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Preparation and properties of π‐conjugated poly(benzimidazole‐4,7‐diyl)s
Author(s) -
Yamamoto Takakazu,
Sugiyama Kiyoshi,
Kanbara Takaki,
Hayashi Hideki,
Etori Hideki
Publication year - 1998
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19980901)199:9<1807::aid-macp1807>3.0.co;2-2
Subject(s) - benzimidazole , monomer , polymer , conjugated system , polymer chemistry , electrochromism , photoluminescence , condensation polymer , chemistry , protonation , absorption (acoustics) , photochemistry , materials science , organic chemistry , ion , optoelectronics , electrode , composite material
Preparation, optical properties, and electrochemical redox behavior of poly(benzimidazole‐4,7‐diyl)s are reported. Dehalogenation polycondensation of 4,7‐dibromobenzimidazole and its derivatives (2‐heptyl and 2‐phenyl derivatives) with zerovalent nickel complexes gives the corresponding polymers in 72–100% yield. Poly(benzimidazole‐4,7‐diyl) and its heptyl derivative have molecular weights of 1.3 × 10 4 and 3.8 × 10 4 , respectively, as determined by light scattering measurements. In non‐acidic solvents the polymers give rise to one absorption peak at about 300 nm, which is assigned to a π‐π * transition occurring in the benzimidazole monomeric unit, and another absorption peak at a longer wavelength, which is considered to originate from the π‐π * transition occurring in the π‐conjugated main chain. The π‐π * absorption peak, as well as the photoluminescence peak of the polymers, are shifted in acidic media due to protonation. The polymers are electrochemically active regarding reduction (or n‐doping) and show electrochromism.