Comparative chemical transfer Gibbs free energy related to solvation of amino acid, L-Histidine in aqueous mixtures of N, N-Dimethylformamide and Protic Glycerol at 298.15 K

S. Roy¹, K. Mahali² and B. K. Dolui^3 
1Department of Chemistry, Shibpur Dinobundhoo Institution (college), Howrah-2, W.B, India.
²Department of Chemistry, University of Kalyani, Nadia, W.B, India-741235.
^3*Department of Chemistry, Visva-Bharati, Santiniketan, W.B, India-731235.
Received: 6 May 2014, Accepted: 9 June 2014, Published Online: 27 July 2014

Abstract
In this article we are reporting the solubilities of L-histidine in aqueous dipolar aprotic N, N-dimethylformamide at 298.15 K using ‘isothermal saturation’ method. The standard transfer Gibbs energy,  and cavity forming enthalpy of transfer,  for the species (i) i.e. L-histidine, have been evaluated. Here also detail theoretical calculations of cavity forming transfer Gibbs free energy, , dipole-dipole interaction effects, have been carried out taking the literature values. The chemical effects of the transfer Gibbs energies of L-histidine, have been obtained by subtracting the cavity effects, , (estimated by the scaled particle theory) and dipole-dipole interaction effects, (calculated by the Keesom orientation expression) from the . In this article a comparative study between aqueous protic and dipolar aprotic solvent, i.e. water-glycerol and water-DMF mixed solvent systems respectively, is presented to discuss about their solvating characteristics as well as stabilizing capacity for the amino acid, L-histidine as well as biomolecules.
Keywords: L-histidine, N, N-dimethylformamide, hydrophilic hydration, acidity-basicity, transfer energetics.