ß-Cyclodextrin Host-Guest Complexes Probed under Thermodynamic Equilibrium: Thermodynamics and AFM Force Spectroscopy

Auletta, Tomasso and Jong de, Menno R. and Mulder, Alart and Veggel van, Frank C.J.M. and Huskens, Jurriaan and Reinhoudt, David N. and Zou, S(han) and Zapotoczny, Szczepan and Schönherr, Holger and Vancso, G. Julius and Kuipers, Laurens (2004) ß-Cyclodextrin Host-Guest Complexes Probed under Thermodynamic Equilibrium: Thermodynamics and AFM Force Spectroscopy. Journal of the American Chemical Society, 126 (5). pp. 1577-1584. ISSN 0002-7863

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Abstract:	The rupture forces of individual host-guest complexes between ß-cyclodextrin (ß-CD) heptathioether monolayers on Au(111) and several surface-confined guests were measured in aqueous medium by single molecule force spectroscopy using an atomic force microscope. Anilyl, toluidyl, tert-butylphenyl, and adamantylthiols (0.2-1%) were immobilized in mixed monolayers with 2-mercaptoethanol on gold-coated AFM tips. For all guests and for all surface coverages, the force-displacement curves measured between the functionalized tips and monolayers of ß-CD exhibited single, as well as multiple, pull-off events. The histograms of the pull-off forces showed several maxima at equidistant forces, with force quanta characteristic for each guest of 39 ± 15, 45 ± 15, 89 ± 15, and 102 ± 15 pN, respectively. These force quanta were independent of the loading rate, indicating that, because of the fast complexation/decomplexation kinetics, the rupture forces were probed under thermodynamic equilibrium.
Item Type:	Article
Copyright:	© 2004 American Chemical Society
Faculty:	Science and Technology (TNW)
Research Group:	Molecular Nanofabrication (MNF) Materials Science and Technology of Polymers (MTP)
Link to this item:	http://purl.utwente.nl/publications/48017
Official URL:	http://dx.doi.org/10.1021/ja0383569
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