Evaluating the solute-solvent interactions of glycine in aqueous solution of choline based ionic liquids through volumetric properties at T = (293.15 to 313.15 K)

Abstract

The molecular interactions of amino acids with the different ionic liquids (ILs) are important in order to study the stability and behavior of the amino acids. In this study, we have examined the interactions of glycine in the aqueous solutions with two aprotic ionic liquids based on cholinium cation, namely, cholinium propanoate [Chl][Pro] and cholinium hexanoate [Chl][Hex]. The different interactions were quantified through their partial molar volumes (Vϕ) where it was found that the shorter chained [Chl][Pro] interacts more with the molecules of the glycine, compared to [Chl][Hex]. The derivation of infinite dilution parameter through the application of the Masson equation revealed further insights into the different types of interactions. The calculated limiting partial molar volume of transfer, (ΔVϕ0 values for water to aqueous solutions of ILs indicated that hydrophobic-hydrophobic interactions dominates over other attractive interactions in longer chain [Chl][Hex] than in [Chl][Pro]. The calculation of hydration number (nH) revealed that with increasing IL concentrations, lesser number of water molecules remain attached to the glycine, indicating the structure breaking nature of the ILs, which were further confirmed from the Hepler equation.