Solvent effects on organic reactivity and on absorption spectra have been studied for more than a century

Absorption spectra of three aminoazobenzene dyes with various molecular size and alkyl tails have been recorded in solvents in the range between 200 to 600 nm. The photophysical behavior of a dissolved dye depends on the nature of its environment, i.e. the intensity, shape, and maximum absorption wavelength of the absorption band of dye in solution depends strongly on the solvent-solute interactions and solvent nature. The solvatochromic behaviors of aminoazobenzene dyes and solventsolute interactions can be analyzed by means of linear solvation energy relationships concept proposed by Kamlet and Taft. Bathochromic shift of absorption maxima of these dyes, λmax, occurs in solvent with the highest proton acceptor ability and dipolarity/polarizability.