Photoinduced Electron-Transfer Reaction of (Phenylazo)triphenylmethane(PAT). Behavior of Generated Trityl Cation

Article abstract of DOI:10.1246/bcsj.69.3325

The decomposition mechanism of photoinduced electron transfer (PET) between electron deficient sensitizers and (phenylazo)triphenylmethane (PAT) was investigated. In 9,10-dicyanoanthracene (DCA) sensitized reaction, benzene, triphenylmethane, 3,3,3-triphenylpropionitrile, and [4-(diphenylmethyl)phenyl]acetonitrile were obtained, and the product distribution was the same as for the direct photolysis and the thermolysis. In the case of 2,4,6-triphenylpyrylium tetrafluoroborate (TPP⁺) sensitization, the product distribution was drastically changed and 9-phenylfluorene was found to be one of the main products. The results of the irradiation wavelength effects indicate that 9-phenylfluorene is produced by the photoreaction of a trityl cation which is generated by the decomposition of a radical cation of PAT. The results of the experiments of laser flash photolysis suggest that the rate of back electron transfer between a radical anion of the sensitizer and a trityl cation plays an important role in these reactions.