Solute-solvent and solvent-solvent interactions and preferential solvation of limonin in aqueous co-solvent mixtures of methanol and acetone

Solute-solvent and solvent-solvent interactions of limonin in binary solvent mixtures of methanol + water and acetone + water were investigated from the solubility data by using the linear solvation energy relationships concept. The variation of limonin solubility depended mainly upon the hydrogen bond basicity for methanol (1) + water (2) mixtures, and the cavity term for acetone (1) + water (2) mixtures. The preferential solvation parameters (delta chi(1,3)) of limonin in two solvent mixtures were derived by means of the inverse Kirkwood-Buff integrals method. delta chi(1,3) values were negative in water-rich mixtures but positive in solvent compositions from 0.24 or 0.20 (0.25) to 1 in mole fraction of methanol or acetone, respectively. It was conjecturable that in water-rich mixtures, the hydrophobic hydration around the nonpolar methyl groups of limonin played a relevant role in the solvation. The preference of limonin in water-rich mixtures could be explained in terms of the higher basic behavior of limonin molecules interacting with the proton-donor functional groups of the water. (C) 2018 Elsevier B.V. All rights reserved.