ABSTRACT
Macromolecules incorporating repeating units connected by covalent bonds are widespread in nature [1]. Synthetic procedures for the construction of their artificial counterparts are well established [2]. Furthermore, the properties of these unnatural macromolecules are now rather well understood and, indeed, polymeric materials have found applications in numerous branches of science and technology [2]. In recent years, synthetic chemists have learned* how to introduce mechanical bonds (Fig. 1) into small molecules. Mechanically interlocked ‘‘rings,’’ as well as ‘‘wheels’’ mechanically trapped onto ‘‘axles,’’ can be constructed efficiently to afford molecular compounds, named catenanes and rotaxanes, respectively.† Metal coordination [18-32], donor/acceptor interactions [33-43], hydrogen bonds [44-64] and/or hydrophobic interactions [65-78] between appropriate components have all been employed to template‡ the formation of these exotic molecules. Making the transition from simple catenanes and rotaxanes to their macromolecular counterparts-namely, polycatenanes and polyrotaxanes,
Figure 1 Schematic representation of an [n]catenane and an [n]rotaxane.
