FLUORESCENCE CHARACTERISTICS OF 1,3-DIHYDROXYNAPHTHALENE, 1,4-DIHYDROXYNAPHTHALENE, 2,3-DIHYDROXYNAPHTHALENE AND 2,7-DIHYDROXYNAPHTHALENE RADICAL CATIONS

We have recorded excitation and fluorescene spectra of 1,3-, 1,4-, 2,3- and 2,7-dihydroxynaphthalene radical cations in a rigid matrix. While the parent compounds give rise to broad and structureless emission bands, the ionic spectra exhibit, in addition to an intense band, a few weaker bands. Excitation wavelength and fluorescence maxima for the cations are shifted towards longer wavelength compared to those for the parent molecules. The characteristic features of the spectra are explained in relation to the position of -OH groups in the molecule.