Chemistry of Materials
Article
NMR (CDCl3, 100 MHz): δ 140.8, 133.8, 128.6, 125.0, 112.5. HRMS
(APPI, C10H6Br2Se2): calcd, 443.7165; found, 443.7154.
130.0, 124.3, 36.6, 31.9, 31.0, 29.8, 29.7, 29.66, 29.6, 29.4, 22.7, 14.1,
−7.97. HRMS (FAB, C44H72Se2Sn2): calcd, 1000.2008; found,
1000.2005.
Synthesis of (E)-1,2-Bis(3-(tetradec-1-yn-1-yl)selenophen-2-yl)-
ethane (6). To a deoxygenated solution of compound 5 (2.60 g,
5.86 mmol) in THF (50 mL) and diisopropylamine (50 mL) was
added Pd(PPh3)2Cl2 (1.03 g, 1.46 mmol, 25 mol %), CuI (280 mg,
1.46 mmol, 25 mol %), PPh3 (380 mg, 1.46 mmol, 25 mol %) and
tetradec-1-yne (3.42 g, 17.57 mmol). The mixture was stirred at 80 °C
for 12 h, and filtered by Celite. The resulting mixture was added to the
saturated NH4Cl solution, and extracted with EA (10 mL × 3). The
combined organic layer was dried over anhydrous MgSO4, filtered, and
concentrated in vacuum. The residue was purified by column
chromatography on silica gel (hexane) to give a yellow solid 6 (3.81
Synthesis of Copolymer PαNDSDTFBT. To a 50 mL round-
bottomed flask were added Sn-4,9-α-aNDS (140 mg, 0.14 mmol), Br-
DTFBT (132.5 mg, 0.14 mmol), Pd2(dba)3 (5.15 mg, 0.0056 mmol),
tri(o-tolyl)phosphine (13.69 mg, 0.045 mmol) and dry chlorobenzene
(5.8 mL). The mixture was degassed, and the reaction was carried out
in the focused microwave instrument under 270 W at 180 °C for 50
min. To end-cap the resultant copolymer, tributyl(thiophen-2-
yl)stannane (26.22 mg, 0.07 mmol) was added to the mixture, and
the microwave reaction was continued for 10 min under 270 W.
Subsequent to the addition of tributyl(thiophen-2-yl)stannane,
another end-capping reagent, 2-bromothiophene (12.37 mg, 0.076
mmol) was added, and the reaction was continued for another 10 min.
The mixture was added into methanol dropwise. The precipitate was
collected by filtration and washed by Soxhlet extraction with acetone
and hexane sequentially for 3 days. The crude polymer was dissolved
in hot chloroform, and the residual Pd catalyst and Sn metal was
removed by Pd-thiol gel and Pd-TAAcOH (Silicycle Int.). After
filtration and removal of the solution, the polymer was redissolved in
THF and reprecipitated by methanol. The resultant polymer was
collected by filtration, and dried under vacuum to afford a dark-blue
fiber-like solid (200 mg, 98%, Mn = 33 300, PDI = 1.29). Anal. Calcd
for C84H122F2N2S3Se2 (a repeating unit of PαNDSDTFBT): C, 69.48;
H, 8.47; N, 1.93. Found: C, 67.49; H, 8.22; N, 1.76.
Synthesis of Copolymer PαNDSDPP. To a 50 mL round-bottomed
flask were added Sn-4,9-α-aNDS (134 mg, 0.134 mmol), Br-DPP
(137.1 mg, 0.134 mmol), Pd2(dba)3 (4.93 mg, 0.0054 mmol), tri(o-
tolyl)phosphine (13.1 mg, 0.043 mmol) and dry chlorobenzene (5.6
mL). The mixture was degassed, and the reaction was carried out in
the focused microwave instrument under 270 W at 180 °C for 50 min.
To end-cap the resultant copolymer, tributyl(thiophen-2-yl)stannane
(25.09 mg, 0.067 mmol) was added to the mixture, and the microwave
reaction was continued for 10 min under 270 W. Subsequent to the
addition of tributyl(thiophen-2-yl)stannane, another end-capping
reagent, 2-bromothiophene (11.84 mg, 0.073 mmol) was added, and
the reaction was continued for another 10 min. The mixture was added
into methanol dropwise. The precipitate was collected by filtration and
washed by Soxhlet extraction with acetone and hexane sequentially for
3 days. The crude polymer was dissolved in hot chloroform, and the
residual Pd catalyst and Sn metal was removed by Pd-thiol gel and Pd-
TAAcOH (Silicycle Int.). After filtration and removal of the solution,
the polymer was redissolved in hot chloroform and reprecipitated by
methanol. The resultant polymer was collected by filtration, and dried
under vacuum to afford a dark-green fiber-like solid (203 mg, 98%, Mn
= 373 900, PDI = 1.97). Anal. Calcd for C92H140N2O2S2Se2 (a
repeating unit of PαNDSDPP): C, 72.31; H, 9.23; N, 1.83. Found: C,
70.00; H, 9.07; N, 1.66.
Bottom-Gate/Top-Contact OFET Devices. An n-type heavily
doped Si wafer with a SiO2 layer of 300 nm and a capacitance of 11
nF/cm2 was used as the gate electrode and dielectric layer. The
substrates were cleaned by ultrasonication in deionized water, acetone
and isopropyl alcohol for 15 min each, and then dried using a N2
stream. After exposed to UV/ozone for 20 min, the substrates were
modified with an octadecyltrichlorosilane (ODTS) self-assembled
monolayer. Thin films (40−60 nm in thickness) of polymers were
deposited on ODTS-treated SiO2/Si substrates. The thin films were
annealed at 200 °C for 10 min. Gold source and drain contact (40 nm
in thickness) were deposited by vacuum evaporation on the organic
layer through a shadow mask. Electrical measurements of OTFT
devices were carried out at room temperature in air using a 4156C,
Agilent Technologies. The field-effect mobility was calculated in the
saturation regime by using the equation Ids = (μWCi/2L)(Vg − Vt)2,
where Ids is the drain-source current, μ is the field-effect mobility, W is
the channel width (1 mm), L is the channel length (100 μm), Ci is the
capacitance per unit area of the gate dielectric layer, Vg is the gate
voltage and Vt is threshold voltage.
1
g, yield: 97%). H NMR (CDCl3, 400 MHz): δ 7.68 (d, J = 5.6 Hz, 2
H), 7.27 (s, 2 H), 7.18 (d, J = 5.6 Hz, 2 H), 2.46 (t, J = 7.0 Hz, 4 H),
1.66−1.63 (m, 4 H), 1.52−1.48 (m, 4 H), 1.37−1.26 (m, 36 H), 0.88
(t, J = 6.8 Hz, 6 H). 13C NMR (CDCl3, 100 MHz): δ 149.8, 133.1,
126.9, 124.8, 124.2, 95.1, 76.4, 31.9, 29.68, 29.67, 29.64, 29.56, 29.3,
29.2, 29.0, 28.8, 22.7, 19.7, 14.1. HRMS (APPI, C38H56Se2 + H): calcd,
673.2788; found, 673.2793.
Synthesis of 5-Dodecyl-6-(3-(tetradec-1-yn-1-yl)selenophen-2-yl)-
benzo[b]selenophene (7). To a deoxygenated N-methyl-2-pyrroli-
done (NMP, 10 mL) solution of compound 6 (1.00 g, 1.49 mmol) was
added 1,8-diazabicycloundec-7-ene (DBU) (0.45 mL, 2.98 mmol).
The reaction was refluxed in the focused microwave instrument under
270 W for 1 h, and then cooled to rt. The resulting mixture was diluted
with water (20 mL), and extracted with EA (10 mL × 3). The
combined organic layer was washed with brine solution (5 mL) and
dried over anhydrous MgSO4. After filtration, the solvent was removed
under vacuum and the residue was purified by column chromatog-
raphy on silica gel (hexane) to give a yellow solid 7 (0.91 g, yield:
91%). 1H NMR (CDCl3, 400 MHz): δ 7.97 (d, J = 6.0 Hz, 1 H), 7.90
(d, J = 6.0 Hz, 1 H), 7.88 (s, 1 H), 7.71 (s, 1 H), 7.53 (d, J = 6.0 Hz, 1
H), 7.32 (d, J = 6.0 Hz, 1 H), 2.77 (t, J = 8.0 Hz, 4 H), 2.17 (t, J = 7.0
Hz, 4 H), 1.37−1.10 (m, 40 H), 0.91−0.87 (m, 6 H). 13C NMR
(CDCl3, 100 MHz): δ 150.8, 142.3, 138.8, 137.7, 132.5, 131.9, 129.3,
128.8, 127.9, 127.4, 125.3, 123.9, 91.4, 33.5, 31.95, 31.94, 30.96, 29.7,
29.6, 29.5, 29.46, 29.43, 29.40, 29.38, 29.1, 28.6, 22.71, 22.70, 19.3,
14.1. HRMS (APPI, C38H56Se2 + H): calcd, 673.2796; found,
673.2793.
Synthesis of 4,9-Didodecylnaphtho[1,2-b:5,6-b′]bis(selenophene)
(4,9-α-aNDS). To a deoxygenated toluene (10 mL) solution of
compound 7 (200 mg, 0.30 mmol) was added PtCl2 (3.97 mg, 0.015
mmol), and stirred at 120 °C for 36 h. The resulting mixture was
filtered by Celite, and concentrated under vacuum. The residue was
purified by column chromatography on silica gel (hexane), and
recrystallized from CH2Cl2/MeOH to give a slight yellow needle 4,9-
α-aNDS (42 mg, yield: 20%). 1H NMR (CDCl3, 400 MHz): δ 8.17 (d,
J = 6.0 Hz, 2 H), 7.94 (s, 2 H), 7.77 (d, J = 6.0 Hz, 2 H), 3.41 (t, J =
8.0 Hz, 4 H), 1.92−1.86 (m, 4 H), 1.64−1.59 (m, 4 H), 1.44−1.27 (m,
36 H), 0.88 (t, J = 6.8 Hz, 6 H). 13C NMR (CDCl3, 100 MHz): δ
139.8, 135.9, 135.8, 130.4, 129.4, 128.1, 125.0, 36.6, 31.9, 31.1, 29.9,
29.7, 29.6, 29.4, 22.7, 14.1. HRMS (APPI, C38H56Se2 + H): calcd,
673.2798; found, 673.2793.
Synthesis of (4,9-Didodecylnaphtho[1,2-b:5,6-b′]bis-
(selenophene)-2,7-diyl)bis(trimethylstannane) (Sn-4,9-α-aNDS). To
an anhydrous THF (7.5 mL) solution of 4,9-α-aNDS (120 mg, 0.18
mmol) was added n-butyllithium (0.22 mL, 2.5 M) slowly at −78 °C.
After stirring for 30 min at −78 °C, trimethyltin chloride (0.72 mL, 1
M) was added. The mixture was warmed to rt and stirred for 12 h, and
then quenched with the saturated NH4Cl solution (10 mL). The
organic layer was separated and the aqueous layer was extracted with
EA (5 mL × 3). The combined organic extract was washed with brine
solution (10 mL) and dried over anhydrous MgSO4. After filtration,
the solvent was removed under vacuum, and the residue was
recrystallized from CH2Cl2/MeOH to give a slight yellow needle
Sn-4,9-α-aNDS (170 mg, yield: 95%). 1H NMR (CDCl3, 400 MHz): δ
7.93 (s, 2 H), 7.92 (s, 2 H), 3.43 (t, J = 7.8 Hz, 4 H), 1.93−1.85 (m, 4
H), 1.66−1.58 (m, 4 H), 1.43−1.27 (m, 36 H), 0.88 (t, J = 6.8 Hz, 6
H). 13C NMR (CDCl3, 100 MHz): δ 144.0, 141.1, 140.4, 136.4, 136.0,
G
Chem. Mater. XXXX, XXX, XXX−XXX