Theoretical and experimental investigation of hydration behavior of choline salicylate ionic liquid in the presence of L- glycine

Choline salicylate [Ch][Sal] an active pharmaceutical ingredient ionic liquid (API-IL) aqueous solutions in the presence of L-glycine that is a simple simulated biological media has been studied. The thermodynamic and transport properties including density, speed of sound, viscosity and electrical conductance have been studied under atmospheric pressure and a temperature range of (288.15 to 318.15) K. The key thermophysical properties, including apparent molar volume (V_φ), apparent molar isentropic compressibility (κ_φ), viscosity B-coefficient, ion association constant (K_a), and limiting molar conductivity (Λ₀) were derived from these data. The transfer properties (Δ_trV_φ⁰, Δ_trκ_φ⁰, and ΔB_tr) demonstrate the dominance hydrophilic-hydrophilic interactions between the IL and L-glycine in the studied systems that increased with L-glycine concentration. The COSMO results revealed that differences in molecular size, stability, and hydration behavior of [Ch][Sal] and L-glycine, with [Ch][Sal] exhibiting stronger hydration due to its larger size and hydrogen bonding capacity. These findings provide insights into solute-solvent interactions and potential synergistic effects of [Ch][Sal] and L-glycine as a simple simulated biological media contributing to the optimization of pharmaceutical formulations and related activities.