Synthesis and Supramolecular Organization of Regioregular Polythiophene Block Oligomers

The self-assembly of functional polythiophenes was studied by a bottom-up approach “from molecule to polymer”. The synthesis and the X-ray structure of 2,5-dibromo-3-styryl and 3-2′,3′,4′,5′,6′-pentafluorostyryl-thiophenes revealed a supramolecular arrangement controlled by π−π interactions between the aromatic rings. A [2 + 2] photocyclization reaction in the solid state of (E)-1-2′,5′-dibromo-3′-thienyl-2-pentafluorophenylethene triggers the formation of a rare cycloadduct comprising thiophene rings. The X-ray analysis confirmed its rctt stereochemistry. The synthesis of P3HT-b-P3ST and P3HT-b-P3STF block oligomers was achieved by a GRIM method in good yields. An indirect proof of well-defined nanostructured organization was provided by the partial photocyclization of pendant styryl moieties under UV irradiation.