Physicochemical study on molecular interactions of the active pharmaceutical ingredient ionic liquid domiphen salicylate with amino acids at different temperatures

Abstract

The molecular interactions between the active pharmaceutical ingredient ionic liquid domiphen salicylate ([Dom][Sal]) and some amino acids (glycine, L-alanine, L-valine, L-leucine) in aqueous solution were studied. In order to accomplish this objective, the volume, conductivity and UV–vis spectroscopy of ternary systems were measured at different temperatures. The infinite dilution apparent molar volume, V2,φ0, transfer volume, ΔtV0, hydration number, nH and infinite dilution apparent molar expansibility, Eφ0 of amino acids in aqueous [Dom][Sal] solution were derived from the measured density data. Side chain contributions to V2,φ0 have been estimated. Critical micelle concentration, cmc, and thermodynamic properties of micellization (ΔGm0, ΔHm0,ΔSm0) for [Dom][Sal] in aqueous amino acids solutions were calculated using electrical conductivity data. The binding constant Kb of the amino acid with [Dom][Sal] was estimated based on the maximum absorbance data of the UV–vis spectroscopy. The impacts of temperature, concentration and the length of aliphatic chain of amino acids on these parameters were discussed. The mentioned parameters was employed to unveil the solute–solvent interactions in ternary systems.