The mechanism of perylene photo-oxidation in a water-soluble polymeric photocatalyst

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 1996-10, Vol.100 (1), p.93-100
• Main Authors: Burke, Nicholas A.D., Templin, Markus, Guillet, James E.
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Perylene; Photo-oxidation; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Polymeric photocatalyst
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/S1010-6030(96)04484-X

The photo-oxidation of perylene in aqueous solutions of a polymeric photocatalyst was investigated to probe the mechanism of polycyclic aromatic hydrocarbon degradation. Perylene and other hydrophobic molecules are efficiently solubilized in aqueous polymer solutions with distribution coefficients as high as 4 x 10 6. The rate of perylene photo-oxidation was much more rapid in aqueous polymer solutions than in organic solvents. In organic solvents, 10 2 sensitizers (rose bengal) had little effect on the reaction, but electron acceptors, such as dicyanobenzene, caused an acceleration in rate. Naphthoquinone was suggested as a potential electron acceptor in the naphthalene-containing polymer, and it was shown to be formed in small concentrations by polymer oxidation. It was concluded that the polymer plays several key functions in perylene photo-oxidation: (1) solubilization of the hydrophobic molecule; (2) energy migration through the polymer coil and energy transfer, providing additional photochemical energy to the reactants; (3) the enhancement of oxidation by photoinduced electron transfer via provision of an electron acceptor and facilitation of charge separation.