Control of photoconversion yield in unidirectional photomolecular motors by push-pull substituents

Roy, Palas, Sardjan, Andy S., Danowski, Wojciech, Browne, Wesley R., Feringa, Ben L. and Meech, Stephen R. ORCID: https://orcid.org/0000-0001-5561-2782 (2023) Control of photoconversion yield in unidirectional photomolecular motors by push-pull substituents. Journal of the American Chemical Society, 145 (36). 19849–19855. ISSN 0002-7863

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Abstract

Molecular motors based on the overcrowded alkene motif convert light energy into unidirectional mechanical motion through an excited state isomerization reaction. The realization of experimental control over conversion efficiency in these molecular motors is an important goal. Here, we combine the synthesis of a novel “push–pull” overcrowded alkene motor with photophysical characterization by steady state and ultrafast time-resolved electronic spectroscopy. We show that tuning of the charge transfer character in the excited state has a dramatic effect on the photoisomerization yield, enhancing it to near unity in nonpolar solvents while largely suppressing it in polar solvents. This behavior is explained through reference to solvent- and substituent-dependent potential energy surfaces and their effect on conical intersections to the ground state. These observations offer new routes to the fine control of motor efficiency and introduce additional degrees of freedom in the synthesis and exploitation of light-driven molecular motors.

Item Type:	Article
Additional Information:	Funding information: Financial support provided by The Netherlands Ministry of Education, Culture and Science (Gravity Program 024.001.035 to W.R.B. and B.L.F.) and the UKRI EPSRC (grants EP/R042357/1 and EP/J009148/1 to S.R.M.) is acknowledged.
Uncontrolled Keywords:	3* ,/dk/atira/pure/researchoutput/REFrank/3_
Faculty \ School:	Faculty of Science > School of Chemistry
UEA Research Groups:	Faculty of Science > Research Groups > Centre for Photonics and Quantum Science Faculty of Science > Research Groups > Chemistry of Light and Energy
Depositing User:	LivePure Connector
Date Deposited:	24 Aug 2023 10:31
Last Modified:	14 Sep 2023 09:30
URI:	https://ueaeprints.uea.ac.uk/id/eprint/92920
DOI:	10.1021/jacs.3c06070

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