Autonomous artificial nanomotor powered by sunlight
- Vincenzo Balzani†,‡,
- Miguel Clemente-León†,§,
- Alberto Credi†,‡,
- Belén Ferrer†,¶,
- Margherita Venturi†,
- Amar H. Flood∥, and
- J. Fraser Stoddart‡,∥
- †Dipartimento di Chimica “G. Ciamician,” Università di Bologna, via Selmi 2, 40126 Bologna, Italy; and ∥California NanoSystems Institute and Department of Chemistry and Biochemistry, 405 Hilgard Avenue, University of California, Los Angeles, CA 90095
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Edited by Jack Halpern, University of Chicago, Chicago, IL, and approved December 6, 2005 (received for review October 14, 2005)
Abstract
Light excitation powers the reversible shuttling movement of the ring component of a rotaxane between two stations located at a 1.3-nm distance on its dumbbell-shaped component. The photoinduced shuttling movement, which occurs in solution, is based on a “four-stroke” synchronized sequence of electronic and nuclear processes. At room temperature the deactivation time of the high-energy charge-transfer state obtained by light excitation is ≈10 μs, and the time period required for the ring-displacement process is on the order of 100 μs. The rotaxane behaves as an autonomous linear motor and operates with a quantum efficiency up to ≈12%. The investigated system is a unique example of an artificial linear nanomotor because it gathers together the following features: (i) it is powered by visible light (e.g., sunlight); (ii) it exhibits autonomous behavior, like motor proteins; (iii) it does not generate waste products; (iv) its operation can rely only on intramolecular processes, allowing in principle operation at the single-molecule level; (v) it can be driven at a frequency of 1 kHz; (vi) it works in mild environmental conditions (i.e., fluid solution at ambient temperature); and (vii) it is stable for at least 103 cycles.
Footnotes
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↵‡ To whom correspondence may be addressed. E-mail: vincenzo.balzani{at}unibo.it, alberto.credi{at}unibo.it, or stoddart{at}chem.ucla.edu.
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↵§ Present address: Instituto de Ciencia Molecular, Universidad de Valencia, Dr. Moliner 20, 46100 Burjassot, Spain.
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↵¶ Present address: Departamento de Química, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain.
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Author contributions: V.B., A.C., M.V., and J.F.S. designed research; M.C.-L. and B.F. performed research; V.B., A.C., B.F., M.V., and A.H.F. analyzed data; and V.B. and A.C. wrote the paper.
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Conflict of interest statement: No conflicts declared.
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This paper was submitted directly (Track II) to the PNAS office.
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Abbreviation: SCE, saturated calomel electrode.
- Copyright © 2006, The National Academy of Sciences
