Nelissen, Hubertus F. M. and Kercher, Michael and De Cola, Luisa and Feiters, Martinus C. and Nolte, Roeland J. M. (2002) Photoinduced electron transfer between metal-coordinated cyclodextrin assemblies and viologens. CHEMISTRY-A EUROPEAN JOURNAL, 8 (23). pp. 5407-5414. ISSN 0947-6539, 1521-3765
Full text not available from this repository. (Request a copy)Abstract
Two novel tris(bipyridine)ruthenium(II) complexes bearing two and six P-cyclodextrin binding sites on their ligands have been synthesised and characterised. Complex 1, bearing two cyclodextrins, adopts a conformation in aqueous solution where parts of the aromatic ligands are self-included into the cyclodextrin moieties. This results in a loss of symmetry of the complex and gives rise to a much more complicated H-1 NMR spectrum than expected. Photophysical studies indicate that the appended cyclodextrins protect the luminescent ruthenium core from quenching by oxygen, which results in longer excited state lifetimes and higher emission quantum yields compared with the reference compound, the unsubstituted ruthenium tris(bipyridine). Inclusion of suitable guests such as dialkyl-viologens leads to a quenching of the luminescence of the central unit. In these supramolecular donor-acceptor dyads an efficient photoinduced electron transfer from the excited ruthenium moiety (the donor) to the viologen unit (the acceptor) is observed. The alkyl chain length of the acceptor plays an important role on the binding properties; when it exceeds a certain limit the binding becomes strong enough for electron transfer to occur. Interestingly, a viologen with only one long alkyl tail instead of two shows no efficient quenching; this indicates that cooperative interactions between two cyclodextrins binding one viologen are essential to raise the binding constant of the supramolecular dyad.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | PHOTOPHYSICAL PROPERTIES; BETA-CYCLODEXTRIN; SUBSTITUTED 2,2'-BIPYRIDYLS; POLYPYRIDINE COMPLEXES; INCLUSION COMPLEXATION; MOLECULAR MACHINES; BINDING-PROPERTIES; TRANSFER RATES; RUTHENIUM(II); PHOTOSYNTHESIS; cyclodextrins; electron transfer; inclusion compounds; ruthenium; supramolecular chemistry |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 26 Aug 2021 10:54 |
| Last Modified: | 26 Aug 2021 10:54 |
| URI: | https://pred.uni-regensburg.de/id/eprint/39570 |
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