fulltext.study @t Gmail

Singlet oxygen quenching by thione analogues of canthaxanthin, echinenone and rhodoxanthin

Paper ID Volume ID Publish Year Pages File Format Full-Text
31235 44576 2006 6 PDF Available
Title
Singlet oxygen quenching by thione analogues of canthaxanthin, echinenone and rhodoxanthin
Abstract

Thione analogues of three naturally occurring carotenones (canthaxanthin, echinenone, and rhodoxanthin) were synthesized just over ten years ago, and it was reported that substitution of the oxygen atom by sulphur brings about a large red shift and some broadening in the optical absorption spectrum of the compound. Since the three carotenothiones are scarce, determination of their molar absorption coefficients presents a challenge. A method for relating the molar absorption coefficient of a carotenothione (Car-S) to that of its ketone analogue (Car-O) has been developed, which has revealed that the peak molar absorption coefficient of a Car-S is only about 60% of the corresponding value for Car-O. Using methylene blue as the sensitizer and acetonitrile as the solvent, we have also investigated the quenching (under photostationary conditions) of the 1270 nm phosphorescence emission of singlet oxygen by each of the six carotenoids. The data conform to the Stern–Volmer relation, and show that substitution of a carbonyl oxygen atom by sulphur does not lead to an appreciable change in the value of the quenching constant, which is close to 1.5 × 1010 M−1 s−1 for all six quenchers.

Keywords
Carotenoids; Carotenothiones; Singlet oxygen
First Page Preview
Singlet oxygen quenching by thione analogues of canthaxanthin, echinenone and rhodoxanthin
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 84, Issue 2, 1 August 2006, Pages 135–140
Authors
, , , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering