An Addressable Supramolecular Rotary Switch Featuring Distinguishable Positions Embedded In A Two-Dimensional Porphyrin-Based Porous Network

In recent years, the attempts to build artificial functional devices from single molecules by the ``bottom-up'' approach were strongly in the focus of surface nanoscience. First experiments with molecules manually arranged by the STM tip gave first hints on the powerful possibilities of such a device. Nevertheless, a simple way to produce supramolecular devices parallel in vast amounts has never been shown before. Herein, we report on a highly complex supramolecular device that reminds of a mechanical rotary switch. It is fabricated on a Cu(111) surface following the ``bottom-up'' approach. Self-assembly of a specially designed porphyrin molecule leads to the formation of porous networks featuring chiral cavities which serve as molecular stators for multi-state molecular rotors. By STM, this rotational behavior was analyzed in detail while the energy barrier for rotation was estimated to be 0.28~eV.