title: Solvatochromic behavior of donor-acceptor-polyenes: dimethylamino-cyano-diphenylbutadiene.
abstract: 4-(Dimethylamino)-4'-cyano-1,4-diphenylbutadiene (DCB) and 4-(dimethylamino)-2,6-dimethyl-4'-cyano-1,4-diphenylbutadiene (DMDCB) have been characterized spectroscopically. Quantum chemical calculations were performed for comparison. Solvatochromic shifts of the fluorescence were strong and showed a linear dependence on the solvent polarity parameters, whereas shifts in the absorption spectra are very weak only correlate better with the polarizability of the solvents. Excited state dipole moments derived from fluorescence using the Onsager model are very large and similar for both compounds. It is concluded that a strongly allowed and highly dipolar pi, pi* state is the lowest excited state in polar solvents. The strong difference in absorption and fluorescence solvatochromic slopes suggests that the simple Onsager model with a point dipole approximation is not sufficient here.
authors.affiliation: Institut für Chemie, Humboldt-Universtät zu Berlin, Brook-Taylor-Strasse 2, D-12489 Berlin, Germany.
authors.forename: Hani
authors.initials: H
authors.lastname: El-Gezawy
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rettig
authors.forename: René
authors.initials: R
authors.lastname: Lapouyade
mesh_terms: D015394:Molecular Structure; D010777:Photochemistry; D011090:Polyenes / Q000737:chemistry*; D011789:Quantum Theory; D012680:Sensitivity and Specificity; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D011090:Polyenes; D012997:Solvents