STEADY-STATE LUMINESCENCE STUDIES OF SOME ALPHA-DERIVATIVES AND BETA-DERIVATIVES OF NAPHTHANILIDE AT 293 K AND 77 K

The absorption and fluorescence excitation spectra of six naphthalene derivatives have been measured in various solvents at 293 K and 77 K. The absorption spectra do not change significantly from dry hydrocarbo n to polar solvents at the two temperatures. The emission spectra meas ured at 293 K exhibit two fluorescence bands: the normal F-1(LE) fluor escence band and the F-2 band, which consists of the F-2'(PT) intramol ecular proton-transfer and the F-2 '' (CT) twisted intramolecular char ge-transfer fluorescence emissions. N,beta-naphthyl-alpha-naphthanilid e (IV) is an exception to that pattern; in all the solvents used, only the F-1(LE) fluorescence has been observed. At 77 K, the total lumine scence shows two resolved bands: the first is either the normal F-1 (L E) (molecules III, IV, V, VI) or the excimer F-agr (molecules I, II) f luorescence band. and the second is the phosphorescence band, F-Ph(LE) . Our spectroscopic studies point that the F-1(LE) and F-Ph(LE) bands originate from perturbed naphthalene moieties. (C) 1998 Elsevier Scien ce S.A. All rights reserved.