ACS Nano (2015)


Conversion of thermal or electrical stimuli into mechanical motion can be controlled at the molecular scale; this has been previously demonstrated, among others, by Gianaurelio Cuniberti and colleagues, who synthesized windmill-shaped supramolecular nanostructures that move on a gold surface when stimulated by a voltage pulse applied through the tip of a scanning tunnelling microscope. Now, this group shows that such nanostructures can also act as molecular electromechanical systems; guided by controlled electrical pulses, they can pick up and transport single gold atoms, gold dimers and small molecules adsorbed on the surface. The researchers verified that the motion is neither due to a mechanical interaction of the tip with the nanostructures nor to direct electrical driving of the transported particles. Depending on the sign of the applied voltage, the loads can be rotated by a small angle or translated by a few ångströms, demonstrating a fine control that may be useful for the realization of more complex molecular machines.