Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.1/6577
Título: A diffuse reflectance comparative study of benzil inclusion within microcrystalline cellulose and beta-cyclodextrin
Autor: Ferreira, Luís F. Vieira
Machado, Isabel Ferreira
Silva, José P. da
Oliveira, A. S.
Data: 2004
Editora: Royal Society of Chemistry
Resumo: Diffuse reflectance and laser-induced techniques were used to study photochemical and photophysical processes of benzil adsorbed on two solid powdered supports, microcrystalline cellulose and beta-cyclodextrin. In both substrates, a distribution of ground-state benzil conformers exists, largely dominated by skew conformations where the carbonyl groups are twisted one to the other. Room temperature phosphorescence was observed in air-equilibrated samples in both cases. The decay times vary greatly and the largest lifetime was obtained for benzil/beta-cyclodextrin, showing that this host's cavity accommodates benzil well, enhancing its room temperature phosphorescence. Triplet - triplet absorption of benzil entrapped in cellulose was detected and benzil ketyl radical formation also occurred. With benzil included into beta-cyclodextrin, and following laser excitation, benzoyl radicals were detected on the millisecond timescale. Product analysis and identification of laser-irradiated benzil samples in the two hosts clearly showed that the main degradation photoproducts were benzoic acid and benzaldehyde. The main differences were a larger benzoic acid/benzaldehyde ratio in the case of cellulose and the formation of benzyl alcohol in this support.
Peer review: yes
URI: http://hdl.handle.net/10400.1/6577
DOI: https://dx.doi.org/10.1039/b307956b
ISSN: 1474-905X
Aparece nas colecções:FCT2-Artigos (em revistas ou actas indexadas)



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