Rotaxane chemistry in a spin

Direct observations that the rings of rotaxanes, which consist of a mechanically interlocked macrocycle encircling a dumbbell-shaped thread, can shuttle back and forth in response to a stimulus have been made by an international team. By pinning the ends of a rotaxane to a gold surface the researchers were able to control the supramolecular entity sufficiently to be able to use scanning tunneling microscopy to observe the shuttling of the macrocycle between different "stations" on the thread. Such evidence, as opposed to indirect spectroscopic studies, ultimately improves the potential for using these molecules as so-called molecular machines.