期刊
ACS NANO
卷 3, 期 2, 页码 291-300出版社
AMER CHEMICAL SOC
DOI: 10.1021/nn8002373
关键词
bistable rotaxanes; electrochemistry; microcantilever; molecular machines; NEMS; supramolecular chemistry
类别
资金
- Air Force Office of Scientific Research [FA9550-08-1-0349]
- Penn State Center for Nanoscale Science (MRSEC)
- National Science Foundation [ECCS-0609128, ECCS-0801922]
- Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy [DE-AC02-05 CH11231]
- Direct For Mathematical & Physical Scien [1041943] Funding Source: National Science Foundation
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [820404] Funding Source: National Science Foundation
- Division Of Chemistry [1041943] Funding Source: National Science Foundation
- Div Of Electrical, Commun & Cyber Sys
- Directorate For Engineering [0801922] Funding Source: National Science Foundation
A microcantilever, coated with a monolayer of redox-controllable, bistable [3]rotaxane molecules (artificial molecular muscles), undergoes reversible deflections when subjected to alternating oxidizing and reducing electrochemical potentials. The microcantilever devices were prepared by precoating one surface with a gold film and allowing the palindromic [3]rotaxane molecules to adsorb selectively onto one side of the microcantilevers, utilizing thiol-gold chemistry. An electrochemical cell was employed in the experiments, and deflections were monitored both as a function of (i) the scan rate (<= 20 mV s(-1)) and (ii) the time for potential step experiments at oxidizing (> +0.4 V) and reducing (< +0.2 V) potentials. The different directions and magnitudes of the deflections for the microcantilevers, which were coated with artificial molecular muscles, were compared with (i) data from nominally bare microcantilevers precoated with gold and (ii) those coated with two types of control compounds, namely, dumbbell molecules to simulate the redox activity of the palindromic bistable [3]rotaxane molecules and inactive 1-dodecanethiol molecules. The comparisons demonstrate that the artificial molecular muscles are responsible for the deflections, which can be repeated over many cycles. The microcantilevers deflect in one direction following oxidation and in the opposite direction upon reduction. The similar to 550 nm deflections were calculated to be commensurate with forces per molecule of similar to 650 pN. The thermal relaxation that characterizes the device's deflection is consistent with the double bistability associated with the palindromic [3]rotaxane and reflects a metastable contracted state. The use of the cooperative forces generated by these self-assembled, nanometer-scale artificial molecular muscles that are electrically wired to an external power supply constitutes a seminal step toward molecular-machine-based nanoelectromechanical systems (NEMS).
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