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Anion Recognition and Cation-Induced Molecular Motion in a Heteroditopic [2]Rotaxane

Authors

  • Dr. Alexandre V. Leontiev,

    1. Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA (UK), Fax: (+44) 1865-272690
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  • Charlotte A. Jemmett,

    1. Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA (UK), Fax: (+44) 1865-272690
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  • Prof. Paul D. Beer

    Corresponding author
    1. Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA (UK), Fax: (+44) 1865-272690
    • Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA (UK), Fax: (+44) 1865-272690
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Abstract

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+, NH4+ and Ba2+ cation recognition capabilities are elucidated by 1H NMR and UV-visible spectroscopic titration experiments. Upon binding of Ba2+, molecular displacement of the axle’s positively charged pyridinium group from the rotaxane’s macrocyclic cavity occurs, whereas the monovalent cations Na+, K+ and NH4+ are bound without causing significant co-conformational change. The barium cation induced shuttling motion can be reversed on addition of tetrabutylammonium sulfate.

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