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Photosensitization versus Photocyclization: competitive reactions of phenylphenalenone in its role as phytoanticipins in plant defense strategies

  • Identification data

    Identifier: imarina:3707868
    Authors:
    Josep CasellasMar Reguero
    Abstract:
    Phenalenone derivatives are involved in plant defense strategies, producing molecular singlet oxygen in a photosensitization process. Many experimental and theoretical studies determined that phenalenone (PN) can carry out this process with a quantum yield close to one. However, it has been observed that the efficiency of some of its derivatives is much lower. This is the case of 9-phenylphenalenone (9-PhPN). To elucidate the factors that determine the different photochemistry of PN and its derivate 9-PhPN, we have developed a CASSCF/CASPT2 study where several deactivation paths through the lowest excited states have been explored. We have found that the characteristics of the low-lying excited states are similar for both PN and 9-PhPN in the areas near the geometry of excitation. Consequently, the first processes that take place immediately after absorption are possible in both systems, including the population of the triplet state responsible for oxygen sensitization. However, 9-PhPN can also undergo cyclisation by a bond formation between the carbonyl oxygen and a carbon atom of the phenyl substituent. This process competes favourably with population of triplet states and is responsible for the decrease of the quantum yield of oxygen sensitization in 9-PhPN relative to PN.
  • Others:

    Author, as appears in the article.: Josep Casellas; Mar Reguero
    Department: Química Física i Inorgànica
    URV's Author/s: Reguero de la Poza, Maria del Mar
    Keywords: Mecanismes de reacció Fotoquímica
    Abstract: Phenalenone derivatives are involved in plant defense strategies, producing molecular singlet oxygen in a photosensitization process. Many experimental and theoretical studies determined that phenalenone (PN) can carry out this process with a quantum yield close to one. However, it has been observed that the efficiency of some of its derivatives is much lower. This is the case of 9-phenylphenalenone (9-PhPN). To elucidate the factors that determine the different photochemistry of PN and its derivate 9-PhPN, we have developed a CASSCF/CASPT2 study where several deactivation paths through the lowest excited states have been explored. We have found that the characteristics of the low-lying excited states are similar for both PN and 9-PhPN in the areas near the geometry of excitation. Consequently, the first processes that take place immediately after absorption are possible in both systems, including the population of the triplet state responsible for oxygen sensitization. However, 9-PhPN can also undergo cyclisation by a bond formation between the carbonyl oxygen and a carbon atom of the phenyl substituent. This process competes favourably with population of triplet states and is responsible for the decrease of the quantum yield of oxygen sensitization in 9-PhPN relative to PN.
    Thematic Areas: Química Physics, atomic, molecular & chemical Physical and theoretical chemistry Odontología Medicine (miscellaneous) Medicina ii Medicina i Materiais Interdisciplinar Geociências General medicine Farmacia Ensino Engenharias iv Engenharias iii Engenharias ii Ciências biológicas ii Ciências biológicas i Ciências ambientais Ciências agrárias i Chemistry, physical Biotecnología Biodiversidade Astronomia / física
    licence for use: https://creativecommons.org/licenses/by/3.0/es/
    ISSN: 15205215
    Author's mail: mar.reguero@urv.cat
    Author identifier: 0000-0001-9668-8265
    Last page: 821
    Record's date: 2024-09-07
    Journal volume: 122
    Papper version: info:eu-repo/semantics/submittedVersion
    Link to the original source: https://pubs.acs.org/doi/10.1021/acs.jpca.7b11569
    Licence document URL: https://repositori.urv.cat/ca/proteccio-de-dades/
    Papper original source: Journal Of Physical Chemistry a. 122 (3): 811-821
    APA: Josep Casellas; Mar Reguero (2018). Photosensitization versus Photocyclization: competitive reactions of phenylphenalenone in its role as phytoanticipins in plant defense strategies. Journal Of Physical Chemistry a, 122(3), 811-821. DOI: 10.1021/acs.jpca.7b11569
    Article's DOI: 10.1021/acs.jpca.7b11569
    Entity: Universitat Rovira i Virgili
    Journal publication year: 2018
    First page: 811
    Publication Type: Journal Publications
  • Keywords:

    Chemistry, Physical,Medicine (Miscellaneous),Physical and Theoretical Chemistry,Physics, Atomic, Molecular & Chemical
    Mecanismes de reacció
    Fotoquímica
    Química
    Physics, atomic, molecular & chemical
    Physical and theoretical chemistry
    Odontología
    Medicine (miscellaneous)
    Medicina ii
    Medicina i
    Materiais
    Interdisciplinar
    Geociências
    General medicine
    Farmacia
    Ensino
    Engenharias iv
    Engenharias iii
    Engenharias ii
    Ciências biológicas ii
    Ciências biológicas i
    Ciências ambientais
    Ciências agrárias i
    Chemistry, physical
    Biotecnología
    Biodiversidade
    Astronomia / física
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