Fluorescent symmetric phenazines from naphthoquinones 3. Steady-state spectroscopy and solvent effect of seven phenazine derivatives: structure-photophysics correlations

The fluorescence spectra of seven phenazines (two belonging to the C-2h poi nt group, two to the C-2v point group, two to the C-s point group and one t o the C-1 point group) in organic solvents of varying polarity show a batho chromic shift in all cases. Fluorescence quantum yields increase as the pol arity of the solvent increases for the C-2h and the C-s compounds, however, no appreciable changes are noted in the C-2v compounds. The unexpectedly s trong solvent interactions with the two centrosymmetric phenazines are expl ained on the basis of a localized excited state. This explanation was suppo rted by excited state dipole moment measurements, which indicated similar m oments for the C-2h and C-2v compounds. Two of the compounds undergo lasing when placed in a laser cavity and pumped with the third harmonic of an Nd- YAG laser. (C) 2000 Elsevier Science S.A. All rights reserved.