Insights into the Thermophysical and Spectroscopic Properties of l -Arginine and l -Threonine in Aqueous [Bmim][Cl] Media across Different Concentrations and Temperatures

This investigation briefs the thermophysical properties of amino acids (l-arginine and l-threonine) in water and in aqueous 1-butyl-3-methylimidazolium chloride solutions (0.05, 0.10, and 0.15 mol kg–1) over the temperature span 293.15 K–318.15 K at ambient pressure (0.1 MPa). The estimated properties were analyzed to attribute the various intermolecular interactions prevailing in the systems. The inferred density data was utilized towards evaluation of apparent molar volume (Vϕ), limiting apparent molar expansibility (Eϕo), limiting apparent molar volume (Vϕo), limiting apparent molar volume of transfer (ΔtrVϕo), and Hepler’s constant (∂Eϕo∂T)P. Further, via data of sound speed, apparent molar isentropic compression (Kϕ,s), limiting apparent molar isentropic compression (Kϕ,so), limiting apparent molar isentropic compression of transfer (ΔtrKϕ,so), and hydration number were inferred. Also, through viscosity data and by the usage of the Jones–Dole equation, the parameters mainly viscosity B-coefficients, temperature derivative of B ( dBdT), and activation parameters of viscous flow (Δμ10, Δμ20, ΔH20, and TΔS20) were inferred. Moreover, through scrutinization of Hepler’s constant and temperature derivative of B, we assessed that both amino acids function as chaotropes in selected solvents (water and aqueous ionic liquid). UV–visible spectroscopic investigations additionally uphold the predominance of hydrophilic–hydrophilic interactions in the considered systems.