β-cyclodextrin host−guest complexes probed under thermodynamic equilibrium: thermodynamics and AFM force spectroscopy

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DOI	Resolve DOI: https://doi.org/10.1021/ja0383569
Author	Search for: Auletta, Tommaso; Search for: de Jong, Menno R.; Search for: Mulder, Alart; Search for: van Veggel, Frank C. J. M.; Search for: Huskens, Jurriaan; Search for: Reinhoudt, David N.; Search for: Zou, Shan; Search for: Zapotoczny, Szczepan; Search for: Schönherr, Holger; Search for: Vancso, G. Julius; Search for: Kuipers, Laurens
Format	Text, Article
Abstract	The rupture forces of individual host−guest complexes between β-cyclodextrin (β-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 β-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. The force values followed the same trend as the free binding energy ΔG° measured for model guest compounds in solution or on β-CD monolayers, as determined by microcalorimetry and surface plasmon resonance measurements, respectively. A descriptive model was developed to correlate quantitatively the pull-off force values with the ΔG° of the complexes, based on the evaluation of the energy potential landscape of tip−surface interaction.
Publication date	2004-02-01
Publisher	American Chemical Society
In	Journal of the American Chemical Society 126, no. 5: 1577–1584.
Language	English
Peer reviewed	Yes
NRC publication	This is a non-NRC publication "Non-NRC publications" are publications authored by NRC employees prior to their employment by NRC.
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Record identifier	8f394ca4-c0d2-4380-a4f2-4ad09a32c825
Record created	2019-04-12
Record modified	2020-05-30

Date modified:: 2026-01-19