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Thermal and photochemical switching of chiral sugar azoalkenes. A mechanistic interrogation

Thermal and photochemical switching of chiral sugar azoalkenes. A mechanistic interrogation
Thermal and photochemical switching of chiral sugar azoalkenes. A mechanistic interrogation
This manuscript describes a thorough study on the thermal and photochemical evolution of carbohydrate-based azoalkenes, which have been proposed as putative intermediates en route to other heterocyclic derivatives and nucleoside analogs. These substances represent new protagonists in the azo chemical space, under intense study due to reversible photoswitching of this functional group suitable for designing artificial nanomachines and responsive materials. Although structurally simple azadienes derived from monosaccharides have long been known, the dynamics of such species in solution and solid phase remains poorly characterized. Here, we show that such azoalkenes undergo 3E→3Z thermal isomerization, which is accelerated by the presence of Brönsted acids. On the other hand, they undergo 1E→1Z isomerization when irradiated by sunlight, while the reverse 1Z→1E isomerization occurs thermally in the dark or under acid catalysis. As a result, sugar monoazadienes not only exhibit inherent chirality, but also dual on-off isomerization under external stimuli. Both experiments and DFT-based computational analyses provide a consistent and unifying mechanistic picture of these transformations.
azoalkene, carbohydrates, chirality, photoswitching, thermal isomerization
1434-193X
2827–2841
Sánchez-León, Ana María
632a02cc-790f-40dd-a3d0-126cb0326b27
Cintas, Pedro
29979233-8382-47a8-bde7-1faf4869308c
Light, Mark
cf57314e-6856-491b-a8d2-2dffc452e161
Palacios, Juan Carlos
c4c41bb9-f9dc-41ff-bcbc-9e7adefd2b4c
Sánchez-León, Ana María
632a02cc-790f-40dd-a3d0-126cb0326b27
Cintas, Pedro
29979233-8382-47a8-bde7-1faf4869308c
Light, Mark
cf57314e-6856-491b-a8d2-2dffc452e161
Palacios, Juan Carlos
c4c41bb9-f9dc-41ff-bcbc-9e7adefd2b4c

Sánchez-León, Ana María, Cintas, Pedro, Light, Mark and Palacios, Juan Carlos (2020) Thermal and photochemical switching of chiral sugar azoalkenes. A mechanistic interrogation. European Journal of Organic Chemistry, 2020 (19), 2827–2841. (doi:10.1002/ejoc.202000029).

Record type: Article

Abstract

This manuscript describes a thorough study on the thermal and photochemical evolution of carbohydrate-based azoalkenes, which have been proposed as putative intermediates en route to other heterocyclic derivatives and nucleoside analogs. These substances represent new protagonists in the azo chemical space, under intense study due to reversible photoswitching of this functional group suitable for designing artificial nanomachines and responsive materials. Although structurally simple azadienes derived from monosaccharides have long been known, the dynamics of such species in solution and solid phase remains poorly characterized. Here, we show that such azoalkenes undergo 3E→3Z thermal isomerization, which is accelerated by the presence of Brönsted acids. On the other hand, they undergo 1E→1Z isomerization when irradiated by sunlight, while the reverse 1Z→1E isomerization occurs thermally in the dark or under acid catalysis. As a result, sugar monoazadienes not only exhibit inherent chirality, but also dual on-off isomerization under external stimuli. Both experiments and DFT-based computational analyses provide a consistent and unifying mechanistic picture of these transformations.

Text
Pedro_Cintas_Ms-EJOC-AZOALKENES_Revised28.03.20 - Accepted Manuscript
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More information

Accepted/In Press date: 8 April 2020
Published date: 22 May 2020
Keywords: azoalkene, carbohydrates, chirality, photoswitching, thermal isomerization

Identifiers

Local EPrints ID: 441481
URI: http://eprints.soton.ac.uk/id/eprint/441481
ISSN: 1434-193X
PURE UUID: 3e64b5b2-777d-4234-8513-8f60b50e7e18
ORCID for Mark Light: ORCID iD orcid.org/0000-0002-0585-0843

Catalogue record

Date deposited: 15 Jun 2020 16:31
Last modified: 26 Nov 2021 05:37

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Contributors

Author: Ana María Sánchez-León
Author: Pedro Cintas
Author: Mark Light ORCID iD
Author: Juan Carlos Palacios

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