Spectroscopic studies of the solvent polarities of room‐temperature liquid ethylammonium nitrate and its mixtures with polar solvents

Abstract

Abstract The maximum wavelength of the solvatochromic absorption band of Dimroth‐Reichardt's dye I , 2,4,6‐triphenylpyridinium N‐4‐(2,6‐diphenylphenoxide) betaine, has been determined at 25°C from the ultraviolet‐visible spectra of solutions of this dye in ethylammonium nitrate (EAN) and its mixtures with several polar solvents. The related molar transition energy, E T (30) in kcal/mol, of the long‐wavelength absorption band increases sharply, when EAN is dissolved at low concentrations in the various solvents. The pronounced blue shift of the absorption band is attributed to the hydrogen‐bond interaction between the ethylammonium cation and the ground state of the betaine molecule.