Molecular nanotechnology. Towards artificial molecular machines and motors

Miniaturization is an essential ingredient of modern technology. In this context, concepts such as that of (macroscopic) device and machine have been extended to the molecular level. A molecular machine can be defined as an assembly of a discrete number of molecular components – that is, a supramolecular system – in which the component parts can display changes in their relative positions as a result of some external stimulus. While nature provides living organisms with a wealth of molecular machines and motors of high structural and functional complexity, chemists are interested in the development of simpler, fully artificial systems. Interlocked chemical compounds like rotaxanes and catenanes are promising candidates for the construction of artificial molecular machines. The design, synthesis and investigation of chemical systems able to function as molecular machines and motors is of interest not only for basic research, but also for the growth of nanoscience and the subsequent development of nanotechnology. A few examples of molecular machines taken from our own research will be illustrated.