title: Ultrafast internal conversion in a model anthocyanin-polyphenol complex: implications for the biological role of anthocyanins in vegetative tissues of plants.
abstract: The red flavylium cations of anthocyanins form ground-state charge-transfer complexes with several naturally occurring electron-donor copigments, such as hydroxylated flavones and hydroxycinnamic or benzoic acids. Excitation of the 7-methoxy-4-methyl-flavylium-protocatechuic acid complex results in ultrafast (240 fs) internal conversion to the ground state of the complex by way of a low-lying charge-transfer state. Thus, both uncomplexed anthocyanins, whose excited state decays by fast (5-20 ps) excited-state proton transfer, and anthocyanin-copigment complexes have highly efficient mechanisms of deactivation that are consistent with the proposed protective role of anthocyanins against excess solar radiation in the vegetative tissues of plants.
authors.affiliation: Centro de Química Estrutural, Technical University Lisbon, Av. Rovisco Pais s/n, 1049-001 Lisbon, Portugal.
authors.forename: Rita França
authors.initials: RF
authors.lastname: Rodrigues
authors.forename: Palmira Ferreira
authors.initials: PF
authors.lastname: da Silva
authors.forename: Karina
authors.initials: K
authors.lastname: Shimizu
authors.forename: Adilson A
authors.initials: AA
authors.lastname: Freitas
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Kovalenko
authors.forename: Nikolaus P
authors.initials: NP
authors.lastname: Ernsting
authors.forename: Frank H
authors.initials: FH
authors.lastname: Quina
authors.forename: António
authors.initials: A
authors.lastname: Maçanita
mesh_terms: D000872:Anthocyanins / Q000737:chemistry* / Q000378:metabolism; D004583:Electrons; D005419:Flavonoids / Q000737:chemistry* / Q000378:metabolism; D010636:Phenols / Q000737:chemistry* / Q000378:metabolism; D010777:Photochemistry; D010944:Plants / Q000378:metabolism; D059808:Polyphenols; D011827:Radiation; D013053:Spectrophotometry
chemical_list: D000872:Anthocyanins; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols