ROTATION OF A SINGLE-MOLECULE WITHIN A SUPRAMOLECULAR BEARING

Experimental visualization and verification of a single-molecule rotor operating within a supramolecular bearing is reported. Using a scanni ng tunneling microscope, single molecules were observed to exist in on e of two spatially defined states Laterally separated by 0.26 nanomete rs. One was identified as a rotating state and the other as an immobil ized state. Calculations of the energy barrier for rotation of these t wo states show that it is below the thermal energy at room temperature for the rotating state and above it for the immobilized state.