Synthesis of thiophene/phenylene co-oligomers. I. Phenyl-capped oligothiophenes

We report the synthesis of phenyl-capped oligothiophenes via improved synthetic schemes. These schemes are based on the Grignard coupling reaction and enable us to obtain the target compounds at high yields. The resulting materials have been fully characterized through nmr and ir spectroscopies. The ir analysis is particularly useful in characterizing the materials of higher molecular weight, since those materials are difficult to dissolve in organic solvent. We also show an improvement on preparation of halogenated (oligo)thiophenes that are used as intermediates for synthesizing the target compounds. An alternative synthetic route to the phenyl-capped oligothiophenes that utilizes the Suzuki coupling reaction is presented as well.