Non-symmetrical oligothiophenes with ‘incompatible’ substituents

The syntheses of oligothiophenes 1 and 2 comprising two different types of peripheral substituents, namely alkyl and perfluoroalkyl, is reported. The key synthetic step is the Pd-catalyzed cross-coupling of perfluoroalkylated bromide 3 with an appropriate boronate. This molecular design is expected to promote unusual two-layer packing, which is of interest for application in electronic devices. Quaterthiophene 1 forms smectic mesophase, though in the narrow temperature range, and is suitable for the fabrication of thin films by solution processing methods.