MONOMER REACTIVITY VS REGIOREGULARITY IN POLYTHIOPHENE DERIVATIVES

It has been recently reported that a simple chemical oxidation of 3-al koxy-4-methylthiophenes leads to highly regioregular polymers with enh anced electrical and optical properties. A joint experimental and theo retical study on different alkyl-, alkylthio-, and alkoxy-substituted thiophenes and bithiophenes has revealed a strong correlation between the distribution of the unpaired electron pi-spin density in the oxidi zed starting compounds and the regiochemical structure of the resultin g polymers. In particular, these calculations have clearly indicated t hat an asymmetric reactivity of the oxidized monomers or dimers at the 2- and 5-positions can lead to polymers with a high head-to-tail cont ent. This theoretical tool should be useful for the future design of r egioregular and nonregioregular polymers from chemical or electrochemi cal oxidative polymerization reactions.