title: Electrooptical Absorption Measurements (EOAM) Testify Existence of two Conformers of Prodan and Laurdan with Different Dipole Moments in Equilibrium Ground and Franck-Condon Excited State.
abstract: The results from the electrooptical absorption measurements (EOAM) on the equilibrium ground and excited Franck-Condon state dipole moments of Prodan and Laurdan in 1,4-dioxane are presented. As follows from experiments Prodan and Laurdan in the equilibrium ground and excited Franck-Condon state have two conformers with considerably different dipole moments. The electrical dipole moments and the transition dipole moment, obtained from the short-wavelength region of the absorption spectrum are parallel. The electrical dipole moments measured at the long-wavelength spectral region are parallel to each other but not parallel to the transition dipole moment m a. The angle θ between the transition dipole moment m a and the dipole moment in the equilibrium ground state μ g of the long-wavelength conformer is about 30(0) for both probes. Obtained results evidence that donor-acceptor pairs of the short-wavelength and long-wavelength conformers are not located on the same axis. Two low-energy conformers of Prodan have been found by density functional theory (DFT) calculations, differing in the orientation of the carbonyl group towards the naphthalene system.
authors.affiliation: Institute of Organic Chemistry, J. Gutenberg-University of Mainz, Duesbergweg 10-14, 55099, Mainz, Germany. n.nemkovich@mail.ru.
authors.forename: N A
authors.initials: NA
authors.lastname: Nemkovich
authors.affiliation: Institute of Organic Chemistry, J. Gutenberg-University of Mainz, Duesbergweg 10-14, 55099, Mainz, Germany. detert@uni-mainz.de.
authors.forename: H
authors.initials: H
authors.lastname: Detert
authors.affiliation: Institute of Organic Chemistry, J. Gutenberg-University of Mainz, Duesbergweg 10-14, 55099, Mainz, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Roeder
keywords: Conformers; Dipole moments; Electrooptical absorption measurements (EOAM); Laurdan; Molecular Stark-effect spectroscopy; Prodan