Dithienobenzimidazole‐containing conjugated donor–acceptor polymers: Synthesis and characterization

摘要： The synthesis of two new conjugated polymers based on the relatively under-exploited monomer, 5,8-dibromo-2-[5-(2-hexyldecyl)-2-thienyl]-1H-dithieno[3,2-e:20,30-g]benzimidazole (dithienobenzimidazole, DTBI), and either 4,7-bis[4-hexyl-5-(trimethylstannyl)-2-thienyl]-2,1,3-benzothiadiazole (BTD) or 2,6-bis(trimethylstannyl)-4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b0]dithiophene (BDT) is described. The polymers were synthesized via Stille polycondensation and characterized by traditional methods (1H NMR, gel-permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, thermal gravimetric analysis, differential scanning calorimetry, ultraviolet–visible spectroscopy, photoluminescence, and cyclic voltammetry). Prior to their synthesis, trimer structures were modeled by DFT calculations facilitating a further understanding of the systems’ electronic and geometric structure. Polymers were titrated with acid and base to take advantage of their amphiprotic imidazole moiety and their optical response monitored with ultraviolet–visible spectroscopy. Finally, pristine polymer thin-films were treated with acid and base to evaluate (de)protonation’s effect on system electronics, but thin-film degradation was encountered.