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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Triplet Excited States and Singlet Oxygen Production by Analogs of Red Wine Pyranoanthocyanins

Texto completo
Autor(es):
Silva, Gustavo Thalmer M. [1] ; Thomas, Suma S. [2, 3] ; Silva, Cassio Pacheco [1] ; Schlothauer, Jan C. [4] ; Baptista, Mauricio S. [4] ; Freitas, Adilson A. [5] ; Bohne, Cornelia [2, 3] ; Quina, Frank H. [1]
Número total de Autores: 8
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Inst Quim, Dept Fundamental Chem, Sao Paulo - Brazil
[2] Univ Victoria, Dept Chem, Victoria, BC - Canada
[3] Univ Victoria, Ctr Adv Mat & Related Technol CAMTEC, Victoria, BC - Canada
[4] Univ Sao Paulo, Inst Quim, Dept Biochem, Sao Paulo - Brazil
[5] Univ Lisbon, Inst Super Tecn, Ctr Quim Estrutural, Lisbon - Portugal
Número total de Afiliações: 5
Tipo de documento: Artigo Científico
Fonte: Photochemistry and Photobiology; v. 95, n. 1, p. 176-182, JAN 2019.
Citações Web of Science: 2
Resumo

During the maturation of red wines, the anthocyanins of grapes are transformed into pyranoanthocyanins, which possess a pyranoflavylium cation as their basic chromophore. Photophysical properties of the singlet and triplet excited states of a series of synthetic pyranoflavylium cations were determined at room temperature in acetonitrile solution acidified with 0.10 mol dm(-3) trifluoroacetic acid (TFA, to inhibit competitive excited state proton transfer) and at 77 K in a rigid TFA-acidified isopropanol glass. In solution, the triplet states of these pyranoflavylium cations are efficiently quenched by molecular oxygen, resulting in sensitized formation of singlet oxygen, as confirmed by direct detection of the triplet-state decay by laser flash photolysis and of singlet oxygen monomol emission in the near infrared. The strong visible light absorption, the relatively small singlet-triplet energy differences, the excited state redox potentials and the reasonably long lifetimes of pyranoflavylium triplet states in the absence of molecular oxygen suggest that they might be useful as triplet sensitizers and/or as cationic redox initiators in polar aprotic solvents like acetonitrile. (AU)

Processo FAPESP: 13/07937-8 - Redoxoma
Beneficiário:Ohara Augusto
Linha de fomento: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs
Processo FAPESP: 16/13433-0 - Espectroscopia do desbalanço redox induzidos por radiação UVA e visível em fibroblastos XPC e em melanócitos
Beneficiário:Jan Caspar Schlothauer
Linha de fomento: Bolsas no Brasil - Pós-Doutorado