Oligo(thienylene ethynylene)s:: A new class of oligomeric model compounds

A series of ethynylene-containing oligothiophenes as new model compounds is reported here. Based on palladium-catalyzed cross-coupling reactions this oligomeric series has been synthesized from a monomer to a tetramer. Their optical and electrochemical properties have been characterized and compared to a structurally related series of oligo(3-hexylthiophene)s, which gives excellent insight into common and deviating physical properties between these two oligomer series. Furthermore, the data analysis provides an insight into the corresponding defectless, infinite polymer chain and gives information about the "effective" conjugation length of the parent real polymer.