Topological quenching of 2,4,6-triphenylpyrylium tetrafluoborate in anionic micelles

Topological quenching of the excited states of the photosensitizer 2,4,6-triphenylpyrylium tetrafluoborate bound to an anionic SDS micelle has been observed by fluorescence spectroscopy. Spectroscopic data suggests that the triphenylpyrylium cation is micellized with the cationic pyrylium moiety slightly projecting out, experiencing the aqueous polar environment. Accordingly, the quenching mechanism varied from static for neutral quenchers and dynamic for the cationic quenchers whereas no quenching was observed for anionic quenchers. Upon irradiation, micellized TP+ undergoes a photoinduced hydrolysis to 1,3,5-triphenyl-1-pentene-1,5-dione, possibly through an electron transfer between triplet excited pyrylium cation and water molecules. This electron transfer leads to the generation of hydroxyl radicals producing the build-up of 10−2 M hydrogen peroxide.