A study of the photophysical properties of 2,4,6-triphenyl pyrylium salts with rigid and non-rigid structures

The photophysical properties of 2,4,6-triphenyl pyrylium salts with rigid and non-rigid structures were investigated. It was found that the polarizability of compound 2 (with a rigid structure) was stronger than that of compound 1 (with a non-rigid structure) in the excited state. The fluorescence quantum yield of compound 1 increased slightly with increasing viscosity of the solvent, while the fluorescence quantum yield of compound 2 decreased dramatically in the same conditions. It was also discovered that the hindered rotation of the 4-phenyl group in the molecules of 2,4,6-triphenyl pyrylium salts inhibits the fluorescence emission of these compounds.