Polydiacetylene chemical structure

Topochemical reactivity and solid-state polymerization strongly merged in the extensive studies of diacetylene (1) polymerization by G. Wegner and collaborators beginning in 1969. There are two recent books devoted to polydiacetylenes (PDA, 2) (9,10), and it is fair to say that the literature of fully ordered macromolecules would be much less voluminous without the extensive research associated with diacetylene polymerization and the chemical, structural, and physical properties of these polymers. 

Figure 1.1 Chemical structures for monomers of the conjugated polymers discussed in this chapter (a) vinylene (the repeat unit of polyacetylene) (b) ethynylene (polydiacetylene is alternating vinylene-ethynylene) (c) phenylene (d) thiophene (e) leucoemeraldine form of polyaniline (f) pernigraniline form ofpolyaniline (the number of protons can vary between the...

In 1987 Ovchinnikov et al. announced the discovery of the first ferromagnetic organic polymer based on polydiacetylene chain with dangling nitroxyl radicals [8,9]. The compound was obtained by bulk polymerization of stable paramagnetic biradical BlPO initiated by light. The chemical structure of this compound is shown below. 

Fig. 26.2 Chemical structure of an asymmetrically substituted polydiacetylene. This polymer can be readily dissolved in chloroform.

While there is substantial theoretical interest in the electronic structure of forms of conjugated carbon beyond graphite (1), at the present time the polydiacetylenes (PDAs) provide the most accessible experimental systems with one-dimensional conjugated polymer chains available in fully ordered single crystal form. As such the PDAs occupy a key position among organic materials which exhibit phenomena indicating delocalized interactions in that quantum chemical calculations (2) estimate bandwidths... 

The diacetylene with R = R = paratoluylsulfonyloximethylene is termed TS6 (sometimes TS). It was shown by G. Wegner and his co-workers in a series of works, pubhshed in the early 1970s [1, 7], that large molecular crystals can be grown from a solution of TS6, e.g. in acetone, and that these monomer diacetylene crystals can be converted by a topo-chemical (or solid state) 1,4-addition reaction to the polydiacetylene single crystals (Fig. 9.2). The crystal structures of TS before and after the reaction have been investigated in detail by Kobelt and Paulus [8], Bloor et al. [8], and Enkelmann [9] and are sketched in Fig. 9.3 and in Tab. 9.1. 

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