Photophysics of N,N-Dimethyldihydrophenazine and Benzoannelated Analogues. Structurally Dependent Excited State Hierarchy

摘要

Absorption and fluorescence spectra, fluorescence lifetimes, and fluorescence quantum yields for 5,10-dimethyl-5,10-dihydrophenazine (DMP), 9,14-dimethyl-9,14-dihydrodibenzoA,C phenzaine (DMAC), 9,14-dimethyl-9,14-dihydrophenanthro4,5-ABCphenazine (DMPP) and 6,13-dimethyl-6,13-dihydrobibenzoB,Iphenazine (DBMI) have been measured in benzene solution at room temperature. The excited state behavior of DMP, DMAC, and DMPP is similar. The long natural radiative lifetimes and large separation between absorption and emission maxima suggest that the first transition is symmetry forbidden. DMBI is unique in the series with a comparatively short natural radiative lifetimes and a relatively small separation between absorption and emission maxima. These results, in conjunction with PPP calculations, reveal a different hierarchy of electronic states for DMBI, such that the first transition is strongly allowed. (Author)