Thermodynamics of the formation of Cu2+–glycyl-glycyl-glycine complex in water–ethanol solutions at 298 K

Abstract

The stability constants of monoligand complexes of copper(II) ions with glycyl-glycyl-glycine zwitterions (triglycine, HL^±) and triglycinate ions (L⁻) in a water–ethanol solvent with 0.0, 0.1, 0.3, and 0.5 mole fractions of ethanol at an ionic strength of 0.1 created by sodium perchlorate and temperature Т = 298.15 K are determined by means of potentiometric titration. It is found that an increase of ethanol content improves the stability of the investigated complexes, due mainly to the resolvation of ligands.