Relationship between the Molecular Structure of Merocyanine Dyes and the Vibrational Fine Structure of Their Electronic Absorption Spectra

Relative intensities of vibronic subbands in the electronic absorption spectra of a new merocyanine dye are influenced by the polarity of the solvent. Increasing solvent polarity leads to an increased π-charge density alternation in the polymethine chain and, consequently, to reduced bond alternation.