A series of pyrylium compounds with different structures have been synthesized. The photophysical behavior of these compounds has also been measured. Results show that the structures of compounds and the polarities of solvents make great effects on the photophysical behaviors of compounds, especially when the structures of compounds are hindered. It indicats that the intramolecular rotation relaxation of compounds in excited state in closely related to the fluorescence quantum yields of compounds.
The spectral properties of 8-(4-methoxyphenyl)methylene-2-phenyl-4-(4-methoxy) phenyl-5,6,7,8-tetrahydrobenzo[b]pyrylium salt in polax solvents (acetonitrile or 1,2-dichloroethane) and in non-polax solvents (toluene or benzene) have been compared.It has been shown that there are dual fluorescence emissions in non-polar solvent at room temperature, one of which corresponds to CT (charge transfer) emission, the other to LE (local excitation) emission, whereas there is only CT fluorescence ethession in polar solventat room temperatare.
