Rotaxanes as ligands: from molecules to materials.

This tutorial review documents the discovery and application of the supramolecular template (1,2-bis(pyridinium)ethane) subset (24-crown-8) for preparing interlocked molecules. Focus is on the supramolecular chemistry of the pseudorotaxanes formed with various pyridinium axles and crown ether wheels and how this particular class of mechanically linked molecule has been (i) used to construct rudimentary molecular machines such as molecular shuttles and flip switches, (ii) used as ligands for coordination chemistry and (iii) used to create metal-organic framework (MORF) materials.