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The Excited‐State Interaction of Resazurin and Resorufin with Aminesin Aqueous Solutions. Photophysics and Photochemical Reaction ¶
Author(s) -
Bueno C.,
Villegas M. L.,
Bertolotti S. G.,
Previtali C. M.,
Neumann M. G.,
Encinas M. V.
Publication year - 2002
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2002)0760385tesior2.0.co2
Subject(s) - resazurin , photochemistry , excited state , chemistry , aqueous solution , organic chemistry , biochemistry , physics , nuclear physics
The photophysics and photochemical behavior of the phenoxazin‐3‐one dyes, resazurin and resorufin, have been studied in aqueous solutions. The irradiation of resazurin in the presence of amines leads to deoxygenation of the N ‐oxide group, giving resorufin. This photoreaction is highly dependent on the amine structure and is efficient only in the presence of tertiary aliphatic amines. The absorption and fluorescence properties of these dyes are dependent on pH. At pH above 7.5 both dyes are in their anionic form. For resorufin this form is highly fluorescent ( Φ F = 0.75 ). At lower pH the fluorescence is strongly reduced. The N ‐oxide dye presents a very weak fluorescence quantum yield (0.11), which also is reduced at low pH. Flash photolysis experiments allowed characterization of the triplet state and the transients formed after irradiation of these dyes in the absence and presence of amines. The triplet quantum yields are 0.08 for resazurin and 0.04 for resorufin. The photodeoxygenation of N ‐oxide in the presence of amines occurs from the triplet state.