JOURNAL OF
POLYMER SCIENCE
ORIGINAL ARTICLE
2
-(2-Hexyldecyl)Thiophene (2)
packed in hexanes using gradient elution up to 9:1 hexanes:
EtOAc. The product was recovered as 18.95 g (53.9% over
two steps) pale orange/yellow oil. H NMR (500.13 MHz,
Thiophene (13.20 g, 156.9 mmol, 1.50 eq.) was weighed into
an oven dried 1 L round-bottomed flask (A) containing a stir
bar. The flask was then cooled in an isopropanol/CO2(s) bath,
evacuated and backfilled with Ar 5×. Anhydrous, deoxygen-
ated THF (~400 mL) was cannulated into A under Ar. Anhy-
drous, deoxygenated THF (~100 mL) was cannulated into an
oven dried 500 mL round-bottomed flask (B) containing a stir
bar under Ar. A solution of n-BuLi (2.5 M in hexanes, 50 mL)
was cannulated into a 100 mL graduated cylinder under Ar. n-
BuLi solution (49 mL, 122.5 mmol, 1.17 eq.) was then cannu-
lated into B under Ar, stirred. B was cooled in an isopropa-
nol/CO2(s) bath. B was cannulated into A dropwise under Ar
over 50 min, maintaining the temperature of both flasks at
1
CDCl
1H), 7.61 (d, J = 4.0 Hz, 2H), 6.87 (d, J = 3.5 Hz, 2H), 2.80 (d,
J = 7.0 Hz, 2H), 1.67 (m, 1H), 1.31–1.22 (m, 24H), 0.87 (t,
C NMR
3
, δ, ppm, Supporting Information Figure S2) 9.82 (bs,
7
1
3
J = 6.8 Hz, 3H), 0.87
5
(t, J = 6.8 Hz, 3H).
(125.76 MHz, CDCl3, δ, ppm, Supporting Information
Figure S3) 182.82, 156.78, 141.92, 137.12, 126.95, 40.18,
35.38, 33.30, 33.28, 32.03, 31.97, 30.02, 29.71, 29.69, 29.44,
26.67, 26.65, 22.82, 22.79, 14.27, and 14.25.
5,8-Dibromo-2-[5-(2-Hexyldecyl)-2-Thienyl]-1H-Dithieno
0
0
[3,2-e:2 ,3 -g]Benzimidazole (7)
ꢀ
ꢀ
0
−
78 C. A was stirred for 1 h at −78 C, the pale-yellow solu-
2,7-Dibromo-benzo[1,2-b:6,5-b ]dithiophene-4,5-dione (6, 1.61 g,
tion was then allowed to warm to room temperature over the
course of 1 h. Meanwhile, 2-hexyldecyl bromide (1) was
added to an oven dried 150 mL round-bottomed flask (C),
sealed with a septum and put under vacuum for 1+ h. C was
then backfilled with Ar and ~50 mL anhydrous THF was can-
nulated into it under Ar. After A had warmed to room temper-
ature, C was cannulated into A dropwise over the course of
4.01 mmol, 1 eq.), 5-(2-hexyldecyl)-2-thiophenecarboxaldehyde
(3, 1.46 g, 4.34 mmol, 1.08 eq.), ammonium acetate (7.41 g,
96.1 mmol, 24.0 eq.), and stir bar were added to a 250 mL
2
round-bottomed flask under N . Glacial acetic acid (40 mL) was
added to the mixture. The flask was fitted with a condenser,
ꢀ
heated to 110 C, and vigorously stirred under N . The reaction
2
mixture was cooled to room temperature after 16 h and then
quenched with 40 mL water. The mixture was extracted with
toluene. The combined extracts were washed with brine and
5
1
0 min under Ar. A became orange, but remained clear. After
.5 h at room temperature, A was warmed to 50 C and stir-
ꢀ
red overnight. After 17 h, the dark orange reaction solution
was cooled to room temperature and quenched with 250 mL
water. THF was removed via rotary evaporation. The hazy
aqueous mixture was then extracted with hexanes. The
4
water then dried over MgSO . The mixture was filtered through
a thin silica layer prepared atop a Celite pad and the toluene was
removed via rotary evaporation. The yellow/brown residue was
purified on a silica column packed in 17:2 v:v CHCl :hexanes.
3
extracts were washed with brine, dried over MgSO , gravity
filtered, and solvent removed via rotary evaporation to yield a
The product was then recrystallized from methanol once and
hexanes once to yield 1.30 g off-white solids (46.8%). H NMR
4
1
dark orange/brown oil. The oil was dissolved in hexanes and
purified by flash column chromatography on SiO packed in
2
hexanes. The unreacted 1 was recovered via Kugelrohr distil-
lation at reduced pressure. The resulting oil (26.51 g)
included product as well as bifunctional (2,5-bis(2-hexyldecyl)
(400.13 MHz, DMSO-d6, δ, ppm, Supporting Information Fig. S4)
13.40 (bs, 1H), 7.92 (s, 2H), 7.62 (d, 1H, J = 3.60 Hz), 6.94 (d, 1H,
J = 3.60 Hz), 2.79 (d, 2H, J = 6.40 Hz), 1.65 (m, 1H), 1.32–1.20
(m, 24H), 0.85 (t, 3H, J = 6.75 Hz), 0.82 (t, 3H, 6.91 Hz). C NMR
(100.62 MHz, DMSO-d6, δ, ppm, Supporting Information Fig. S5):
δ 146.98, 145.86, 131.38, 127.61, 127.17, 126.62, 125.07,
112.97, 34.33, 33.12, 33.01, 31.77, 31.72, 29.74, 29.47, 29.38,
29.14, 26.40, 26.35, 22.56, 14.42, and 14.40.
1
3
thiophene). The faintly orange oil was used without further
1
purification. H NMR (500.13 MHz, CDCl
3
, δ, ppm, Supporting
Information Figure S1) 7.11 (d, J = 5.2 Hz, 2H), 6.91 (t,
J = 4.1 Hz, 2H), 6.75 (d, J = 2.7 Hz, 2H), 2.75 (d, J = 6.7 Hz,
0
0
2H), 1.99 (t, J = 7.7 Hz, 1H), 1.35–1.20 (m, 24H), 0.88 (t,
Poly(2-[5-(2-Hexyldecyl)-2-Thienyl]-1H-Dithieno[3,2-e:2 ,3 -
g]Benzimidazole-2,5-Diyl-Alt-4,7-Bis[4-Hexyl-2-Thienyl]-
J = 6.6 Hz, 6H).
2
,1,3-Benzothiadiazole) (PDTBI-BTD)
5
-(2-Hexyldecyl)-2-Thiophenecarboxaldehyde (3)
7 (66.5 mg, 0.0957 mmol, 0.957 eq.) and 10 (81.8 mg,
0.103 mmol, 1 eq. (adjusted for impurity)) were carefully
weighed and added to a 10 mL heavy-walled microwave vial
along with a stir bar. The vial was loaded into an Ar-filled dry
Anhydrous DMF (14.6 mL, 188.6 mmol, 2.20 eq.) was added
to an oven dried, septum sealed, 100 mL round-bottomed
flask containing a stir bar under N
2
via syringe. The flask was
ꢀ
then cooled to 0 C. Phosphoryl chloride (8.0 mL, 86.1 mmol,
glovebox where Pd
2 3
(dba) (3.0 mg, 0.003 mmol, 0.03 eq.) and
1.00 eq.) was added to the flask dropwise over 10 min via
P(o-tol) (4.2 mg, 0.014 mmol, 0.14 eq.) were carefully
3
syringe. The mixture was stirred for 20 min before deoxygen-
ated 2-(hexyldecyl)thiophene (2, 26.51 g, 85.9 mmol, 1.00 eq.)
weighed and added to the vial. Distilled toluene (3.0 mL) was
then added to the vial via syringe. The vial was sealed with a
septum, removed from the glovebox, and reacted in a CEM
was added to the flask dropwise via cannula under N . The
2
ꢀ
ꢀ
flask was then heated at 100 C for 3 h. After cooling to room
Discover SP for 30 s at 110 C (250 W max) and 45 min at
ꢀ
ꢀ
temperature, the flask’s contents were poured onto ice in a
separatory funnel. The mixture was extracted with diethyl
ether. The extracts were washed with water and brine, dried
150 C (300 W max). By holding the temperature at 110 C
ꢀ
for 30 s before heating to 150 C, the vial did not pressurize
at a rate which could trigger the microwave’s rapid pressuri-
over MgSO , gravity filtered, and solvent removed via rotary
evaporation. The brown residue was then dissolved in hex-
zation safety feature. Following polymerization, the black mix-
ture was diluted with toluene and dripped into 0 C stirred,
4
ꢀ
anes and purified via flash column chromatography on SiO2
acidic methanol. The fine black solids were filtered through a
6
2
JOURNAL OF POLYMER SCIENCE, PART A: POLYMER CHEMISTRY 2019, 57, 60–69