Anellated Dipyrrolyl Systems: Synthesis and Electrical Properties of the Polymers

Abstract

Functionalization of heterocyclic monomers with medium-length alkyl chains^1,2 has provided a route to the obtainment of (at least partially) soluble polymers. To minimize interference of the functionalization with the planarity and regularity of the polymer, we have approached the problem starting from monomers constituted by two heterocycles separated by a conjugatively unsaturated spacer:³ this can be a ring onto which the terminal heterocycles are anellated and it is intended to be the site of functionalization. In view of the merits of polypyrrole,⁴ we have focused our attention on systems (1)–(4), in which two terminal pyrrole units are anellated to a central aromatic ring. Heterocycles (1)–(4) are all isomers and constitute a body of structural and electronic variation of the same skeleton. A further electronic variation is provided by saturation on the double bond of the ethenylic fragment joining the two nitrogen atoms in (4): for this reason also the dihydro compound (5) was included in the series. Results are reported on the oxidative electrochemical polymerization of the above monomers.