Abstract
Electronic absorption and fluorescence spectra of anthracene-9-carboxylic acid (ANCA) were
studied in different homogeneous solvents, binary protic/aprotic solvent mixtures and in heterogeneous
solutions of the cationic cetyltrimethyl ammonium bromide (CTAB) micelle. Different chemical species of
ANCA were identified spectroscopically in different media. The results are discussed on the basis of a mechanism
that involves two equilibria: acid-base equilibrium and monomer-dimer equilibrium. These equilibria
were found to be very sensitive to the nature of the medium and the concentration of ANCA.Moreover, while it is photostable in most solvents studied, the ANCA was found to be photolabile in aqueous
media of different pHs. The acid-base catalyzed photodegradation rate was studied by following up
absorption and/or fluorescence intensities as a function of illumination dose. The determined rate of the
photochemical degradation of ANCA depends on the nature of the medium. The first order degradation rate
constant is remarkably enhanced in heterogeneous medium of CTAB. As expected, the determined activation
energy is low (