Vectorial Electron Transfer in Donor–Photosensitizer–Acceptor Triads Based on Novel Bis‐tridentate Ruthenium Polypyridyl Complexes |
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Authors: | Rohan?J Kumar Dr Susanne Karlsson Daniel Streich Alice Rolandini?Jensen Michael Jäger Dr Hans‐Christian Becker Dr Jonas Bergquist Prof Olof Johansson Dr Leif Hammarström Prof |
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Institution: | 1. Department of Photochemistry and Molecular Science, Uppsala University, Box 523, 751 20 Uppsala (Sweden), Fax: (+46)?18‐471‐6844;2. Department of Physical and Analytical Chemistry, Uppsala University, Box 599, 751 24 Uppsala (Sweden) |
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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 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 (τCSS ( 1 a )=140 ns, τCSS ( 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 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. |
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Keywords: | donor– acceptor systems electron transfer photochemistry ruthenium tridentate ligands |
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