Photophysics of 1-hydroxy- and 1-methoxy-9-fluorenone: II. Non-radiative deactivation

Absorption, fluorescence, fluorescence excitation spectra and time dependence fluorimetric studies of 1-hydroxy-9-fluorenone (1-HFu) and 1-methoxy-9-fluorenone (1-MFu) have been studied in different solvents and binary solvent mixtures. Fluorescence quantum yields (ϕf) of both the molecules increase in polar/aprotic solvents. In protic solvents ϕf of 1-HFu decreases with increase in their polarity, whereas in case of 1-MFu it increases up to ethanol and then decreases in methanol and water. Importance of inter- and intramolecular hydrogen bonding (IHB) has been studied by using binary mixtures of solvents, like trifluoroethanol (TFE)–cyclohexane and acetonitrile–water mixtures.