The Annulenes, Dehydrobenzoannulenes, and Phenylacetylene Scaffolding

Even though the octayne derivative marked the longest linear diphenylpolyacetylene, multiple phenylacetylene scaffold topologies were developed in the following decade. Representative examples include carbon rods 67 and 68 produced by Misumi in 1961 (Fig. 1.5b) [60], Misumi and coworkers also produced several mixed hybrid scaffolds combining ethenyl and ethynyl spacers, such as 69 (Fig. 1.5b) as well as conformational isomeric ethenyl rods, such as 70, in 1962 [61]. Meier further discusses defined-length carbon-rich oligomers in Chapter 11, and the use of carbon-rich molecules as molecular wires is presented by Harriman and Ziessel in Chapter 2. 

The ene-yne polymeric structure was the result of multiple 1,4-additions between adjacent molecules. Wegner originally utilized different monomeric functional groups and determined that those capable of H-bonding, such as urethanes and diols, provided the necessary intermolecular alignment to facilitate the conjugate addition. Fowler and Lauher further elaborate on soUd-state formation and chemistry of polydiacetylene and polytriacetylene in Chapter 5. 

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