PHOTOSENSITIZATION OF PYRIMIDINES BY 2‐METHYLNAPHTHOQUINONE IN WATER: A LASER FLASH PHOTOLYSIS STUDY

2 January 1983

journal article
research article
Published by Wiley in Photochemistry and Photobiology

Vol. 37 (1) , 27-32
https://doi.org/10.1111/j.1751-1097.1983.tb04429.x

Abstract

2‐Methylnaphthoquinone (MQ) has been excited in water with a 20 ns laser flash at 353 nm and the resultant transient species have been observed optically. Triplet‐state MQ (³MQ) decays on a sub‐microsecond time scale. It has been characterized in terms of its absorption spectrum and quantum yield. Rate constants have been measured for the decay of³MQ in infinitely dilute solution, for self‐quenching by ground‐state MQ, and for reactions of³MQ with oxygen, thymine, uracil, 6‐methyluracil, and orotic acid. The interaction of³MQ with pyrimidines involves charge transfer to give the pyrimidine cation radical and the MQ : anion radical. These reactions are discussed in relation to the mechanism of pyrimidine photooxidation sensitized by MQ.

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