Abstract
Cosolvent-modified ionic liquid (IL)-based binary mixtures have been used in several chemical applications. Therefore, the molecular-level understanding of these binary mixtures is of utmost necessity to enhance their utility in applications in several fields. This work involves the spectroscopic study of the binary mixture of the IL 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) and ethylene glycol monomethyl ether (EGME) using several polarity-based absorbence and fluorescence probes (Reichardt's dye 33, pyrene, and 1-pyrene carboxaldehyde) and the microviscosity probe 9-(2,2-dicyanovinyl) julolidine (DCVJ). The behaviour of these probes hints at the synergistic behaviour of the IL-EGME mixtures. The Kamlet-Taft parameters have also been calculated and provide an understanding of the solutesolvent and/or solvent-solvent interactions. Further, the dynamic viscosity and Fourier transform infrared spectroscopy (FTIR) results suggest strong hydrogen bonding between the IL and EGME molecules. The preferential solvation model also indicates the formation of a new entity due to solvent-solvent interactions. (C) 2022 Elsevier B.V. All rights reserved.