Electron-transfer reactions of quinones, hydroquinones and methyl viologen, photosensitized by tris(2,2′-bipyridine)-ruthenium(II)
- 1 January 1981
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics
- Vol. 77 (2) , 373-382
- https://doi.org/10.1039/f29817700373
Abstract
The photosensitized reactions of tris(2,2′-bipyridine)-ruthenium(II)[Ru(bpy)3 2+] with quinones and hydroquinones have been studied by conventional and nanosecond flash photolysis. Quenching of the excited state [*Ru(bpy)3 2+] by quinone occurs rapidly (kq > 2 × 109 dm3 mol–1 s–1) but the yield of electron-transfer products observed by nanosecond absorption spectroscopy is small (kq < 5 × 107 dm3 mol–1 s–1) but the yield of electron-transfer products is considerably greater. These processes generate the semiquinone radical anion Q[graphic omitted], Ru(bpy)3 3+ and Ru(bpy)3 +. Semiquinone disproportionates to give Q and QH2(hydroquinine). Ru(bpy)3 3+ and Ru(bpy)3 + react rapidly (k > 2 × 109 dm3 mol–1 s–1) with QH2 and Q, respectively. Ru(bpy)3 3+ is also formed when Ru(bpy)3 2+ is quenched by methyl viologen (MV2+) and QH2 can act as electron donor for the Ru(bpy)3 2+/MV2+ photoredox couple. No permanent storage of energy is achieved, however, since MV[graphic omitted] reacts rapidly (k > 2 × 109 dm3 mol–1 s–1) with quinones which are produced by disproportionation of Q[graphic omitted] or are present in the original hydroquinone samples.Keywords
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