Polycyclic Aromatic Nitrogen Heterocycles. Part VI. Fluorescence Emission and Quenching Behavior of Select Phenyl- and Alkyl-derivatives Dissolved in Nonelectrolyte Solvents

Abstract

Abstract Fluorescence emission spectra are reported for 6,7-dimethyldibenzo[c,f][2,7]naphthyridine, 6-ethyl-7-methyldibenzo[c,f][2,7]naphthyridine, 11, 12-dimethyldibenzo[a,c]phenazine, 7-phenyldibenzo[b,h][l,6] naphthyridine, and 7,8-dihydro-7,7-dimethyl-6-H-quino[2,3,4krl]acridine dissolved in organic nonelectrolyte solvents of varying polarity and acidity. Results of these were used to screen PANHs for potential use as spectroscopic probes. The effect of nitromethane as a selective quenching agent on both the unprotonated and protonated PANHs was also examined. Nitromethane was found to quench fluorescence emission of 7,8-dihydro-7,7-dimethyl-6-H-quino[2,3,4kl] acridine. Emission intensities of the remaining four PANHs, and of the four protonated PANHs for which an emission spectra could be obtained, remained essentially constant and were not affected by nitromethane.