A SOLVENT-DEPENDENT LUMINESCENCE STUDY ON 9-PHENYL CARBAZOLE

A detailed investigation on the absorption and emission characteristic s of 9-phenyl carbazole (PhC) has been carried out in different solven ts at room temperature (300 K) and 77 K. Analyses of spectra and radia tive/non-radiative rate parameters suggest that the phenyl group at th e position 9 in PhC is twisted out of the plane of carbazolo moiety. Q uantum mechanical calculations have also been done to identify ground and excited states and to get optimized geometries in S-0 and S-1 leve ls. In aqueous medium PhC form dimer or higher aggregates even in very dilute solution. Deaggregation is proposed to account for the P-cyclo dextrin-induced effects. In highly acidic HCl medium, PhC decomposes t o non-fluorescent product(s) through an intermediate fluorescing speci es. (C) 1998 Elsevier Science B.V. All rights reserved.