N. Wintjes, D. Bonifazi, F. Cheng, A. Kiebele, M. Stoehr, T. Jung, H. Spillmann, F. Diederich,
Angew. Chem., Int. Ed. 2007, 46, 4089-4092
Spinning tops: A supramolecular rotary device, reminiscent of a mechanical rotary switch, was engineered by a bottom-up approach. Self-assembly of a functionalized porphyrin molecule leads to the formation of a porous network that features chiral cavities. These serve as hosts for molecular guests, which can be induced to rotate either thermally or by using the scanning tunneling microscopy tip (see images).