Understanding the solvation behavior of tetramethylguanidinium based ionic liquids in dilute aqueous solutions through apparent molar properties

摘要

Abstract The solvation behavior of ionic liquids containing a common, 1,1,3,3-tetramethylguanidinium cation and different anions, phenylacetate and cinnamate, in water is examined through apparent molar properties. These ionic liquids were chosen because of their versatile applications as environment-friendly solvent, catalyst, and for dissolution and stability of biomolecules. In order to understand the ion-ion and ion-solvent interactions and effect of anion in dilute aqueous solutions of studied ionic liquids, the experimental measurements of density and speed of sound have been carried out as a function of molality (0.01 to 0.2mol·kg?1) and temperature from 293.15 to 318.15K. Experimental data have been used to calculate the apparent molar and other derived thermodynamic properties. Further, Redlich-Meyer equation has been employed to obtain the apparent molar volume and isentropic compressibility at infinite dilution and the empirical parameters which are crucial in understating the hydrophilic and hydrophobic nature of studied ionic liquids. Graphical abstract Display Omitted Highlights ? New 1,1,3,3-tetramethyl guanidinium [TMG] based protic ionic liquids (PILs) have been synthesized. ? Redlich-Mayer equation has been employed to calculate the limiting apparent molar properties. ? Apparent molar volumes at infinite dilution found to increase with the size of anion of [TMG] based PILs. ? Ion-solvent interactions are stronger for [TMG][CNM] than [TMG][PAA] in aqueous solutions. ]]>