Comparison of UV-Vis changes observed in deprotonation of 2-heptylbenzimidazole, 2-heptyl-4,7-diphenylbenzimidazole, and poly(2-heptylbenzimidazole-4,7-diyl)

Shifts of the UV-vis peak caused by deprotonation of 2-heptylbenzimidazole and sterically strained 2-heptyl-4,7-diphenyl-benzimidazole and poly(2-heptylbenzimidazole-4,7-diyl) (P[4,7-Bim(Hep)]) are discussed. The pi-pi* absorption band of the strained molecules showed a large shift to a longer wavelength on deprotonation with NaOH. P[4,7-Bim(Hep)] showed a new absorption peak at about 400 nm.