Thermodynamics of Complexation Reactions of Nd3+ and Eu3+ Ions with Glycyl-DL-Alanine, Glycyl-DL-Leucine, and Glycyl-DL-Tyrosine in Aqueous Solution in the pH Range рН 1.6–7.5

Abstract

The calorimetric enthalpies of complexation of selected dipeptides, namely, glycyl-DL-alanine, glycyl-DL-leucine, and glycyl-DL-tyrosine (HL^±), with Nd³⁺ and Eu³⁺ ions at 298.15 K and an ionic strength of 0.1 (on the background of KNO₃) were determined. Thermodynamic characteristics of formation were calculated for the LnL²⁺ and LnHL³⁺ complexes of these dipeptides with Nd³⁺ and Eu³⁺ ions for various molar ratios [metal] : [ligand] in the pH range 1.6–7.5. The obtained thermodynamic parameters served to infer the structures of the complexes.