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A macrocyclic receptor containing two viologen species connected by conjugated terphenyl groups
journal contribution
posted on 2023-06-09, 13:51 authored by Long Chen, Kate Lim, Takhur Singh Babra, James O Taylor, Martin Pizl, Robert Evans, Ann M Chippendale, František Hart, Howard M Colquhoun, Barnaby GreenlandBarnaby GreenlandA 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 ?-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 ?-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.
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Publication status
- Published
File Version
- Accepted version
Journal
Organic and Biomolecular ChemistryISSN
1477-0520Publisher
Royal Society of ChemistryExternal DOI
Issue
27Volume
16Page range
5006-5015Department affiliated with
- Chemistry Publications
Full text available
- No
Peer reviewed?
- Yes
Legacy Posted Date
2018-06-20First Compliant Deposit (FCD) Date
2018-06-19Usage metrics
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