PHOTOINDUCED ELECTRON TRANSFER REACTIONS IN PHTHALOCYANINE DISPERSIONS

Abstract— The photochemistry of phthalocyanine particles suspended in a fluid has been investigated. In alcoholic media, these particles were shown to be capable of reducing benzoquinone and oxidizing hydroquinone. In aqueous media the light induced formation of superoxide was detected. This reaction could be substantially enhanced by addition of EDTA. The role of surfactant in the photoproduction of superoxide is associated with the charge acquired by the particle as a result of the surfactant used. These results can be explained in terms of the band model for semiconductors where band bending by surfactant molecules is invoked. Such studies have relevance to photoevents occurring in photosynthesis, photocatalysis and to the types of solar energy conversion systems where a photoactive semiconductor interfaces with an aqueous medium.