On the mechanism of vibrational control of light-induced charge transfer in donor–bridge–acceptor assemblies

Nuclear–electronic (vibronic) coupling is increasingly recognized as a mechanism of major importance in controlling the light-induced function of molecular systems. It was recently shown that infrared light excitation of intramolecular vibrations can radically change the efficiency of electron trans...

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Veröffentlicht in:Nature chemistry 2015-09, Vol.7 (9), p.689-695
Hauptverfasser: Delor, Milan, Keane, Theo, Scattergood, Paul A., Sazanovich, Igor V., Greetham, Gregory M., Towrie, Michael, Meijer, Anthony J. H. M., Weinstein, Julia A.
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Sprache:eng
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Zusammenfassung:Nuclear–electronic (vibronic) coupling is increasingly recognized as a mechanism of major importance in controlling the light-induced function of molecular systems. It was recently shown that infrared light excitation of intramolecular vibrations can radically change the efficiency of electron transfer, a fundamental chemical process. We now extend and generalize the understanding of this phenomenon by probing and perturbing vibronic coupling in several molecules in solution. In the experiments an ultrafast electronic–vibrational pulse sequence is applied to a range of donor–bridge–acceptor Pt( II ) trans -acetylide assemblies, for which infrared excitation of selected bridge vibrations during ultraviolet-initiated charge separation alters the yields of light-induced product states. The experiments, augmented by quantum chemical calculations, reveal a complex combination of vibronic mechanisms responsible for the observed changes in electron transfer rates and pathways. The study raises new fundamental questions about the function of vibrational processes immediately following charge transfer photoexcitation, and highlights the molecular features necessary for external vibronic control of excited-state processes. The ultrafast and mode-specific infrared excitation of several donor–bridge–acceptor (DBA) assemblies in solution has been shown to modulate their light-induced electron transfer properties. New insights are afforded into the role of vibrational processes immediately following light absorption in charge-transfer molecules and a recipe for efficient ‘vibrational control’ of electron transfer is proposed.
ISSN:1755-4330
1755-4349
DOI:10.1038/nchem.2327