Substituent positional effect on radiative lifetimes of anthracene sulphonates

Abstract

Excited state lifetimes of anthracene-1-sulphonate, anthracene-2-sulphonate, anthracene-1,5-disulphonate, and anthracene-1,8-disulphonate have been studied by photoselection and single photon counting methods. Experimental lifetimes are compared with theoretical values. For anthracene- monosulphonates, exciplex formation with water is proposed. In the case of anthracene-1,8-disulphonate, distortion in molecular geometry is found responsible for the higher non-radiative decay constant. Summation of nonradiative decay constants, Σki, increase in the series [Formula: see text]. The sharp increase for 1,8-AS is perhaps due to distortion of the molecular geometry due to steric effect of two bulky and charged —SO3− groups on the same side of the anthracene skeleton.