LIGHT‐INDUCED ELECTRON TRANSFER BETWEEN CHLOROPHYLL AND HYDROQUINONE AND THE EFFECT OF OXYGEN AND β‐CAROTENE
- 1 November 1966
- journal article
- Published by Wiley in Photochemistry and Photobiology
- Vol. 5 (11-12) , 877-887
- https://doi.org/10.1111/j.1751-1097.1966.tb05934.x
Abstract
Abstract— Light‐induced electron spin resonance (ESR) absorption is not observed in degassed benzene solutions of chlorophyll a with hydroquinone. In the presence of methanol, however, the characteristic hyperfine pattern of p‐benzosemiquinone ion radical is formed. This photo‐reduction of chlorophyll a by hydroquinone is enhanced apparently by a small amount of triethylamine and inhibited by β‐carotene.Chlorophyll excited in the presence of oxygen produces a single broad ESR signal in benzene solutions which is enhanced by hydroquinone and quenched by β‐carotene, alcohol, and a mine. Their quenching effect is in parallel with their inhibition of the photoauto‐oxidation of chlorophyll. The high quenching capacity of triethylamine for this ESR signal is reduced by the addition of β‐carotene. In methanol solutions, the initial production of the single broad signal is followed by gradual development of the hypertine structure of p‐benzo‐semiquinone ion radical. This development can be accelerated by triethylamine. The mechanism of these changes is discussed on the primary interaction of excited chlorophyll with oxygen.Keywords
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