An Efficient Regeneration of Singlet Oxygen from 2,5-Diphenylfuran Endoperoxide Produced by a Dye-Sensitized Oxygenation

Abstract

The maximum quantum yield of 4.5 was evaluated from the kinetic analysis for the Methylene Blue-sensitized oxygenation of 2,5-diphenylfuran, and the contribution of a chain process to produce the furan endoperoxide was suggested. After the photoreaction, the thermolysis of the endoperoxide occurred to regenerate 2,5-diphenylfuran and singlet oxygen and to produce cis-1,2-dibenzoylethylene simultaneously. The activation energy of singlet oxygen recovery was estimated to be 18.5 kcal mol−1. The reversible conversion of singlet oxygen took place efficiently with thiazine and xanthene dyes. A concerted dissociation of singlet oxygen from the endoperoxide was supposed from the negative value of activation enthropy (−9.8 e.u.) for the reaction.

Amphiphilic Rhenium-Oxo Corroles as a New Class of Sensitizers for Photodynamic Therapy

“…The solution was magnetically stirred during irradiation and shaken after each irradiation period to ensure air-saturated conditions. Singlet oxygen quantum yields were determined relative to methylene blue, Φ Δ = 0.48, which is the average of two values reported by Gross et al and Usui et al…”

The synthesis and photophysical properties of polyether substituted phthalocyanines of potential use in photodynamic therapy

“…Acetonitrile: methylene blue in air equilibrated acetonitrile for which φ ∆ = 0.52. 26 Benzene: phenazine in air equilibrated benzene for which φ ∆ = 0.88. 27 Methanol: methylene blue in air equilibrated monodeuterated methanol for which φ ∆ = 0.58.…”

Modulation of singlet oxygen generation in halogenated BODIPY dyes by substitution at their meso position: towards a solvent-independent standard in the vis region

“…This result in turn also validates the singlet oxygen quantum yield determined for RB in ACN (F D ¼ 0.53), for which very scattered values (F D ¼ 0.42-0.83) may be found in the literature. [33][34][35] In the following, the analysis of singlet oxygen quantum yields of 7 in several solvents of various polarities was addressed. It should be stressed here that the solvent polarity is not the only factor governing singlet oxygen quenching and lifetimes and that other parameters dealing with the formation and stability of the collision complex between a solvent molecule S and oxygen (S-O 2 ), out of the scope of the present paper, have to be considered.…”