A comparative study of the photophysics and photochemistry of 4-chlorophenol adsorbed on silicalite and beta-cyclodextrin

Da Silva, José Paulo; Ferreira, Luís F. Vieira; Silva, Abílio M. da; Oliveira, A. S.

http://hdl.handle.net/10400.1/6546

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Authors

Da Silva, José Paulo

Ferreira, Luís F. Vieira

Silva, Abílio M. da

Oliveira, A. S.

Abstract(s)

The photochemistry and photophysics of 4-chlorophenol (4-CP) were studied onto two model solid supports, silicalite and beta-cyclodextrin (beta-Cl)), using time resolved diffuse reflectance techniques and product degradation analysis. The results have shown that the photochemistry and photophysics of 4-CP are different from solution and depend on the solid. Ground state diffuse reflectance and time resolved luminescence demonstrated the inclusion of the probe in both substrates. 4-CP exhibits room temperature luminescence in both hosts, being structured and much more intense in beta-CD. The emission was assigned to phosphorescence of the inclusion complex. Transient absorption demonstrated the formation of the unsubstituted phenoxyl radical and of 4-chlorophenoxyl radical in beta-CD. In silicalite only the later was detected. The studies of the photodegradation products indicate that phenol is the main photoproduct in beta-CD. In silicalite the chromatographic analysis indicates the presence of products that involve the ring cleavage. (C) 2002 Elsevier Science B.V. All rights reserved.