THEORETICAL-STUDY OF SINGLET EXCITED-STATES OF DONOR-ACCEPTOR NAPHTHALENE DERIVATIVES

A series of donor-acceptor derivatives of naphthalene have been studie d theoretically by the INDO/S CI method and compared to experimental d ata. The dimethylamino and the pyrrolo groups in 1- and 2-positions se rved as donors while the cyano group in position 4 was used as an acce ptor. Transition energies, transition moments and electric dipole mome nts of the lowest 10 singlet states have been calculated for two confo rmations of the donor group - planar and perpendicular to the naphthal ene moiety. Two groups of highly polar biradicaloid charge transfer st ates have been observed. It is shown that energetic factors alone are not sufficient to explain the observed differences in the fluorescence spectra of 1- and 2-derivatives. The role of the ground state geometr y in the formation of twisted intramolecular charge transfer states is also discussed.