Broken π-conjugated thiophene systems: 1. Synthesis and polymerization of 2,2′-di(alkylthienyl) methanes

A series of 2,2′-di(alkylthienyl)methanes has been synthesized by chloroalkylation of 3-alkylthiophenes in the presence of zinc chloride. These monomers were oxidatively polymerized with iron(III) chloride to yield the respective partially broken π-conjugated poly(2,2′-di(alkylthienyl)methane)s. Solubility and processability properties of the polymers were dependent on the alkyl groups attached to the thiophene ring. The new polymers contain quinoidal segments due to dehydrogenation of the bridge carbon during polymerization, which can be seen by UV–Vis and 1H NMR spectroscopy. Due to the quinoidal segments, these polymers show conductivity in the range from 10−6 to 10−4 S/cm.