Change of the luminescence properties of charge-transfer complexes in liquid solutions

The deactivation mechanism of the excited charge-transfer complex in non-polar and polar solvents has been discussed on the basis of measured quantum yields and decay times of fluorescence of charge-transfer complexes of pyromellitic dianhydride with some methylbenzenes. It has been pointed out that great changes of electronic structure in the excited state, caused by strong excited complex—solvent interaction, are responsible for the very low fluorescence quantum yield observed in polar solvents.