A non-pertubative approach to solvatochromic shifts of push-pull chromophores

The two-state model for push-pull chromophores (the DA dimer model) is extended to account for the coupling of electrons to molecular vibrations and for the interaction with the solvent. The resulting self-consistent two-state model is solved exactly. In this Letter, we present exact results on linear absorption and emission spectra. Standard perturbative treatments of both vibronic and solvent effects on spectral properties are proved to fail in highly non-linear systems as push-pull chromophores. The use of solvatochromic data to extract mesomeric dipole moments as well as to investigate the dynamics of the solvent relaxation is critically reviewed. (C) 1999 Elsevier Science B.V. All rights reserved.