Induction of Motion in a Synthetic Molecular Machine: Effect of Tuning the Driving Force |
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| Authors: | Dr Jacob Baggerman Dr Natalia Haraszkiewicz Piet G Wiering Dr Giulia Fioravanti Dr Massimo Marcaccio Prof Dr Francesco Paolucci Dr Euan R Kay Prof Dr David A Leigh Prof Dr Albert M Brouwer |
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| Institution: | 1. Van ‘t Hoff Institute for Molecular Science, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam (The Netherlands);2. Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio 1, 67100 L'Aquila (Italy);3. Dipartimento di Chimica “G.Ciamician”, Università di Bologna, Via Selmi 2, 40126 Bologna (Italy);4. School of Chemistry, University of Edinburgh, The King's Buildings, West Mains Road, Edinburgh, EH9 3JJ (UK) |
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| Abstract: | Rotaxane molecular shuttles were studied in which a tetralactam macrocyclic ring moves between a succinamide station and a second station in which the structure is varied. Station 2 in all cases is an aromatic imide, which is a poor hydrogen‐bond acceptor in the neutral form, but a strong one when reduced with one or two electrons. When the charge density on the hydrogen‐bond‐accepting carbonyl groups in station 2 is reduced by changing a naphthalimide into a naphthalene diimide radical anion, the shuttling rate changes only slightly. When station 2 is a pyromellitimide radical anion, however, the shuttling rate is significantly reduced. This implies that the shuttling rate is not only determined by the initial unbinding of the ring from the first station, as previously supposed. An alternative reaction mechanism is proposed in which the ring binds to both stations in the transition state. |
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| Keywords: | electrochemistry molecular shuttles photochemistry reaction mechanisms rotaxanes |
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