Photochemistry and Photophysics of Papaverine N-Oxide

Souto-Bachiller, Fernando A.; Rodríguez-Rodríguez, L. A.; Coronado-Pérez, M. E.; Pérez‐Inestrosa, Ezequiel; Suau, Rafael; Rico-Gómez, Rodrigo

doi:10.1562/0031-8655(1999)070<0875:papopo>2.3.co;2

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“…The photoinduced deoxygenation of N ‐oxides has been reported previously for other molecules (10) and was found to proceed on irradiation of N ‐oxide alone or in the presence of suitable acceptors such as amines (11,12). But in most cases the reaction is accompanied by side reactions and rearrangements of the N ‐oxide (13). More recently, we found that the two related dyes, resazurin and resorufin, in the presence of triethanolamine (TEOHA) produce radicals that are efficient photoinitiators of aqueous acrylamide polymerization (14).…”

Section: Introductionmentioning

confidence: 99%

The Excited-State Interaction of Resazurin and Resorufin with Aminesin Aqueous Solutions. Photophysics and Photochemical Reaction¶

Bueno¹,

Villegas²,

Bertolotti³

et al. 2002

Photochemistry and Photobiology

174

106

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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 (ΦF= 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.

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Section: Introductionmentioning

confidence: 99%