A.M. Spring et al. / Polymer 119 (2017) 13e27
15
2.4. Synthesis of precursor (6)
(125 MHz, CDCl
3
)
d: 179.32, 177.44, 159.12, 137.99, 127.56, 124.29,
115.02, 68.13, 47.79, 45.80, 42.96, 33.91, 29.04, 28.93, 25.78,
1
,8-Dibromooctane (31.49 g, 123.35 mmol) and anhydrous po-
24.59 ppm. HRMS (FABþ) calculated for C23
5
H27NO : m/z 397.1889;
tassium carbonate (15.99 g, 115.69 mmol) were dissolved in
acetonitrile (500 mL) and heated to a temperature of 70 C. Pre-
Found: m/z 397.1887.
ꢀ
cursor (3) (14.80 g, 57.98 mmol) was then dissolved in hot tetra-
hydrofuran (100 mL) and added dropwise very slowly using a
syringe pump over a period of 5 h. After complete addition, the
mixture was refluxed for an additional 48 h. The mixture was
allowed to cool and the acetonitrile was removed by rotary evap-
orator. The crude product was purified by column chromatography
using a solvent system of 10% ethyl acetate and 90% hexanes. The
resulting off white solid was further purified by recrystallization
from boiling ethanol allowing isolation in a yield of 41%.3 H NMR
2.7. Synthesis of monomer (5)
Monomer (5) has been utilized in previous investigations and so
its preparation will not be described here. It was originally prepared
by other groups [13] and later optimized by ourselves [19,42]. For
details see supporting information section 4.
2.8. Synthesis of monomer (9)
9 1
(
6
2
400 MHz, CDCl
3
)
d
: 7.14 (d, J ¼ 8.7 Hz, 2H), 6.93 (d, J ¼ 8.7 Hz, 2H),
.34 (s, 2H), 3.96 (t, J ¼ 5.8 Hz, 2H), 3.41 (t, J ¼ 6.7 Hz, 2H), 3.39 (s,
H), 2.87 (s, 2H), 1.91e1.72 (m, 4H), 1.64 (m, 2H), 1.56e1.21 (m, 8H)
The chromophore (Cr) (2.44 g, 3.54 mmol), 4-
dimethylaminopyridine (0.43 g, 3.54 mmol), N,N’-dicyclohex-
ylcarbodiimide (0.71 g, 3.54 mmol) and precursor (8) (1.41 g,
13
ꢀ
ppm. C NMR (125 MHz, CDCl
3
)
d: 177.55, 159.26, 138.12, 127.68,
3.54 mmol) were transferred to a flask and cooled to -5 C using a
1
2
4
24.40, 115.17, 68.28, 47.94, 45.92, 43.09, 34.17, 32.91, 29.28, 28.81,
chiller. A flask containing anhydrous tetrahydrofuran (100 mL) was
also cooled to -5 C. Tetrahydrofuran (30 mL) was transferred to the
ꢀ
8.23, 26.04 ppm. HRMS (EIþ) calculated for C23
H
28BrNO
3
: m/z
45.1253; Found: m/z 445.1255.
reaction vessel by syringe under a nitrogen atmosphere and the
ꢀ
mixture was stirred for an additional 48 h at -5 C under nitrogen.
2
.5. Synthesis of precursor (7)
After allowing to warm to room temperature the tetrahydrofuran
was evaporated using a rotary evaporator and the crude material
was purified by column chromatography with a solvent system of
50% tetrahydrofuran and 50% hexanes. The resulting green solid
was then washed with excess ethanol to remove any residual N,N’-
dicyclohexylcarbodiimide. After which the solid was dried in a
Precursor (6) (7.20 g, 16.12 mmol) was dissolved in acetone
100 mL) and stirred vigorously. To this vessel a solution of silver
(
nitrate (10.95 g, 169.87 mmol) in deionized water (100 mL) was
added dropwise over a period of 30 min, after which the mixture
was heated under reflux for 12 h. When cool the acetone was
removed by rotary evaporator and the crude product was extracted
with chloroform and dried under anhydrous magnesium sulfate.
The chloroform solution was filtered through a pad of celite to
remove any residual silver salts. Evaporation of the chloroform by
rotary evaporator yielded a yellow oil. The crude product was pu-
rified by column chromatography with a solvent system of 20%
tetrahydrofuran and 80% hexanes. The isolated off white solid was
further purified by recrystallization from a mixture of boiling
ꢀ
vacuum oven at 50 C for 12 h affording the desired material in a
4
3 1
yield of 30%. H NMR (400 MHz, CDCl
3
)
d
: 7.78 (d, J ¼ 15.4 Hz, 1H),
7.44e7.59 (m, 11H), 7.27 (s, 2H), 7.13 (m, 3H), 6.91 (m, 3H), 6.56 (d,
J ¼ 14.9 Hz, 1H), 6.34 (m, 3H), 6.27 (m, 1H), 5.19 (s, 2H), 4.22 (t,
J ¼ 6.2 Hz, 2H), 3.90 (t, J ¼ 6.7 Hz, 2H), 3.61 (t, J ¼ 6.2 Hz, 2H), 3.38 (s,
2H), 3.02 (s, 3H), 2.83 (s, 2H), 2.25 (t, J ¼ 7.7 Hz, 2H), 1.01e1.97 (m,
13
3
12H) ppm. C NMR (125 MHz, CDCl ) d: 177.30, 175.35, 173.48,
161.79, 158.96, 158.84, 158.57, 151.53, 151.42, 137.87, 136.66, 135.69,
132.01, 131.38, 129.65, 128.62, 128.15, 128.12, 127.47, 126.72, 125.40,
124.26, 116.81, 114.87, 113.84, 111.28, 111.08, 110.09, 110.64, 105.48,
96.48, 70.50, 68.02, 67.88, 60.82, 50.75, 47.73, 45.68, 42.84, 38.66,
34.14, 30.23, 28.99, 28.89, 25.75, 25.53, 24.85, 24.63, 21.09 ppm.
4
0 1
hexanes and tetrahydrofuran in a yield of 72%. H NMR (400 MHz,
CDCl
5
3
)
d
: 7.14 (d, J ¼ 9.6 Hz, 2H), 6.95 (d, J ¼ 8.7 Hz, 2H), 6.34 (s, 2H),
.30 (s, 1H), 3.96 (t, J ¼ 6.7 Hz, 2H), 3.64 (t, J ¼ 5.8 Hz, 2H), 3.39 (s,
2
H), 2.84 (s, 2H), 1.92e1.73 (m, 2H), 1.67 (m, 2H), 1.51e1.19 (m, 8H)
HRMS (FABþ) calculated for C62
54 3 5 7
H F N O S: m/z 1069.3696;
Found: m/z 1070.3785. EA: calculated C: 69.58%, H: 5.09%, N: 6.54%.
Found C: 67.53%, H: 6.03%, N: 6.79%.
13
ppm. C NMR (125 MHz, CDCl
3
)
d
: 178.10, 159.84, 138.61, 128.25,
124.26, 115.73, 68.92, 63.77, 48.51, 46.48, 43.65, 33.46, 30.01, 29.80,
2
6.61, 26.34 ppm.
2.9. Synthesis of chromophore (Cr)
2.6. Synthesis of precursor (8)
The chromophore (Cr) used in this investigation was synthe-
3
0,36 1
Periodic acid (11.40 g, 50 mmol) and chromium trioxide (23 mg,
.2 mol%) were dissolved in wet acetonitrile (0.75v% water)
sized according to literature procedures.
H NMR (400 MHz,
1
(
CDCl
(d, J ¼ 15.9 Hz, 1H), 6.92 (d, J ¼ 3.8 Hz, 1H), 6.55 (d, J ¼ 14.9 Hz, 1H),
6.38 (dd, J
3
)
d
: 7.78 (d, J ¼ 15.9 Hz), 7.59e7.32 (m, 11H), 7.27 (s, 2H), 7.15
114 mL) by stirring for 3 h. Precursor (7) (5.40 g, 14.20 mmol) was
ꢀ
dissolved in wet acetonitrile (71 mL) and cooled to 0e5 C. The
1
¼ 8.7 Hz, J ¼ 2.4 Hz, 1H), 6.27 (d, J ¼ 1.9 Hz, 1H), 5.19 (s,
2
periodic acid/chromium trioxide solution (81 mL) was added
2H), 3.78 (q, J ¼ 3.7 Hz, 2H), 3.52 (t, J ¼ 5.8 Hz, 2H), 3.04 (s, 3H) ppm.
dropwise over a period of 1 h. The mixture was then stirred at
ꢀ
0
e5 C for an additional 1 h. The reaction was quenched by the
2.10. Synthesis of homopolymer (10a) and copolymer series (10b-
10g)
dropwise addition of a solution of disodium phosphate (4.26 g,
0 mmol) in deionized water (71 mL). An excess of dichloro-
3
methane was added and the organic layer was washed firstly with
brine and then an aqueous solution of disodium phosphate (1.56 g
in 35.5 mL) and finally brine again. The dichloromethane was
evaporated and the crude product was further purified by column
chromatography in a solvent system of 50% ethyl acetate and 50%
To produce homopolymer (10a) and the copolymer series (10b-
10g) the same procedure was used for each polymer. The mass of
monomer (5) utilized to prepare homopolymer (10a) was 0.50 g
and this was maintained at 0.50 g for each of the copolymers in the
series (10b-10g). The mass of monomer (9) was varied as follows;
(10b) 0.05 g, (10c) 0.10 g, (10d) 0.20 g, (10e) 0.30 g, (10f) 0.40 g,
(10g), 0.50 g. Monomer (5) (0.50 g, 2.04 mmol) and the desired
mass of monomer (9) (0e0.5 g, 0e0.46 mmol) were transferred to a
Schlenk tube and purged with nitrogen. Anhydrous chloroform
41 1
hexanes in a yield of 55%.
3
H NMR (400 MHz, CDCl ) d: 7.14 (d,
J ¼ 9.2 Hz, 2H), 6.94 (d, J ¼ 9.2 Hz, 2H), 6.33 (m, 2H), 3.96 (t,
J ¼ 6.7 Hz, 2H), 3.39 (s, 2H), 2.83 (s, 2H), 2.35 (t, J ¼ 6.2 Hz, 2H),
1
.77e1.71 (m, 2H), 1.56 (m, 2H), 1.51e1.28 (m, 8H) ppm. 13C NMR