Ultrafast internal conversion in a model anthocyanin-polyphenol complex: implications for the biological role of anthocyanins in vegetative tissues of plants.
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.
Rodrigues
Rita França
RF
Centro de Química Estrutural, Technical University Lisbon, Av. Rovisco Pais s/n, 1049-001 Lisbon, Portugal.
da Silva
Palmira Ferreira
PF
Shimizu
Karina
K
Freitas
Adilson A
AA
Kovalenko
Sergey A
SA
Ernsting
Nikolaus P
NP
Quina
Frank H
FH
Maçanita
António
A
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
D000872:Anthocyanins; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols