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

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 5percent ethyl acetate/hexaneas eluent to obtain M5 as bright orange solid (0.101 g, 95percent). Meltingpoint = 258 °C. 1HNMR (300 MHz, CDCl3) d: 7.85(s, 2H), 7.80(d, 2H), 7.13(d, 2H) [29] (see Scheme 5).Preparation of bis-4, 7-(2'-bromo-5'-thienyl)-2, 1, 3-benzothiadiazole (N2S-1)-T2-Br2 A 5-liter reactor equipped with agitator, condenser and thermometer, were charged with o-dichlorobenzene (3L), 4, 7-bis(thien-2-yl)-2, 1, 3-benzothiadiazole (150.0 g, 0.5 mol) and NBS (170.0 g, 0.95 mol). The mixture was heated slowly to 55° C. After stirring at 55° C. for 3 hours, the resulting slurry was heated to 150° C. to dissolve the solids. When all solids disappeared, the mixture was allowed to cool to room temperature. Stirring was stopped and the supernatant liquid was drawn off by vacuum (aspirator) using a glass fritted sparge tube (removing as much liquid as possible). The remaining wet cake was slurried/stirred with water (2.x.2, 500 mL) and ethanol (500 mL), and each time the supernatant liquid was drawn off by vacuum as described above. The wet cake was dried by passing a nitrogen stream over the solids, followed by pulling vacuum on the vessel. The crude product which had 98.4percent purity by GC area, was recrystallized from o-dichlorobenzene as follows: 1, 200 mL of o-dichlorobenzene was added to the reactor. The mixture was heated with stirring to 150° C. until all solids were dissolved, then allowed to cool to room temperature. The liquid was drawn off in vacuo using a glass fritted sparge tube, the reactor was recharged with 1, 200 mL of o-dichlorobenzene and the above recrystallization process repeated. The wet cake was washed with o-dichlorobenzene (100 mL) and ethanol (400 mL) and dried at 50° C./2-3mmHg overnight. Pure product (194.2 g) was obtained in 84.8percent yield, which was of 99.7percent of purity as measured by GC area. M.p.247-248° C., 1H NMR spectroscopic analysis:(300 MHz/DMSO-d6) 8.16 (s, 2H), 7.97(m, 2H), 7.39 (m, 2H).4, 7-Di(thiophen-2-yl)benzo[c][1, 2, 5]thiadiazole (4.0 g, 13.3 mmol) was dissolved in CHCl3 (100 mL) and a catalyticamount of acetic acid. Then, N-bromosuccinimide(NBS) (5.5 g, 30.6 mmol) was added portion wise, andthe mixture was stirred for 36 h at room temperature withlight protection. The precipitate was filtered through aBüchner funnel, and then washed with copious amountsof MeOH, water, and acetone. The product was collectedas a red solid (4.6 g, 76percent). 1H NMR (400 MHz, CDCl3: 7.80 (dd, 4 H), 7.13 (d, 2 H). 13C NMR (400 MHz, CDCl3: 154.2, 140.8, 131.1, 129.6, 129.1, 128.0, 111.6.4, 7-Bis(5-bromothiophen-2-yl)benzo(1, 2, 5)thiadiazole (M1) Compound 3 (100 mg, 0.332 mmol) and 1.5 mL acetic acid and 3 mL of CHCl3 were stirredat 0 °C under nitrogen purging for 10 min. NBS (130 mg, 0.732 mmol) was added in portionsat the same temperature and the reaction mixture stirred for 24 h at rt under inert atmosphere.Then it was poured into water and extracted with dichloromethane. The organic phase wasdried over anhydrous sodium sulfate and concentrated in a rotary evaporator under reducedpressure. Further purification of the monomer M1 was carried out by columnchromatography with hexane as the eluent. Yield: 60percent

Molecular Weight:458.2
XLogP3:6.5
Hydrogen Bond Acceptor Count:5
Rotatable Bond Count:2
Exact Mass:457.80394
Monoisotopic Mass:455.80599
Topological Polar Surface Area:111
Heavy Atom Count:21
Complexity:355
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes