Synthesis and photophysical properties of novel 4-aryl substituted thiophen derivatives with a vinyl-quinoline unit

Article abstract of DOI:10.3184/174751913X13726023145369

(E)-2-[2-(4-bromothiophen-2-yl)vinyl]quinoline was prepared through an acid catalysed condensation of 2-methylquinoline and 4-bromothiophene-2- carbaldehyde. Subsequent palladium-catalysed cross-coupling with various arylboronic acids gave a series of novel fluorescent thiophene and quinoline derivatives. The structures of the products were characterised using IR, ¹H NMR, ¹³C NMR, and elemental analysis. The UV-Vis absorption and photoluminescence spectra of these derivatives were investigated.

Full text of DOI:10.3184/174751913X13726023145369

JOURNAL OF CHEMICAL RESEARCH 2013
RESEARCH PAPER 441
JULY, 441–443
Synthesis and photophysical properties of novel 4-aryl substituted
thiophen derivatives with a vinyl-quinoline unit
Zhaozhe Xua, Dian Yub and Mingxin Yua*
aDepartment of Chemistry, Zhejiang University, Hangzhou 310027, P. R. China
bDepartment of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, 310027, P. R. China
(E)-2-[2-(4-bromothiophen-2-yl)vinyl]quinoline was prepared through an acid catalysed condensation of 2-meth-
ylquinoline and 4-bromothiophene-2-carbaldehyde. Subsequent palladium-catalysed cross-coupling with various
arylboronic acids gave a series of novel fluorescent thiophene and quinoline derivatives. The structures of the
products were characterised using IR, 1H NMR, 13C NMR, and elemental analysis. The UV-Vis absorption and photo-
luminescence spectra of these derivatives were investigated.
Keywords: thiophene, arylboronic acid, benzyl cyanide, quinoline derivatives, photophysical properties
Since the 1990s, motivated by the promise of the use in flat
panel displays,1 there has been increasing interest and research
activity in the field of organic light emitting materials.1–4
Enormous progress has been made in the improvements of
colour gamut, luminance efficiency and device reliability, as
well as the performance and durability of blue, green, red, and
white OLEDs for display and lighting.2,4
Among the various types of OLED materials, thiophene-
based materials have shown improved optical performance,5–8
due to their outstanding chemical and physical properties.
Furthermore, thiophene chemistry is extensively developed
which makes enormous structural variation possible.5,9 Mean-
while, quinoline derivatives are also well-known fluorescent
compounds which exhibit excellent intense emission of high
quantum yield.10–12
Experimental
Pd(PPh3)4, 2-methylquinoline, 4-bromothiophene-2-carbaldehyde,
arylboronic acids, Na2CO3 and 1,2-dimethoxyethane were purchased
from Aldrich Chemical Co. Sodium tert-butoxide was purchased from
Alfa-Aesar and stored in a glove box. All chemicals were used as
supplied.
All melting points were determined with a WRS-1A melting point
apparatus and were uncorrected. 1H NMR and 13C NMR spectra
were run in CDCl3 on a Bruker Avance III 400 NMR spectrometer. IR
spectra were recorded in KBr on a Nicolet NEXUS 470 FTIR spectro-
photometer. Elemental analyses were performed using aVario MICRO
cube. UV–Vis spectra were taken using a Hitachi U-3300 model,
while a Hitachi F-4500 fluorescence spectrophotometer was used to
obtain the PL spectra.
(E)-2-[2-(4-Bromothiophen-2-yl)vinyl]quinoline (1): A solution of
2-methylquinoline (0.143g, 1.00 mmol), 4-bromothiophene-2-carbal-
dehyde (0.191 g, 1.00 mmol), in acetic anhydride (2 mL) was stirred
for 18h at 150 °C in a 25 mL round bottom flask. The mixture was
then poured as a hot stream into 10% NaOH solution while stirring.
The mixture was cooled to room temperature, and filtered. The brown
precipitate was washed with water to pH = 7. The crude product was
purified by column chromatography on silica gel using ethyl acetate–
petroleum ether (b.p. 60–90 °C) (1:5) as eluent to give a pale yellow
solid.Yield: 60%; m.p. 188 °C. IR (KBr, νmax/cm−1): 3096, 3062, 3031,
Results and discussion
Because of the excellent optical properties of quinoline
derivatives, and based on our continuing studies on organic
light-emitting device materials,12–16 we became interested in
the synthesis of new functionalised quinoline derivatives for
potential applications in organic light-emitting devices. We
now report the synthesis and photophysical properties of novel
quinoline derivatives. The structures of these compounds were
characterised by IR, 1H and 13C NMR, and by elemental analy-
sis. The UV-Vis absorption and photoluminescence spectra of
the new compounds in CH2Cl2 were investigated.
4-Bromothiophene-2-carbaldehyde is cheap, easy to obtain
and highly reactive. Compound 1 was a new conjugated thio-
phene and quinoline derivative. (E)-2-[2-(4-bromothiophen-2-
yl)vinyl]quinoline (1) was prepared through an acid catalysed
condensation of 2-methylquinoline and 4-bromothiophene-2-
carbaldehyde. Subsequent palladium-catalysed cross-coupling
with various arylboronic acids gave compounds 2a–g. Com-
pound 2g was then condensed with 2-(3,4-dimethoxyphenyl)
acetonitrile which gave compound 3. The reaction sequence is
presented in Scheme 1.
In order to investigate their photophysical properties, the
UV-Vis (Fig. 1) and PL spectra (Fig. 2) of 2a–f and 3 in dilute
dichloromethane solution were recorded.All of the compounds
displayed two absorptions peaks at 273–293, 364–373 nm.
The εmax values and fluorescence quantum yields of the
compounds are shown in Table 1.
The emission peaks of all these compounds were located at
420–457 nm (see Table 1). The emission peak of 2f was red
shifted by 16 nm compared to 2d. In order to investigate the
introduction of an arylacrylonitrile group, we compared the
emission peak of 2a and 3. There was a significant 28 nm red
shift, as a result of the extension of the conjugated chain.
1
2840, 1595, 1506, 1426, 955, 826. H NMR (400 MHz, CDCl3) δH
8.11 (1H, d, J = 8.8 Hz, ArH), 8.06 (1H, d, J = 8.4 Hz, ArH), 7.77 (1H,
d, J = 6.4 Hz, ArH), 7.74 (1H, d, J = 15.6 Hz, =CH–), 7.72–7.68 (1H,
m, ArH), 7.54 (1H, d, J = 8.8 Hz, ArH), 7.51–7.48 (1H, m, ArH), 7.18
(1H, d, J = 16.0 Hz, –CH=), 7.16 (1H, s, ArH), 7.12 (1H, s, ArH). 13
C
NMR (100 MHz, CDCl3) δc 155.87, 148.22, 142.94, 136.53, 129.93,
129.79, 129.29, 129.19, 127.54, 127.44, 126.40, 125.96, 122.87,
119.54, 119.53. Anal. Calcd for C21H15NS: C, 56.97; H, 3.19; N, 4.43.
Found: C, 56.98; H, 3.23; N, 4.40%.
Synthesis of compounds (2a–g); general procedure
Compound 1 (0.315 g, 1.00 mmol), an aromatic boronic acid
(1.10 mmol), Pd(PPh3)4 (0.012 g, 0.01 mmol) and sodium carbonate
(0.233 g, 2.20 mmol) was added to a 50 mL sidearm flask. The flask
was evacuated and back-filled with nitrogen; this process was repeated
three times. EtOH (3.0 mL), 1,2-dimethoxyethane (7.5 mL), H2O
(2.0 mL) were injected into the flask from a syringe. The reaction
mixture was heated and stirred at 85 °C under nitrogen for 8h until the
reaction was completed. The reaction mixture was then cooled to
room temperature, filtered through a pad of celite and silica gel and
washed with dichloromethane. The filtrate was washed with water and
then dried with MgSO4. Concentration of the filtrate on a rotary evap-
orator followed by washing of the solid material with ethanol afforded
the desired crude product. The crude product was purified by column
chromatography on silica gel using dichloromethane-petroleum ether
(b.p. 60–90 °C)-ethyl acetate (1:2:0.2) as eluent.
(E)-2-[2-(4-Phenylthiophen-2-yl)vinyl]quinoline (2a): Yellow
solid.Yield: 81%, m.p. 198 °C. IR (KBr, νmax/cm−1): 3102, 3059, 3033,
1
2843, 1596, 1504, 1426, 958, 829. H NMR (400 MHz, CDCl3) δH
8.12 (1H, d, J = 8.4 Hz, ArH), 8.07 (1H, d, J = 8.4 Hz, ArH), 7.87 (1H,
d, J = 16.0 Hz, =CH–), 7.78 (1H, d, J = 8.0 Hz, ArH), 7.73–7.68 (1H,
m, ArH), 7.60 (3H, d, J = 8.4 Hz, ArH), 7.51–7.47 (2H, m, ArH),
7.44–7.40 (3H, m, ArH), 7.33–7.30 (1H, m, ArH), 7.24 (1H, d,
* Correspondent. E-mail: mingxinyu@zju.edu.cn

442 JOURNAL OF CHEMICAL RESEARCH 2013
Scheme 1
Table 1 Photophysical properties of compounds (2a–f) and
(3)a
Entry CH2Cl2
λabs /nm λem/nm
CH2Cl2 Stokes shifts εa /mol L–1 cm–1 Φf /%b
/nm
2a
2b
2c
2d
2e
2f
273, 367
275, 368
276, 367
277, 364
274, 368
293, 369
293, 373
429
435
428
420
435
436
457
62
67
61
56
67
67
84
25941, 13111 10.3
30105, 15987 15.0
34262, 14459
33355, 15266
21874, 10671
30809, 17605
6.1
4.3
5.6
8.1
3
28606, 51491 18.2
a Extinction coefficients determined in CH2Cl2 solutions when
the concentration of each compound is 1.0 ×10–5 M.
b Relative quantum yields [with 9,10-bis(phenylethynyl)anthrac
ene in cyclohexane Φf = 0.95 as a standard].
J = 16.0 Hz, –CH=). 13C NMR (100 MHz, CDCl3) δc 155.42, 148.27,
142.96, 142.70, 136.44, 135.47, 129.85, 129.13, 128.88, 128.46,
127.52, 127.41, 127.35, 127.31, 127.07, 126.29, 126.20, 120.91,
119.45. Anal. Calcd for C21H15NS: C, 80.48; H, 4.82; N, 4.47. Found:
C, 80.30; H, 5.12; N, 4.45%.
Fig. 1 UV-Vis spectra of compounds 2a–f, 3 in CH2Cl2.
(E)-2-{2-[4-(p-Tolyl)thiophen-2-yl]vinyl}quinoline (2b): Yellow
solid. Yield: 83%; m.p. 172 °C. FTIR (KBr pellet, cm−1): 3099,
1
3058, 2918, 1610, 1594, 1504, 1428, 1184, 956, 819, 756. H NMR
(400 MHz, CDCl3) δH 8.12 (1H, d, J = 8.0 Hz, ArH), 8.07 (1H, d,
J = 8.4 mHz, ArH), 7.86 (1H, d, J = 16.0 Hz, =CH–), 7.78 (1H, d, J =
8.0 Hz, ArH), 7.73–7.69 (1H, m, ArH), 7.59 (1H, d, J = 8.8 Hz, ArH),
7.53–7.48 (3H, m, ArH), 7.46 (1H, s, ArH), 7.37–7.42 (3H, m, ArH),
7.23 (1H, d, J = 16.4Hz, –CH=). 13C NMR (100 MHz, CDCl3)
δc 155.25, 148.15, 142.98, 141.65, 133.90, 136.51, 133.19, 129.91,
129.05, 129.01, 128.60, 127.52, 127.48, 127.35, 127.14, 126.69,
126.28, 121.12, 119.44. Anal. Calcd for C21H14ClNS: C, 72.51; H,
4.06; N, 4.03. Found: C, 72.60; H, 4.36; N, 4.03%.
(400 MHz, CDCl3) δH 8.12 (1H, d, J = 8.4 Hz, ArH), 8.09 (1H, d,
J = 8.4 Hz, ArH), 7.87 (1H, d, J = 16.4 Hz, =CH–), 7.77 (1H, d, J =
8.0 Hz, ArH), 7.72–7.69 (1H, m, ArH), 7.59 (1H, d, J = 8.8 Hz, ArH),
7.51–7.47 (4H, m, ArH), 7.36 (s, 1H), 7.27 (1H, d, J = 16.0 Hz,
–CH=). 7.24 (1H, d, J = 10.8 Hz, ArH), 7.21 (1H, s, ArH), 2.38 (3H,
s, –CH3). 13C NMR (100 MHz, CDCl3) δc 155.33, 147.86, 142.94,
142.44, 137.20, 136.68, 132.62, 130.00, 129.56, 128.83, 127.87,
127.76, 127.53, 127.29, 127.24, 126.27, 126.14, 120.53, 119.37,
21.17. Anal. Calcd for C22H17NS: C, 80.70; H, 5.23; N, 4.28. Found:
C, 80.76; H, 5.41; N, 4.26%.
(E)-2-{2-[4-(4-(Trifluoromethyl)phenyl)thiophen-2-yl]vinyl}quino-
line (2d): Pale yellow solid. Yield: 79%, m.p. 202–203 °C. IR (KBr,
νmax/cm−1):3102, 3057, 3036, 2923, 1614, 1501, 1334, 1111, 1072,
(E)-2-{2-[4-(4-Chlorophenyl)thiophen-2-yl]vinyl}quinoline (2c):
Yellow solid. Yield: 87%, m.p. 174 °C. IR (KBr, νmax/cm−1): 3076,
3021, 3000, 1595, 1505, 1496, 1430, 1096, 948, 819. 1H NMR
1
829. H NMR (400 MHz, CDCl3) δH 8.14 (1H, d, J = 8.4 Hz, ArH),
8.08 (1H, d, J = 8.4 Hz, ArH), 7.88 (1H, d, J = 16.0 Hz, =CH–), 7.79

JOURNAL OF CHEMICAL RESEARCH 2013 443
J = 8.4 Hz, ArH), 7.93 (2H, d, J = 8.4 Hz, ArH), 7.88 (1H, d, J =
16.0 Hz, =CH–), 7.80–7.70 (4H, m, ArH), 7.60 (1H, d, J = 8.4 Hz,
ArH), 7.56–7.49 (3H, m, ArH), 7.26 (1H, d, J = 16.4 Hz, –CH=). 13
C
NMR (100 MHz, CDCl3) δc 191.82, 155.27, 148.40, 143.51, 141.52,
141.16, 136.62, 135.25, 130.60, 130.05, 129.29, 129.23, 127.69,
127.52, 126.91, 126.74, 126.66, 126.46, 123.02, 119.61. Anal. Calcd
for C22H15NOS: C, 77.39; H, 4.43; N, 4.10. Found: C, 77.44; H, 4.65;
N, 4.08%.
(Z)-2-(3,4-Dimethoxyphenyl)-3-{4-[5-((E)-2-(quinolin-2-yl)vinyl]-
thiophen-3-yl}phenyl}acrylonitrile (3): A solution of compound 2g
(0.341 g, 1 mmol), 2-(3,4-dimethoxyphenyl)acetonitrile (0.214g,
1.20 mmol) and sodium methoxide (0.54 mg, 0.01 mmol) in EtOH
(10 mL) was stirred for 4–8h at 60°C in a 25 mL round bottom flask
and then filtered. The precipitate was washed with water to pH = 7,
and then recrystallised to give the product as a yellow solid. Yield:
92%, m.p. 191–192 °C. IR (KBr, νmax/cm−1): 3078, 3003, 2932, 2837,
2209, 1595, 1519, 1504, 1464, 1271, 1252, 1171, 1141, 1020, 825. 1H
NMR (400 MHz, CDCl3) δH 8.14–8.03 (2H, m, ArH), 7.92 (2H, d,
J = 8.8 Hz, ArH), 7.88 (1H, d, J = 16.4 Hz, =CH–), 7.78 (1H, d,
J = 8.0 Hz, ArH), 7.71–7.66 (3H, m, ArH), 7.60 (1H, d, J = 8.4 Hz,
ArH), 7.54–7.48 (3H, m, ArH, Ar–CH=C–CN), 7.42 (1H, s, ArH),
7.28–7.23 (2H, m, ArH, –CH=), 7.16 (1H, s, ArH), 6.92 (1H, d, J =
8.8 Hz, ArH), 3.97 (3H, s, –OCH3), 3.93 (3H, s, –OCH3). 13C NMR
(100 MHz, CDCl3) δc 155.21, 150.14, 149.36, 143.08, 141.84, 139.70,
136.95, 136.60, 132.86, 130.44, 129.97, 129.78, 129.02, 128.63,
127.55, 127.41, 127.38, 127.25, 126.67, 126.53, 126.33, 121.98,
119.46, 119.07, 118.31, 111.37, 111.01, 108.85, 56.11, 56.08. Anal.
Calcd for C32H24N2O2S: C, 76.77; H, 4.83; N, 5.60. Found: C, 76.70;
H, 4.97; N, 5.54%.
Fig. 2 Photoluminescence spectra of compounds 2a–f, 3 in
CH2Cl2.
(1H, d, J = 8.0 Hz, ArH), 7.72–7.65 (5H, m, ArH), 7.60 (1H, d, J =
8.4 Hz, ArH), 7.52–7.49 (3H, m, ArH), 7.26 (1H, d, J = 16.0 Hz,
–CH=). 13C NMR (100 MHz, CDCl3) δc 155.21, 143.31, 141.42,
138.78, 136.52, 131.28, 129.92, 129.17, 127.56, 127.41, 126.61,
126.45, 126.36, 126.33, 125.95, 125.91, 125.87, 124.89, 122.23,
119.49. Anal. Calcd for C22H14F3NS: C, 69.28; H, 3.70; N, 3.67.
Found: C, 69.42; H, 4.01; N, 3.71%.
The project is sponsored by the Natural Science Foundation
(N20120500) for the Education Ministry of Zhejiang Province.
(E)-2-{2-[4-(3,5-Dimethylphenyl)thiophen-2-yl]vinyl}quinoline
(2e):Yellow solid.Yield: 91%, m.p. 116 °C. IR (KBr, νmax/cm−1): 3105,
3027, 2915, 2855, 2724, 1596, 1503, 1428, 951, 830. 1H NMR
(400 MHz, CDCl3) δH 8.08–8.05 (2H, m, ArH), 7.83 (1H, d, J =
16.0 Hz, =CH–), 7.74 (1H, d, J = 8.0 Hz, ArH), 7.70–7.66 (1H, m,
ArH), 7.55 (1H, d, J = 8.4 Hz, ArH), 7.48–7.45 (2H, m, ArH), 7.34
Received 25 March 2013; accepted 6 May 2013
Paper 1301858 doi: 10.3184/174751913X13726023145369
Published online: 18 July 2013
References
1
2
L.S. Hung and C.H. Chen, Mater. Sci. Eng. Rev., 2002, 39, 143.
A.P. Kulkarni, C.J. Tonzola, A. Babel and S.A. Jenekhe, Chem. Mater.,
2004, 16, 4556.
(1H, s, ArH), 7.26–7.19 (4H, m, ArH, –CH=), 2.36 (6H, s, –CH3). 13
C
NMR (100 MHz, CDCl3) δc 155.45, 148.27, 143.12, 142.42, 138.32,
136.32, 135.33, 129.76, 129.12, 129.05, 128.31, 127.49, 127.31,
127.29, 127.21, 126.11, 124.18, 120.69, 119.37, 21.38. Anal. Calcd
for C23H19NS: C, 80.90; H, 5.61; N, 4.10. Found: C,80.90; H, 5.77; N,
4.10%.
3
S. Reineke, F. Lindner, G. Schwartz1, N. Seidler, K. Walzer, B. Lussem and
K. Leo, Nature, 2009, 459, 234.
4
5
6
J. Xiao and Z.B. Deng, J. Lumin., 2012, 132, 2863.
A. Mishra, C.Q. Ma and P. Bauerle, Chem. Rev., 2009, 109, 1141.
J. Lu, P.F. Xia, P.K. Lo, Y. Tao and M.S. Wong, Chem. Mater., 2006, 18,
6194.
(E)-2-{2-[4-(Naphthalen-2-yl)thiophen-2-yl]vinyl}quinoline (2f):
Yellow solid. Yield: 87%, m.p. 191 °C. IR (KBr, νmax/cm−1): 3099,
3048, 2923, 1593, 1501, 1426, 950, 826. 1H NMR (400 MHz, CDCl3)
δH 8.13 (1H, d, J = 8.4 Hz, ArH), 8.09 (1H, d, J = 8.0 Hz, ArH), 8.05
(1H, s, ArH), 7.93–7.84 (4H, m, ArH, =CH–), 7.79 (1H, d, J = 8.0 Hz,
ArH), 7.75–7.70 (2H, m, ArH), 7.66 (1H, s, ArH), 7.62 (1H, d, J =
8.8 Hz, ArH), 7.53–7.47 (4H, m, ArH), 7.28 (1H, d, J = 15.6 Hz,
–CH=). 13C NMR (100 MHz, CDCl3) δc 155.35, 148.10, 142.83,
142.78, 136.54, 133.66, 132.73, 132.67, 129.02, 129.92, 128.55,
128.43, 128.08, 127.69, 127.52, 127.42, 127.34, 127.17, 126.45,
126.25, 125.95, 124.73, 127.70, 121.32, 119.42. Anal. Calcd for
C25H17NS: C, 82.61; H, 4.71; N, 3.85. Found: C, 82.70; H, 4.99; N,
3.83%.
7
8
9
J. Khunchalee, R. Tarsang, N. Prachumrak, S. Jungsuttiwong, T. Keawin,
T. Sudyoadsuk and V. Promarak, Tetrahedron, 2012. 68, 8416.
S.I. Panchamukhi, N. Belavagi, M.H. Rabinal and I.A. Khazi. J Fluoresc.,
2011, 21, 1515.
X. Sun, Y. Liu, S. Chen, W. Qiu, G. Yu, Y. Ma, T. Qi, H. Zhang, X. Xu and
D. Zhu, Adv. Funct. Mater., 2006, 16, 917.
10 M. Rahimizadeh, M. Pordel, M. Bakavoli and H. Eshghi. Dyes Pigm.,
2010, 86, 266.
11 E. Gondek, A. Danel, J. Nizio, P. Armatyse, I.V. Kityk, P. Szlachcic,
M. Karelus, T. Uchacz, J. Chwast and G. Lakshminarayana, J. Lumin.,
2010, 130, 2093.
12 Q. Li, B. Li, B. Liu and M.X. Yu, J. Chem. Res., 2010, 34, 379.
13 M.X. Yu, J.P. Duan, C.H. Lin, C.H. Cheng, and Y.T. Tao, Chem. Mater.,
2002, 14, 3958.
14 M.X. Yu, W.J. Wen and C.H. Chen, Chin. J. Org. Chem., 2006, 26, 1239.
15 M.X. Yu, L.C. Chang, C.H. Lin, J.P. Duan, F.I. Wu, I.C. Chen and
C.H. Cheng, Adv. Funct. Mater., 2007, 17, 369.
(E)-4-{5-[2-(Quinolin-2-yl)vinyl]thiophen-3-yl}benzaldehyde (2g):
Pale yellow solid. Yield: 93%, IR (KBr, νmax/cm−1): 3072, 3021, 2825,
1
2738, 1697, 1602, 1174, 948, 817. H NMR (400 MHz, CDCl3) δH
10.03 (1H, s, Ar–CHO), 8.14 (1H, d, J = 8.8 Hz, ArH), 8.08 (1H, d,
16 Z.Z. Xu, D. Yu and M.X. Yu, Dyes Pigm., 2012, 95, 358.

Copyright of Journal of Chemical Research is the property of Science Reviews 2000 Ltd. and
its content may not be copied or emailed to multiple sites or posted to a listserv without the
copyright holder's express written permission. However, users may print, download, or email
articles for individual use.