Effect of water—ethanol solvent on the stability of copper(ii) coordination compound with the nicotinate ion

• DOI: 10.1007/s11172-015-1195-9
• Publication Date: 2016-09-26T09:54:36Z
• Authors: K. V. Grazhdan; A. S. Gushchina; S. V. Dushina; V. A. Sharnin; N. N. Kuranova; A. A. Ekimovskaya
• Keywords: Electroanalytical method

The stability constants of copper(II) complexes with nicotinate ion in water—ethanol solvent were determined by the potentiometric method at 25.0±0.1 °C and ionic strength of 0.25 (NaClO4) in the range XEtOH = 0—0.7 mole fractions. The stability constant of copper(II) nicotinate complex considerably increases with increasing ethanol concentration in the solvent. The contributions of reactants to the Gibbs energy of the complex formation reaction on going from water to aqueous ethanol were analyzed. The results of thermodynamic analysis of solvation effects were used to evaluate the ratio of the ion and ligand transfer Gibbs energy contributions to the change in the reaction Gibbs energy in the water—ethanol system.