Lophine derivatives as activators in peroxyoxalate chemiluminescence

Date
2015-01-01Author
Alves, J.
Boaro, A.
Silva, J. S. da [UNIFESP]
Ferreira, T. L. [UNIFESP]
Keslarek, V. B.
Cabral, C. A.
Orfao, R. B.
Ciscato, L. F. M. L.
Bartoloni, F. H.
Type
ArtigoISSN
1474-905XIs part of
Photochemical & Photobiological SciencesDOI
10.1039/c4pp00311jMetadata
Show full item recordAbstract
Lophine and four of its derivatives were used as activators (ACTs) of the chemiluminescent peroxyoxalate (PO) reaction of bis(2,4,6-trichlorophenyl) oxalate with H2O2, catalysed by imidazole. Kinetic emission assays have shown that with the tested compounds the reaction mechanism, regarding the formation of the high energy intermediate (HEI) of the PO reaction, occurs as previously seen for commonly used ACTs. A bimolecular interaction of the compounds with the HEI leads to chemiexcitation through the chemically initiated electron exchange luminescence (CIEEL) mechanism, as confirmed by a linear free-energy correlation between the relative catalytic rate constants and the oxidation potentials of the compounds. the yields of excited state formation and light emission, in the range of 10(-2)-10(-3) E mol(-1), are comparable to the ones seen with commonly used ACTs. A Hammett plot with rho = -0.90 indicates the buildup of a partial positive charge on the transition step of the catalytic process, consistent with the formation of a radical cation of the ACT, being an additional validation of the CIEEL mechanism in this system.
Citation
Photochemical & Photobiological Sciences. Cambridge: Royal Soc Chemistry, v. 14, n. 2, p. 320-328, 2015.Sponsorship
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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