Synthesis and self-organization of α,ω-substituted oligothiophenes with long, branched alkyl substituents

A series of long oligothiophenes without beta-substituents, up to an undecamer, as highly attractive electronic materials is presented. The new synthetic strategy for these compounds is based on the combination of ring-closure and metal-catalyzed coupling reactions. The use of a soluble diketo precursor preserves good solubility of the intermediate products in the course of the multistep synthesis until the very last reaction and gives rise to good yields and high purity of the final oligomers. The characterization of the oligothiophenes by UV-vis spectroscopy reveals the formation of aggregates in solution. Additionally, DSC measurements and polarization microscopy show the presence of thermotropic liquid crystalline phases of some of the oligomers.