Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation.
Archer, Stuart A.
Meijer, Anthony J. H. M.
Sazanovich, Igor V.
Greetham, Gregory M.
Weinstein, Julia A.
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AbstractUltrafast electron transfer in condensed-phase molecular systems is often strongly coupled to intramolecular vibrations that can promote, suppress and direct electronic processes. Recent experiments exploring this phenomenon proved that light-induced electron transfer can be strongly modulated by vibrational excitation, suggesting a new avenue for active control over molecular function. Here, we achieve the first example of such explicit vibrational control through judicious design of a Pt(II)-acetylide charge-transfer Donor-Bridge-Acceptor-Bridge-Donor “fork” system: asymmetric 13C isotopic labelling of one of the two -C≡C-bridges makes the two parallel and otherwise identical Donor→Acceptor electron-transfer pathways structurally distinct, enabling independent vibrational perturbation of either. Applying an ultrafast UVpump(excitation)-IRpump(perturbation)-IRprobe(monitoring) pulse sequence, we show that the pathway that is vibrationally perturbed during UV-induced electron-transfer is dramatically slowed down compared to its unperturbed counterpart. One can thus choose the dominant electron transfer pathway. The findings deliver a new opportunity for precise perturbative control of electronic energy propagation in molecular devices.
CitationDelor, M. et al. (2017) ‘Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation’, Nature Chemistry, 9 (11), pp. 1099–1104. doi: 10.1038/nchem.2793