Photoinduced Electron Transfer in a Phenothiazine-Riboflavin Dyad Assembled by Zinc-Imide Coordination in Water
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- 作者：Burkhard Kö ; nig ; Mario Pelka ; Harald Zieg ; Tobias Ritter ; Henri Bouas-Laurent ; Roland Bonneau ; and Jean-Pierre Desvergne
- 刊名：Journal of the American Chemical Society
- 出版年：1999
- 出版时间：March 3, 1999
- 年：1999
- 卷：121
- 期：8
- 页码：1681 - 1687
- 全文大小：114K
- 年卷期：v.121,no.8(March 3, 1999)
- ISSN：1520-5126
文摘
The known electron acceptor systems whereby the redox centers are linked by reversible noncovalentinteractions are in most cases restricted to organic solvents. A kinetically labile coordinative bond has beendesigned for self-assembly of an electron donor (phenothiazine) and a photoinducible electron acceptor(riboflavin) in water at neutral pH. The pH dependent formation of the donor-acceptor complex in water wasinvestigated by potentiometric titrations showing a binding constant of log K = 5.9. The strong binding constantsupports the observed large fluorescence deactivation of the riboflavin emission by the phenothiazine zinccomplex. The riboflavin fluorescence lifetime was found to be constant (
= 4.7 ns) whatever the quencherconcentration, clear evidence for a static quenching mechanism. A strong thermodynamical driving force andthe observation of the riboflavin radical anion and phenothiazine radical cation by transient spectroscopy provideevidence for intramolecular electron transfer as the likely mechanism for the fluorescence quenching.
= 4.7 ns) whatever the quencherconcentration, clear evidence for a static quenching mechanism. A strong thermodynamical driving force andthe observation of the riboflavin radical anion and phenothiazine radical cation by transient spectroscopy provideevidence for intramolecular electron transfer as the likely mechanism for the fluorescence quenching.