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Org Biomol Chem. 2013 Feb 21;11(7):1234-41. doi: 10.1039/c2ob27282b.

Cucurbit[7]uril host-guest complexes and [2]pseudorotaxanes with N-methylpiperidinium, N-methylpyrrolidinium, and N-methylmorpholinium cations in aqueous solution.

Author information

1
Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, ON K7L 3N6, Canada.

Abstract

The formations of host-guest complexes between cucurbit[7]uril and a series of N-substituted N-methylpiperidinium, N-methylpyrrolidinium, and N-methylmorpholinium cations in aqueous solution have been investigated using (1)H NMR spectroscopy and electrospray ionization mass spectrometry. Dications comprising the N-methylheterocyclic head groups, bridged by a decamethylene chain, form sequential 1 : 1 ([2]pseudorotaxanes) and 2 : 1 host-guest complexes with cucurbit[7]uril. The cucurbituril initially resides over the decamethylene chain, however with further additions of the host molecule a translocation of the hosts to the cationic N-heterocyclic head groups occurs. The order of the magnitude of the cucurbituril host-guest stability constants, determined by competitive (1)H NMR binding experiments, follows the trend in the hydrophobicity of the quaternary ammonium cations.

PMID:
23314170
DOI:
10.1039/c2ob27282b
[Indexed for MEDLINE]

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