Abstract
•Apparent molar properties of amino acids in aqueous ILS have been discussed.•Thermodynamic parameters have been calculated.•Discussion on solute-co-solute interactions.•Interpretation of structure making and breaking ability of co-solute has been done.
To study the molecular interactions between the ternary mixtures containing long chain imidazolium based ionic liquid as a common solvent with substituted amino acids L-phenyl glycine and L-phenylalanine respectively, densities and speed of sound have been measured at three different temperatures viz. T = 288.15 K, 298.15 K, 318.15 and 318.15 K under 0.1 MPa pressure. The density and speed of sound data have been further utilized to calculate the apparent molar volume and apparent molar isentropic compression. From the data obtained, apparent molar volume (Vϕ), partial molar volume (Vϕ0), and standard partial molar volumes of transfer (ΔVϕ0). Positive values of apparent molar volume indicate strong interactions. Also, partial molar isentropic compression of transfer (ΔKϕ,S0) and partial molar isentropic compression (Kϕ,s) have been calculated from the sound of speed. Furthermore, structure making and structure breaking ability of solute have been discussed by evaluation of apparent molar expansivity, (ϕE0), Hepler's constant values ∂/∂Tp. The obtained results have been discussed in terms of solvation behavior, structural changes and various interactions present in different ternary mixtures (1-dodecyl-3-methylimidazolium bromide + amino acids + water).