Combined effect of linear and nonlinear dipole-dipole interactions on the electronic spectra of van der Waals complexes in solutions

A new semiempirical approach previously proposed by the author for describing the regularities of the shift of absorption bands in the IR spectra of ultimately ordered van der Waals complexes is extended to the case of three-component solutions of dyes in binary solvents consisting of neutral (nonpolar) and active (polar) components. This approach is based on the analysis of the specific features of the combined manifestation of nonlinear (complex formation) and linear (solvation) intermolecular forces of dipole-dipole nature in the change in the electrical parameters of interacting molecules. It is shown that the concepts developed enable correct quantitative interpretation of a large amount of available spectral-luminescent data for complexes of 1:1 composition between molecules of amino-substituted derivatives of phthalimide and molecules of the active component of a binary solvent, with these complexes being solvated by molecules of the nonpolar component of the solvent.