Issue 7, 2013

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

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 1H 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 1H NMR binding experiments, follows the trend in the hydrophobicity of the quaternary ammonium cations.

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

Supplementary files

Article information

Article type
Paper
Submitted
25 Nov 2012
Accepted
20 Dec 2012
First published
21 Dec 2012

Org. Biomol. Chem., 2013,11, 1234-1241

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

M. A. Gamal-Eldin and D. H. Macartney, Org. Biomol. Chem., 2013, 11, 1234 DOI: 10.1039/C2OB27282B

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