Solvent effects on the photophysical properties of 9,10-dicyanoanthracene

Abstract

The quantum yields of fluorescence, Φ_F and of triplet state production, Φ_T of 9,10-dicyanoanthracene and the fluorescence lifetimes have been measured in fourteen different solvents. It has been shown that Φ_F + Φ_T is less than one in all the solvents except bromobenzene. Delayed fluorescence of 9,10-dicyanoanthracene arising following triplet–triplet annihilation is observed in all solvents. It consists of excimer as well as monomer emission, the relative intensities of which were shown to be different from the ratio for prompt fluorescence and to vary with solvent polarity. The rate constants for fluorescence quenching by the three heavy-atom-containing quenchers, iodopropane, iodobenzene and dimethyliodobenzene, k_IP^S, k_IB^S and k_DMIB^S, respectively have been measured and in all solvents it was found that k_IP^S<k_IB^S<k_DMIB^S. Reasons for this are discussed in terms of the charge transfer interactions of the first excited singlet state of 9,10-dicyanoanthracene with the quenchers and with the different solvents.