Solvatochromism effects on the dipole moments and photo-physical behavior of some azo sulfonamide dyes

Absorption and emission spectra of three azo sulfonamide dyes with various molecular structures have been studied in different solvents. The solute photo-physical behavior depends strongly on the solvent–solute interactions and solvent microenvironment. In order to understand the effect of intermolecular interactions on spectral behaviors of these dyes in different solvents and to conceive nature and extent of solvent–solute interactions the spectral variations were analyzed by the linear solvation energy relationships concept. In addition, by means of solvatochromic method the dipole moments of these dyes, in ground and excited states, were investigated.

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► The dipolarity/polarizability and hydrogen bonding controlled azo sulfonamide interactions.
► The azo sulfonamide shows large change in the dipole moment on excitation.
► The azo sulfonamide dyes structural configuration can be changed in excited state.
► TICT increases planarity and polarity of azo sulfonamide dye upon excitation.