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

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