Polycatenanes main-chain

Scheme 1 illustrates the simplest structures of rotaxane, catenane, and knot besides polyrotaxane and polycatenane. From the fact that the main chain-type polyrotaxane at the left side is the only interlocked polymer synthesized so far among the three polymers shown at the bottom of the scheme, progress in synthesis of interlocked polymers appears to be sluggish judging from the level of activity in synthetic polymer chemistry in the world. 

More detailed general structures of the representative polyrotaxanes and polycatenanes are shown in Scheme 2. Polyrotaxanes can be categorized into two types one is the polyrotaxanes consisting of the main chains of covalent type as shown in the top four examples (A-D), while the other involves the polyrotaxanes of which monomer linking units are constructed by the rotaxane structure as shown in the following two structures (E, F). The essen-... 

A and B Main chain polycatenanes C and D Side chain polycatenanes ... 

As illustrated by types C and D in Figure 17.1, side-chain polycatenanes are polymers that contain catenane subunits within their pendant groups, and which are expected to possess different properties compared to the main-chain polycatenanes. However, due to similar synthetic problems being encountered as for the preparation of linear poly[ ]catenanes, only poly[2]catenane-type side-chain polycatenanes have been reported to date. 

Poly[2]catenane occupies an important position of the topologically linked polycatenanes that incorporate the [2]cate-nane linkages in the main chain. Its preparation usually requires the polymerization of two reactive-sites-containing [2]catenane or ditopic [2]catenane. For this purpose, various... 

Figure 31 Polycatenanes (a) summary of types (i) linear, (ii) main-chain, and (iii) pendant (b) Sauvage s main-chain poly([2]catenane) and (c) Stoddart s pendant poly([2]catenane).

Type III The metal is part of a polymer chain or network. This type considers homochain or heterochain polymers with covalent bonds to the metal, coordinative bonds between metal ions and a polyfunctional ligand (coordination polymers), Ti-complexes in the main chain with a metal, cofacially stacked polymer metal complexes and different types (polycatenanes, polyrotaxanes, dendrimers with metals) (Figure 3). 

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