4,7-Bis(2-bromo-5-thienyl)-2,1,3-benzothiadiazole

4,7-bis(5-bromothiophen-2-yl)benzo[c][1,2,5]thiadiazole is often used as an electron acceptor to synthesize donor–acceptor conjugated polymers. For example, it can be used as a high-purity monomer with 4-(4-((2-ethylhexyl)oxy)phenyl)-4H-dithieno[3,2-b:2′,3′-d]pyrrole (EPDP) through direct (hetero)arylation polymerization and using Pd(OAc)₂ as a catalyst system to prepare donor-acceptor (D–A) conjugated polymers. This polymer can be used in the preparation of organic solar cells based on bulk-heterojunction (BHJ) structures[1].

4,7-Bis(2-bromo-5-thienyl)-2,1,3-benzothiadiazole can be used as organic synthesis intermediates and pharmaceutical intermediates, mainly used in laboratory research and development processes and pharmaceutical and chemical production processes.

M4 (0.07 g, 0.233 mmol) was dissolved in 3.3 mLdry CHCl3 followed by addition of NBS (0.87 g, 0.489 mmol) at 0 °C.The reaction was conducted in dark by covering the flask withaluminium foil. The product was extracted with CHCl3 and thesolvent was evaporated to obtain crude product which was purifiedby silica gel column chromatography using 5% ethyl acetate/hexaneas eluent to obtain M5 as bright orange solid (0.101 g, 95%). Meltingpoint = 258 °C.

[1] Mai H, et al. Synthesis and characterization of donor–acceptor semiconducting polymers containing 4-(4-((2-ethylhexyl)oxy)phenyl)-4H-dithieno[3,2-b:2′,3′-d]pyrrole for organic solar cells. New Journal of Chemistry, 2020; 44: 16900-16912