Synthesis and Properties of Novel Optically Active Poly(thiophenyleneethynylene-phenyleneethynylene)s

The Sonogashira–Hagihara coupling polymerization of L-alanine-derived 2,5-dibromothiophene monomers 1a–1d with p- and m-diethynylbenzenes 2p and 2m gave novel optically active poly(thiophenyleneethynylene-phenyleneethynylene)s poly(1a-2p)–poly(1d-2m). p-Phenylene-linked poly(1b-2p)–poly(1d-2p) bearing amide-amide side chains exhibited CD signals based on chiral aggregates, while the m-phenylene-linked counterparts poly(1b-2m)–poly(1d-2m) exhibited no evidence of the formation of secondary structures. Poly(1a-2p) and poly(1a-2m) bearing amide-ester side chains exhibited no CD signal as well.