Elucidation of molecular interactions between amino acid and imidazolium based ionic liquid in an aqueous system: Volumetric and acoustic studies

Some of the most active academic and scientific research faces of the past decade are on ionic liquids and their behavior for industrial purposes. In the present work, the densities and sound velocities of an amino acid (glycine) in pharmaceutically active ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate [BMIm][PF₆] solutions were measured at different temperatures ranging from 293.15 K to 318.15 K under atmospheric pressure. The experimental data has been further used to calculate volumetric and acoustic parameters such as apparent molar volumes, V_Φ and apparent molar isentropic compression, K_Φ partial molar expansion, E_Φ⁰ partial molar volume, V_Φ⁰ and partial molar isentropic compression K_Φ⁰ and corresponding empirical constants, S_v and S_k. The negative values are obtained for partial molar volume of transfer, Δ_tV_Φ^o at all temperatures and become more negative by increasing the concentration of the ionic liquid. The positive values of partial molar expansibilities, E_Φ^o are decreasing with an increase in temperature predict increasing electrostriction. The obtained values of expansibilities show the structure-making/breaking ability of glycine in investigated solutions.