Synthesis and characterization of 3,4-diaryl-substituted polythiophene derivatives

A series of polythiophene derivatives bearing 3,4-diaryl substituents were synthesized starting from commercially available 3,4-dibromothiophene. The effects of two different aryl substituents, either a 5-octyl-2-thienyl or a 4-octylphenyl, were investigated in this study. To minimize steric effects on polymerization and conjugation, polymers were synthesized with a bithiophene or a triple-bond spacer. The resulting polymers show varying solubility in common organic solvents and their UV-visible absorption spectra in solution exhibit maxima in the range 434-484 nm, which are significantly red-shifted as compared to those of 3,4-dialkyl-substituted polythiophenes. Gel permeation chromatography analysis using polystyrene standards shows a weight-average molecular weight range of 1.50 x 10(4)-4.40 x 10(4) g mol(-1) for the various polymers. (C) 2011 Society of Chemical Industry