G. Wu et al. / Dyes and Pigments 99 (2013) 653e660
655
0
Scheme 2. Synthetic route to J5 and J6. (a) NBS, DMF, room temperature, 5 h; (b) 2,2 -bithiophene-5-boronic acid pinacol ester, Pd(PPh
3
)
4
, K
2 3 3
CO , 1,4-dioxane, reflux, 24 h; (c) POCl ,
3
DMF, reflux, 4 h; (d) cyanoacetic acid or rhodanine-3-acetic acid, CH CN, piperidine, reflux, 15 h.
0
0
cyanoacetic acid or rhodanine-3-acetic acid via the Knoevenagel
2.1.4. 2-Cyano-3-(5 -julolidinyl-2,2 -bithiophen-5-yl)acrylic acid
reaction.
(J5)
An acetonitrile solution (25 mL) of JTeCHO (142 mg,
0.39 mmol), cyanoacetic acid (40 mg, 0.47 mmol) and piperidine
(0.2 mL) was heated under reflux for 8 h under a argon atmosphere.
After removal of acetonitrile in vacuo, the crude product was
purified by column chromatography (methylene chloride/
2
.1.1. 9-Bromo-julolidine (JeBr)
A 10 mL DMF solution of julolidine (675 mg, 3.90 mmol) and NBS
(
832 mg, 4.68 mmol) was stirred for 5 h at room temperature. The
crude product was purified by silica column chromatography
hexane/methylene chloride ¼ 3/1) toobtain JeBr (786 mg, 80%) as a
1
(
methanol ¼ 7/1) to obtain J5 (135 mg, 80%) as a red solid. H NMR
1
red oil. H NMR (500 MHz, CDCl
J ¼ 5.50 Hz), 2.70 (t, 4H, J ¼ 6.35 Hz),1.94 (m, 4H). C NMR (500 MHz,
CDCl ): /ppm: 142.0, 129.3, 123.7, 107.3, 50.0, 27.6, 21.9. IR (KBr,
3
):
d
/ppm: 6.87 (s, 2H), 3.10 (t, 4H,
(500 MHz, DMSO- d
6
):
d
/ppm: 8.29 (s, 1H), 7.80 (d, 1H, J ¼ 3.5 Hz),
13
7.44 (d,1H, J ¼ 2.9 Hz), 7.41 (d,1H, J ¼ 4.0 Hz), 7.21 (d,1H, J ¼ 3.5 Hz),
3
d
7.02 (s, 2H), 3.11 (t, 4H, J ¼ 5.0 Hz), 2.65 (t, 4H, J ¼ 5.6 Hz), 1.82 (m,
ꢀ
1
13
cm ): 3045, 2935, 2836,1581,1506,1462,1446,1310. TOFMS-EI (m/
z): calcd. for (M)
4H, J ¼ 5.5 Hz). C NMR (500 MHz, DMSO- d
6
): d/ppm: 163.8, 147.2,
þ
C
12
H14NBr: 251.0310, found: 251.0309.
145.2, 144.5, 143.0, 140.5, 133.5, 130.9, 128.0, 124.0, 123.7, 121.7,
ꢀ
1
121.0, 119.4, 117.6, 100.7, 49.2, 27.1, 21.2. IR (KBr, cm ): 3416, 3072,
0
2.1.2. 9-(2,2 -Bithiophen-5-yl)-julolidine (JT)
3032, 2922, 2849, 2210, 1672, 1606, 1579, 1537, 1489, 1369, 1312.
0
e
The mixture of JeBr (582 mg, 2.31 mmol), 2,2 -bithiophene-5-
24 19 2 2 2
FTMS-ESI (m/z): calcd. for (MeH) C H N O S : 431.0884, found:
boronic acid pinacol ester (810 mg, 2.77 mmol), Tetrakis (triphe-
nylphosphine) palladium (0) (61 mg, 0.05 mmol) and potassium
carbonate (2 mL, 10% aq.) in 1,4-dioxane (25 mL) was heated under
reflux for 24 h under a argon atmosphere. The crude product was
purified by column chromatography (petroleum ether/methylene
431.0883.
0
0
2.1.5. 2-(5-(5 -julolidinyl-2,2 -bithiophen-5-yl)-4-oxo-2-
thioxothiazolidin-3-yl)acetic acid (J6)
A procedure similar to that for J5 but with rhodanine-3-acetic
acid (74 mg, 0.39 mmol) instead of cyanoacetic acid was used.
The crude product was purified by column chromatography
1
chloride ¼ 3/1) to obtain JT (608 mg, 78%) as a yellow solid. H NMR
(
500 MHz, CDCl
3
):
d
/ppm: 7.15 (d, 1H, J ¼ 5.0 Hz), 7.12 (d, 1H,
J ¼ 3.0 Hz), 7.06 (d, 1H, J ¼ 3.5 Hz), 7.03(s, 2H), 6.99 (d, 1H,
(methylene chloride/methanol ¼ 6/1) to obtain J6 (156 mg, 89%) as
1
J ¼ 6.5 Hz), 6.98 (d,1H, J ¼ 3.5 Hz), 3.15 (t, 4H, J ¼ 5.5 Hz), 2.77 (t, 4H,
a red solid. H NMR (500 MHz, DMSO- d
6
):
d
/ppm: 8.08 (s, 1H), 7.73
13
J ¼ 6.2 Hz), 1.99 (m, 4H, J ¼ 6.0 Hz). C NMR (500 MHz, CDCl
3
):
d
/
(d, 1H, J ¼ 4.0 Hz), 7.48 (d, 1H, J ¼ 4.0 Hz), 7.44 (d, 1H, J ¼ 3.5 Hz),
ppm: 144.2, 142.2, 137.6, 133.4, 127.3, 124.0, 123.1, 122.3, 121.1, 121.0,
7.23 (d,1H, J ¼ 3.5 Hz), 7.04 (s, 2H), 3.14(t, 4H, J ¼ 5.5 Hz), 2.68 (t, 4H,
ꢀ1
13
1
20.4, 113.6, 49.5, 27.2, 21.5. IR (KBr, cm ): 3103, 3065, 3026, 2922,
J ¼ 6.0 Hz), 1.85 (m, 4H, J ¼ 5.5 Hz). C NMR (500 MHz, DMSO-d
6
):
2
849, 1607, 1577, 1520, 1496, 1455, 1310. TOFMS-EI (m/z): calcd. for
d/ppm: 191.6, 166.0, 164.1, 151.2, 147.5, 146.0, 138.1, 133.2, 131.2,
þ
(
M)
C
20
H19NS
2
: 337.0959, found: 337.0953.
129.6, 128.3, 127.9, 123.9, 122.7, 121.3, 119.0, 118.5, 49.3, 44.8, 27.0,
ꢀ
1
21.3. IR (KBr, cm ): 3448, 3063, 3025, 2920, 2848,1730, 1693, 1604,
0
0
2
.1.3. 9-(5 -Formyl-2,2 -bithiophen-5-yl)-julolidine (JTeCHO)
1573, 1522, 1494, 1463, 1365, 1314, 1117. FTMS-ESI (m/z): calcd. for
To a solution of JT (450 mg, 1.33 mmol) in DMF (20 mL) was
(M þ H)þ
C
26
H
23
N
2
O
3
S
4
: 539.0586, found: 539.0577.
ꢁ
added phosphorus oxychloride (0.15 mL, 1.61 mmol) at 0 C. The
solution was warmed to room temperature and stirred for an
additional 2 h. After removal of DMF in vacuo, the reaction mixture
was neutralized with sodium acetate and extracted with methylene
chloride. The crude product was purified by column chromatog-
2.2. Preparation of dye-sensitized TiO
2
thin films
The colloidal TiO
out according to the previous paper [43]. Firstly, the TiO
2
nanoparticle fabrication process was carried
paste was
2
raphy (petroleum ether/acetic ester ¼ 3/1) to obtain JTeCHO
screen-printed onto FTO coated glass (TECe15, LOF), then sintered
1
ꢁ
(
400 mg, 82%) as a red solid. H NMR (500 MHz, CDCl
3
):
d/ppm: 9.82
at 450 C for 30 min under air. The TiO
2
thin-film electrode of 10
mm
(
s, 1H), 7.63 (d, 1H, J ¼ 4.2 Hz), 7.26 (d, 1H, J ¼ 3.6 Hz), 7.17 (d, 1H,
thickness was obtained, which was measured by a profilometer
(XPe2, AMBIOS Technology Inc., USA). After the film preparation,
J ¼ 4.2 Hz), 7.04(s, 2H), 7.03 (d,1H, J ¼ 4.2 Hz), 3.19 (t, 4H, J ¼ 5.7 Hz),
13
ꢁ
2
.77 (t, 4H, J ¼ 6.3 Hz), 1.98 (m, 4H, J ¼ 6.0 Hz). C NMR (500 MHz,
CDCl ): /ppm: 182.5, 148.3, 143.4, 140.7, 137.9, 132.3, 127.5, 124.7,
23.2, 121.7, 121.4, 120.7, 50.1, 27.9, 22.0. IR (KBr, cm ): 3081, 3057,
the films were calcined at 450 C for 30 min in air. Afterward, the
ꢀ1
3
d
2
TiO films were immersed in 0.3 mmol L ethanol solution of the
ꢀ1
1
3
1
dyes for 12 h.
037, 2930, 2850, 2791, 2741, 1661, 1606, 1578, 1519, 1500, 1469,
The solar cell used for photovoltaic measurements consisted of a
þ
452, 1312. FTMS-ESI (m/z): calcd. for (M)
C
21
H19NOS
2
: 365.0897,
2
dye-adsorbed TiO electrode, a counter electrode, a 60 mm thermal
found: 365.0903.
adhesive film (Surlyn, DuPont) and an organic electrolyte. The