Chemistry with Amide-Based Catenanes and Rotaxanes

4 Chemistry with Amide-Based Catenanes and Rotaxanes 

Amide-linked catenanes and rotaxanes, readily accessible via nonionic template synthesis, are molecules with fascinating topology, but their final breakthrough was only achieved when they became substrates for further chemical derivatiza-tion. A potential reaction site in the catenanes and rotaxanes presented so far is the sulfonamide group, because the proton can be selectively abstracted in the presence of carbon amide groups. Subsequent alkylation offers numerous possibilities of catenane and rotaxane chemistry. 

The attachment of bipyridine moieties also enables the synthesis of homo- and heteroleptic ruthenium(II)trisbipyridyl complexes with interesting photochemical properties [56]. 

The great synthetic potential of the covalent linkage of catenanes and rotaxanes via sulfonamide groups in such a way enables the chemist to construct larger topologically interesting assemblies and to aim at nanoscale architectures. 

Catenanes and rotaxanes have made their way from being considered laboratory curiosities to become highlights in supramolecular chemistry. The synthesis of 

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The sulfonamide macrocycle proved to be a hospitable template, and at the same time the sulfonamide functionality bears the possibility of farther derivatiza-tion of [2]rotaxanes (see Section 8.4 Chemistry with Amide-Based Catenanes and Rotaxanes). Furthermore the expansion of the cavity did not afford a change of the blocking group - no disassembly of wheel and axle was detected. 

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