A macrocyclic receptor containing two viologen species connected by conjugated terphenyl groups


A macrocyclic receptor molecule containing two viologen species connected by conjugated terphenyl groups has been designed and synthesised. The single-crystal X-ray structure shows that the two viologen residues have a transannular N…N separation of ca. 7.4 Å. Thus, the internal cavity dimensions are suitable for the inclusion of π-electron-rich species. The macrocycle is redox active, and can accept electrons from suitable donor species including triethylamine, resulting in a dramatic colour change from pale yellow to dark green as a consequence of the formation of a paramagnetic bis(radical cationic) species. Cyclic voltammetry shows that the macrocycle can undergo two sequential and reversible reduction processes (E1/2 = -0.65 and -0.97 V vs Fc/Fc+). DFT and TD-DFT studies accurately replicate the structure of the tetracationic macrocycle and the electronic absorption spectra the three major redox states of the system. These calculations also showed that during electrochemical reduction, the unpaired electron density of the radical cations remains relatively localised within the heterocyclic rings. The ability of the macrocycle to form supramolecular complexes was confirmed by the formation of a pseudorotaxane with a guest molecule containing a π-electron-rich 1,5-dihydroxynaphthalene derivative. Threading and dethreading of the pseudorotaxane was fast on the NMR timescale, and the complex exhibited an association constant of 150 M-1 (± 30 M-1) as calculated from 1H NMR titration studies.

Publication DOI: https://doi.org/10.1039/C8OB00919H
Divisions: College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
College of Engineering & Physical Sciences > Aston Institute of Materials Research (AIMR)
Additional Information: © The Royal Society of Chemistry 2018
Publication ISSN: 1477-0539
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Related URLs: http://pubs.rsc ... 9h#!divAbstract (Publisher URL)
PURE Output Type: Article
Published Date: 2018
Published Online Date: 2018-06-19
Accepted Date: 2018-06-19
Authors: Chen, Long
Lim, Kate J.C.
Babra, Tahkur S.
Taylor, James O.
Pižl, Martin
Evans, Robert D (ORCID Profile 0000-0003-1471-201X)
Chippindale, Ann M.
Hartl, František
Colquhoun, Howard M.
Greenland, Barnaby W.



Version: Accepted Version

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