Synthesis and Optical Properties of π-Conjugated Polymers Containing Fused Imidazole Skeleton

Fused imidazole monomers (1b, 1i, and 2b) having the octyl group were synthesized by the microwave-assisted intramolecular direct arylation, which were subjected to the cross-coupling polymerization. For obtaining π-conjugated polymers with better solubility, fused imidazole monomers (si-1b and si-3b) having the bulky trisiloxane-terminated decyl chain were likewise synthesized and polymerized. On the basis of absorption and emission spectra of obtained π-conjugated polymers in conjunction with the X-ray crystal structure of model compounds and theoretical calculation, the fused structure and coupling partner were found to affect the optical properties in CHCl3 solution as a result of steric and electronic factors. The spectroscopic measurements in film revealed that the bulky trisiloxane group helps π-conjugated polymers to form the π-stacked structure upon thermal annealing. The proton doping experiment was also carried out to find out that the protonation of imidazole nitrogen results in the different ...