Isotropic and anisotropic environment effects on the UV/vis absorption spectra of three disperse azo dyes

Absorption spectra of three disperse azo dyes with various molecular sizes and alkyl tails have been recorded in isotropic and anisotropic solvents in the range between from 200 to 700 nm. The photo-physical 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 depends strongly on the solute-solvent interactions and solvent nature. The solvatochromic behaviors of disperse azo dyes and solute-solvent interactions can be analyzed by means of the linear solvation energy relationship concept proposed by Kamlet and Taft. Bathochromic shift of absorption maxima of these dyes, λmax, occurs in solvents with highest proton acceptor ability and dipolarity/polarizability.