Synthesis, characterization and electrochemistry of polycyclic fused aromatic pyrroles and their conjugated polymers

Abstract

Polycyclic fused aromatic pyrrole-based compounds, benzodipyrrole, naphthobipyrrole and their alkylated derivatives, were synthesized and studied electrochemically. Amongst these, naphthobipyrrole having a tetracyclic fused aromatic structure was electrochemically polymerized to give the homopolymer of naphthobipyrrole, poly(naphthobipyrrole), indicating good reactivity of α,α′-pyrrolic positions towards oxidative coupling. As a strategic approach towards the synthesis of copolymers, naphthobipyrrole was copolymerized with arylaldehyde to afford poly(arylmethylene naphthobipyrrole) by exploring the reactivity of β,β′-pyrrolic positions. Moreover, optical and electrochemical studies showed that the copolymer possessed a low optical bandgap and an elevated HOMO level. The scan rate dependent cyclic voltammetry studies of the copolymer film showed the formation of an electroactive material.