title: Electron-Transfer Rates in Host-Guest Assemblies at β-Cyclodextrin Monolayers.
abstract: The effect of the distance between a β-cyclodextrin (βCD) host core and a conductive substrate on the electron-transfer rate of complexed guests as well as of free-diffusing electrochemically active probes has been studied. First we have evaluated a set of short-tethered βCD adsorbates bearing different anchoring groups in order to get a reliable platform for the study of short-distance electron transfer. An electrochemically active trivalent guest was immobilized on these host monolayers in a selective and reversible manner, providing information about the packing density. Iodine- and nitrile-functionalized βCD monolayers gave coverages close to maximum packing. Electron transfer in the presence of Fe(CN)63-/4-studied by impedance spectroscopy revealed that the electron transfer of the diffusing probe was 3 orders of magnitude faster than when the βCD cores were separated from the surface by undecyl chains. When an electrochemically active guest was immobilized on the surface, electron-transfer rate measurements by cyclic voltammetry and capacitance spectroscopy showed differences of up to a factor of 8 for different βCD monolayers. These results suggest that increasing the distance between the βCD core and the underlying conductive substrate leads to a diminishing of the electron-transfer rate.
authors.affiliation: Molecular Nanofabrication Group and ‡Inorganic Materials Science Group, Department of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Méndez-Ardoy
authors.affiliation: Molecular Nanofabrication Group and ‡Inorganic Materials Science Group, Department of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Tom
authors.initials: T
authors.lastname: Steentjes
authors.affiliation: Molecular Nanofabrication Group and ‡Inorganic Materials Science Group, Department of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Boukamp
authors.affiliation: Molecular Nanofabrication Group and ‡Inorganic Materials Science Group, Department of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Pascal
authors.initials: P
authors.lastname: Jonkheijm
authors.affiliation: Molecular Nanofabrication Group and ‡Inorganic Materials Science Group, Department of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Tibor
authors.initials: T
authors.lastname: Kudernac
authors.affiliation: Molecular Nanofabrication Group and ‡Inorganic Materials Science Group, Department of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Jurriaan
authors.identifier: 0000-0002-4596-9179
authors.initials: J
authors.lastname: Huskens