World's Smallest Electric Motor

New Scientist reports: [edited]

For the first time, an electric motor has been made from a single molecule. At 1 nanometre long, that makes the organic compound the smallest electric motor ever.

E. Charles Sykes at Tufts University in Boston and colleagues used asymmetric butyl methyl sulphide, a sulphur atom with a chain of four carbons on one side and a lone carbon atom on the other. They anchored the molecule to a copper surface via the sulphur atom, producing a lopsided, horizontal "propeller" that is free to rotate about the vertical copper-sulphur bond (see diagram).

Above the molecule they placed a metal needle a few atoms wide at its tip. When they flowed a current from this tip, through the molecule, to the conductive copper below, the molecule converted the electrical energy into rotational energy. It bounced around in jittery hops about 50 times a second.

Sykes hopes to harness his tiny motor to fight the friction that slows fluid flow in nano-sized tubes.
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