Coordination polymers containing rotaxane linkers

A class of coordination polymers in which the linking ligands are mechanically interlocked rotaxane molecules is reviewed. To date, four different, axle - wheel templating motifs have been used to create the [2]pseudorotaxane linkers for these unique solid-state materials; (1) protonated diaminoalkane axles with cucurbit[6]uril wheels, (2) 1,2-bis(4,4'-bipyridinio) ethane axles with dibenzo[24]crown-8 wheels, (3) 2,6-naphthalene dicarboxylate axles with tetra-imidazolium macrocycle wheels and (4) a Cu(I) complex of a 1,10-phenanthroline containing dicarboxylate axle with a 1,10-phenanthroline containing crown ether wheel. The synthesis and solid state structure of each coordination polymer is described. The future directions of this area of research and some designs for the next generation of these compounds are discussed.