Individual supramolecular host-guest interactions studied by dynamic single molecule force spectroscopy

Supramolecular host-guest interactions in aqueous environment were studied by dynamic single molecule force spectroscopy. The unbinding between ferrocene moieties immobilized on atomic force microscopy tips and beta-cyclodextrin receptors in highly ordered self-assembled monolayers on Au(111) was studied. The rupture force of individual ferrocene-beta-cyclodextrin complexes was found to be 56 +/- 10 pN. The value of this unbinding force was independent of the unloading rate. This was attributed to the fast (de)complexation kinetics of the host-guest complex.