Synthesis and characterization of potential efficient electroluminescent materials: 2-Phenyl-5-[4-(4-phenylamino-2H-1,2,3-triazol-2-yl)]phenyl-1,3,4- oxadiazole derivatives

Article abstract of DOI:10.1246/bcsj.79.644

Recently, 1,3,4-oxadiazole-based on heterocyclic compounds were investigated as electroluminescent materials. In this work, we first introduce 1,2,3-triazole to synthesize a series of 1,3,4-oxadiazole-1,2,3-triazole hybrids derivatives as potential electr

Full text of DOI:10.1246/bcsj.79.644

644 Bull. Chem. Soc. Jpn. Vol. 79, No. 4, 644–648 (2006)
Ó 2006 The Chemical Society of Japan
Synthesis and Characterization of Potential Efficient
Electroluminescent Materials: 2-Phenyl-5-[4-(4-phenylamino-
2H-1,2,3-triazol-2-yl)]phenyl-1,3,4-oxadiazole Derivatives
ꢀ2
ꢀ1;3
Jia-Xing Zhou,1 Fung Fuh Wong, Chun-Yen Chen,1 and Mou-Yung Yeh
1Department of Chemistry, National Cheng Kung University, No. 1, Ta Hsueh Rd., Tainan 70101, Taiwan
2Sustainable Environment Research Center, National Cheng Kung University,
No. 500, Sec. 3, An-ming Rd., Tainan 709, Taiwan
3Nan Jeon Institute of Technology, No. 178, Chaocin Rd., Yanshuei Township, Tainan 737, Taiwan
Received June 15, 2005; E-mail: wongfungfuh@yahoo.com.tw
Recently, 1,3,4-oxadiazole-based on heterocyclic compounds were investigated as electroluminescent materials. In
this work, we first introduce 1,2,3-triazole to synthesize a series of 1,3,4-oxadiazole–1,2,3-triazole hybrids derivatives as
potential electroluminescent materials and explore the effect of modification of the 1,2,3-triazole moiety. The ꢀmax val-
ues of the UV–vis of 1,3,4-oxadiazole–1,2,3-triazole hybrids are promoted to longer wavelengths (340–350 nm) than the
traditional 1,2,3-triazole derivatives (280–330 nm) in solutions and have a bathochromic shift to 350–360 nm in THF
solution. The ꢀmax values of the photoluminescence (PL) spectra are in the range 406–480 nm in solutions. Compound
7h evaporated to form films on quartz substrates, had a maximum at 455 nm and showed a red-shift (ꢁ40 nm) with
respect to the solution spectrum. The solution fluorescence quantum yields (ꢀf) were measured, all of which fell into
the range 0.65–0.76, and were determined relative to that of 2-phenyl-5-(4-biphenyl)-1,3,4-oxadiazole in benzene
(ꢀf ¼ 0:80). 1,3,4-Oxadiazole–1,2,3-triazole hybrids derivatives show unclearly reversible reduction processes in cyclic
voltammogram measurements. Following spectroscopic studies and observation of the electrochemical behaviors, 1,3,4-
oxadiazole–1,2,3-triazole derivatives were determined to be highly potential efficient blue electroluminescent materials.
1,3,4-Oxadiazole derivatives have been widely exploited as
electron-transporting, hole-blocking (ETHB) materials in elec-
Results and Discussion
troluminescent (EL) devices due to their electron-deficient na-
ture, their high thermal stability and high photoluminescence
quantum yield (PLQL).1,2 1,3,4-Oxadiazole-based heterocyclic
compounds have also been eagerly investigated, for example,
1,3,4-oxadiazole–pyridine hybrids,3 1,3,4-oxadiazole–pyrimi-
dine hybrids,4 1,3,4-oxadiazole–carbazole,5 and 1,3,4-oxadi-
azole–spirobifluorene.6 Since the heterocyclic moieties on the
molecular structure can provide improved hole injection, trans-
port properties, and confer rigidity, we have developed and pre-
pared three types of heteroaromatics electroluminescent mate-
rials: 1,3,4-oxadiazole–triazolopyridinone, 1,3,4-oxadiazole–
pyrazole, and 1,3,4-oxadiazole–pyridine–carbazole deriva-
tives.7 In our previous investigations, most heterocyclic moie-
ties (pyrazole, pyridine, and triazolopyridinone) on a 1,2,3-tri-
azole core exhibited significant a bathochromic shift (red shift)
due to the substitution effect of the conjugation system.
1,2,3-Triazole derivatives possess a multitude of biological
and medicational activities.8 In this paper, we first introduce
1,2,3-triazole to synthesize 1,3,4-oxadiazole–1,2,3-triazole hy-
brid derivatives as potential electroluminescent materials, and
then explore the effect of modification of the 1,2,3-triazole
moiety. Following spectroscopic studies and measurements
of cyclic voltammogram measurements, 1,3,4-oxadiazole–
1,2,3-triazole derivatives were determined to be potential high-
ly efficient blue electroluminescent materials.
Synthesis of 1,3,4-Oxadiazole–1,2,3-Triazole Derivatives
7a–7h.
New potential efficient blue electroluminescent
materials of 1,3,4-oxadiazole–1,2,3-triazole hybrid derivatives
7a–7h were synthesized and their synthetic routes are shown
in Scheme 1. Sydnones have attracted extensive interest for
biological, pharmaceutical, and synthetic applications and for
their photochromic properties.9,10 We have enthusiastically
explored new applications of sydnones in electroluminescent
materials by forming the 1,3,4-oxadiazole hybrid derivatives.
The sydnone compounds 1 were easily converted to the 3-aryl-
4-formylsydnone derivatives 2 in a solution of POCl3 and
DMF by the Schmidt reaction in 52–66% yields.11 Following
the literature procedure,12 3-(4-ethoxycarbonylbenzo)sydnone
was dissolved in solution of EtOAc with a small amount of
HClaq and stirred at room temperature to provide ethyl 4-
hydrazinylbenzoate.
The 3-aryl-4-formylsydnone derivatives 2 were mixed with
ethyl 4-hydrazinylbenzoate and stirred in an EtOH solution to
achieve the elimination and give the corresponding products in
good yields (3a–3d, 80–83%). The acidic decomposition of
compounds 3a–3d was performed in the acidic EtOAc solu-
tion; the sydnone rings rearranged and sequentially underwent
ring opening and decarboxylation to provide the 4-arylamino-
1,2,3-triazoles 4a–4d.10 Treating the 4-arylamino-1,2,3-tri-
azoles 4a–4d with hydrazine monohydrate according to the
Published on the web April 7, 2006; DOI: 10.1246/bcsj.79.644

J.-X. Zhou et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 4 (2006)
645
OHC
N
ethyl 4-hydrazinylbenzoate
hydrochloride
O
O
POCl3
DMF
R1
N
R1
O
O
EtOH
N
N
1a R1 = CH3, 1b R1 = OEt
1c R1 = F, 1b R1 = Br
2a R1 = CH3, 2b R1 = OEt
2c R1 = F, 2b R1 = Br
R1
H
R1
N
N
N
HN
HCl
COOEt
N
COOEt
N
N
EtOAc, 60 °C
N
O
O
H
4a R1 = CH3, 4b R1 = OEt
4c R1 = F, 4d R1 = Br
3a R1 = CH3, 3b R1 = OEt
3c R1 = F, 3d R1 = Br
R2
COCl
R1
N
.
NH2NH2 H2O
N
CONHNH2
R2 = CH3, Cl
pyridine, CH2Cl2
EtOH, reflux
N
N
H
5a R1 = CH3, 5b R1 = OEt
5c R1 = F, 5d R1 = Br
R1
N
N
O
6a R1 = CH3, R2 = CH3, 6b R1 = CH3, R2 = Cl
6c R1 = OEt, R2 = CH3, 6d R1 = OEt, R2 = Cl
6e R1 = F, R2 = CH3, 6f R1 = F, R2 =Cl
N
CONHNH
N
H
6g R1 = Br, R2 = CH3, 6h R1 = Br, R2 = Cl
R2
POCl3 R1
N
N
N
O
7a R1 = CH3, R2 = CH3, 7b R1 = CH3, R2 = Cl
7c R1 = OEt, R2 = CH3, 7d R1 = OEt, R2 = Cl
7e R1 = F, R2 = CH3, 7f R1 = F, R2 =Cl
N
N
N
H
R2 7g R1 = Br, R2 = CH3, 7h R1 = Br, R2 = Cl
Scheme 1.
published reports13 afforded benzohydrazide compounds 5a–
5d in 76–83% yields. Condensation of benzohydrazide com-
pounds with benzoyl chloride yielded the bis(benzohydrazide)
6a–6h. We treated the raw materials 6a–6h directly with
Fig. 1). The solution fluorescence quantum yields (ꢀf) of
7a–7h, all of which fall in the range 0.65–0.76, were deter-
mined relative to that of 2-phenyl-5-(4-biphenyl)-1,3,4-oxa-
diazole in benzene (ꢀf ¼ 0:80).17
14
POCl3 to obtain the cyclized 1,3,4-oxadiazole–1,2,3-triazole
The photoluminescence (PL) spectra of 1,3,4-oxadiazole–
1,2,3-triazole derivatives shown in Table 1 have ꢀmax values
in the range 406–480 nm in CH2Cl2, CHCl3, and THF solu-
tions. Similar bathochromic shifts of the solvent effect (ꢁ20
nm) are also found in the emission spectra in CH2Cl2 and
THF solutions. The substitution effect of 1,2,3-triazole on
the main core is a clear red-shift (ꢁ30{100 nm) with respect
to 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD, 370
nm).15 The compounds of 7c and 7d, including the electron-
donating group (R1 ¼ OEt), exhibit an intense deep-blue fluo-
rescence in CH2Cl2 and THF solutions (ꢀmaxs of PL is 470–
480 nm, Table 1 and Fig. 2). The PL spectrum of 7h of vacu-
um evaporated films on quartz substrates, with a maximum at
455 nm, shows a red-shift (ꢁ40 nm) with respect to the solu-
tion spectrum, as shown in Fig. 3.
hybrid derivatives 7a–7h, which could be purified easily by
column chromatography. Their structures were determined
by high-field NMR spectroscopy and CHN analysis.
Photophysical Properties. The UV–vis spectra of the
1,3,4-oxadiazole–1,2,3-triazole derivatives 7a–7h were mea-
sured in THF, CH2Cl2, and CHCl3 solutions. The ꢀmax values
of 7a–7h are in the range 340–350 nm in CH2Cl2 and CHCl3
solutions and have a bathochromic shift to 350–360 nm in
THF solution (see Table 1). The main absorptions of the low
ꢀ
energy (ꢁ–ꢁ ) transitions of the traditional 1,2,3-triazole de-
rivatives are at 280–330 nm.15 The 1,3,4-oxadiazole–1,2,3-tri-
azole derivatives 7a–7h exhibited significant red shifts due to
the substitution effect of conjugation with the 1,3,4-oxadiazole
moiety.16 The long range of the substitution effects on R1 and
R2 positions are not clearly a function of absorption and the
results are shown in Table 1. The ꢀmax values of 7b and 7d
are approximately at 354–358 nm in THF solution when the
R1-substituted group is CH3 or OEt and R2 is Cl group (see
Cyclic Voltammetry Measurements. The electrochemi-
cal behaviors of the 1,3,4-oxadiazole–1,2,3-triazole derivatives
7a–7h were investigated by cyclic voltammetry in solution.
The measurements were carried out at a platinum electrode

646 Bull. Chem. Soc. Jpn. Vol. 79, No. 4 (2006)
New Electroluminescent of 1,3,4-Oxidiazole–1,2,3-Triazole Hybrids
Table 1. UV–Vis Absorption Maxima and Photoluminescence Peak Wavelength of 1,3,4-Oxadiazole–1,2,3-
Triazole Derivatives 7a–7h
a)
Compound
R1
ꢀ
max/nm of UV–vis
CH2Cl2
ꢀ
max/nm of PL
CH2Cl2
ꢀf
R2
CHCl3
THF
CHCl3
THF
7a
7b
7c
7d
7e
7f
–CH3
–CH3
–OEt
–OEt
–F
–F
–Br
–Br
–CH3
–Cl
–CH3
–Cl
–CH3
–Cl
–CH3
–Cl
348
352
340
344
342
340
346
348
348
352
344
348
344
342
350
348
360
358
358
354
350
348
356
354
432
428
443
453
416
415
406
409
439
443
472
472
423
428
416
420
446
449
473
480
424
738
422
430
0.75
0.72
0.68
0.76
0.69
0.74
0.65
0.68
7g
7h
a) ꢀf: Fluorescence quantum efficiency, relative to 2-phenyl-5-(4-biphenyl)-1,3,4-oxadiazole in benzene
(ꢀf ¼ 0:80).
Table 2. Electrochemical Properties of 1,3,4-Oxadiazole–1,2,3-Triazole Derivatives 7a–7h
d),f)
Eg =
Bandgap
energy/eV
a)
b)
c),f)
e),f)
Eonset
/V
E0onset
/V
Ip
= EHOMO
/eV
Ea
= ELUMO
/eV
Compound
7a
7b
7c
7d
7e
7f
1.21
1.19
1.05
1.15
1.22
1.15
1.35
1.38
1.02
1.00
0.86
0.96
1.03
0.96
1.16
1.19
ꢂ5:63
ꢂ5:61
ꢂ5:47
ꢂ5:57
ꢂ5:64
ꢂ5:57
ꢂ5:77
ꢂ5:80
3.16
3.14
3.13
3.05
3.20
3.20
3.19
3.19
ꢂ2:47
ꢂ2:47
ꢂ2:34
ꢂ2:52
ꢂ2:44
ꢂ2:37
ꢂ2:58
ꢂ2:61
7g
7h
a) Measured vs ferrocene/ferrocenium. b) E0onset ¼ Eonset ꢂ 0:19 eV (measured vs Ag/
AgCl). c) Ip ¼ ꢂðE0onset þ 4:8Þ. d) Eg: the bandgap energy estimated from the onset wave-
length of UV–vis absorption. e) Ea ¼ Ip þ Eg. f) 1 eV = 96.5 kJ molꢂ1
.
Fig. 1. UV–vis spectra of 1,3,4-oxadiazole–1,2,3-triazole
derivatives 7b and 7d in THF solution.
Fig. 2. Normalized photoluminescence spectra of 1,3,4-
oxadiazole–1,2,3-triazole derivatives 7a, 7c, 7e, and 7g.
using a millimolar solution of CH2Cl2 containing 0.1 M of the
supporting electrolyte, tetrabutylammonium hexafluorophos-
phate (TBAPF6), in a three electrode cell and potentiostat as-
sembly.18 The potential was measured against Ag/AgCl as the
reference electrode and each measurement was calibrated with
an internal standard, a ferrocene/ferrocenium (Fc) redox sys-
tem.19 Upon anodic sweep, 7a–7h showed unclearly reversi-
ble reduction processes and the data are tabulated in Table 2.
As an example, the cyclic voltammogram of 7c is shown in
Fig. 4. In the case of 7c, the reversibility of oxidation was es-
timated with the HOMO value of ꢂ5:47 eV with respect to
Ag/AgCl (ꢂ5:66 eV with respect to Fc). The bandgap energies
of the 1,3,4-oxadiazole–1,2,3-triazole derivatives 7a–7h were
estimated from the onset wavelength (ꢀonset) of the UV–vis
absorption.15 From their high electron affinities, 7a–7h have
earned the potential of being electron-transporting and highly
efficient blue electroluminescent materials.
Experimental
Experimental procedure, spectral data, and physical properties
of compounds 3a–3d, 4a–4d, 5a–5d, and 6a–6h are provided in
the supporting information section.

J.-X. Zhou et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 4 (2006)
647
Ar-H), 7.48 (d, J ¼ 8:2 Hz, 2H, Ar-H), 7.73 (s, 1H, CH), 8.02
(d, J ¼ 8:0 Hz, 2H, Ar-H), 8.15 (d, J ¼ 8:6 Hz, 2H, Ar-H), 8.29
(d, J ¼ 8:4 Hz, 2H, Ar-H), 9.27 (s, 1H, NH); 13C NMR (DMSO-
d6, 75 MHz): ꢂ 20.71, 116.30, 117.76, 118.43, 120.63, 122.64,
126.83, 128.86, 129.92, 130.00, 137.17, 139.56, 141.81, 151.23,
162.38, 164.12; IR (KBr) 3301 (br, NH), 1608 (m, C=O), 1565,
1499, 1482, 1432 cmꢂ1; FABMS m=z (relative intensity) 430
(M þ 2, 15), 429 (M þ 1, 33), 428 (Mþ, 23), 155 (19), 154
(100), 138 (33), 137 (66), 136 (98). Anal. Calcd for C23H17Cl-
N6O: C, 64.41; H, 4.00; N, 10.60%. Found: C, 64.40; H, 4.04;
N, 10.63%.
2-{4-[4-(4-Ethoxyphenylamino)-2H-1,2,3-triazol-2-yl]phenyl}-
5-(4-methylphenyl)-1,3,4-oxadiazole (7c). The standard proce-
dure was followed to prepare 7c as a white powder in 83% yield:
mp 179–180 ꢃC; 1H NMR (DMSO-d6, 300 MHz) ꢂ 1.31 (t, J ¼
7:2 Hz, 3H, CH3), 2.48 (s, 3H, CH3), 3.99 (q, J ¼ 7:2 Hz, 2H,
CH2), 6.90 (d, J ¼ 8:8 Hz, 2H, Ar-H), 7.54 (d, J ¼ 9:0 Hz, 4H,
Ar-H), 7.68 (s, 1H, CH), 8.01 (d, J ¼ 8:7 Hz, 2H, Ar-H), 8.10 (d,
J ¼ 8:8 Hz, 2H, Ar-H), 8.24 (d, J ¼ 8:7 Hz, 2H, Ar-H), 9.09 (s,
1H, NH); 13C NMR (DMSO-d6, 75 MHz): ꢂ 15.19, 21.56, 63.59,
115.50, 117.72, 119.78, 120.34, 122.34, 126.32, 127.05, 128.65,
130.39, 137.79, 142.83, 143.18, 151.48, 153.32, 162.38, 164.12;
IR (KBr) 3400 (br, NH), 1613 (m, C=O), 1510 cmꢂ1; FABMS
m=z (relative intensity) 440 (M þ 2, 5), 439 (M þ 1, 19), 438
(Mþ, 24), 155 (19), 154 (23), 138 (8), 137 (14), 136 (23). Anal.
Calcd for C25H22N6O2: C, 68.48; H, 5.06; N, 19.17%. Found: C,
68.44; H, 5.06; N, 19.15%.
Fig. 3. Normalized photoluminescence spectra of 7h (blue
line: diluted in CH2Cl2 solution; red line: vacuum evapo-
rated film).
2-(4-Chlorophenyl)-5-{4-[4-(4-ethoxyphenylamino)-2H-1,2,3-
triazol-2-yl]phenyl}-1,3,4-oxadiazole (7d). The standard proce-
dure was followed to prepare 7d as a white powder in 82% yield:
mp 288–290 ꢃC; 1H NMR (DMSO-d6, 300 MHz) ꢂ 1.30 (t, J ¼ 7:2
Hz, 3H, CH3), 3.97 (q, J ¼ 7:2 Hz, 2H, CH2), 6.91 (d, J ¼ 8:8 Hz,
2H, Ar-H), 7.33 (d, J ¼ 8:8 Hz, 2H, Ar-H), 7.53 (d, J ¼ 9:0 Hz,
2H, Ar-H), 7.65 (s, 1H, CH), 8.04 (d, J ¼ 8:7 Hz, 2H, Ar-H),
8.08 (d, J ¼ 8:8 Hz, 2H, Ar-H), 8.23 (d, J ¼ 8:7 Hz, 2H, Ar-H),
9.10 (s, 1H, NH); 13C NMR (DMSO-d6, 75 MHz): ꢂ 17.35, 62.55,
115.39, 116.93, 117.22, 121.41, 124.63, 125.83, 126.90, 128.52,
129.75, 132.96, 136.29, 142.11, 152.43, 153.78, 163.84, 164.42;
IR (KBr) 3407 (br, NH), 1593 (m, C=O), 1426 cmꢂ1; FABMS m=z
(relative intensity) 460 (M þ 2, 6), 459 (M þ 1, 5), 458 (Mþ, 3),
155 (19), 154 (79), 138 (37), 137 (56), 136 (100). Anal. Calcd
for C24H19ClN6O2: C, 62.82; H, 4.17; N, 18.31%. Found: C,
62.91; H, 4.23; N, 18.29%.
2-{4-[4-(4-Fluorophenylamino)-2H-1,2,3-triazol-2-yl]phenyl}-
5-(4-methylphenyl)-1,3,4-oxadiazole (7e). The standard proce-
dure was followed to prepare 7e as a white powder in 82% yield:
mp 252–254 ꢃC; 1H NMR (DMSO-d6, 300 MHz) ꢂ 2.23 (s, 3H,
CH3), 7.25 (d, J ¼ 8:8 Hz, 2H, Ar-H), 7.49 (d, J ¼ 8:7 Hz, 2H, Ar-
H), 7.58 (d, J ¼ 8:4 Hz, 2H, Ar-H), 7.66 (s, 1H, CH), 8.07 (d,
J ¼ 8:2 Hz, 2H, Ar-H), 8.15 (d, J ¼ 8:2 Hz, 2H, Ar-H), 8.30 (d,
J ¼ 8:4 Hz, 2H, Ar-H), 9.42 (s, 1H, NH); 13C NMR (DMSO-d6,
75 MHz): ꢂ 116.25, 117.62, 118.39, 121.10, 122.18, 126.23,
127.36, 128.34, 129.33, 132.49, 133.28, 141.55, 142.93, 151.53,
164.09, 164.78; IR (KBr) 3309 (br, NH), 1606 (m, C=O), 1573,
1507, 1455 cmꢂ1; FABMS m=z (relative intensity) 414 (M þ 2,
22), 413 (M þ 1, 44), 412 (Mþ, 37), 155 (22), 154 (100), 138 (47),
137 (58), 136 (44). Anal. Calcd for C23H17FN6O: C, 66.98; H,
4.15; N, 20.38%. Found: C, 66.97; H, 4.17; N, 20.39%.
Fig. 4. Cyclic voltammogram of 7c in CH2Cl2 containing
0.1 M TBAPF6 at a scan rate of 50 mV sꢂ1
.
Standard Procedure of Dehydration–Cyclization (7a–7h).10
A solution of 4-[4-(4-substituted phenylamino)-2H-1,2,3-triazol-
2-yl]-N2-(4-substituted benzoyl)benzohydrazides (6a–6h, ꢁ230
mg) in POCl3 (10 mL) was stirred at 90 ꢃC for 10 h. After the re-
action was completed, cold water (10 mL) was added to the reac-
tion mixture, and the mixture was neutralized with a NaOH aque-
ous solution (10 mL) to precipitate the reaction product. The prod-
uct was washed with cold water (5 mL), filtrated and dried in a
vacuum oven overnight to give the desired product (7a–7h).
2-(4-Methylphenyl)-5-{4-[4-(4-methylphenylamino)-2H-1,2,3-
triazol-2-yl]phenyl}-1,3,4-oxadiazole (7a). The standard proce-
dure was followed to prepare 7a as a white powder in 85% yield:
mp 231–233 ꢃC; 1H NMR (DMSO-d6, 300 MHz) ꢂ 2.24 (s, 3H,
CH3), 2.41 (s, 3H, CH3), 7.12 (d, J ¼ 8:8 Hz, 2H, Ar-H), 7.40 (d,
J ¼ 8:8 Hz, 2H, Ar-H), 7.44 (d, J ¼ 8:0 Hz, 2H, Ar-H), 7.73 (s,
1H, CH), 8.02 (d, J ¼ 8:0 Hz, 2H, Ar-H), 8.12 (d, J ¼ 8:8 Hz, 2H,
Ar-H), 8.26 (d, J ¼ 8:8 Hz, 2H, Ar-H), 9.22 (s, 1H, NH); 13C NMR
(DMSO-d6, 75 MHz): ꢂ 116.55, 117.16, 118.73, 119.93, 121.64,
125.94, 127.37, 129.23, 132.13, 134.45, 138.16, 142.11, 152.47,
163.78, 164.12; IR (KBr) 3300 (br, NH), 1612 (m, C=O), 1567,
1494, 1432 cmꢂ1; FABMS m=z (relative intensity) 410 (M þ 2,
10), 409 (M þ 1, 64), 408 (Mþ, 48), 155 (19), 154 (94), 138 (33),
137 (51), 136 (100). Anal. Calcd for C24H20N6O: C, 70.57; H,
4.94; N, 20.57%. Found: C, 70.51; H, 4.99; N, 20.55%.
2-(4-Chlorophenyl)-5-{4-[4-(4-methylphenylamino)-2H-1,2,3-
triazol-2-yl]phenyl}-1,3,4-oxadiazole (7b). The standard proce-
dure was followed to prepare 7b as a white powder in 83% yield:
mp 229–231 ꢃC; 1H NMR (DMSO-d6, 300 MHz) ꢂ 2.25 (s, 3H,
CH3), 7.18 (d, J ¼ 8:4 Hz, 2H, Ar-H), 7.42 (d, J ¼ 8:6 Hz, 2H,
2-(4-Chlorophenyl)-5-{4-[4-(4-fluorophenylamino)-2H-1,2,3-
triazol-2-yl]phenyl}-1,3,4-oxadiazole (7f). The standard proce-
dure was followed to prepare 7f as a white powder in 88% yield:
mp 265–267 ꢃC; 1H NMR (DMSO-d6, 300 MHz) ꢂ 7.27 (d, J ¼

648 Bull. Chem. Soc. Jpn. Vol. 79, No. 4 (2006)
New Electroluminescent of 1,3,4-Oxidiazole–1,2,3-Triazole Hybrids
8:4 Hz, 2H, Ar-H), 7.47 (d, J ¼ 8:4 Hz, 2H, Ar-H), 7.72 (s, 1H,
CH), 7.99 (d, J ¼ 8:4 Hz, 2H, Ar-H), 8.08 (d, J ¼ 8:4 Hz, 2H,
Ar-H), 8.14 (d, J ¼ 8:2 Hz, 2H, Ar-H), 8.27 (d, J ¼ 8:2 Hz, 2H,
Ar-H), 9.36 (s, 1H, NH); 13C NMR (DMSO-d6, 75 MHz): ꢂ 115.13,
117.22, 118.19, 121.05, 123.74, 126.78, 127.11, 128.74, 129.85,
132.19, 132.48, 141.35, 141.69, 150.59, 163.99, 164.42; IR
(KBr) 3407 (br, NH), 1593 (m, C=O), 1426 cmꢂ1; FABMS m=z
(relative intensity) 434 (M þ 2, 19), 433 (M þ 1, 40), 432 (Mþ,
28), 155 (20), 154 (81), 138 (40), 137 (69), 136 (100). Anal. Calcd
for C22H14ClFN6O: C, 61.05; H, 3.26; N, 19.42%. Found: C,
61.11; H, 3.26; N, 19.44%.
Supporting Information
Experimental procedures and characterization data for new
compounds. This material is available free of charge on line at
http://www.csj.jp/journals/bcsj/.
References
1
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2-{4-[4-(4-Bromophenylamino)-2H-1,2,3-triazol-2-yl]phenyl}-
5-(4-methylphenyl)-1,3,4-oxadiazole (7g). The standard proce-
dure was followed to prepare 7g as a white powder in 85% yield:
mp 257–259 ꢃC; 1H NMR (DMSO-d6, 300 MHz) ꢂ 2.41 (s, 3H,
CH3), 7.40–7.52 (m, 6H, Ar-H), 7.76 (s, 1H, CH), 8.03 (d, J ¼
8:0 Hz, 2H, Ar-H), 8.14 (d, J ¼ 8:8 Hz, 2H, Ar-H), 8.27 (d, J ¼
8:2 Hz, 2H, Ar-H), 9.60 (s, 1H, NH); 13C NMR (DMSO-d6, 75
MHz): ꢂ 20.75, 117.98, 120.16, 120.66, 121.00, 121.73, 125.67,
127.06, 128.67, 129.32, 132.19, 141.37, 142.66, 144.70, 152.53,
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2-{4-[4-(4-Bromophenylamino)-2H-1,2,3-triazol-2-yl]phenyl}-
5-(4-chlorophenyl)-1,3,4-oxadiazole (7h). The standard proce-
dure was followed to prepare 7h as a white powder in 83% yield:
mp 261–263 ꢃC; 1H NMR (DMSO-d6, 300 MHz) ꢂ 7.46 (d, J ¼ 8:6
Hz, 4H, Ar-H), 7.71 (d, J ¼ 8:6 Hz, 2H, Ar-H), 7.78 (s, 1H, CH),
8.15 (d, J ¼ 8:6 Hz, 4H, Ar-H), 8.28 (d, J ¼ 8:6 Hz, 2H, Ar-H),
9.55 (s, 1H, NH); 13C NMR (DMSO-d6, 75 MHz): ꢂ 115.63,
118.33, 119.09, 120.60, 124.24, 127.07, 127.83, 129.53, 130.17,
131.84, 141.62, 142.73, 143.79, 152.37, 163.44, 164.37; IR (KBr)
3313 (br, NH), 1605 (m, C=O), 1560, 1484 cmꢂ1; FABMS m=z
(relative intensity) 495 (M þ 2, 26), 494 (M þ 1, 24), 493 (Mþ,
21), 155 (26), 154 (100), 138 (33), 137 (63), 136 (75). Anal. Calcd
for C22H14BrClN6O: C, 53.52; H, 2.86; N, 17.02%. Found: C,
53.55; H, 2.86; N, 17.03%.
799.
3
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Conclusion
We were successful in introducing a triazole moiety into the
skeletal structure of 1,3,4-oxadiazole to provide a series of
new potential blue electroluminescent materials. The triazole
moiety plays an excellent role as an asistant in controlling fun-
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We are grateful to the National Science Council of the
Republic of China for financial support.