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Article: Choosing sides: unusual ultrafast charge transfer pathways in an asymmetric electron-accepting cyclophane that binds an electron donor

TitleChoosing sides: unusual ultrafast charge transfer pathways in an asymmetric electron-accepting cyclophane that binds an electron donor
Authors
Issue Date2019
Citation
Chemical Science, 2019, v. 10, n. 15, p. 4282-4292 How to Cite?
AbstractConstructing functional molecular systems for solar energy conversion and quantum information science requires a fundamental understanding of electron transfer in donor-bridge-acceptor (D-B-A) systems as well as competitive reaction pathways in acceptor-donor-acceptor (A-D-A) and acceptor-donor-acceptor′ (A-D-A′) systems. Herein we present a supramolecular complex comprising a tetracationic cyclophane having both phenyl-extended viologen (ExV2+) and dipyridylthiazolothiazole (TTz2+) electron acceptors doubly-linked by means of two p-xylylene linkers (TTzExVBox4+), which readily incorporates a perylene (Per) guest in its cavity (Per ⊂ TTzExVBox4+) to establish an A-D-A′ system, in which the ExV2+ and TTz2+ units serve as competing electron acceptors with different reduction potentials. Photoexcitation of the Per guest yields both TTz+-Per+-ExV2+ and TTz2+-Per+-ExV+in <1 ps, while back electron transfer in TTz2+-Per+-ExV+proceeds via the unusual sequence TTz2+-Per+-ExV+→ TTz+-Per+-ExV2+ → TTz2+-Per-ExV2+. In addition, selective chemical reduction of TTz2+ gives Per ⊂ TTzExVBox3+ turning the complex into a D-B-A system in which photoexcitation of TTz+results in the reaction sequence 2*TTz+-Per-ExV2+ → TTz2+-Per-ExV+→ TTz+-Per-ExV2+. Both reactions TTz2+-Per+-ExV+→ TTz+-Per+-ExV2+ and TTz2+-Per-ExV+→ TTz+-Per-ExV2+ occur with a (16 ± 1 ps)−1 rate constant irrespective of whether the bridge molecule is Per+or Per. These results are explained using the superexchange mechanism in which the ionic states of the perylene guest serve as virtual states in each case and demonstrate a novel supramolecular platform for studying the effects of bridge energetics within D-B-A systems.
Persistent Identifierhttp://hdl.handle.net/10722/333696
ISSN
2023 Impact Factor: 7.6
2023 SCImago Journal Rankings: 2.333
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorZhou, Jiawang-
dc.contributor.authorWu, Yilei-
dc.contributor.authorRoy, Indranil-
dc.contributor.authorSamanta, Avik-
dc.contributor.authorStoddart, J. Fraser-
dc.contributor.authorYoung, Ryan M.-
dc.contributor.authorWasielewski, Michael R.-
dc.date.accessioned2023-10-06T05:21:40Z-
dc.date.available2023-10-06T05:21:40Z-
dc.date.issued2019-
dc.identifier.citationChemical Science, 2019, v. 10, n. 15, p. 4282-4292-
dc.identifier.issn2041-6520-
dc.identifier.urihttp://hdl.handle.net/10722/333696-
dc.description.abstractConstructing functional molecular systems for solar energy conversion and quantum information science requires a fundamental understanding of electron transfer in donor-bridge-acceptor (D-B-A) systems as well as competitive reaction pathways in acceptor-donor-acceptor (A-D-A) and acceptor-donor-acceptor′ (A-D-A′) systems. Herein we present a supramolecular complex comprising a tetracationic cyclophane having both phenyl-extended viologen (ExV2+) and dipyridylthiazolothiazole (TTz2+) electron acceptors doubly-linked by means of two p-xylylene linkers (TTzExVBox4+), which readily incorporates a perylene (Per) guest in its cavity (Per ⊂ TTzExVBox4+) to establish an A-D-A′ system, in which the ExV2+ and TTz2+ units serve as competing electron acceptors with different reduction potentials. Photoexcitation of the Per guest yields both TTz+-Per+-ExV2+ and TTz2+-Per+-ExV+in <1 ps, while back electron transfer in TTz2+-Per+-ExV+proceeds via the unusual sequence TTz2+-Per+-ExV+→ TTz+-Per+-ExV2+ → TTz2+-Per-ExV2+. In addition, selective chemical reduction of TTz2+ gives Per ⊂ TTzExVBox3+ turning the complex into a D-B-A system in which photoexcitation of TTz+results in the reaction sequence 2*TTz+-Per-ExV2+ → TTz2+-Per-ExV+→ TTz+-Per-ExV2+. Both reactions TTz2+-Per+-ExV+→ TTz+-Per+-ExV2+ and TTz2+-Per-ExV+→ TTz+-Per-ExV2+ occur with a (16 ± 1 ps)−1 rate constant irrespective of whether the bridge molecule is Per+or Per. These results are explained using the superexchange mechanism in which the ionic states of the perylene guest serve as virtual states in each case and demonstrate a novel supramolecular platform for studying the effects of bridge energetics within D-B-A systems.-
dc.languageeng-
dc.relation.ispartofChemical Science-
dc.titleChoosing sides: unusual ultrafast charge transfer pathways in an asymmetric electron-accepting cyclophane that binds an electron donor-
dc.typeArticle-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1039/C8SC05514A-
dc.identifier.scopuseid_2-s2.0-85064177256-
dc.identifier.volume10-
dc.identifier.issue15-
dc.identifier.spage4282-
dc.identifier.epage4292-
dc.identifier.eissn2041-6539-
dc.identifier.isiWOS:000465271800013-

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