Photoinduced intramolecular electron transfer in peptide-bridged molecules

Two series of molecules have been prepared and characterized in which a polypyridyl Ru(II) complex is linked to p-dimethoxybenzene (DMB) and p-benzoquinone (Q) moieties by peptide bridges containing the amino acid L-proline (Pro). The photophysical properties of the metal-to-ligand charge transfer (...

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Bibliographic Details
Published in:Journal of the American Chemical Society 1988-02, Vol.110 (4), p.1180-1186
Main Authors: Schanze, Kirk S, Sauer, Kenneth
Format: Article
Language:English
Subjects:
Chemistry
Exact sciences and technology
General and physical chemistry
Photochemistry
Physical chemistry of induced reactions (with radiations, particles and ultrasonics)
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Summary:Two series of molecules have been prepared and characterized in which a polypyridyl Ru(II) complex is linked to p-dimethoxybenzene (DMB) and p-benzoquinone (Q) moieties by peptide bridges containing the amino acid L-proline (Pro). The photophysical properties of the metal-to-ligand charge transfer (MLCT) excited state of the Ru(II) chromophore have been examined for the complexes with 0, 1, 2, 3, and 4 intervening Pro residues. Steady state and time resolved luminescence experiments on the Pro-bridged DMB system show that the properties of the Ru MLCT excited state are only slightly modified from those of an unsubstituted model complex by the presence of covalently attached DMB peptides. The quenching process is ascribed to long-range intramolecular Ru-to-Q electron transfer. This hypothesis is supported by time-resolved luminescence data which suggest that the average electron transfer rate falls sharply with an increase in the peptide bridge length.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja00212a029