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Vectorial Electron Transfer in Donor–Photosensitizer–Acceptor Triads Based on Novel Bis‐tridentate Ruthenium Polypyridyl Complexes
Author(s) -
Kumar Rohan J.,
Karlsson Susanne,
Streich Daniel,
Rolandini Jensen Alice,
Jäger Michael,
Becker HansChristian,
Bergquist Jonas,
Johansson Olof,
Hammarström Leif
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200902716
Subject(s) - photosensitizer , ruthenium , electron donor , chemistry , photochemistry , moiety , acceptor , electron transfer , electron acceptor , excited state , pyridine , photoinduced electron transfer , stereochemistry , catalysis , organic chemistry , physics , nuclear physics , condensed matter physics
The first examples of rodlike donor–photosensitizer–acceptor arrays based on bis‐2,6‐di(quinolin‐8‐yl)pyridine Ru II complexes 1 a and 3 a 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 ( τ CSS ( 1 a )=140 ns, τ CSS ( 3 a )=200 ns) formed by stepwise electron transfer. The overall yields of charge separation (≥50 % for complex 1 a and ≥95 % for complex 3 a ) are unprecedented for bis‐tridentate Ru II 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.