INFLUENCE OF FLUORINATED GROUP ON THE PHOTOPHYSICS OF 7-AMINOCOUMARINS

The photophysical properties of fluorinated 7-aminocoumarin derivative s with different alkylation degree at the amino group are studied in w ater/ethanol mixtures. The effect of the molecular structure of the ch romophore and solute-protic solvent interactions are considered to exp lain the observed spectral shifts and the internal conversion process. The radiationless deactivation process is analyzed on the basis of th e formation of a twisted intramolecular charge transfer state and a pl anar-to-pyramidal structural change of the amino group.