Although chemists have made small-molecule rotary motors, to date there have been no reports of small-molecule linear motors. Here we describe the synthesis and operation of a 21-atom two-legged molecular unit that is able to walk up and down a four-foothold molecular track. High processivity is conferred by designing the track-binding interactions of the two feet to be labile under different sets of conditions such that each foot can act as a temporarily fixed pivot for the other. The walker randomly and processively takes zero or one step along the track using a ‘passing-leg’ gait each time the environment is switched between acid and base. Replacing the basic step with a redox-mediated, disulfide-exchange reaction directionally transports the bipedal molecules away from the minimum-energy distribution by a Brownian ratchet mechanism. The ultimate goal of such studies is to produce artificial, linear molecular motors that move directionally along polymeric tracks to transport cargoes and perform tasks in a manner reminiscent of biological motor proteins.
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We thank the Engineering and Physical Sciences Research Council (EPSRC) National Mass Spectrometry Service Centre (Swansea, UK) for high-resolution mass spectrometry and Juraj Bella for assistance with high-field NMR spectroscopy. This research was funded through the European Research Council Advanced Grant WalkingMols. D.A.L. is an EPSRC Senior Research Fellow and holds a Royal Society–Wolfson Research Merit Award.
The authors declare no competing financial interests.
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von Delius, M., Geertsema, E. & Leigh, D. A synthetic small molecule that can walk down a track. Nature Chem 2, 96–101 (2010). https://doi.org/10.1038/nchem.481
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