Molecular interactions between glycylglycine and Mn(COOCH3) 2 in aqueous and aqueous ethanol mixtures

Abstract

This paper reports the variations of different physical and thermodynamic properties of a mixture of dipeptide-metal salt in aqueous solutions as well as in aqueous ethanol mixtures. Specifically, the apparent molar volumes and apparent molar compressibilities of glycylglycine and Mn(COOCH<inf>3</inf>) <inf>2</inf> have been determined at T = (288.15 to 318.15) K, and the resulting data have been used to estimate the limiting volume (?0 <inf>V</inf>) and compressibility (?0<inf>K</inf>). Their concentration variations are examined to study the effect due to solute-solute and solvent-solvent interactions. The resulting data have been used to interpret the volume and compressibility contributions of the components in terms of H-bonding and dipole-dipole interactions. It was found that these interactions in aqueous solutions were measurably distinct in some cases from those in alcohols. An unusual behavior in the refractive index values indicates a measure of the relative extent of the polar domains. © 2009 American Chemical Society.