Solvatochromism and solvatofluorochromism of the intramolecular charge transfer band of 4-dimethylaminochalcone in the electronic spectra of its solutions

The solvatochromic and solvatofluorochromic dependences pertaining to the intense intramolecular charge transfer electronic band of the 4-dimethylaminochalcone molecule, widely used as an efficient spectralluminescent probe in various medical and biological studies, are systematically and quantitatively investigated. The data obtained are interpreted based on the new variant of the semiempirical theory of the influence of the dielectric properties of individual solvents on the shift in the optical spectra of molecules occurring as a result of the gas-solution phase transition that was proposed previously by one of the authors of this study. It is shown that the main contribution (at least 70–80%) to the absolute solvation shift in the absorption and fluorescence spectra of the 4-dimethylaminochalcone molecule is made by universal dipole-dipole interactions of orientation, induction, dispersion, and inductive-resonance nature, as well as by repulsive forces.