EXPERIMENTAL AND THEORETICAL STUDY OF THE EXCITED STATE OF 2 ACETYLTHIANTHRENE

The properties of the excited state of 2-acetylthianthrene (emission maxima, quantum yields,natural lifetime) were investigated in several solvents by means of steady-state fluorescencespectroscopy. The experimental data pointed out a significant bathochromic shift of the emissionmaxima in polar solvents. Considering the dependence of F or ! Stokes on both the solventpolarity function (Lippert- Mataga model) and the ETN values, the increase in the dipole momentvalue upon excitation was estimated. The results can be rationalized in terms with a pronouncedintramolecular charge transfer character of the first excited state. MO calculations bysemiempirical and ab initio methods were performed to support the experimental data.