Vectorial electron transfer in donor-photosensitizer-acceptor triads based on novel bis-tridentate ruthenium polypyridyl complexes

Rohan J. Kumar, Susanne Karlsson, Daniel Streich, Alice Rolandini Jensen, Michael Jäger, Hans Christian Becker, Jonas Bergquist, Olof Johansson, Leif Hammarström

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Abstract

The first examples of rodlike donor-photosensitizer-acceptor arrays based on bis-2,6-di(quinolin-8-yl)pyridine RuII complexes 1a and 3a for photoinduced electron transfer have been synthesized and investigated. The complexes are synthesized in a convergent manner and are isolated as linear, single isomers. Time-resolved absorption spectroscopy reveals long-lived, photoinduced charge-separated states (τCSS (1a)=140 ns, τCSS (3a)=200 ns) formed by stepwise electron transfer. The overall yields of charge separation (≥50% for complex 1a and ≥95% for complex 3a) are unprecedented for bis-tridentate RuII polypyridyl complexes. This is attributed to the long-lived excited state of the [Ru(dqp)2]2+ complex combined with fast electron transfer from the donor moiety following the initial charge separation. The rodlike arrangement of donor and acceptor gives controlled, vectorial electron transfer, free from the complications of stereoisomeric diversity. Thus, such arrays provide an excellent system for the study of photoinduced electron transfer and, ultimately, the harvesting of solar energy.

Original languageEnglish
Pages (from-to)2830-2842
Number of pages13
JournalChemistry - A European Journal
Volume16
Issue number9
DOIs
Publication statusPublished - Mar 1 2010

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Keywords

  • Donor-acceptor systems
  • Electron transfer
  • Photochemistry
  • Ruthenium
  • Tridentate ligands

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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