Strategien und Taktiken für die metallgesteuerte Synthese von Rotaxanen, Knoten, Catenanen und Verschlingungen höherer Ordnung

The widespread use of controlled molecular-level motion in key natural processes suggests that great rewards could come from bridging the gap between the present generation of synthetic molecular systems, which by and large rely upon electronic and chemical effects to carry out their functions, and the machines of the macroscopic world, which utilize the synchronized movements of smaller parts to perform specific tasks. This is a scientific area of great contemporary interest and extraordinary recent growth, yet the notion of molecular-level machines dates back to a time when the ideas surrounding the statistical nature of matter and the laws of thermodynamics were first being formulated. Here we outline the exciting successes in taming molecular-level movement thus far, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion. We also highlight some of the issues and challenges that still need to be overcome.

The [enPd(II)]2+ (en = ethylenediamine) unit has emerged as a versatile building block in molecular self-assembly. In particular, the 90 degrees coordination angle of the metal has been judiciously used in the design of new discrete two- and three-dimensional structures. Our last 15 years of work with the Pd(II)-cornered unit is summarized in this Account, from the spontaneous formation of a Pd4 square metal complex to a family of architectures such as cages, bowls, boxes, tubes, catenanes, and spheres.