EVIDENCE OF THE SPECIFIC SOLVATION OF SELECTED FLUORESCENT DYES WITH METHOXY GROUP AND ITS ANALOGS DERIVATIVES OF THE 7H-INDOLO[1,2-A]QUINOLINIUM SYSTEM

The fluorescence quantum yield of the xyphenyl)-7,7-dimethyl-7H-indolo [1,2-a]quinolinium perchlorate and its analogues was determined in 12 selected solvents of the hydroxyl and CH-acid type and in the dichloro methane-acetonitrile binary system at constant and variable temperatur e. The quenching process, which depends on the dye and solvent structu re, in hydroxylic ones was caused by dissociation of the solvent-dye c omplex. A rare phenomenon of the dye fluorescence quantum yield raisin g along with the increase in temperature is observed. It has been prov ed that methoxy group and its derivatives is a negatively charged comp lexing centre and the complex stability raises along with the increasi ng electron donor character of alkyl fragment. This conclusion is supp orted by theoretical calculations of bonding energy. The important rol e of a local dielectric constant and the method of its calculation are discussed. (C) 1998 Elsevier Science S.A. All rights reserved.