Incorporation of a conjugated side‐chain in regioregular polythiophenes: Chiroptical properties and selective oxidation

The synthesis, aggregation, and optical properties of a chiral, regioregular polythiophene, substituted with a conjugated substituent, are described. The polymer was prepared using a Stille coupling reaction. The fact that the side‐chain contributes to the absorption (UV‐vis), emission (fluorescence), and redox behavior (cyclic voltammetry) of the material demonstrates that the substituent contributes to the electronic properties. It was shown that the conjugated side‐chain chirally stacks in conditions in which the polymer backbone aggregates, which demonstrates the ability of conjugated polymers to induce a (chiral) lamellar organization of conjugated moieties, present in their side‐chain. The aggregation of both the side‐chain and the backbone was monitored using UV‐vis and CD spectroscopy. Finally, it is shown that the conjugated side‐chain can selectively be oxidized, without oxidizing the polythiophene backbone. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1891–1900, 2009