Optically active polyalkylthiophenes: synthesis and polymerization of chiral, symmetrically substituted, quinquethiophene monomer

A novel optically active quinquethiophene monomer bearing at the C-β position of thiophene ring a linear C6 alkyl chain and an enantiomerically pure chiral alkyl group, namely 3,3⁗-di n-hexyl-4′,3‴-di[( S)-(+)-2-methylbutyl]-2,2′:5′,2″:5″,2‴:5‴,2⁗-quinquethiophene, has been synthesized and characterized. The regioregular optically active polymer deriving from oxidative polymerization of the monomer has also been characterized. The spectroscopic and chiroptical properties of the polymeric derivative, in particular, indicate enhanced conjugation extension with respect to similar poly(3-alkylthiophene)s reported in the literature and the presence of supramolecular chiral conformations in the microaggregate state.