Solvatochromic Effect Studies on the Absorption Spectra of 4-[(E)-(3-formayl-4-hydroxyphynyl) diazneyl] benzene sulphonic acid and 2-hydroxy-5-[(E)-(2-nitrophynyl)diazneyl] benzaldehyde Azo Compounds

Abstract

The electronic absorption spectra of some azo dyes in various solvents of different polarities have been studied at room temperature. The solvent effects on the wave numbers of the absorption band maxima (vmax) were discussed using the following solvent parameters, refractive index, n, dielectric constant, ε, empirical Kamlet–Taft, Catalân and Hansen solvent parameters. The solute–solvent interactions were determined based on multilinear solvation energy relationships concept. The fitting coefficients obtained from this analysis allowed us to estimate the contribution of each type of interactions to the total spectral shifts in solution. The established dependences between (vmax) and the solvent parameters emphasize that the visible band of the studied molecules is affected by both non-specific and specific solute–solvent interactions.