Chirality induced by microaggregation of regioregular polyhiophenes with side-chain optically active substituent

The effect of the addition of a poor solvent to a solution of regioregular chiral polythiophenes in a good solvent is described in terms of formation of chiral supramolecular microaggregates. Two novel optically active terthiophene and bithiophene monomers bearing at the C-b position of thiophene ring an enantiomerically pure chiral alkyl group, namely 3,3"-di[2-((S)-(1)-2-methylbutoxy) ethyl]-2,20:50,2"-terthiophene and 3,30-di[2-((S)-(1) -2-methylbutoxy) ethyl]-2:20-bithiophene, have been synthesized and characterized. Being symmetrically substituted, their polymerization adopting simple and economic method, such as the chemical oxidation with iron (III) trichloride, allowed to obtain regioregular macromolecules. The synthesized polymers have been investigated by CD in solution as well as in the microaggregated state upon gradual addition of a poor solvent. The results display different CD behaviors related to their chemical structure.