Thermodynamics of the complex formation between Cu2+ and triglycine in water–ethanol solutions at 298 K

Resumo

Thermodynamic functions Δ_rH, Δ_rG, and TΔ_rS of the complex formation between Cu²⁺ and triglycine in water–ethanol solutions are calculated on the basis of calorimetric data. It is found that raising the concentration of EtOH results in a monotonic increase in the exothermic effect of [CuHL]²⁺ complex formation due to the weakening of triglycine solvation with the mutual compensation of ion solvation contributions. The enthalpy of [CuL]⁺ complex formation has an exothermic maximum at 0.1−0.3 molar fractions of EtOH due to competition between the solvation contributions from ions and ligands.