A reversal from endothermic to exothermic behavior of imidazolium-based ionic liquids in molecular solvents

► An interesting reversal in the enthalpic behavior from endothermic to exothermic on increasing the carbon chain length attached to the imidazolium ring in the imidazolium-based ionic liquids. ► The excess partial molar enthalpy, HILE directly measured using isothermal titration calorimeter at 298.15 K for the interactions operating between cation and anion of four imidazolium ionic liquids with aqueous and various non-aqueous solvents. ► This reversal behavior analyzed in terms of hydrophobic and solvation effects.