Approaches to Bridged Planar Polypyridine, Polypyrazine, and Polythiophene Derivatives for Maximization of Extended pi-Conjugation.

We have been directing synthetic efforts toward the construction of conjugated macromolecules that are fixed in a planar conformation. The planar conformations should maximize the extended pi-conjugation. Additionally, the bridging units, if sp2-hybridized, should further increase the extended pi-conjugation of the macromolecular systems. We previously described a synthetic route to planar poly(p- phenylene) derivatives by the retrosynthetic approach outlined in eq 1 (M = metal). The actual synthetic components are shown in eq 2. jg p.3