Triazine dyes as photosensitizers for dye-sensitized solar cells

Article abstract of DOI:10.1016/j.tet.2012.10.046

A new series of triazine-containing donor-π-acceptor organic sensitizers (TCT-(7-19)) with broad absorptions and high molar extinction coefficients have been designed and synthesized based on our previous work. All these dyes were completely characterized

Full text of DOI:10.1016/j.tet.2012.10.046

Tetrahedron 69 (2013) 190e200
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Triazine dyes as photosensitizers for dye-sensitized solar cells
,
,
b
,
a,b,
Jian Liu a b, Kai Wang a, Xiaopeng Zhang a, Chenghui Li a , Xiaozeng You
*
*
a State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing National Laboratory of Microstructures, Nanjing University,
Nanjing 210093, PR China
b Academician Work Station of Changzhou Trina Solar Energy Co., Ltd., Changzhou 213022, Jiangsu Province, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 13 June 2012
Received in revised form 9 October 2012
Accepted 16 October 2012
Available online 23 October 2012
A new series of triazine-containing donorep-acceptor organic sensitizers (TCT-(7e19)) with broad
absorptions and high molar extinction coefficients have been designed and synthesized based on our
previous work. All these dyes were completely characterized by 1H NMR, ESI-MS, EA, IR, UVevis, and
cyclic voltammetry. The photovoltaic performances of dye-sensitized solar cells (DSSCs) based on these
dyes were investigated. The effect of conjugating length and terminating groups on the absorption
properties and photovoltaic performances were discussed. An overall photon-to-electron conversion
efficiency of 3.69% was achieved with the DSSC based on the dye TCT-13 (Jsc¼7.76 mA cmꢀ2, Voc¼691 mV,
FF¼68.8%) under AM 1.5G illumination (100 mW/cm2).
Keywords:
Triazine
Triphenylamine
Dye-sensitized solar cells
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
derivates.8 In our previous work, a new type of De
sensitizers utilizing triazine as spacer has been developed for
p-A organic
p
Due to the energy crisis, a variety of light-harvesting devices
have been intensively investigated in recent years.1 Among these
devices, dye-sensitized solar cells (DSSCs) have received consider-
able attention since Gratzel’s pioneering report in 1991.2
Ruthenium-based dyes (such as N3, N719, and black dye) have
been considered as the most efficient sensitizers, which have
reached the promising solar-energy-to-electricity conversion effi-
ciencies of 11% under AM 1.5 irradiation.3 In view of the limited
ruthenium resource, however, sensitizers based on non-Ru system
DSSCs.9 The cyanoacrylic acid dye TCT-1 with two electron donat-
ing triphenylamine moieties exhibits better photovoltaic perfor-
mance than other dyes with one donor moiety. The DSSC based on
TCT-1 shows a high open-circuit photovoltage (Voc) of 757 mV,
which is comparative with some reported excellent dyes. However,
its short-circuit photocurrent densities (Jsc) is quite low
(3.33 mA cmꢀ2) due to its narrow absorption. Based on these re-
sults, we decided to tailor the chemical structure to optimize their
photovoltaic properties. The molecular structures of the new sen-
sitizers designed and synthesized in this work are given in
Figs. 1e3. Red-shifted and broadened absorptions were realized,
DSSCs with better photovoltaic performance have been obtained.
The correlations between structure, absorption, and photovoltaic
performance were discussed.
are sorely needed. In this regard, conjugated donore
p-acceptor
(De -A) chromophores have been intensively investigated as
p
promising candidates due to their large molar extinction co-
efficient, tunable absorption wavelength, facile synthesis, and
lower cost.4 Recently, Gratzel’s group reported the porphyrin-
sensitized solar cells with the highest solar-energy-to-electricity
conversion efficiencies of 12.3%.5
2. Results and discussion
p-Conjugated compounds based on triazine have been studied
as an attractive candidate in functional photoelectric materials
owing to the intriguing structural and electronic properties of tri-
azine moiety.6 Structurally, triazine unit is a symmetric core with
three active substituted places, which is promising for derivation
through organic synthesis.7 Moreover, triazine unit is a typical
electron-accepting unit and would be able to improve the electron-
injection and electron-transportation abilities of its conjugated
Increasingtheconjugation lengthisaneffectivewayto expandthe
absorption of De
a series of -conjugated linker between the triphenylamine and tri-
p
-A chromophores.10 Therefore, we synthesized
p
azine in TCT-1 according to the synthetic protocol illustrated in
Schemes 1e3. Double aryl substitutions of the cyanuric chloride with
the corresponding Grignard reagents gave 2a,b. Compounds 3a,b
were obtained by bromination of 2a,b using NBS.11 The reactions of
3a,b with triethyl phosphate in the presence of Lewis acid afford the
Horner reagents 4a,b.12 The aldehydes 6a,b were readily prepared by
Suzuki coupling between 4-bromotriphenylamine and the aromatic
* Corresponding authors. Tel.: þ86 25 83592969; fax: þ86 25 83314502; e-mail
addresses: chli@nju.edu.edu (C. Li), youxz@nju.edu.edu, youxz@nju.edu.cn (X. You).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.10.046

J. Liu et al. / Tetrahedron 69 (2013) 190e200
191
Fig. 1. Molecular structure of TCT dyes.
boron acids (5a,b). Compound 6c was purchased from commercial
suppliers and used as received. The subsequent reactions between
4a,b and 6aec were carried out in anhydrous THF using sodium hy-
dride as base. However, the HornereWadswortheEmmons reactions
didn’t occur as expected. Instead, the chlorine was substituted by
hydroxyl in the reaction to give TCT-(7e12) (Schemes 1 and 2). In
order to obtain the mono-chlorine substituted triazine compounds,
we also investigated other mild conditions, which may favor the
HornereWadswortheEmmons reactions. Unfortunately, only com-
pound 7 wasobtained inlow yield(20%) from4b and 6cwhent-BuOK
was used as base at 0 ꢁC. Other reactions resulted in either no reaction
or extremely low yields. The subsequent Suzuki coupling with
4-formylphenylboronic acid was performed to give compound 8 in
moderate yield. Finally, the TCT-13 was obtained through Knoeve-
nagel reaction (Scheme 3).13
To compare with the hydroxyl dyes (TCT-(7e12)), we also
designed and synthesized a series of dyes (TCT-(14e19)) with one or
two carboxyl groups. The target compounds were synthesized in
moderated overall yield through the routes described in Schemes 4
and 5. Suzuki coupling between 2b and 4-ethoxycarbonylphe-
nylboronic acid affords compound 9, which was transformed to
Horner reagent 13 through bromination and substitution by triethyl
phosphate successively. The HornereWadswortheEmmons re-
actions between 13 and 6aec and subsequent hydrolysis were carried
out in THF using sodium hydride as base in one-pot to afford the
desired mono-carboxyl dyes TCT-(14e16), respectively. The dyes TCT-
(17e19) with two carboxyl groups were synthesized in a similar way.
The absorption spectra of TCT-7, TCT-10, TCT-13, TCT-14, TCT-16,
TCT-17, and TCT-19 in DMF are representatively presented in Fig. 2a,
while the detailed parameters of all TCT dyes are collected in
Table 1. All the TCT dyes show a strong absorption maximum in the
visible region corresponding to intramolecular charge transfer ab-
sorption. In comparison with TCT-1, TCT-13 exhibits 60 nm bath-
ochromic shift owing to its longer conjugation as well as
introducing another donor (thiophene unit), which enhance the
intramolecular charge separation tendency. Similarly, TCT dyes
containing additional furan rings exhibit significant bathochromic
shift in absorption spectra as compared to their analogues.10a TCT-
10 and TCT-11 with the longest conjugation length show the
maximum red-shift in absorption peak (around 500 nm), which are
comparable to the black dye.3b The dyes with two carboxyl groups
(TCT-(17e19)) show similar absorption characteristics as those of
the mono-carboxyl ones (TCT-(14e16)) without a distinct bath-
ochromic shift. The absorption spectra of adsorbed TCT dyes on
TiO2 films are very similar to TCT dyes in DMF solution while the
absorption peak wavelengths are red-shifted by 40e70 nm rela-
tively (Fig. 2b). Such a red-shift is attributable to aggregation of the
dyes on TiO2 electrode as reported previously.4c
Cyclic voltammetry experiments were conducted on triazine
dyes at room temperature to investigate their electrochemical
properties. Both quasi-reversible oxidation and reversible reduction
processes were observed in DMF solutions with 0.1 M n-Bu4NClO4 as
a supporting electrolyte. The first oxidation potentials (Eox), corre-
sponding to the HOMO level of dyes, were calculated by using the
oxidation potential (after being converted to the potential relative to
the standard hydrogen electrode potential, NHE) and the Ag/AgCl
energy level of ꢀ4.44 eV (relative to the vacuum level) as the stan-
dard.14 The LUMO levels of sensitizer were estimated by the values of
Eox and the E0e0 band gaps, while the latter were estimated from the
absorption spectra (absorption edge) of the compounds. The data are

192
J. Liu et al. / Tetrahedron 69 (2013) 190e200
tert-butanol (1:1, v/v) as the redox electrolyte (details of the device
1.2
1.0
0.8
0.6
0.4
0.2
0.0
(a)
fabrication and characterization are described in the Experimental).
The incident photon-to-current conversion efficiency (IPCE) spec-
tra of TCT-7, TCT-10, TCT-13, TCT-14, TCT-16, TCT-17, and TCT-19 are
representatively depicted in Fig. 3. The photo-to-current conver-
sion areas of these dyes lie in the range of 400e650 nm, which
match well with the absorption spectra. The IPCE spectra of TCT
dyes containing additional thiophene or furan rings extend to
longer wavelengths as compared to their analogues. This feature is
in agreement with the trend in absorption spectra.16 The DSSCs
based on TCT-13 show IPCE >50% from 420 nm to 600 nm and IPCE
maxima of 60% around 500 nm, which are the best among TCT-
(7e19) and also better than that of TCT-1.
The photocurrentevoltage curves of TCT-7, TCT-10, TCT-13,
TCT-14, TCT-16, TCT-17, and TCT-19 are representatively shown in
Fig. 4, while the detailed photovoltaic parameters of all TCT dyes
were listed in Table 2. The short-circuit photocurrent densities
(Jsc) are 3.07e7.76 mA cmꢀ2, and the open-circuit photovoltages
(Voc) are in the range from 0.583 V to 0.691 V. The solar-energy-to-
TCT-7
TCT-10
TCT-13
TCT-14
TCT-16
TCT-17
TCT-19
300
400
500
600
700
800
Wavelength (nm)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
electricity conversion yield values (
to 3.69%.
Two interesting observations can be made by comparing the
absorption spectra of TCT-(7e19) with their photovoltaic perfor-
mances. Firstly, the TCT dyes with terminating hydroxyl groups
show poor photovoltaic performances in spite that they exhibit
h) of TCT dyes vary from 1.20%
(b)
TCT-7
TCT-10
TCT-13
TCT-14
TCT-16
TCT-17
TCT-19
good absorption characteristics, indicating
a lower electron-
injecting efficiency from the LUMO orbital of the sensitizers to
the conduct band of the TiO2 through hydroxyl group.17 Secondly,
the di-carboxyl dye (e.g., TCT-19) exhibits better DSSCs perfor-
mance than the corresponding mono-carboxyl ones (e.g., TCT-16),
due to their better anchoring on the semiconductor surface, which
results in higher electron-injecting efficiency into TiO2.18
In TCT-13, the carboxyl and cyano groups are directly connected
to eCH]CHe unit, which may play an important role in effective
electron-injection into the conduction band of TiO2, resulting the
better photovoltaic performance as compared to other TCT dyes. In
order to get further insight into this issue, frontier orbital calcula-
tions with density functional theory (DFT) methods were per-
formed.19 TCT-13, TCT-16, and TCT-19 were chosen as the model
compounds since they have the same conjugated length between
triphenylamine moieties and triazine moieties. Fig. 5 shows the
frontier molecular orbitals of TCT-13, TCT-16, and TCT-19. The
highest occupied molecular orbitals (HOMOs) of these dyes are
similar and mainly located in the electron donating triphenylamine
moiety. However, the lowest unoccupied molecular orbitals
(LUMOs) of TCT-13 exhibit differences from those of TCT-16 and
TCT-19. For TCT-13, the LUMO is mainly distributed in triazine and
cyanoacetic acid moieties, indicating that the HOMOeLUMO exci-
tation moves the electron distribution from the triphenylamine
moiety to the triazine and cyanoacetic acid unit, thus allowing an
efficient photo-induced electron transfer from the dye to the TiO2
electrode under light irradiation. In contrast, the LUMO orbitals of
TCT-16 and TCT-19 are mainly located on triazine and thiophene
moieties. Therefore, the excited electrons cannot be directly injec-
ted into the conduction band of TiO2. They have to get across the
phenyl moiety before injecting into the conduction band of TiO2 via
carboxyl groups, resulting in the relatively lower photovoltaic
performance.
400
500
600
700
800
Wavelength (nm)
Fig. 2. Absorption of TCT dyes 2ꢂ10ꢀ5 M (a) in DMF and on TiO2 film (b).
80
N3
TCT-7
70
TCT-10
TCT-13
60
TCT-14
TCT-16
50
TCT-17
TCT-19
40
30
20
10
0
400
500
600
700
800
Wavelength (nm)
Fig. 3. IPCE values for DSSCs based on the TCT and N3 dyes.
summarized in Table 1. The LUMO energy levels for these dyes are
higher than the energy level of TiO2 conduction band (ꢀ0.5 V vs
NHE), indicating that these dyes can inject electrons to conduction
band of TiO2 electrode in their potential DSSCs applications.15
The photovoltaic performance of these dyes as the sensitizers
for DSSCs was evaluated with a sandwich DSSC cell with 0.05 M
iodine, 0.5 M LiI, and 0.05 M tert-butylpyridine in acetonitrile and
3. Conclusions
To summarize, a new series of triazine-containing donorep-
acceptor organic sensitizers with broad absorptions and high
molar extinction coefficients have been designed and synthesized
based on our previous work. The photovoltaic performances of
DSSCs based on these dyes were investigated. Better photovoltaic

J. Liu et al. / Tetrahedron 69 (2013) 190e200
193
Scheme 1. Synthesis of TCT-(7e9).
performances have been realized through optimizing the chem-
ical structure. The correlations between structure, absorption, and
photovoltaic performance were discussed. The new type dyes
with terminating hydroxyl group exhibit relatively poor
photovoltaic performances due to inefficient electron-injecting
from the LUMO orbital of the sensitizers to the conduct band of
the TiO2 through hydroxyl group. However, these dyes show
strong and broad absorption in visible region, which are
Scheme 2. Synthesis of TCT-(10e12).

194
J. Liu et al. / Tetrahedron 69 (2013) 190e200
Scheme 3. Synthesis of TCT-13.
comparable to the black dye. Di-carboxyl dye exhibits better
DSSCs performance than the corresponding mono-carboxyl ones
due to their better anchoring on the semiconductor surface.
Triazine dyes with cyanoacetic acid as the anchoring groups show
good photovoltaic performances owning to their favorable spatial
distribution in the LUMO orbital. All these results provide novel
insights into the further design of efficient organic sensitizers
based on triazine derivate dyes.
Scheme 4. Synthesis of TCT-(14e16).

J. Liu et al. / Tetrahedron 69 (2013) 190e200
195
Scheme 5. Synthesis of TCT-(17e19).
Table 1
Optical properties of TCT dyes in DMF and their energy levels of HOMO and LUMO
a
N3
Dye
lmax
/
3
max (nm/dm3
ledge/E0e0
(nm/eV)
EHOMOb (V)
ELUMOb,c (V)
molꢀ1 cmꢀ1
)
TCT-7
TCT-10
TCT-13
TCT-14
TCT-16
TCT-17
TCT-19
15
10
5
TCT-7
TCT-8
448/77,035, 306/39,100
455/68,220, 361/55,050,
308/48,315
436/66,580, 310/51,760
493/61,254, 304/34,850
498/63,720, 386/46,525,
305/45,160
477/59,684, 366/34,950,
304/41,460
459/75,840, 338/83,790
465/81,340, 297/47,425
479/79,215, 359/51,090,
299/53,860
614/2.02
616/2.01
1.26
1.30
ꢀ0.76
ꢀ0.71
TCT-9
TCT-10
TCT-11
574/2.16
636/1.95
639/1.94
1.45
1.27
1.31
ꢀ0.71
ꢀ0.68
ꢀ0.63
TCT-12
600/2.07
1.42
ꢀ0.65
TCT-13
TCT-14
TCT-15
562/2.21
589/2.11
590/2.10
1.32
1.23
1.24
ꢀ0.89
ꢀ0.88
ꢀ0.86
TCT-16
TCT-17
TCT-18
451/70,045, 302/58,140
463/79,825, 297/42,240
473/75,840, 357/48,645,
302/49,260
555/2.24
593/2.09
592/2.09
1.34
1.24
1.26
ꢀ0.9
0
ꢀ0.85
ꢀ0.83
0.0
0.2
0.4
0.6
0.8
Voltage (V)
TCT-19
451/72,490, 304/43,465
560/2.21
1.35
ꢀ0.86
Fig. 4. Photocurrent densityevoltage curves of DSSCs based on TCT dyes.
a
E0e0 was estimated by the absorption edge for the dyes in DMF.
Versus normal hydrogen electrode (NHE).
ELUMO¼EoxꢀE0e0.
b
c
4. Experimental section
Table 2
Photovoltaic performances of DSSCs based on TCT dyes
4.1. Materials and instruments
Dye
Voc (V)
Jsc (mA cmꢀ2
)
FF (%)
h (%)
All reagents were purchased from commercial suppliers and
used as received. Tetrahydrofuran (THF) was used after distillation
under sodium and benzophenone. Elemental analyses for C, H, and
N were performed on a PerkineElmer 240C analyzer. H NMR
spectra were obtained on a DRX 500 NMR spectrometer. Chemical
shifts are reported in parts per million (positive) downfield from
TMS. Coupling constants are given in hertz. Mass spectra were
acquired on LCQ Fleet ESI Mass Spectrometer.
TCT-1
TCT-7
TCT-8
TCT-9
757
602
615
607
591
611
608
691
631
614
619
639
583
601
711
3.32
3.65
3.72
3.07
3.97
4.16
3.49
7.76
5.65
6.18
5.21
6.29
6.58
5.60
13.59
71.8
62.1
59.5
64.4
66.1
59.5
56.3
68.8
61.1
61.1
60.9
67.0
72.2
64.1
70.2
1.81
1.37
1.36
1.20
1.55
1.51
1.20
3.69
2.17
2.32
1.97
2.70
2.77
2.15
6.78
TCT-10
TCT-11
TCT-12
TCT-13
TCT-14
TCT-15
TCT-16
TCT-17
TCT-18
TCT-19
N3
4.2. Photophysical and electrochemical measurements
The absorption spectra of the triazine dyes either in solution or
on the absorbed TiO2 film were measured by PerkineElmer 950

196
J. Liu et al. / Tetrahedron 69 (2013) 190e200
Fig. 5. Schematic representation of the frontier molecular orbitals of the HOMO and LUMO of TCT dyes by TDDFT calculations.
spectrophotometer. Absorption of the dye on the TiO2 surface was
done by soaking the TiO2 electrode in DMF solutions at room
temperature for 24 h. Infrared spectra were recorded on a Vector22
Bruker spectrophotometer with KBr pellets in the 400e4000 cmꢀ1
region.
Electrochemical measurements were performed at room tem-
perature on an Im6eX electrochemistry working station. All CV
measurements were carried out in DMF containing 0.1 M TBAP as
a supporting electrolyte, purged with argon prior to conduct the
experiment. Platinum electrode, Ag/AgCl in saturated KCl (aq), and
a platinum wire were used as working electrode, reference elec-
trode, and counter electrode, respectively. The scan rate was
100 mV/s.
4.6. The detailed experimental procedures and characteriza-
tion data
4.6.1. Synthesis of 2-chloro-4,6-di-p-tolyl-1,3,5-triazine (2a). A solu-
tion of compound 1a (17.1 g, 100 mmol) in anhydrous THF (120 mL)
was added dropwise to a suspension of iodine-activated magnesium
(2.88 g,120 mmol) in anhydrous THF (20 mL) over 30 min. In the case
of a delayed start to the reaction, brief heating was carried out. After
complete addition, the reaction mixture was maintained for 3 h at
reflux temperature and then cooled to room temperature. The
Grignard solution was added dropwise to a solution of cyanuric
chloride (6.53 g, 35.7 mmol) in anhydrous THF (50 mL) while the
temperature was maintained at 0e10 ꢁC. When the addition was
completed, the mixture was stirred for 10 h at 50 ꢁC and then poured
into ice water (150 mL). The water suspension was extracted twice
with DCM (300 mL). The organic phase was combined, washed with
water and brine, dried over anhydrous sodium sulfate, and then
concentrated. The residue was purified by flash chromatography on
silica gel (hexane/DCM 10:1) to afford 2a (6.3 g, 60%) as a white solid.
IR (KBr, cmꢀ1): 1613, 1518, 1366, 1245, 1183, 802; 1H NMR (500 MHz,
4.3. Fabrication of DSSCs
Photoanodes composed of transparent TiO2 (20 nm) layer and
FTO glass were obtained by following an already reported pro-
cedure.20 The TiO2 electrodes were immersed into the dye solution
(0.5 mM in DMF). The dye-adsorbed TiO2 electrode and Pt counter
electrode were assembled into a sealed sandwich-type cell. A drop
of electrolyte was then introduced into the cell, which was com-
posed of 0.05 M iodine, 0.5 M LiI, and 0.05 M tert-butylpyridine in
acetonitrile and tert-butanol (1:1, v/v). It was introduced into the
inter-electrode space from the counter electrode side through
predrilled holes.
CDCl3):
d
7.62 (d, J¼8.5 Hz, 4H), 7.36 (d, J¼8.5 Hz, 4H), 2.52 (s, 6H).
FABMS (m/z): 295.1 (Mþ). Anal. Calcd for C17H14ClN3: C, 69.03; H,
4.77; N, 14.21. Found: C, 68.91; H, 4.72; N, 14.02.
4.6.2. Synthesis of 2-chloro-4,6-bis(5-methylthiophen-2-yl)-1,3,5-
triazine (2b). Compound 2b was prepared as light yellow solid
(6.9 g, 63% yield) from 1b by using the method established for 2a. IR
(KBr, cmꢀ1): 1645,1556,1531,1455, 789; 1H NMR (500 MHz, CDCl3):
d
8.06 (d, J¼4.0 Hz, 2H), 6.89 (d, J¼4.0 Hz, 2H), 2.60 (s, 6H). FABMS
4.4. Characterization of DSSCs
(m/z): 307 (Mþ). Anal. Calcd for C13H10ClN3S2: C, 50.72; H, 3.27; N,
13.65. Found: C, 50.63; H, 3.21; N, 13.58.
The photocurrentevoltage (IeV) was recorded under the sim-
ulated AM 1.5 irradiation (100 mW cmꢀ2) using a Keithley 2400
digital source meter controlled by a computer. The active electrode
area was 0.36 cm2. The IPCE spectra were measured under mono-
chromatic irradiation with a xenon lamp and a monochromator.
4.6.3. Synthesis of 2,4-bis(4-(bromomethyl)phenyl)-6-chloro-1,3,5-
triazine (3a). N-Bromosuccimide (NBS) (0.79 g, 22 mmol) was
added to a stirred solution of compound 2a (2.95 g, 10 mmol) in
CCl4 (50 mL). The mixture was heated under reflux. AIBN was added
in catalytic amounts over a period of 1 h. After being cooled to room
temperature, the mixture was filtered. The solid residue was
washed with DCM (2ꢂ30 mL). The solvent was evaporated under
reduced pressure, and the residue was purified by flash chro-
matograph on silica gel (hexane/DCM 10:1) to afford 3a (3.83 g,
85%) as a white solid. IR (KBr, cmꢀ1): 1632,1525,1493, 1372, 802; 1H
4.5. DFT calculations
All calculations were carried out with Gaussian03 programs.19
The geometries of the organic dyes were fully optimized by
B3LYP method without any symmetry constraint. The calculations
NMR (500 MHz, CDCl3):
d
8.61 (d, J¼8.0 Hz, 4H), 7.67 (d, J¼8.0 Hz,
were carried out using the 6-31g basis set for all the atoms.
*

J. Liu et al. / Tetrahedron 69 (2013) 190e200
197
4H), 4.58 (s, 4H). FABMS (m/z): 450.91 (Mþ). Anal. Calcd for
C17H12Br2ClN3: C, 45.02; H, 2.67; N, 9.26. Found: C, 44.92; H, 2.61; N,
9.15.
added to a solution of 4b (2.0 g, 3.46 mmol) in dry THF (50 mL) at
0 ꢁC. After initial effervescence the suspension was stirred for 1 h at
0
ꢁC under argon. A solution of 6c (2.08 g, 7.60 mmol) in dry THF
(30 mL) was added dropwise. The mixture was stirred at 0 ꢁC for
additional 12 h and then quenched with HoAc. All solvents were
then removed under reduced pressure. The remaining solid was
dissolved in DCM, washed with distilled H2O, and dried over
MgSO4. Evaporation of the solvent under vacuum, the crude
product was purified by column chromatography with dichloro-
methane/hexane (1/1 v/v) as eluant to yield the desired product 7
as a wine-colored powder (0.564 g, 20%). IR (KBr, cmꢀ1): 1581,1500,
4.6.4. Synthesis of 2,4-bis(5-(bromomethyl)thiophen-2-yl)-6-chloro-
1,3,5-triazine (3b). Compound 3b was prepared as light yellow solid
(5.9 g, 82% yield) from 2b by using the method established for 3a. IR
(KBr, cmꢀ1): 1645, 1512, 1455, 1264, 1208, 802; 1H NMR (500 MHz,
CDCl3):
d
8.10 (d, J¼4.0 Hz, 2H), 7.22 (d, J¼4.0 Hz, 2H), 4.75 (s, 4H).
FABMS (m/z): 462.82 (Mþ). Anal. Calcd for C13H8Br2ClN3S2: C, 33.53;
H, 1.73; N, 9.02. Found: C, 33.38; H, 1.75; N, 8.96.
1436, 1277, 758, 694; 1H NMR (500 MHz, CDCl3):
d
8.20 (d, J¼4.0 Hz,
4.6.5. Synthesis of Horner reagent 4a. Triethyl phosphate (16.6 g,
100 mmol) was added to a stirred solution of 3a (4.51 g, 10 mmol) in
anhydrous DCM (50 mL), followed by Lewis acid as a catalyst. The
resulting mixture was stirred at reflux for 12 h. After being cooled to rt,
water (50 mL) was added. The mixture was extracted with DCM. The
organic fractionwaswashed with brine, dried with anhydroussodium
sulfate, and evaporated. The residue was purified by column chro-
matography (hexane/EA 1:1) to afford 4a (5.1 g, 90%) as a light yellow
solid. IR (KBr, cmꢀ1): 2975, 1613, 1537, 1372, 1245, 1024, 967, 821; 1H
2H), 7.36 (d, J¼8.0 Hz, 4H), 7.31e7.34 (m, 12H), 7.22 (d, J¼16.0 Hz,
2H), 7.13e7.17 (m, 12H), 7.03 (d, J¼8.0 Hz, 4H). FABMS (m/z): 817.2
(Mþ). Anal. Calcd for C51H36ClN5S2: C, 74.84; H, 4.43; N, 8.56. Found:
C, 74.76; H, 4.33; N, 8.39.
4.6.10. Synthesis of 4-(4,6-bis(5-(4-(diphenylamino)styryl)thiophen-
2-yl)-1,3,5-triazin-2-yl)benzaldehyde (8). 4-Formylphenylboronic
acid (0.112 g, 0.75 mmol), potassium carbonate (0.207 g, 1.5 mmol),
and H2O (10 mL) were added sequentially to a stirred solution of
compound 7 (0.408 g, 0.5 mmol) in 1,4-dioxane (40 mL), followed
by PddppfCl2 (0.04 g, 0.05 mmol). The resulting mixture was stirred
at 90 ꢁC under argon atmosphere for 5 h. The solvent was evapo-
rated under reduced pressure. The residue was treated with water
(30 mL), extracted twice with DCM (40 mLꢂ3). The organic layer
was combined and washed twice with water and once with brine,
dried over anhydrous sodium sulfate. After removing the solvent
under reduced pressure, the residue was loaded onto silica gel
column with PE/EA (10:1, v/v) as eluent to give desired aldehyde as
a red solid (0.32 g, 72%). IR (KBr, cmꢀ1): 1696, 1588, 1505, 1436,
NMR (500 MHz, CDCl3):
d
8.56 (d, J¼7.5 Hz, 4H), 7.48 (d, J¼7.5 Hz, 4H),
4.75 (q, J¼6.5 Hz, 8H), 3.29 (s, 2H), 3.26 (s, 2H), 1.28 (t, J¼6.5 Hz,12H).
FABMS (m/z): 567.15 (Mþ). Anal. Calcd for C25H32ClN3O6P2: C, 52.87; H,
5.68; N, 7.40. Found: C, 52.81; H, 5.61; N, 7.28.
4.6.6. Synthesis of Horner reagent 4b. Compound 4b was prepared
as light yellow solid (5.3 g, 91% yield) from 3b by using the method
established for 4a. IR (KBr, cmꢀ1): 2982, 1645, 1537, 1455, 1271,
1030, 802; 1H NMR (500 MHz, CDCl3):
d
8.11 (d, J¼4.0 Hz, 2H), 7.11
(d, J¼4.0 Hz, 2H), 4.13 (q, J¼7.0 Hz, 8H), 3.46 (s, 2H), 3.41 (s, 2H),1.33
(t, J¼7.0 Hz, 12H). FABMS (m/z): 579.06 (Mþ). Anal. Calcd for
C21H28ClN3O6P2S2: C, 43.49; H, 4.87; N, 7.24. Found: C, 43.36; H,
4.81; N, 7.18.
1277, 758, 701; 1H NMR (500 MHz, CDCl3):
d 10.14 (s, 1H), 8.80
(d, J¼8.5 Hz, 2H), 8.20 (d, J¼3.5 Hz, 2H), 8.04 (d, J¼8.5 Hz, 2H), 7.40
(d, J¼8.5 Hz, 4H), 7.31e7.34 (m, 12H), 7.22 (d, J¼16.0 Hz, 2H),
7.13e7.17 (m, 12H), 7.06 (d, J¼8.5 Hz, 4H). FABMS (m/z): 887.3 (Mþ).
Anal. Calcd for C58H41N5OS2: C, 78.44; H, 4.65; N, 7.89. Found: C,
78.31; H, 4.58; N, 7.83.
4.6.7. Synthesis of 5-(4-(diphenylamino)phenyl)thiophene-2-
carbaldehyde (6a). Water of 30 mL was added to a suspension of
compound 5a (2.40 g, 17.11 mmol), 4-bromotriphenylamine (4.62 g,
14.26 mmol), and potassium carbonate (5.9 g, 42.78 mmol) in 1,4-
dioxane (120 mL), followed by adding of PddppfCl2 (0.82 g,
1 mmol). The resulting mixture was stirred at 105 ꢁC under argon
atmosphere for 5 h. The solvent was evaporated under reduced
pressure. The residuewastreated with water (50 mL), extracted twice
with DCM (80 mLꢂ3). The organic layer was combined and washed
twice with water and once with brine, dried over anhydrous sodium
sulfate. After removing the solvent under reduced pressure, the res-
idue was purified by flash chromatography on silica gel column with
PE/EA (10/1, v/v) as eluent to give a yellow solid (3.63 g, 75%). IR (KBr,
cmꢀ1): 1670, 1588, 1486, 1448, 1284, 1227, 1055, 815, 745, 694; 1H
4.6.11. Synthesis of ethyl 4-(4,6-bis(5-methylthiophen-2-yl)-1,3,5-
triazin-2-yl)benzoate (9). Water of 10 mL was added to a suspen-
sion of compound 2b (0.634 g, 2.05 mmol), 4-(ethoxycarbonyl)
phenylboronic acid (0.49 g, 2.46 mmol), and potassium
carbonate(0.85 g, 7.15 mmol) in 1,4-dioxane (40 mL), followed by
PddppfCl2 (0.23 g, 0.2 mmol). The resulting mixture was stirred at
90 ꢁC under argon atmosphere for 8 h. The solvent was evaporated
under reduced pressure. The residue was treated with water
(40 mL), extracted twice with DCM (40 mLꢂ3). The organic layer
was combined and washed twice with water and once with brine,
dried over anhydrous sodium sulfate. After removing the solvent
under reduced pressure, the residue was purified by column
chromatography (hexane/EA 10:1) to afford 9 as a yellow solid
(0.69 g, 79%). IR (KBr, cmꢀ1): 1721, 1581, 1512, 1461, 1366, 1277, 770;
NMR (500 MHz, CDCl3):
d
9.86 (s, 1H), 7.73 (d, J¼4.5 Hz, 1H), 7.54
(d, J¼9.0 Hz, 2H), 7.30e7.34 (m, 5H), 7.15e7.17 (m, 4H), 7.08e7.12
(m, 4H). FABMS(m/z):355.1 (Mþ). Anal. Calcd forC23H17NOS: C, 77.72;
H, 4.82; N, 3.94. Found: C, 77.59; H, 4.72; N, 3.77.
1H NMR (500 MHz, CDCl3):
d
8.70 (d, J¼8.5 Hz, 2H), 8.21
(d, J¼8.5 Hz, 2H), 8.15 (d, J¼3.5 Hz, 2H), 6.92 (d, J¼3.5 Hz, 2H), 4.46
(q, J¼7.0 Hz, 2H), 2.63 (s, 6H), 1.46 (t, J¼7.0 Hz, 3H). FABMS (m/z):
421.1 (Mþ). Anal. Calcd for C22H19N3O2S2: C, 62.68; H, 4.54; N, 9.97.
Found: C, 62.56; H, 4.48; N, 9.81.
4.6.8. Synthesis of 5-(4-(diphenylamino)phenyl)furan-2-
carbaldehyde (6b). Compound 6b was prepared as light yellow
solid (5.4 g, 65% yield) from 5b by using the method established for
6a. IR (KBr, cmꢀ1): 1670, 1594, 1480, 1328, 1277, 1024, 751, 701; 1H
NMR (500 MHz, CDCl3):
d
9.66 (s, 1H), 7.69 (d, J¼4.5 Hz, 2H),
4.6.12. Synthesis of diethyl 5-(4,6-bis(5-methylthiophen-2-yl)-1,3,5-
triazin-2-yl)benzene-1,3-dioate (10). Water of 15 mL was added to
7.31e7.34 (m, 5H), 7.13e7.17 (m, 4H), 7.09e7.12 (m, 4H), 6.73 (d,
J¼3.5 Hz, 1H). FABMS (m/z): 339.1 (Mþ). Anal. Calcd for C23H17NO2:
C, 81.40; H, 5.05; N, 4.13. Found: C, 81.29; H, 5.02; N, 4.05.
a
suspension of compound 2b (1.29 g, 4.17 mmol), 3,5-
di(ethoxycarbonyl)phenylboronic acid (1.36 g, 5.01 mmol), and
potassium carbonate (1.8 g, 13.04 mmol) in 1,4-dioxane (60 mL),
followed by PddppfCl2 (0.34 g, 0.3 mmol). The resulting mixture
was stirred at 90 ꢁC under argon atmosphere for 12 h. The solvent
was evaporated under reduced pressure. The residue was treated
4.6.9. Synthesis of N-(4-((1E)-2-(5-(4-(5-(4-(diphenylamino)styryl)
thiophen-2-yl)-6-chloro-1,3,5-triazin-2-yl)thiophen-2-yl)vinyl)phe-
nyl)-N-phenylbenzenamine (7). t-BuOK (0.774 g, 6.91 mmol) was

198
J. Liu et al. / Tetrahedron 69 (2013) 190e200
with water (60 mL), extracted twice with DCM (50 mLꢂ3). The
organic layer was combined and washed twice with water and once
with brine, dried over anhydrous sodium sulfate. After removing
the solvent under reduced pressure, the residue was purified by
column chromatography (hexane/EA 10:1) to afford 10 as a yellow
solid (1.3 g, 63%). IR (KBr, cmꢀ1): 1734, 1601, 1518, 1461, 1360, 1284,
with EtOH. All solvents were then removed under reduced pres-
sure. The residue was purified by column chromatography with
DCM/MeOH (30:1 v/v) as eluant to yield the desired product as
a wine-colored solid (0.247 g, 52%). IR (KBr, cmꢀ1): 3432,1645,1581,
1544, 1500, 745, 691; 1H NMR (500 MHz, DMSO-d6):
d 12.86 (brs,
1H), 8.45 (d, J¼6.0 Hz, 4H), 7.80 (d, J¼6.0 Hz, 4H), 7.62 (d, J¼8.0 Hz,
4H), 7.35e7.40 (m, 12H), 7.31 (d, J¼15 Hz, 2H), 7.13 (d, J¼15 Hz, 2H),
7.05e7.11 (m, 12H), 7.02 (d, J¼8.0 Hz, 4H). ESI (m/z): 950.3 (Mꢀꢀ1).
Anal. Calcd for C63H45N5OS2: C, 79.47; H, 4.76; N, 7.35. Found: C,
79.34; H, 4.68; N, 7.28.
1233, 1030, 758; 1H NMR (500 MHz, CDCl3):
d 9.42 (s, 2H), 8.80
(s, 1H), 8.17 (d, J¼3.5 Hz, 2H), 6.91 (d, J¼3.5 Hz, 2H), 4.52
(q, J¼7.0 Hz, 4H), 2.62 (s, 6H), 1.51 (t, J¼7.0 Hz, 6H). FABMS (m/z):
493.1 (Mþ). Anal. Calcd for C25H23N3O4S2: C, 60.83; H, 4.70; N, 8.51.
Found: C, 60.66; H, 4.58; N, 8.40.
4.6.18. Synthesis of TCT-8. TCT-8 was prepared as a wine-colored
solid (0.912 g, 55% yield) from 4a and 6b by using the method
established for TCT-7. IR (KBr, cmꢀ1): 3445, 2913, 1664, 1584, 1544,
4.6.13. Synthesis of compound 11. N-Bromosuccinimide (NBS)
(0.59 g, 3.3 mmol) was added to a stirred solution of compound 9
(0.634 g, 1.5 mmol) in CCl4 (30 mL). The mixture was heated under
reflux. AIBN was added in catalytic amounts over a period of 1 h.
After being cooled to room temperature, the mixture was filtered,
and the solid residue was washed with DCM (2ꢂ30 mL). The sol-
vent was evaporated under reduced pressure. The residue was
purified by flash chromatograph on silica gel (hexane/EA 10:1) to
afford 11 (0.69 g, 80%) as a yellow solid. IR (KBr, cmꢀ1): 1721, 1581,
1486,1366, 751, 701; 1H NMR (500 MHz, DMSO-d6):
d 13.09 (brs,1H),
8.55 (d, J¼6.5 Hz, 4H), 7.80 (d, J¼6.5 Hz, 4H), 7.73 (d, J¼8.5 Hz, 4H),
7.33e7.37 (m, 12H), 7.18 (d, J¼15 Hz, 2H), 7.10 (d, J¼15 Hz, 2H),
7.05e7.08 (m, 8H), 7.02 (d, J¼8.5 Hz, 4H), 6.94 (d, J¼3 Hz, 2H), 6.76
(d, J¼3 Hz, 2H). ESI (m/z): 918.3 (Mꢀꢀ1). Anal. Calcd for C63H45N5O3:
C, 82.24; H, 4.93; N, 7.61. Found: C, 82.13; H, 4.86; N, 7.48.
1518, 1271, 770; 1H NMR (500 MHz, CDCl3):
d
8.69 (d, J¼8.5 Hz, 2H),
4.6.19. Synthesis of TCT-9. TCT-9 was prepared as a yellow solid
(0.756 g, 53% yield) from 4a and 6c by using the method established
for TCT-7. IR (KBr, cmꢀ1): 3439,1677,1581,1537,1500,1290, 751, 694;
8.21 (d, J¼8.5 Hz, 2H), 8.15 (d, J¼3.5 Hz, 2H), 7.23 (d, J¼3.5 Hz, 2H),
4.79 (s, 4H), 4.46 (q, J¼7.5 Hz, 2H), 1.46 (t, J¼7.5 Hz, 3H). FABMS
(m/z): 576.91 (Mþ). Anal. Calcd for C22H17Br2N3O2S2: C, 45.61; H,
2.96; N, 7.25. Found: C, 45.46; H, 2.90; N, 7.11.
1H NMR (500 MHz, DMSO-d6):
d
12.92(brs,1H), 8.44 (d, J¼8.0 Hz, 4H),
7.78 (d, J¼8.0 Hz, 4H), 7.57 (d, J¼8.5 Hz, 4H), 7.43 (d, J¼16 Hz, 2H),
7.33e7.36 (m, 8H), 7.10 (d, J¼16 Hz, 2H), 7.06e7.11 (m, 12H), 6.97
(d, J¼8.5 Hz, 4H). ESI (m/z): 786.3 (Mꢀꢀ1). Anal. Calcd for C55H41N5O:
C, 83.84; H, 5.24; N, 8.89. Found: C, 83.70; H, 5.30; N, 8.81.
4.6.14. Synthesis of compound 12. Compound 12 was prepared as
light yellow solid (0.813 g, 83% yield) from 10 by using the method
established for 11. IR (KBr, cmꢀ1): 1721, 1518, 1468, 1239, 1018, 802,
758; 1H NMR (500 MHz, CDCl3):
d
9.41 (s, 2H), 8.89 (s, 1H), 8.18
4.6.20. Synthesis of TCT-10. TCT-10 was prepared as a red solid
(1.0 g, 58% yield) from 4b and 6a by using the method established
for TCT-7. IR (KBr, cmꢀ1): 3432, 1664, 1581, 1537, 1493, 1423, 1271,
(d, J¼3.5 Hz, 2H), 7.24 (d, J¼3.5 Hz, 2H), 4.79 (s, 4H), 4.52
(q, J¼7.0 Hz, 4H), 1.52 (t, J¼7.0 Hz, 6H). FABMS (m/z): 648.9 (Mþ).
Anal. Calcd for C25H21Br2N3O4S2: C, 46.10; H, 3.25; N, 6.45. Found: C,
46.02; H, 3.14; N, 6.41.
795, 694; 1H NMR (500 MHz, DMSO-d6):
d 12.69 (brs, 1H), 8.01 (d,
J¼3.5 Hz, 2H), 7.62 (d, J¼8.5 Hz, 4H), 7.33e7.37 (m, 12H), 7.22 (d,
J¼16.0 Hz, 2H), 7.12 (d, J¼16.0 Hz, 2H), 7.05e7.08 (m, 14H), 7.00 (d,
J¼8.5 Hz, 4H). ESI (m/z): 962.2 (Mꢀꢀ1). Anal. Calcd for
C59H41N5OS4: C, 73.49; H, 4.29; N, 7.26. Found: C, 73.32; H, 4.21; N,
7.17.
4.6.15. Synthesis of compound 13. Triethyl phosphate (1.66 g,
10 mmol) was added to a stirred solution of 11 (0.577 g, 1 mmol) in
anhydrous DCM (30 mL), followed by Lewis acid as a catalyst. The
resulting mixture was stirred at reflux for 12 h. The solvent was
evaporated under reduced pressure. The residue was purified by
column chromatography (DCM/MeOH 20:1) to afford 13 (0.48 g,
90%) as a light yellow solid. IR (KBr, cmꢀ1): 2982, 1714, 1518, 1461,
4.6.21. Synthesis of TCT-11. TCT-11 was prepared as a red solid
(0.957 g, 57% yield) from 4b and 6b by using the method estab-
lished for TCT-7. IR (KBr, cmꢀ1): 3445, 1664, 1581, 1486, 1423, 1271,
1277, 1018, 770; 1H NMR (500 MHz, CDCl3):
d
8.43 (d, J¼8.5 Hz, 2H),
745, 688; 1H NMR (500 MHz, DMSO-d6):
d 12.69 (brs, 1H), 8.06
8.06 (d, J¼8.5 Hz, 2H), 7.89 (d, J¼3.0 Hz, 2H), 7.11 (d, J¼3.0 Hz, 2H),
4.43 (q, J¼7.0 Hz, 2H), 4.33 (q, J¼7.0 Hz, 8H), 3.56 (s, 2H), 3.51
(s, 2H), 1.47 (t, J¼7.0 Hz, 3H), 1.38 (t, J¼7.0 Hz, 12H). FABMS (m/z):
693.15 (Mþ). Anal. Calcd for C30H37N3O8P2S2: C, 51.94; H, 5.38; N,
6.06. Found: C, 51.81; H, 5.22; N, 5.92.
(d, J¼3.0 Hz, 2H), 7.69 (d, J¼8.5 Hz, 4H), 7.33e7.37 (m, 10H), 7.25
(d, J¼15.5 Hz, 2H), 7.08 (d, J¼15.5 Hz, 2H), 7.05e7.08 (m, 12H), 7.00
(d, J¼8.5 Hz, 4H), 6.91 (d, J¼3.0 Hz, 2H), 6.76 (d, J¼3.0 Hz, 2H). ESI
(m/z): 930.3 (Mꢀꢀ1). Anal. Calcd for C59H41N5O3S2: C, 76.02; H,
4.43; N, 7.51. Found: C, 75.94; H, 4.26; N, 7.48.
4.6.16. Synthesis of compound 14. Compound 14 was prepared as
light yellow solid (1.38 g, 93% yield) from 12 by using the method
established for 13. IR (KBr, cmꢀ1): 2982, 1727, 1518, 1455, 1239,
4.6.22. Synthesis of TCT-12. TCT-12 was prepared as a yellow solid
(0.737 g, 51% yield) from 4b and 6c by using the method established
for TCT-7. IR (KBr, cmꢀ1): 3445, 1657, 1588, 1493, 1448, 1271, 751,
1030, 758; 1H NMR (500 MHz, CDCl3):
d
9.13 (s, 2H), 8.69 (s, 1H),
688; 1H NMR (500 MHz, DMSO-d6):
d 11.89 (brs, 1H), 8.13
7.95 (d, J¼2.5 Hz, 2H), 7.17 (d, J¼2.5 Hz, 2H), 4.48 (q, J¼7.5 Hz, 4H),
4.33 (q, J¼7.0 Hz, 8H), 3.15 (s, 2H), 3.01 (s, 2H), 1.50 (t, J¼7.5 Hz, 6H),
1.38 (t, J¼7.0 Hz, 12H). FABMS (m/z): 765.2 (Mþ). Anal. Calcd for
C33H41N3O10P2S2: C, 51.76; H, 5.40; N, 5.49. Found: C, 51.71; H, 5.24;
N, 5.32.
(d, J¼3.0 Hz, 2H), 7.54 (d, J¼8.5 Hz, 4H), 7.33e7.37 (m, 12H), 7.19
(d, J¼16.0 Hz, 2H), 7.10 (d, J¼16.0 Hz, 2H), 7.05e7.08 (m,10H), 6.89 (d,
J¼8.5 Hz, 4H). ESI (m/z): 798.2 (Mꢀꢀ1). Anal. Calcd for C51H37N5OS2:
C, 76.57; H, 4.66; N, 8.75. Found: C, 76.42; H, 4.56; N, 8.64.
4.6.23. Synthesis of TCT-13. A mixture of the above aldehyde 8
(0.230 g, 0.26 mmol), cyanoacetic acid (0.085 g, 1 mmol), ammo-
nium acetate (0.077g, 1 mmol), DCM (10 mL), and acetic acid
(20 mL) was stirred at reflux for 12 h. The solvent was evaporated
under reduced pressure. The residue was treated with 50 mL of
water. The precipitate was collected by filtration and washed with
ethanol to afford the desired product TCT-13 as yellow solid
4.6.17. Synthesis of TCT-7. NaH (0.06 g, 1.5 mmol, 60% suspension
in oil) was added to a solution of 4a (0.282 g, 0.5 mmol) in dry THF
(50 mL) at 0 ꢁC. After initial effervescence the suspension was
stirred for 1 h at room temperature under argon. A solution of 6a
(0.373 g, 1.05 mmol) in dry THF (20 mL) was added dropwise. The
mixture was heated to 50 ꢁC for 4 h and then cooled and quenched

J. Liu et al. / Tetrahedron 69 (2013) 190e200
199
(0.171 g, 69%). IR (KBr, cmꢀ1): 3413, 1682, 1594, 1493, 1436, 1277,
815, 701; 1H NMR (500 MHz, DMSO-d6):
13.41 (brs, 1H), 8.71
(d, J¼9.0 Hz, 2H), 8.36 (s, 1H), 8.11e8.18 (m, 4H), 7.38 (d, J¼7.5 Hz,
4H), 7.25e7.31 (m, 12H), 7.12 (d, J¼16.0 Hz, 2H), 7.08 (d, J¼16.0 Hz,
2H), 6.97e7.06 (m, 14H). ESI (m/z): 953.3 (Mꢀꢀ1). Anal. Calcd for
C61H42N6O2S2: C, 76.71; H, 4.43; N, 8.80. Found: C, 76.59; H, 4.41;
N, 8.68.
1H NMR (500 MHz, DMSO-d6):
d
13.51 (brs, 2H), 9.18 (s, 2H), 8.67
d
(s, 1H), 8.13 (d, J¼3.0 Hz, 2H), 7.51 (d, J¼8.0 Hz, 4H), 7.38e7.42 (m,
12H), 7.17 (d, J¼16.0 Hz, 2H), 7.05e7.09 (m, 12H), 6.85 (d, J¼8.0 Hz,
4H). ESI (m/z): 946.3 (Mꢀꢀ1). Anal. Calcd for C59H41N5O4S2: C,
74.74; H, 4.36; N, 7.39. Found: C, 74.57; H, 4.25; N, 7.31.
Acknowledgements
4.6.24. Synthesis of TCT-14. NaH (5 equiv, 60% suspension in oil)
was added to a solution of WittigeHorner reagent 13 (0.16 g,
0.299 mmol) in THF at 0 ꢁC. After initial effervescence the sus-
pension was stirred for 1 h at room temperature the corresponding
aldehyde 6a (0.235 g, 0.658 mmol) was added. The mixture was
heated to 50 ꢁC for 12 h and then cooled and quenched with EtOH.
All solvents were then removed under reduced pressure. The
remaining solid was washed with ethanol, then purified by column
chromatography with DCM/MeOH (10:1 v/v) as eluant to yield the
desired product TCT-14 as red solid (0.22 g, 69%). IR (KBr, cmꢀ1):
3425, 1685, 1594, 1500, 1423, 1366, 694; 1H NMR (500 MHz, DMSO-
This work was supported by the National Basic Research
Program of China (2011CB933303, and 2011CB808704), the
National Natural Science Foundation of China (21021062, 91022031
and 21001063), and the funding from Academician Workstation in
Changzhou Trina Solar Energy Co. Ltd., Jiangsu Province.
References and notes
1. Hagberg, D. P.; Jiang, X.; Gabrielsson, E.; Linder, M.; Marinado, T.; Brinck, T.;
Hagfeldt, A.; Sun, L. J. Mater. Chem. 2009, 19, 7232.
€
2. O’Regan, B.; Gratzel, M. Nature 1991, 353, 737.
3. (a) Nazeeruddin, M. K.; Kay, A.; Rodicio, I.; Humphry-Baker, R.; Muller, E.; Liska, P.;
d6):
d
8.60 (d, J¼8.0 Hz, 2H), 8.23 (d, J¼3.5 Hz, 2H), 8.14 (d, J¼8.0 Hz,
€
Vlachopoulos, N.; Gratzel, M. J. Am. Chem. Soc. 1993, 115, 6382; (b) Nazeeruddin,
ꢀ
2H), 7.55 (d, J¼8.5 Hz, 4H), 7.37 (d, J¼16.0 Hz, 2H), 7.33e7.37 (m,
12H), 7.22 (d, J¼16.0 Hz, 2H), 7.05e7.08 (m, 14H), 6.94 (d, J¼8.5 Hz,
4H). ESI (m/z): 1066.3 (Mꢀꢀ1). Anal. Calcd for C66H45N5O2S4: C,
74.20; H, 4.25; N, 6.56. Found: C, 74.03; H, 4.16; N, 6.39.
M. K.; Pechy, P.; Renouard, T.; Zakeeruddin, S. M.; Humphry-Baker, R.; Liska, P.;
€
Cevey, L.; Costa, E.; Shklover, V.; Spiccia, L.; Deacon, G. B.; Bignozzi, C. A.; Gratzel,
M. J. Am. Chem. Soc. 2001, 123, 1613; (c) Nazeeruddin, M. K.; Zakeeruddin, S. M.;
Humphry-Baker, R.; Jirousek, M.; Liska, P.; Vlachopoulos, N.; Shklover, V.; Fisher,
€
C. H.; Gratzel, M. Inorg. Chem. 1999, 38, 6298.
4. (a) Horiuchi, T.; Miura, H.; Sumioka, K.; Uchida, S. J. Am. Chem. Soc. 2004, 126,
12218; (b) Hagberg, D. P.; Edvinsson, T.; Marinado, T.; Boschloo, G.; Hagfeldt, A.;
Sun, L. Chem. Commun. 2006, 2245; (c) Kim, S.; Lee, J. W.; Kang, S. O.; Ko, J.;
4.6.25. Synthesis of TCT-15. TCT-15 was prepared as a red solid
(0.256 g, 67% yield) from 13 and 6b by using the method estab-
lished for TCT-14. IR (KBr, cmꢀ1): 3432, 1687, 1588, 1500, 1429, 1271,
€
Yum, J.-H.; Fantacci, S.; De Angellis, F.; Di Censo, D.; Nazeeruddin, M. K.; Gratzel,
M. J. Am. Chem. Soc. 2006, 128, 16701; (d) Wang, Z.-S.; Cui, Y.; Hara, K.; Dan-oh,
Y.; Kasada, C.; Shinpo, A. Adv. Mater. 2007, 19, 1138; (e) Wang, Z.-S.; Koumura,
N.; Cui, Y.; Takahashi, M.; Sekiguchi, H.; Mori, A.; Kubo, T.; Furube, A.; Hara, K.
Chem. Mater. 2008, 20, 3993; (f) Qin, H.; Wenger, S.; Xu, M.; Gao, F.; Jing, X.;
701; 1H NMR (500 MHz, DMSO-d6):
d
8.50 (d, J¼8.5 Hz, 2H), 8.26
(d, J¼3.0 Hz, 2H), 8.03 (d, J¼8.5 Hz, 2H), 7.74 (d, J¼8.5 Hz, 4H),
7.33e7.37 (m, 12H), 7.18 (d, J¼16.0 Hz, 2H), 7.05e7.08 (m, 12H), 6.96
(d, J¼8.5 Hz, 4H), 6.91 (d, J¼3.0 Hz, 2H), 6.80 (d, J¼3.0 Hz, 2H). ESI
(m/z): 1034.3 (Mꢀꢀ1). Anal. Calcd for C66H45N5O4S2: C, 76.50; H,
4.38; N, 6.76. Found: C, 76.41; H, 4.26; N, 6.63.
€
Wang, P.; Zakeeruddin, S. M.; Gratzel, M. J. Am. Chem. Soc. 2008, 130, 9202; (g)
Wang, Z.-S.; Cui, Y.; Dan-oh, Y.; Kasada, C.; Shinpo, A.; Hara, K. J. Phys. Chem. C
2008, 112, 17011; (h) Ito, S.; Miura, H.; Uchida, S.; Takata, M.; Sumioka, K.; Liska,
ꢀ
€
P.; Comte, P.; Pechy, P.; Gratzel, M. Chem. Commun. 2008, 5194; (i) Ning, Z.-J.; Fu,
Y.; Tian, H. Energy Environ. Sci. 2010, 3, 1170; (j) Tang, J.; Hua, J.-L.; Wu, W.-J.; Li,
J.; Jin, Z.-G.; Long, Y.-T.; Tian, H. Energy Environ. Sci. 2010, 3, 1736; (k) He, J.-X.;
Wu, W.-J.; Hua, J.-L.; Jiang, Y.-H.; Qu, S.-Y.; Li, J.; Long, Y.-T.; Tian, H. J. Mater.
Chem. 2011, 21, 6054; (l) Numata, Y.; Islam, A.; Shirai, Y.; Han, L. Y. Chem.
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X.-Y.; Zhang, L.; Long, Y.-T.; Tian, H. J. Mater. Chem. 2011, 21, 10666; (n) Zhu,
W.-H.; Wu, Y.-Z.; Wang, S.-T.; Li, W.-Q.; Li, X.; Chen, J.; Wang, Z.-S.; Tian, H. Adv.
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4.6.26. Synthesis of TCT-16. TCT-16 was prepared as a yellow solid
(0.205 g, 71% yield) from 13 and 6c by using the method established
for TCT-14. IR (KBr, cmꢀ1): 3432,1689,1594,1500,1436,1277, 701; 1H
NMR (500 MHz, DMSO-d6):
d
8.60 (d, J¼8.0 Hz, 2H), 8.23 (d, J¼3.5 Hz,
2H), 8.13 (d, J¼8.0 Hz, 2H), 7.55 (d, J¼8.0 Hz, 4H), 7.33e7.37 (m, 10H),
7.22 (d, J¼16.0 Hz, 2H), 7.05e7.08 (m, 14H), 6.95 (d, J¼8.0 Hz, 4H). ESI
(m/z): 902.3 (Mꢀꢀ1). Anal. Calcd for C58H41N5O2S2: C, 77.05; H, 4.57;
N, 7.75. Found: C, 77.01; H, 4.38; N, 7.73.
5. Yella, A.; Lee, H. S.; Tsao, H. N.; Yi, C.-Y.; Chandiran, A. K.; Nazeeruddin, M.
€
K.; Diau, E. W.-G.; Yeh, C.-Y.; Zakeeruddin, S. M.; Gratzel, M. Science 2011,
334, 629.
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4.6.27. Synthesis of TCT-17. TCT-17 was prepared as a red solid
(0.324 g, 65% yield) from 14 and 6a by using the method established
for TCT-14. IR (KBr, cmꢀ1): 3432,1696,1594,1500,1423,1277, 694; 1H
NMR (500 MHz, DMSO-d6):
d
9.14 (s, 2H), 8.74 (s,1H), 8.19 (d, J¼3.5 Hz,
2H), 7.56 (d, J¼8.5 Hz, 4H), 7.44 (d, J¼15.5 Hz, 2H), 7.33e7.37 (m,14H),
7.18 (d, J¼15.5 Hz, 2H), 7.05e7.08 (m, 12H), 6.96 (d, J¼8.5 Hz, 4H). ESI
(m/z): 1110.2 (Mꢀꢀ1). Anal. Calcd for C67H45N5O4S4: C, 72.34; H, 4.08;
N, 6.30. Found: C, 72.29; H, 3.95; N, 6.18.
4.6.28. Synthesis of TCT-18. TCT-18 was prepared as a wine-colored
solid (0.182 g, 75% yield) from 14 and 6b by using the method
established for TCT-14. IR (KBr, cmꢀ1): 3425, 1702, 1594, 1505, 1429,
1284, 694; 1H NMR (500 MHz, DMSO-d6):
d 9.18 (s, 2H), 8.72 (s, 1H),
12. Rajeshwaran, G. G.; Nandakumar, M.; Sureshbabu, R.; Mohanakrishnan, A. K.
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8.20 (d, J¼3.0 Hz, 2H), 7.70 (d, J¼8.0 Hz, 4H), 7.38e7.42 (m, 10H),
7.34 (d, J¼16.0 Hz, 2H), 7.15 (d, J¼16.0 Hz, 2H), 7.05e7.09 (m, 12H),
7.01 (d, J¼8.0 Hz, 4H), 6.92 (d, J¼3.0 Hz, 2H), 6.78 (d, J¼3.0 Hz, 2H).
ESI (m/z): 1078.3 (Mꢀꢀ1). Anal. Calcd for C67H45N5O6S2: C, 74.49; H,
4.20; N, 6.48. Found: C, 74.29; H, 4.03; N, 6.29.
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(0.350 g, 75% yield) from 14 and 6c by using the method established
for TCT-14. IR (KBr, cmꢀ1): 3432, 1696, 1588, 1505, 1429, 1271, 701;

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