Ultrafast excited state dynamics in a first generation photomolecular motor
File(s)
Author(s)
Type
Journal Article
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 S1 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.
Date Issued
2020-02-03
Date Acceptance
2020-01-01
Citation
ChemPhysChem: a European journal of chemical physics and physical chemistry, 2020, 21 (7), pp.594-599
ISSN
1439-4235
Publisher
Wiley
Start Page
594
End Page
599
Journal / Book Title
ChemPhysChem: a European journal of chemical physics and physical chemistry
Volume
21
Issue
7
Copyright Statement
© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000510510800001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Physical Sciences
Chemistry, Physical
Physics, Atomic, Molecular & Chemical
Chemistry
Physics
excited state
fluorescence
coherence
molecular motor
photochemistry
ultrafast dynamics
MOLECULAR MOTORS
UNIDIRECTIONAL ROTATION
VIBRATIONAL COHERENCE
PHOTOISOMERIZATION
ACCELERATION
SPEED
Publication Status
Published
Date Publish Online
2020-01-23