Catenanes and rotaxanes of the amide type

Abstract

New catenane (cf. 3) and rotaxane (cf. 26) types have been obtained in remarkable yields via supramolecular template syntheses. The amide-based mechanically bonded structures can be designed by appropriate choice of building units. The selective formation of stable out/out in/in and in/out [2]catenane isomers (cf. Scheme 2), which were separated, allowed conclusions concerning their mechanism of formation. It was demonstrated that one of the two macromonocycles of the catenane molecule forms initially and acts as a host cavity for a building block of the second, interlocking macro cycle. This knowledge made a simple synthesis of amide-linked rotaxanes possible. The first X-ray structural analysis of a furano-catenane revealed a self-assembled, interlocked system held together by networks of inter- and intramolecular hydrogen bonds, including the amide groups and the furan oxygen atoms. There is no doubt that these new intertwined amide systems will be extendable to higher catenanes and rotaxanes.