complexes has been also discussed,and regulating the pH of system around 6.0 the complexes will exist stablely in system.The enthalpy change makes a predominant contribution to the stability of these complexes. The increase of the polarity of R group in amino acids(R-CH(NH + 3)COO -) resists to make complexes. The ring in amino acid associated with La 3+ ,Pr 3+ or Sm 3+ helps to enhance the stability of complexes