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Sardjan, Andy S., Roy, Palas, Danowski, Wojciech, Bressan, Giovanni 
ORCID: https://orcid.org/0000-0001-7801-8495, Nunes dos Santos Comprido, Laura, Browne, Wesley R., Feringa, Ben L. and Meech, Stephen R. ORCID: https://orcid.org/0000-0001-5561-2782
(2020)
Ultrafast excited state dynamics in a first generation photomolecular motor.
ChemPhysChem, 21 (7).
pp. 594-599.
ISSN 1439-4235
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Abstract
Efficient photomolecular motors will be critical elements in the design and development of molecular machines. Optimisation of the quantum yield for photoisomerisation requires a detailed understanding of molecular dynamics in the excited electronic state. Here we probe the primary photophysical processes in the archetypal first generation photomolecular motor, with sub-50 fs time resolved fluorescence spectroscopy. A bimodal relaxation is observed with a 100 fs relaxation of the Franck-Condon state to populate a red-shifted state with a reduced transition moment, which then undergoes multi-exponential decay on a picosecond timescale. Oscillations due to the excitation of vibrational coherences in the S 1 state are seen to survive the ultrafast structural relaxation. The picosecond relaxation reveals a strong solvent friction effect which is thus ascribed to torsion about the C−C axle. This behaviour is contrasted with second generation photomolecular motors; the principal differences are explained by the existence of a barrier on the excited state surface in the case of the first-generation motors which is absent in the second generation. These results will help to provide a basis for designing more efficient molecular motors in the future.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | acceleration,molecular motors,photoisomerization,speed,unidirectional rotation,vibrational coherence,coherence,excited state,fluorescence,molecular motor,photochemistry,ultrafast dynamics |
| Faculty \ School: | Faculty of Science > School of Chemistry |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 21 Jan 2020 10:48 |
| Last Modified: | 09 Feb 2023 13:47 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/73709 |
| DOI: | 10.1002/cphc.201901179 |
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