Thermodynamics of citrate complexation with Mn2+, Co 2+, Ni2+ and Zn2+ ions

Abstract

Isothermal titration calorimetry has been used to determine the stoichiometry, formation constants and thermodynamic parameters (ΔG o, ΔH, ΔS) for the formation of the citrate complexes with the Mn2+, Co2+, Ni2+ and Zn2+ ions. The measurements were run in Cacodylate, Pipes and Mes buffer solutions with a pH of 6, at 298.15 K. A constant ionic strength of 100 mM was maintained with NaClO4. The influence of a metal ion on its interaction energy with the citrate ions and the stability of the resulting complexes have been discussed. © 2009 The Author(s).