Polycyclic Aromatic Nitrogen Heterocycles. Part V: Fluorescence Emission Behavior of Select Tetraaza- and Diazaarenes in Nonelectrolyte Solvents

Abstract

Fluorescence emission spectra are reported for tricycloquinazoline, dibenzo[c,f][2,7]naphthyridine, dibenzo[a,c]phenazine, dibenz[b,h]-indeno[1,2,3de][1,6]naphthyridine, and dibenz[c,f]indeno[l,2,3ij]-[2,7]naphthyridine dissolved in organic nonelectrolyte solvents of varying polarity and acidity. Results of these experiments were used to screen PANHs for potential probe character. 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 dibenzo[c,f][2,7]naphthyridine. Emission intensities of the remaining four PANHs, and of the three protonated PANHs for which emission spectra could be obtained, remained essentially constant and were not affected by nitromethane.