Silicon tetrabenzotriaza corrole and silicon phthalocyanine: Synthesis, photophysics and singlet oxygen generation

Synthesis, photophysical and photochemical measurements were carried out on silicon tetrabenzotriaza corrole. The results were compared with that of phosphorous tetrabenzotriaza corrole and silicon phthalocyanine. UV–vis absorption spectra, fluorescence emission spectra, fluorescence quantum yields and lifetimes, triplet–triplet absorption spectra, triplet formation quantum yields and lifetimes, and singlet delta oxygen quantum yields were measured in DMF. Silicon tetrabenzotriaza corrole exhibits quite different spectral and photophysical properties from both silicon phthalocyanine and phosphorous tetrabenzotriaza corrole. Silicon tetrabenzotriaza corrole features a longest fluorescence lifetime of 5.84 ns, but a lowest fluorescence quantum yield of 0.24. The quantum yields of the triplet state formation and sensitized generation of singlet delta oxygen by silicon tetrabenzotriaza are 0.72 and 0.61, respectively, which are significantly higher than those of silicon phthalocyanine and phosphorous tetrabenzotriaza corrole. Silicon tetrabenzotriaza corrole also showed a long triplet lifetime of 143 μs. Silicon tetrabenzotriaza corrole is therefore a very efficient photosensitizer for singlet oxygen generation.