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Phototoxic Phytoalexins. Processes that Compete with the Photosensitized Production of Singlet Oxygen by 9-Phenylphenalenones

Authors

  • Cristina Flors,

    1. Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, E-08017, Barcelona, Spain
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    • This paper is part of a special issue dedicated to Professor J. C. (Tito) Scaiano on the occasion of his 60th birthday.

  • Peter R. Ogilby,

    1. Department of Chemistry, University of Aarhus, DK-8000, Århus, Denmark
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  • Javier G. Luis,

    1. Instituto Universitario de Bio-Orgánica “Antonio González,” Universidad de La Laguna, E-38206 La Laguna, Spain
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  • Teresa A. Grillo,

    1. Instituto Universitario de Bio-Orgánica “Antonio González,” Universidad de La Laguna, E-38206 La Laguna, Spain
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  • Laura R. Izquierdo,

    1. Instituto Universitario de Bio-Orgánica “Antonio González,” Universidad de La Laguna, E-38206 La Laguna, Spain
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  • Pier-Luigi Gentili,

    1. European Laboratory for Non-Linear Spectroscopy (LENS), Università di Firenze, Firenze, Italy
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  • Laura Bussotti,

    1. European Laboratory for Non-Linear Spectroscopy (LENS), Università di Firenze, Firenze, Italy
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  • Santi Nonell

    Corresponding author
    1. Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, E-08017, Barcelona, Spain
    • To whom correspondence should be addressed: Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390. E-08017, Barcelona, Spain. Fax: 34 93 205 6266; e-mail: s.nonell@iqs.url.edu

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  • Current address: Department of Chemistry, Katholicke Universitát Leuven, Heverlee, Belgium.

ABSTRACT

Experiments were performed to elucidate the excited-state behavior of 9-phenylphenalenones, which are phototoxic plant secondary metabolites involved in mechanisms of light-mediated plant defense. Using a combination of time-resolved and steady-state UV/visible spectroscopies, time-resolved IR absorption spectroscopy, time-resolved singlet oxygen phosphorescence measurements and cyclic voltammetry, we provide evidence of an intramolecular charge-transfer process in the excited singlet and the triplet states of 9-phenylphenalenones that modulates the photosensitized production of singlet oxygen.

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