Synthesis and conformational analysis of an α-cyclodextrin [2]-rotaxane
- 1 January 1999
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 17,p. 2501-2506
- https://doi.org/10.1039/a902176k
Abstract
An α-cyclodextrin [2]-rotaxane has been prepared in 10% yield, by threading α-cyclodextrin (α-CD) with (E)-4,4′-diaminostilbene in aqueous solution and capping the included guest through reaction with 2,4,6-trinitrobenzene-1-sulfonate. 1D 1H NMR spectroscopy and DQCOSY and ROESY experiments show that the α-CD rotates freely around the axle of the rotaxane, but is localised over the olefinic moiety of the stilbene. The pKa values of the α-CD [2]-rotaxane were found to be 9.3 and 9.6, which are attributable to deprotonations of the (E)-4,4′-bis(2,4,6-trinitrophenylamino)stilbene moiety. NMR experiments show that these deprotonations do not perturb the conformation of the rotaxane.Keywords
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