Nitrogen-functionalized polythiophenes: Potential routes to new low band gap materials

Due to the stability and ease of synthetic modification, polythiophenes containing a wide variety of functionalized side chains have been investigated. The majority of functionalized polythiophenes, however, contain functional groups isolated from the polymer backbone by an alkyl spacer. As a result, the side chain acts primarily to modify physical properties and any electronic effect is due to steric-induced conformational changes. The exception to this is the inclusion of alkoxy or alkylmercapto groups, where the heteroatom is directly attach-ed to the polymer backbone. An extension of polyalkoxythiophenes is the investigation of additional heteroatom-functionalized polythio-phenes. Our work has generated an interest in nitrogen-derivatized polythiophenes, thus initiating new synthetic routes to N-function-alized poly(3-aminothiophene)s and poly(dithieno[3,2-b:2′,3′-d]pyrrole)s. Here we report synthetic routes for the necessary monomeric precursors, chemical and electrochemical polymerization studies, as well as initial characterization of the polymeric materials.