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Perinaphthenone phototransformation in a model of leaf epicuticular waxes

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posted on 14.08.2015 by Aurelien S. Trivella, Shirin Monadjemi, David Worrall, Iain Kirkpatrick, Emmanuel Arzoumanian, Claire Richard
Perinaphthenone (1H-phenalen-1-one, PN) is a reference photosensitizer producing singlet oxygen with a quantum yield close to one in a large variety of solvents. It is also the basic structure of a class of phototoxic phytoalexins. In this work, the PN photoreactivity was studied for the first time in a paraffinic wax, used as model of leaf epicuticular waxes. The PN photodegradation was monitored by UV–Vis spectroscopy. The triplet excited state, singlet oxygen and the hydroxyperinaphthenyl radical were detected by diffuse reflectance laser flash photolysis, near infrared phosphorescence and by EPR spectroscopy, respectively. The PN phototransformation was found to be fivefold faster in the wax than in n-heptane under steady-state irradiation. The hydroxyperinaphthenyl radical formation was observed in aerated irradiated paraffin wax while in n-heptane solution the radical was observed only in the absence of oxygen. These results show that under continuous irradiation, PN is much more easily phototransformed in a solid environment than in solution. Several photoproducts were identified, in particular phenalanone, PN dimers, and oxidized PN-alkanes adducts. Finally, when pyrethrum extract is added into the wax along with PN, the hydroxyperinaphthenyl radical concentration was increased by a factor of 2.4. Such photochemical reactions may occur when systemic pesticides enter the plant cuticle.

History

School

  • Science

Department

  • Chemistry

Published in

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY

Volume

130

Pages

93 - 101 (9)

Citation

TRIVELLA, A.S. ... et al, 2014. Perinaphthenone phototransformation in a model of leaf epicuticular waxes. Journal of Photochemistry and Photobiology B- Biology, 130, pp. 93 - 101.

Publisher

© Elsevier

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2014

Notes

This article was accepted for publication in the serial, Journal of Photochemistry and Photobiology B- Biology [© Elsevier]. The definitive version is available at: http://dx.doi.org/10.1016/j.jphotobiol.2013.10.009

ISSN

1011-1344

Language

en

Exports