LAUSR

Abstract This study reports the various physicochemical properties of imidazolium based ionic liquids (ILs) 1-butyl 3-methyl imidazolium tetrafluoroborate (C4mimBF4) and 1-decyl 3-methyl imidazolium tetrafluoroborate (C10mimBF4) in absence and presence of the antibacterial drug rifampicin. The interactions have been studied in terms of maximum surface excess concentration (Γmax), minimum surface area per ionic liquid molecule (Amin), effectiveness of surface tension reduction (πcmc), adsorption efficiency (pC20) and packing parameter (P) by using surface tension. The negative values of free energy of micellization (ΔGm0) and free energy of adsorption (ΔGad0) shows the spontaneity and stability of the processes. Fluorescence measurements have also been employed to study the effect of ILs on the solubility of rifampicin, the entrapping of the drug molecules by the IL micelle and enhancing the solubility of drug as shown by the blue shift. The interactions between ILs and drug molecules are stabilized by presence of van der Waals forces, electrostatic, hydrophobic and π-π interactions. Thus, the processes are well balanced by these forces and are spontaneous in nature.