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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

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Author(s):
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]
Total Authors: 8
Affiliation:
[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
Total Affiliations: 5
Document type: Journal article
Source: Photochemistry and Photobiology; v. 95, n. 1, p. 176-182, JAN 2019.
Web of Science Citations: 2
Abstract

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)

FAPESP's process: 16/13433-0 - Spectroscopy of redox misbalance induced by UVA and vis radiation on XPC fibroblasts and melanocytes
Grantee:Jan Caspar Schlothauer
Support Opportunities: Scholarships in Brazil - Post-Doctoral
FAPESP's process: 13/07937-8 - Redoxome - Redox Processes in Biomedicine
Grantee:Ohara Augusto
Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC