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temperature for 8 h. The reaction mixture was poured into
water and extracted with chloroform. The organic layers
were separated, dried over magnesium sulfate and filtered.
Solvents were removed and the crude residue was further
purified by recrystallization from chloroform/methanol (1/4,
v/v) to give 2 as yellow powder (0.16 g, 51% yield). MS
with Soxhlet extraction using methanol, hexane, acetone, and
chloroform. Finally, the polymer in chloroform fraction was
recovered by evaporation of the solvent to give S-polymer as
dark yellowish powder (0.23 g, 74% yield). Mw ¼ 67900 g/
mol and PDI ¼ 3.18 GPC (THF).
1H NMR (CDCl3, 600 MHz): d (ppm) ¼ 8.01–7.91 (broad),
7.77–7.27 (broad), 7.18–7.05 (broad), 2.18–2.01 (broad),
1.90–1.81 (broad), 1.70–1.42 (broad), 1.30–0.62 (broad),
0.59–0.37 (broad). 13C NMR (CDCl3, 125 MHz): d (ppm) ¼
154.2, 152.9, 150.8, 150.0, 140.4, 139.4, 133.1, 132.4, 129.5,
129.3, 128.8, 128.3, 127.7, 126.7, 125.7, 133.7, 122.4, 121.6,
119.6, 119.4, 118.9, 54.1, 39.3, 30.5, 28.7, 22.7, 21.6, 13.1.
Anal. Calcd. For C35H38N2S2: C, 76.32%; H, 6.95%; N, 5.09%.
Found: C, 75.14%; H, 7.05%; N, 4.72%.
ꢃ
(GC): m/z ¼ 376. Melting point: 169–171 C.
1H NMR (600 MHz, CDCl3): d (ppm) ¼ 8.01 (d, 1H), 7.78 (d,
1H), 7.69 (dd, 1H), 7.40 (s, 1H). 13C NMR (125 MHz, CDCl3):
d (ppm) ¼ 155.2, 153.2, 137.8, 132.5, 129.2, 127.0, 125.9,
121.7, 111.4, 110.4.
4-Bromo-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (3)
A mixture of 4,7-bromo-2,1,3-benzothiadiazole (0.50 g, 1.70
mmol), 2-(tributylstannyl)thiophene (0.64 g, 1.72 mmol) and
bis(triphenylphosphine)palladium(II) dichloride (0.013 g,
0.017 mmol) was dissolved in 10 mL THF. After refluxing for
12 h under argon, the mixture was poured into water and
extracted with chloroform. The organic layers were sepa-
rated, dried over magnesium sulfate and filtered. Upon sol-
vent evaporation, the residues were subjected to column
chromatography using chloroform/n-hexane (1/4, v/v) to
give 3 as orange solid (0.35 g, 63% yield). MS (GC): m/z ¼
M-Polymer
4 (0.12 g, 0.32 mmol) and 9,9-dihexylfluorene-2,7-diboronic
acid bis(1,3-propandiol) ester (0.28 g, 0.32 mmol) were dis-
solved in 6 mL dry toluene under argon. The mixture was
purged with argon to remove oxygen. Tetrakis(triphenyl-
phosphine)palladium(0) (0.015 g, 0.013 mmol) and degassed
2 M potassium carbonate aqueous solution (4 mL) were
added. The mixture was stirred at 90 ꢃC for 48 h under
argon. Upon completion of the reaction, the mixture was
poured into methanol and the precipitate was collected by
suction filtration. Then, the resultant solid was dissolved in
THF and filtered. The filtrate was poured into methanol
again. The precipitate was further purified with Soxhlet
extraction using methanol, hexane, acetone, and chloroform.
Finally, the polymer in chloroform fraction was recovered by
evaporation of the solvent to give M-polymer as reddish
powder (0.13 g, 62% yield). Mw ¼ 25800 g/mol and PDI ¼
2.58 GPC (THF).
ꢃ
295. Melting point: 88–89 C.
1H NMR (600 MHz, CDCl3): d (ppm) ¼ 8.10 (d, 1H), 7.86 (d,
1H), 7.73 (d, 1H), 7.49 (d, 1H), 7.21 (dd, 1H). 13C NMR (125
MHz, CDCl3): d (ppm) ¼ 153.7, 152.9, 151.8, 138.4, 132.3,
128.1, 127.3, 125.8, 113.9, 112.3.
4-Bromo-7-(5-bromothiophen-2-yl)benzo[c][1,2,5]
thiadiazole (4)
A mixture of 3 (0.43 g, 1.45 mmol) and NBS (0.28 g, 1.59
mmol) in THF was stirred at room temperature for 8 h. The
reaction mixture was poured into water and extracted with
chloroform. The organic layers were separated, dried over
magnesium sulfate and filtered. Upon solvent evaporation,
the crude residue was further purified by recrystallization
from chloroform/methanol (1/3, v/v) to give 4 as red pow-
der (0.29 g, 53% yield). MS (GC): m/z ¼ 376. Melting point:
1H NMR (CDCl3, 600MHz): d (ppm) ¼ 8.13–8.22 (broad),
7.68–8.10 (broad), 7.51–7.59 (broad), 2.05–2.25 (broad),
1.03–1.17 (broad), 0.71–0.99 (broad). 13C NMR (CDCl3, 125
MHz): d (ppm) ¼ 154.3, 152.9, 152.3, 151.8, 146.3, 140.6,
138.6, 136.7, 133.3, 130.1, 128.7, 128.3, 127.9, 126.3, 125.5,
125.0, 124.0, 120.1, 55.8, 40.4, 31.5, 29.8, 24.0, 22.6, 14.1.
Anal. Calcd. For C35H38N2S2: C, 76.32%; H, 6.95%; N, 5.09%.
Found: C, 74.61%; H, 6.61%; N, 4.67%.
ꢃ
174–175 C.
1H NMR (600 MHz, CDCl3): d (ppm) ¼ 7.85 (d, 1H), 7.79 (d,
1H), 7.65 (d, 1H), 7.16 (d, 1H). 13C NMR (125 MHz, CDCl3):
d (ppm) ¼ 153.7, 151.4, 139.8, 132.3, 130.8, 127.7, 126.1,
125.2, 115.1, 112.8.
RESULTS AND DISCUSSION
Synthesis and Characterization
S-Polymer
The detailed synthetic route to monomers and polymers is
given in Scheme 1. The monomer (2) for S-Polymer was pre-
pared by two-step reaction sequence starting from 4-bromo-
2,1,3-benzothiadiazole. First, Suzuki coupling reaction
between 4-bromo-2,1,3-benzothiadiazole and 3-thienylbor-
onic acid was conducted to afford 1 as viscous liquid. Bromi-
nation with NBS was then carried out to obtain monomer
(2) as yellowish solid. Similar two-step synthetic procedure
was used for the synthesis monomer (4) for M-polymer. By
Stille coupling reaction between 4,7-dibromo-2,1,3-benzo-
thiadiazole and 2-(tributylstannyl)thiophene, 3 was prepared
as orange solid. Bromination with NBS was then executed to
yield monomer (4) as red solid. Each dibromo-monomer (2)
2 (0.21 g, 0.57 mmol) and 9,9-dihexylfluorene-2,7-diboronic
acid bis(1,3-propandiol) ester (0.285 g, 0.57 mmol) were dis-
solved in 6 mL dry toluene under argon. The mixture was
purged with argon to remove oxygen. Tetrakis(triphenyl-
phosphine) palladium(0) (0.026 g, 0.022 mmol) and
degassed 2 M potassium carbonate aqueous solution (4 mL)
ꢃ
were added. The mixture was stirred at 90 C for 48 h under
argon. Upon completion of the reaction, the mixture was
poured into methanol and the precipitate was collected by
suction filtration. Then the resultant solid was dissolved in
THF and filtered. The filtrate was poured into methanol
again. The precipitate was collected and further purified
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JOURNAL OF POLYMER SCIENCE PART A: POLYMER CHEMISTRY 2012, 50, 271–279