Spectroscopic Properties of Polycyclic Aromatic Compounds. Part IV: Effect of Solvent Polarity and Nitromethane on the Fluorescence Emission Behavior of Select Bipolycyclic Aromatic Hydrocarbons

Abstract

Fluorescence emission behavior is reported for 1,1′-binaphthalene, 2,2′-binaphthalene, 9,9′-bianthracene, 9,9′-biphenanthrene, 1,1′-methylene-bisnaphthalene, and 1,1′,2,2′-tetrahydro-5,5′-biacenaphthylene dissolved in organic nonelectrolyte solvents of varying polarity, refractive index, and dielectric constant. Fluorescence measurements are used to classify the six bipolycyclic aromatic hydrocarbon (bi-PAH) solutes as either solvatochromic probe or nonprobe molecules, depending upon whether measured fluorescence properties vary with solvent nature. Of the bi-PAHs studied, only 9,9′-bianthracene exhibited probe character. Possible correlations between 9,9′-bianthracene's maximum intensity emission wavelength and select functions of solvent refractive index and dielectric constant were examined. Also reported is the effect that nitromethane has on bi-PAH fluorescence emission intensities.