Solvatochromic Absorbance Probe Behavior and Preferential Solvation in Aqueous 1-Butyl-3-methylimidazolium Tetrafluoroborate

Abstract

The hypothesis that aqueous, rather than pure, ionic liquids provide substantially altered physicochemical properties and versatile/increased solute solvation is addressed. Solvatochromic absorbance probes are utilized to gather information on aqueous solutions of a completely water-miscible ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF 4 ). A simplistic solvation model suggests possible preferential solvation of a water-soluble betaine dye by bmimBF 4 . The lowest-energy electronic absorption band of this dye is further used to interpret dipolarity/polarizability and hydrogen-bond donating (HBD) acidity of aqueous bmimBF 4 . On the basis of the responses of two other probes, N, N -diethyl-4-nitroaniline and 4-nitroaniline, dipolarity/polarizability, HBD acidity, and hydrogen-bond accepting basicity are separately assessed.