Complex multistate photophysics of a rhodanine photoswitch

Fatima, Anam, Chakraborty, Pratip, Xu, Xinyue, Jones, Garth A., Chambrier, Isabelle, Logan, Giorgia, Cammidge, Andrew N., Smith, Trevor, Hall, Christopher R. and Meech, Stephen R. (2025) Complex multistate photophysics of a rhodanine photoswitch. Angewandte Chemie-International Edition. ISSN 1433-7851

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Abstract

Development of new and improved photoswitches for molecular photonics and photo-pharmaceutics is an increasingly important research objective. Recently a promising family of photoswitches based on the rhodanine motif was described. Here, the photophysics of a typical example are investigated by ultrafast UV and IR spectroscopy and quantum chemical calculations. Remarkably, the photophysics are very different to and more complex than those of closely related monomethine photoswitches, which relax by ultrafast internal conversion to the electronic ground state. In the rhodanine photoswitch, the allowed Franck–Condon excited state also relaxes on a sub-picosecond timescale, but the ground state is repopulated only after several hundred picoseconds. Instead, the Franck–Condon state relaxes through (at least) two intermediate states. These states are characterized by transient spectroscopy, and the reaction pathway is modeled by quantum chemical calculations. Comparison of calculated and measured IR data suggests that a triplet mediated isomerization pathway is responsible for the slow excited state dynamics. The triplet state is rapidly populated via coupling of a nearly degenerate nπ* state populated by ultrafast internal conversion from the bright ππ* state. This unexpected isomerization pathway has important implications for the synthesis, analysis, and application of rhodanine photoswitches.

Item Type:	Article
Additional Information:	Data Availability Statement: The data that support the findings of this study are available from the corresponding author upon reasonable request. Research funding: EPSRC. Grant Numbers: EP/Y021525/1, EP/X011410/1; Australian Research Council. Grant Number: FT210100113
Uncontrolled Keywords:	3* ,/dk/atira/pure/researchoutput/REFrank/3_
Faculty \ School:	Faculty of Science > School of Chemistry, Pharmacy and Pharmacology
UEA Research Groups:	Faculty of Science > Research Groups > Centre for Photonics and Quantum Science Faculty of Science > Research Groups > Chemistry of Materials and Catalysis Faculty of Science > Research Groups > Chemistry of Light and Energy
Depositing User:	LivePure Connector
Date Deposited:	06 Aug 2025 09:30
Last Modified:	07 Aug 2025 00:29
URI:	https://ueaeprints.uea.ac.uk/id/eprint/100059
DOI:	10.1002/anie.202506137

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