Effects of thermodynamics on the solvation of amino acids in the pure and binary mixtures of solutions: A review

The standard total transfer free energies, ∆ Gt0(i) and entropies, T ∆ St0(i) of amino acids in pure aqueous, aqueous mixtures of salts, aqueous-organic, aqueous ionic liquid, non-aqueous organic binary solvent at 298.15 K are briefly described here. The transfer energies have been determined from solubility measurements of the amino acids and the different techniques of saturated solubility measurement are also discussed. In the present review, the solubilities of the six amino acids (glycine, dl-alanine, dl-α-amino butyric acid, dl-nor-valine, dl-phenylalanine and dl-serine) are summarized here in different solvents systems like in pure water, 0 to 100 wt% organic mixed solvents, NaCl + water (0.5 to 6.0 molality), KCl + water (0.5 to 5.0 molality), NaNO3 + water and KNO3 + water (0.5 to 3.0 molality), etc., and the solubilities were found to agree mostly to within 3.0% uncertainties in the literatures. The reported chemical parts of the free energies, ∆ Gt,ch0(i) and entropies, T ∆ St,ch0(i) of transfer of the amino acids have been computed by subtracting the cavity effects and dipole-dipole interaction effects from the total transfer energies. Different kind of non-covalent interactions which are directly involved for the solvation of amino acids as well as protein molecules are discussed briefly. Not only of aqueous, non-aqueous binary solvent system but also behavior of different amino acids in pure and aqueous ionic liquid are also discussed. In different field the application of those data and future prospect which are the most important in modern science are marked out. First time we are summarizing the stability and interaction of amino acids in pure as well as in binary solvent system in terms of standard transfer free energy and standard transfer entropy with historical steps as a review.