Intramolecular and intermolecular hydrogen-bonding effects on the dipole moments and photophysical properties of some anthraquinone dyes

Absorption and fluorescence spectra of three anthraquinone dyes with various substituents and molecular size were studied in different solvents. The photo-physical behavior of a dissolved dye depends strongly on the solvent–solute interactions and solvent nature. The solvatochromic method was used to investigate dipole moments of these dyes in ground and excited states. The spectral variations were analyzed by means of linear solvation energy relationships concept proposed by Kamlet and Taft. The results conceive the nature and extend of, specific and non-specific, solvent–solute interactions.

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► The anthraquinones interactions are controlled by intramolecular hydrogen bonding.
► Strong intramolecular hydrogen bonding restricts intermolecular hydrogen bonding.
► The anthraquinone dyes structures can be deformed with changing solvent.
► Anthraquinones planar and deformed structures possess different dipole moments.