Thermodynamic characteristics of 2,2′-Dipyridyl solvation in binary methanol-acetonitrile solvents

The heat effects of 2,2′-dipyridyl (2,2′-Dipy) dissolution were measured by the calorimetric method at 298.15 K over the whole range of the mixed methanol-acetonitrile (MeOH-AN) solvent compositions. Transfer enthalpies of 2,2′-Dipy from MeOH into its mixtures with AN were calculated according to the obtained data. It was found that passing from MeOH to AN leads to a slight decrease in exothermicity of 2,2′-Dipy solvation in the solvents of compositions X _AN = 0.6–1.0, which probably indicates the prevailing contribution of desolvation of the nitrogen atoms over the one of the solvation of the aromatic rings of 2,2′-Dipy molecule with decreasing the basicity of the solvent.