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Anion Recognition and Cation‐Induced Molecular Motion in a Heteroditopic [2]Rotaxane
Author(s) -
Leontiev Alexandre V.,
Jemmett Charlotte A.,
Beer Paul D.
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201002405
Subject(s) - rotaxane , pyridinium , chemistry , amide , ion , polyamide , titration , stereochemistry , crystallography , carboxylate , supramolecular chemistry , polymer chemistry , medicinal chemistry , inorganic chemistry , organic chemistry , crystal structure
A heteroditopic [2]rotaxane consisting of a calix[4]diquinone–isophthalamide macrocycle and 3,5‐bis‐amide pyridinium axle components with the capability of switching between two positional isomers in response to barium cation recognition is synthesised. The anion binding properties of the rotaxane’s interlocked cavity together with Na + , K + , NH 4 + and Ba 2+ cation recognition capabilities are elucidated by 1 H NMR and UV‐visible spectroscopic titration experiments. Upon binding of Ba 2+ , molecular displacement of the axle’s positively charged pyridinium group from the rotaxane’s macrocyclic cavity occurs, whereas the monovalent cations Na + , K + and NH 4 + are bound without causing significant co‐conformational change. The barium cation induced shuttling motion can be reversed on addition of tetrabutylammonium sulfate.