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Synchronized rotation of a network of molecular rotors

Published in Nature Nanotechnology

by PREVOTS Evelyne, PREVOTS Evelyne - published on , updated on

The local electric field induced by the tip of the scanning tunneling microscope allows us to switch the simultaneous rotation of a large number of molecular rotors of 3 nm in diameter.

A Franco-American team composed of CEMES-CNRS, University Paul Sabatier of Toulouse and the University of Ohio observed and triggered a synchronized rotation movement of a network of rotors deposited on a copper surface which paves the way for information transfer by mechanical means at the molecular scale over great distances. This result constitutes an important step in order to work in a network and in a concerted way with an organized and two-dimensional set of molecular machines.

Published in the journal Nature Nanotechnology, this work uses an original double-decker molecule designed and synthesized in CEMES. The lower deck (the stator) is a phthalocyanine functionalised by eight sulfur atoms which make it possible to organize these molecules in a regular network on the surface of a copper crystal. The second deck (the rotor) is a dissymmetrical porphyrin whose originality stems from the existence of an important electrical dipole due to the presence of an electron-rich fragment carrying a negative charge (in blue) An electron-poor fragment carrying a positive charge (in red). This molecule can thus respond to the application of an electric field. The central europium atom (in green) makes it possible to connect the two stages while leaving free the rotation of the upper part if the molecule does not interact with its neighbors.

When the tip of a scanning tunneling microscope (STM) induces an electric field in the vicinity of some of these molecules, the latter are aligned in a synchronized manner. They then cause the rotation of a large number of other molecules and this at a great distance from the first ones, thanks to the electrostatic interactions between dipole moments. We have shown that the propagation of this rotational movement occurs up to several hundred nanometers away from the position of the STM tip.

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Chemical structure (left) of one of the double-decker molecular rotors anchored on a copper surface via eight points of attachment (S-sulfur atoms). Behavior of a self-assembled monolayer (right) that under the effect of a local electric field induced by the STM tip causes synchronous rotation of the network of molecules (experimental images at the top and explanatory diagram. At the bottom, the yellow circle indicates the position of the STM tip during the experiment).
© G. Rapenne, CEMES-CNRS / UPS



Simultaneous and Coordinated Rotational Switching of All Molecular Rotors in a Network, Y. Zhang, H. Kersell, R. Stefak, J. Echeverria, V. Iancu, G. Perera, Y. Li, A. Deshpande, K.-F. Braun, C. Joachim, G. Rapenne, S.-W. Hla, Nature Nanotechnology, 2016, 11, 706. DOI : 10.1038/nnano.2016.69.



rapenne at cemes.fr

Gwénaël RAPENNE, Professor at Université Paul Sabatier, Toulouse and Christian JOACHIM, Director of Research CNRS, researchers in the NanoSciences Group in CEMES.