Double molecular photoswitch driven by light and collisions

Bull, James N. ORCID:, Scholz, Michael S., Carrascosa, Eduardo, Da Silva, Gabriel and Bieske, Evan J. (2018) Double molecular photoswitch driven by light and collisions. Physical Review Letters, 120 (22). ISSN 0031-9007

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The shapes of many molecules can be transformed by light or heat. Here we investigate collision- and photon-induced interconversions of EE, EZ, and ZZ isomers of the isolated Congo red (CR) dianion, a double molecular switch containing two NN azo groups, each of which can have the E or Z configuration. We find that collisional activation of CR dianions drives a one-way ZZ→EZ→EE cascade towards the lowest-energy isomer, whereas the absorption of a single photon over the 270-600 nm range can switch either azo group from E to Z or Z to E, driving the CR dianion to lower- or higher-energy forms. The experimental results, which are interpreted with the aid of calculated statistical isomerization rates, indicate that photoisomerization of CR in the gas phase involves a passage through conical intersection seams linking the excited and ground state potential energy surfaces rather than through isomerization on the ground state potential energy surface following internal conversion.

Item Type: Article
Uncontrolled Keywords: physics and astronomy(all) ,/dk/atira/pure/subjectarea/asjc/3100
Faculty \ School: Faculty of Science > School of Chemistry
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Depositing User: LivePure Connector
Date Deposited: 28 Feb 2019 16:30
Last Modified: 09 Feb 2023 13:46
DOI: 10.1103/PhysRevLett.120.223002

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