Spectroscopic Properties of Polycyclic Aromatic Compounds: Examination of Nitromethane as a Selective Fluorescence Quenching Agent for Alternant Polycyclic Aromatic Nitrogen Hetero-Atom Derivatives

Abstract

Nitromethane is examined as a selective fluorescence quenching agent for alternant polycyclic aromatic nitrogen hetero-atoms (PANHs). Fluorescence emission behavior is reported for 1-azapyrene, 2-azapyrene, 4-azapyrene, 4-azachrysene, 12-azabenzo[a]pyrene, phenanthro[9, 10g]isoquinoline, phenanthro[2,3h]isoquinoline, phenanthro[3,2h]-isoquinoline, 2-azabenz[a]anthracene, 1-azabenz[a]anthracene, 9-azabenz[a]anthracene, dibenzo[c,i]phenanthro[1,10,9,8anmlk]phenanthridine, diphenanthro[9,10,1def;1',10',9'hij]phthalazine, and benz[de]isoquino[1,8gh]quinoline dissolved in acetonitrile or aqueous-acetonitrile solvent mixtures at various nitromethane concentrations. Results of these measurements show that nitromethane does quench fluorescence emission of ten of the solutes studied; however, phenanthro-[2,3h]isoquinoline, 9-azabenz[a]anthracene, benz[de]isoquino[1,8gh]-quinoline, and dibenzo[c,i]phenanthro[1,10,9,8anmlk]phenanthridine are notable exceptions.