Polymeric catenanes

A molecular entity consisting of two or more polymeric rings interlinked together but not covalently bonded to each other. Mitochondrial DNA are known to form catenated structures consisting of two interlinked nucleic acid circles (i.e., a [2]catenane). 

A different approach to the synthesis of oligo[2]calenanes was chosen by Mullen et al. in 1995 [57]. The bromo-substituted in/out catenane 111 was coupled with appropriate comonomers under Suzuki conditions [58]. The degree of polymerization was between one and five for the resulting oligomers 112 (Figure 45). In 1997 the same group reported the first synthesis of poly[2]catenanes of the... 

The interest in macromolecular systems containing defined topological bonds, such as polyrotaxanes 7, multicatenanes 8, polycatenanes 9, poly[2]catenanes 10, and polymeric catenanes 11, is dual. First, these macromolecules represent daunting synthetic and characterization challenges which deserve attention in their own... 

Scheme 3. Pictorial representation of polyrotaxane 7, multicatenane 8, polycate-nane 9, poly[2]catenane 10, and polymeric catenane 11.

Scheme 25. Directed synthetic strategy of the polymeric catenane 64, according to Coqueret and Wegner [32].

Scheme 26. Proposed synthesis of polymeric catenane 11, with anion-exchange separation of cyclic species from linear polymers [33].

To be comprehensive, it should also be mentioned that besides the unique example of the polymeric catenane 72, there exist numerous examples of DNA catenanes [34, 50, 51, 69-73] and a few examples of protein catenanes [74]. However, these aspects are beyond the scope of this section and are treated in Chapter 12. 

With the exception of DNA catenanes and protein catenanes, and despite various synthetic attempts, only one polymeric catenane structure, i.e. the catenated block copolymer 72, is known [31]. Evidently, the fact that the two constitutive cyclic polymers have two different chemical structures greatly facilitates the syn-... 

Scheme 29. Unreported macromolecular architectures containing defined topological bonds polycatenane 9, linear poly[3]catenane 74, poly[2]catenane network 75, multicatenane network 76, rigid polymeric catenane 77, polymeric trefoil knot 78, and polyknot 79.

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