Synthesis and characterization of new electroluminescent materials of 1,3,4-oxadiazole-1,2,3-triazole hybrids and 1,3,4-oxadiazole-1,2,3-triazole- pyridine derivatives

Article abstract of DOI:10.1002/hc.20210

New electroluminescent materials of 1,3,4-oxadiazole-1,2,3-triazole and 1,3,4-oxadiazole-1,2,3-triazole-pyridine hybrid derivatives were synthesized and characterized. Following spectroscopic studies and characterization of their electronic properties, 1,

Full text of DOI:10.1002/hc.20210

Heteroatom Chemistry
Volume 17, Number 4, 2006
Synthesis and Characterization of New
Electroluminescent Materials of
1,3,4-Oxadiazole–1,2,3-Triazole Hybrids and
1,3,4-Oxadiazole–1,2,3-Triazole–Pyridine
Derivatives
Jia-Xing Zhou,2 Fung Fuh Wong,1 Chun-Yen Chen,2
and Mou-Yung Yeh2,3
1Sustainable Environment Research Center, National Cheng Kung University,
No. 500, Sec. 3, An-ming Road, Tainan City 709, Taiwan
2Department of Chemistry, National Cheng Kung University, No. 1, Ta Hsueh Road,
Tainan 70101, Taiwan
3Nan Jeon Institute of Technology, No. 178, Chaocin Road, Yanshuei Township,
Tainan County 737, Taiwan
Received 12 May 2005; revised 5 September 2005
ABSTRACT: New electroluminescent materials of
1,3,4-oxadiazole–1,2,3-triazole and 1,3,4-oxadiazole–
1,2,3-triazole–pyridine hybrid derivatives were synthe-
sized and characterized. Following spectroscopic stud-
ies and characterization of their electronic proper-
ties, 1,3,4-oxadiazole–1,2,3-triazole hybrids and 1,3,4-
INTRODUCTION
oxadiazole–1,2,3-triazole–pyridine derivatives were
found to be potentially efficient blue electrolumi-
1,3,4-Oxadiazole-based heterocyclic compounds [1]
are the most widely studied classes of electron-
injection and/or hole-blocking materials, mainly
because of their electron deficiency, high-photo-
luminescence quantum yield, and good thermal and
chemical stabilities [2]. We have developed and pre-
pared a series of 1,3,4-oxadiazole-based heterocyclic
hybrid derivatives as organic electroluminescent ma-
terials including 1,3,4-oxadiazole–pyrazole, 1,3,4-
oxadiazole–pyridine–carbazole, 1,3,4-oxadiazole–1,-
2,3-triazole, and 1,3,4-oxadiazole–triazolo-pyridi-
none derivatives [3]. Pyridine is a moderately
electron-deficient ꢀ system, hybrids of pyridine
and 1,3,4-oxadiazole could lead to increased
ꢀ
C
nescent materials.
2006 Wiley Periodicals, Inc. Het-
eroatom Chem 17:322–328, 2006; Published online in
Wiley InterScience (www.interscience.wiley.com). DOI
10.1002/hc.20210
Correspondence to: Fung Fuh Wong; e-mail: wongfungfuh@
yahoo.com.tw.
Contract grant sponsor: National Science Council of Republic
of China.
c
ꢀ
2006 Wiley Periodicals, Inc.
322

Synthesis and Characterization of New Electroluminescent Materials of 1,3,4-Oxadiazole–1,2,3-Triazole Hybrids 323
electron-injection ability [4]. In this paper, we focus
tively [6]. Following the literature procedure [7],
3-(4-ethoxycarbonylbenzoyl)sydnone was dissolved
in a solution of EtOAc with a few drops of HCl(aq)
and stirred at room temperature to provide ethyl
4-hydrazinylbenzoate.
on the synthesis and structure of the 1,2,3-triazole
unit as incorporated into the 1,3,4-oxadiazole and
explore the substituent effects of 2-substituted 1,3,4-
oxadiazole with phenyl or pyridinyl groups. Follow-
ing spectroscopic studies and cyclic voltammogram
measurements, 1,3,4-oxadiazole–1,2,3-triazole hy-
brids and 1,3,4-oxadiazole–1,2,3-triazole–pyridine
derivatives were found to be potentially highly effi-
cient blue electroluminescent materials, and 1,3,4-
oxadiazole–1,2,3-triazole–pyridine has a red-shift
due to the substitution effect of pyridine moiety on
the 2-position of 1,3,4-oxadiazole.
4-Formyl-3-arylsydnone derivatives 2a, 2b were
mixed with ethyl 4-hydrazinylbenzoate and stirred
in the EtOH solution to carry out the imination, giv-
ing the corresponding products in good yields (3a,
3b, 80–83%). Compounds 3a and 3b were performed
the acidic decomposition in the acidic EtOAc so-
lution; the syndnones ring rearranged and the ring
opening and decarboxylation proceeded sequentially
to provide 4-arylamino-1,2,3-triazoles 4a, 4b [5].
Treating 4-arylamino-1,2,3-triazoles 4a, 4b with hy-
drazine monohydrate according to the published re-
ports [8] afforded benzohydrazide compounds 5a
and 5b in 80–83% yields. Condensation of benzo-
hydrazide compounds with benzoyl chloride yielded
the dihydrazide products 6a and 6b. We treated the
raw materials 6a and 6b directly with POCl3 [9] to
obtain the cyclized 1,3,4-oxadiazol–1,2,3-triazole hy-
brids derivatives 7a, 7b, which could be purified eas-
ily by column chromatography. The total synthesis
route is shown in Scheme 1; structures were de-
termined by high-field NMR spectroscopy and CHN
analysis.
RESULTS AND DISCUSSION
New potential efficient blue electroluminescent
materials of 1,3,4-oxadiazole–1,2,3-triazole 7a, 7b
and 1,3,4-oxadiazole–1,2,3-triazole–pyridine hybrid
derivatives 7c, 7d were synthesized and character-
ized for comparison. The sydnone starting materials
1a and 1b were prepared by the published proce-
dure [5]. Sydnone compounds 1a and 1b were conve-
niently converted to 4-formyl-3-arylsydnone deriva-
tives 2a, 2b in a solution of POCl3 and DMF by
the Schmidt reaction in 70 and 60% yields, respec-
SCHEME 1
Heteroatom Chemistry DOI 10.1002/hc

324 Zhou et al.
SCHEME 2
Benzohydrazide compounds 5a and 5b were
treated with isonicotinoyl chloride hydrochloride to
perform the condensation and yield the dihydrazide
products (6c and 6d) in 77–78% yields. Compounds
6c and 6d were directly reacted with POCl3 [10]
to obtain 1,3,4-oxadiazol–1,2,3-triazole–pyridine hy-
brids 7c, 7d, which could be purified by column
chromatography, their structures were determined
by high-field NMR spectroscopy and CHN analysis
(see Scheme 2).
UV–Vis spectra of 1,3,4-oxadiazol–1,2,3-triazole
7a, 7b and 1,3,4-oxadiazol–1,2,3-triazole–pyridine
derivatives 7c, 7d were measured in THF, CH2Cl2,
and CHCl3 solutions. The λmax values of 7a–7d are
in the range 346–362 nm in CH2Cl2 and CHCl3 so-
lutions and have a red-shift to 356–368 nm in THF
solution due to the bathochromic shift in polar sol-
vent effect (see Table 1) [11]. Compounds 7b and 7d
exhibited a blue-shift (6–8 nm) due to the electron-
withdrawing group ( Br) in the para-position on the
N-phenyl group in the conjugation core (see Fig. 1).
Photoluminescence (PL) spectra of 1,3,4-oxadia-
zol derivatives 7a–7d were shown in Table 1 and the
λmax values are in the range 409–469 nm in CH2Cl2,
CHCl3, and THF solutions. Similarly, bathochromic
shifts (∼20 nm) are also found on the emission
spectra in CH2Cl2 and THF solutions. Compounds
7b and 7d including the electron-withdrawing
FIGURE 1 UV–Vis spectra of 1,3,4-oxadiazol–1,2,3-triazole
derivatives with p-bromo-N-phenyl group 7b and 7d in THF
solution.
group (R = Br) exhibit a blue-shift (∼15 nm). The
1,3,4-oxadiazol–1,2,3-triazole–pyridine hybrids 7c,
7d have a red-shift (∼20 nm, see Fig. 2) and 7d
exhibits intense deep-blue fluorescence in THF so-
lution (λmaxs of PL is 469 nm, see Fig. 3). The PL
spectrum 7b and 7d of vacuum-evaporated films on
quartz substrates, with a maximum at 435 and 475
nm, shows a red-shift (∼20–30 nm), with respect to
the solution spectrum as shown in Fig. 4.
The solution fluorescence quantum yields (ꢀf)
of 7a–7d, all of which fall in the range 0.68–0.74,
were determined relative to that of 2-phenyl-5-
(4-biphenyl)-1,3,4-oxadiazole in benzene (ꢀf = 0.80)
TABLE 1 UV–Vis Absorption Maxima and Photoluminescence Peak Wavelength of 1,3,4-Oxadiazol–1,2,3-Triazole Derivatives
7a–7d
λ
max
(nm) of UV−Vis
CH2Cl2
λ
max
(nm) of PL
CH2Cl2
a
ꢀ
f
Compound
R
CHCl3
THF
CHCl3
THF
Benzene
7a
7b
7c
7d
Me
Br
Me
Br
352
346
360
352
356
350
362
356
364
356
368
362
424
409
448
427
441
419
464
440
446
426
469
449
0.74
0.68
0.72
0.69
aꢀf: fluorescence quantum efficiency, relative to 2-phenyl-5-(4-biphenyl)-1,3,4-oxadiazole in benzene (ꢀf = 0.8).
Heteroatom Chemistry DOI 10.1002/hc

Synthesis and Characterization of New Electroluminescent Materials of 1,3,4-Oxadiazole–1,2,3-Triazole Hybrids 325
FIGURE 2 Normalized photoluminescence spectra of 7a
and 7c in THF solution.
FIGURE 4 Normalized photoluminescence spectra of 7b
and 7d in solid state (vacuum-evaporated film on quartz sub-
strate).
FIGURE 3 Normalized photoluminescence spectra of 7b
and 7d in THF solution.
[12]. By comparison with their corresponding spec-
tra in dilute solutions, the emission spectra of films
of 7c and 7d are red-shifted by ∼25 nm due to the
substitution effect of pyridine on the main core of
1,3,4-oxadiazol–1,2,3-triazole–pyridine hybrids.
The electrochemical behavior of 1,3,4-oxadia-
zol–1,2,3-triazole derivatives (7a–7d) was inves-
tigated by cyclic voltammetry in solution. The
measurements were carried out at a platinum
electrode using CH2Cl2 containing 0.1 M of the sup-
porting electrolyte, tetrabutylammonium hexafluo-
rophosphate (TBAPF6), in a three-electrode cell po-
tentiostat assembly. The potential was measured
against Ag/AgCl as a reference electrode and each
measurement was calibrated with an internal stan-
dard, ferrocene/ferrocenium (Fc) redox system [13].
FIGURE 5 Cyclic voltammogram of 7d in CH2Cl2 containing
0.1 M TBAPF6 at a scan rate 50 mV/s.
The data were tabulated in Table 2. Upon the anodic
sweep, 7a–7d showed unclear reversible reduction
processes. The bandgap energies of 1,3,4-oxadiazol–
1,2,3-triazole derivatives (7a–7d) were estimated
from the onset wavelength (λonset) of the UV–Vis ab-
sorption [4]. From the high-electron affinities, 7a–7d
are potentially electron-transporting, highly efficient
blue electroluminescent materials. As an example,
the cyclic voltammogram of 7d is shown in Fig. 4. In
the case of 7d, the oxidation peak was estimated and
the HOMO value is −5.68 eV with respect to Ag/AgCl
(see Fig. 5).
TABLE 2 Electrochemical Properties of 1,3,4-Oxadiazol–1,2,3-Triazole Derivatives 7a–7d
Compound
Eoanset (V)
Eꢁb
(V)
I pc, f = EHOMO (eV)
Egd, f = bandgap energy (eV)
Eae, f = ELUMO (eV)
onset
7a
7b
7c
7d
099
1.10
1.01
1.07
0.80
0.91
0.82
0.88
−5.60
−5.71
−5.62
−5.68
3.17
3.16
3.10
3.12
−2.43
−2.55
−2.52
−2.56
aMeasured vs. ferrocene/ferrocenium.
b Eoꢁnset = Eonset−0.19 eV (measured vs. Ag/AgCl).
c Ip = −(E ꢁonset + 4.8).
d Eg: the bandgap energy estimated from the onset wavelength of UV–Vis absorption.
eEa = Ip + E ꢁ
.
f 1 eV = 96.5 kJ/mol.
Heteroatom Chemistry DOI 10.1002/hc

326 Zhou et al.
CONCLUSION
EtOAc (30 mL) was stirred at 60◦C. After the reaction
was completed, the reaction mixture was concen-
trated and i-PrOH (15 mL) was added. The residues
were concentrated again to remove the water. i-PrOH
(15 mL) and activated carbon (∼0.3 g) were added
to the reaction mixture and stirred at room tem-
perature for 1 h. The reaction mixture was filtered
and cold water was added to precipitate the corre-
sponding product (4a or 4b). The product (4a or 4b)
was dried in a vacuum oven overnight to give the
4-aryamino-1,2,3-triazoles 4a, 4b in 52–64% yields.
We have successfully introduced 1,2,3-triazole
and/or pyridine moieties into the core of 1,3,4-
oxadiazole to provide a series of new potential blue
electroluminescent materials. 1,3,4-Oxadiazole–
1,2,3-triazole and 1,3,4-oxadiazole–1,2,3-triazole–
pyridine hybrids are potentially highly efficient
blue electroluminescent materials, by inducing
1,2,3-triazole and pyridine moieties to play an ex-
cellent assistant role in controlling the fundamental
photolytic process. 1,3,4-Oxadiazole–1,2,3-triazole–
pyridine have a red-shift due to the substituent
effect of the pyridine moiety on the 2-position of
1,3,4-oxadiazole.
Ethyl 4-(4-(p-Tolylamino)-2H-1,2,3-triazol-2-yl)-
benzoate 4a. The standard procedure was followed
to prepare 4a as white powder in 64% yield. 1H NMR
(DMSO-d6, 200 MHz): δ 1.28 (t, J = 7.0 Hz, 3H, CH3),
2.41 (s, 3H, CH3), 4.31 (q, J = 7.0 Hz, 2H, CH2), 7.02
(d, J = 8.6 Hz, 2H, Ar-H), 7.47 (d, J = 8.8 Hz, 2H, Ar-
H), 7.80 (s, 1H, CH), 8.05–8.10 (m, 4H, Ar-H), 9.18
(s, 1H, NH).
EXPERIMENTAL
Standard Procedure for Imination [5]
A solution of 4-formylsydnones (2, 6.0 g, 0.03 mol,
1.0 equiv.) was stirred in EtOH solution at room tem-
perature. Ethyl 4-hydrazinylbenzoate hydrochloride
(7.8 g, 0.035 mol, 1.1 equiv.) was added to the re-
action mixture and stirred at room temperature
for 3 h. After the reaction was completed, the re-
action mixture was filtered and washed with cold
EtOH. The wet cake was dried in a vacuum oven
overnight and crystallized from CH2Cl2 to give 3-
arylsydnonecarbaldehyde-4-aryl 3a, 3b in 80–83%
yields.
Ethyl 4-(4-(4-Bromophenylamino)-2H-1,2,3-tri-
azol-2-yl)benzoate 4b. The standard procedure was
followed to prepare 4b as white powder in 52%
yield. 1H NMR (DMSO-d6, 200 MHz): δ 1.30 (t,
J = 7.0 Hz, 3H, CH3), 4.28 (q, J = 7.0 Hz, 2H, CH2),
7.08 (d, J = 8.6 Hz, 2H, Ar-H), 7.53 (d, J = 8.8 Hz,
2H, Ar-H), 7.72 (s, 1H, CH), 8.04–8.12 (m, 4H, Ar-H),
9.36 (s, 1H, NH).
Standard Procedure for Preparation of
4-Aryamino-1,2,3-triazol-2-yl-benzohydrazides
5a,b [5]
3-(4-Methylphenyl)-formylsydnone-p-ethoxycar-
bonylbenzoyl-hydrazone 3a. The standard proce-
dure was followed to prepare 3a as white powder
1
in 80% yield. H NMR (DMSO-d6, 200 MHz): δ 1.26
A solution of 4-aryamino-1,2,3-triazol-2-yl-benzo-
ates 4a or 4b was stirred in EtOH (25 mL) and ex-
cess amount of hydrazine monohydrate (5.0 mL) so-
lution. The reaction mixture was heated up to reflux.
After the reaction was completed, the reaction mix-
ture was concentrated and cold EtOAc (40 mL) was
added to precipitate the corresponding products 5a
or 5b. The products were filtered, washed, and dried
in a vacuum oven overnight to give 5a and 5b in 72–
75% yields.
(t, J = 7.0 Hz, 3H, CH3), 2.48 (s, 3H, CH3), 4.24 (q,
J = 7.0 Hz, 2H, CH2), 6.70 (d, J = 8.7 Hz, 2H, Ar-H),
7.52 (s, 1H, CH), 7.54 (d, J = 8.7 Hz, 2H, Ar-H),
7.67–7.75 (m, 4H, Ar-H), 10.92 (s, 1H, NH).
3-(4-Bromophenyl)-formylsydnone-p-ethoxycar-
bonylbenzoyl-hydrazone 3b. The standard proce-
dure was followed to prepare 3b as white powder in
83% yield. 1H NMR (DMSO-d6, 200 MHz): δ 1.26 (t,
J = 7.2 Hz, 3H, CH3), 4.20 (q, J = 7.2 Hz, 2H, CH2),
6.59 (d, J = 8.6 Hz, 2H, Ar-H), 7.52 (s, 1H, CH), 7.72
(d, J = 8.6 Hz, 2H, Ar-H), 7.79 (d, J = 8.6 Hz, 2H,
Ar-H), 10.97 (s, 1H, NH).
4-(4-(p-Tolylamino)-2H-1,2,3-triazol-2-yl)benzo-
hydrazide 5a. The standard procedure was followed
to prepare 5a as white powder in 72% yield. 1H
NMR (DMSO-d6, 200 MHz): δ 2.23 (s, 1H, CH3), 4.51
(s, 2H, NH2), 7.11 (d, J = 8.6 Hz, 2H, Ar-H), 7.38 (d,
J = 8.4 Hz, 2H, Ar-H), 7.67 (s, 1H, CH), 7.93–7.97
(m, 4H, Ar-H), 9.15 (s, 1H, NH), 9.82 (s, 1H, NH).
Standard Procedure for Preparation of 4-
Aryamino-1,2,3-triazol-2-yl-benzoates 4a,b [5]
A solution of 3-phenyl-formylsydnone-p-ethoxycar-
bon-ylbenzoyl-hydrazonecompounds (3a or 3b,
3.0 g) and conc. HCl aqueous solution (3.0 mL) in
4-(4-(4-Bromophenylamino)-2H-1,2,3-triazol-2-yl)-
benzohydrazide 5b. The standard procedure was
Heteroatom Chemistry DOI 10.1002/hc

Synthesis and Characterization of New Electroluminescent Materials of 1,3,4-Oxadiazole–1,2,3-Triazole Hybrids 327
followed to prepare 5b as white powder in 71%
yield. H NMR (DMSO-d6, 200 MHz): δ 4.51 (s, 2H,
NH2), 7.45 (d, J = 8.6 Hz, 4H, Ar-H), 7.72 (s, 1H,
CH), 7.45 (d, J = 8.6 Hz, 4H, Ar-H), 9.47 (s, 1H, NH),
9.84 (s, 1H, NH).
J = 8.2 Hz, 2H, Ar-H), 7.94–8.24 (m, 4H, Ar-H, Py-H),
8.79 (d, J = 8.2 Hz, 2H, Py-H), 9.50 (s, 1H, NH), 10.71
(s, 1H, NH), 10.85 (s, 1H, NH).
1
Standard Procedure for Preparation of 1,2,4-
Oxadiazole–1,2,3-Triazole Hybrids 7a–7h [6]
Standard Procedure for Preparation of
4-Aryamino-1,2,3-triazol-2-yl-benzoic Acid
Hydrazides 6a–6d [5]
A solution of 4-aryamino-1,2,3-triazol-2-yl-benzoic
acid hydracids (6a–6h, ∼230 mg) in POCl3 (10 mL)
was stirred at 90◦C for 10 h. After the reaction was
completed, cold water (10 mL) was added to the
reaction mixture and neutralized with NaOH aque-
ous solution (10 mL) to precipitate. The product was
washed with cold water (5 mL), filtered, and dried in
a vacuum oven overnight to give the desired product
(7a–7h).
A solution of 4-aryamino-1,2,3-triazol-2-yl-benzo-
hydrazides (5a or 5b, 3.40 g, 1.0 equiv.) and pyri-
dine (0.5 mL) were stirred in CH2Cl2 (15 mL) for
10 min. Benzoyl chloride or isonicotinoyl chloride
hydrochloride (1.5 equiv.) was added to the reac-
tion mixture and stirred at room temperature for
2–3 h. After the reaction was completed, the reac-
tion mixture was filtered and washed with cold water
(10 mL). The solid was dried in a vacuum oven
overnight to give 6a–6d in 77–84% yields.
2-(4-(5-Phenyl-1,3,4-oxadiazol-2-yl)phenyl)-N-
p-tolyl-2H-1,2,3-triazol-4-amine 7a. The standard
procedure was followed to prepare 7a as white pow-
der in 87% yield; mp 263–265◦C. 1H NMR (DMSO-d6,
300 MHz): δ 2.24 (s, 3H, CH3), 7.14 (t, J = 8.0 Hz,
1H, Ar-H), 7.41 (d, J = 8.2 Hz, 2H, Ar-H), 7.50–7.74
(m, 4H, Ar-H), 7.73 (s, 1H, CH), 8.14 (d, J = 8.2 Hz,
2H, Ar-H), 8.27 (d, J = 8.0 Hz, 2H, Ar-H), 9.25 (s,
1H, NH); 13C NMR (DMSO-d6, 75 MHz): δ 20.72,
116.29, 117.80, 120.80, 123.77, 126.80, 127.10,
128.75, 129.11, 129.86, 129.95, 132.47, 139.57,
141.78, 151.22, 164.02, 164.38; IR (KBr): 3334 (br,
NH), 1611 (m, C O), 1565, 1499, 1432 cm−1; FABMS
m/z (relative intensity): 397 (M + 2, 15), 396 (M + 1,
57), 396 (M+, 41), 155 (19), 155 (30), 154 (100), 138
(41), 137 (79), 136 (76). Anal. Calcd for C23H18N6O:
C, 70.04; H, 4.60; N, 21.31. Found: C, 70.04; H, 4.56;
N, 21.29.
Benzoic Acid N ꢁ-4-(4-p-Tolylamino-1,2,3-triazole-
2-yl)benzoyl Hydrazide 6a. The standard procedure
was followed to prepare 6a as white powder in 81%
1
yield. H NMR (DMSO-d6, 200 MHz): δ 2.42 (s, 3H,
CH3), 7.12 (t, J = 8.2 Hz, 1H, Ar-H), 7.41 (d, J = 8.0
Hz, 2H, Ar-H), 7.50 (d, J = 7.6 Hz, 2H, Ar-H), 7.58
(d, J = 7.4 Hz, 2H, Ar-H), 7.71 (s, 1H, CH), 7.93 (d,
J = 7.6 Hz, 2H, Ar-H), 8.00–8.10 (m, 4H, Ar-H), 9.19
(s, 1H, NH), 10.53 (s, 1H, NH), 10.58 (s, 1H, NH).
Benzoic Acid N ꢁ-4-(4-Bromophenylamino-1,2,3-
triazole-2-yl)benzoyl Hydrazide 6b. The standard
procedure was followed to prepare 6b as white pow-
1
der in 84% yield. H NMR (DMSO-d6, 200 MHz):
δ 7.42–7.56 (m, 9H, Ar-H), 7.76 (s, 1H, Ar-H), 7.93
(d, J = 8.2 Hz, 2H, Ar-H), 8.08 (d, J = 8.2 Hz, 2H, Ar-
H), 9.52 (s, 1H, NH), 10.53 (s, 1H, NH), 10.59 (s, 1H,
NH).
N-(4-Bromophenyl)-2-(4-(5-phenyl-1,3,4-oxadi-
azol-2-yl)phenyl)-2H-1,2,3-triazol-4-amine 7b. The
standard procedure was followed to prepare 7b as
white powder in 86% yield; mp 254–256◦C. 1H NMR
(DMSO-d6, 300 MHz): δ 7.42–7.64 (m, 4H, Ar-H),
7.66–7.78 (m, 3H, Ar-H), 7.79 (s, 1H, CH), 8.15 (d,
J = 8.6 Hz, 2H, Ar-H), 8.29 (d, J = 8.6 Hz, 2H, Ar-H),
9.59 (s, 1H, NH); 13C NMR (DMSO-d6, 75 MHz):
δ 111.44, 117.97, 118.18, 119.60, 123.74, 127.10,
128.73, 129.83, 132.17, 132.47, 141.35, 141.68,
145.32, 153.97, 164.41, 164.87; IR (KBr): 3310 (br,
NH), 1601 (m, C=O), 1558, 1490, 1429 cm−1; FABMS
m/z (relative intensity): 461 (M + 2, 50), 460 (M +
1, 44), 459 (M+, 51), 155 (24), 154 (100), 138 (28),
137 (59), 136 (63). Anal. Calcd for C22H15BrN6O: C,
57.53; H, 3.29; N, 18.30. Found: C, 57.49; H, 3.30; N,
18.33.
Isonicotinic Acid N ꢁ-4-(4-p-Tolylamino-1,2,3-tri-
azole-2-yl)benzoyl Hydrazide 6c. The standard pro-
cedure was followed to prepare 6c as white powder
1
in 77% yield. H NMR (DMSO-d6, 200 MHz): δ 2.25
(s, 3H, CH3), 7.13 (d, J = 8.2 Hz, 2H, Ar-H), 7.41
(d, J = 8.2 Hz, 2H, Ar-H), 7.75 (s, 1H, CH), 7.83 (d,
J = 8.2 Hz, 2H, Ar-H), 8.00–8.22 (m, 4H, Ar-H, Py-H),
8.79 (d, J = 8.2 Hz, 2H, Py-H), 9.18 (s, 1H, NH), 10.69
(s, 1H, NH), 10.85 (s, 1H, NH).
Isonicotinic Acid N ꢁ-4-[4-(-Bomophenylamino)-
1,2,3-triazole-2-yl]benzoyl Hydrazide 6d. The stan-
dard procedure was followed to prepare 6d as white
powder in 78% yield. 1H NMR (DMSO-d6, 200 MHz):
δ 7.36–7.62 (m, 4H, Ar-H), 7.76 (s, 1H, CH), 7.83 (d,
Heteroatom Chemistry DOI 10.1002/hc

328 Zhou et al.
2-(4-(5-(Pyridin-4-yl)-1,3,4-oxadiazol-2-yl)phenyl)-
REFERENCES
N-p-tolyl-2H-1,2,3-triazol-4-amine 7c. The standard
procedure was followed to prepare 7c as white
powder in 82% yield; mp 269–271◦C. 1H NMR
(DMSO-d6, 300 MHz): δ 2.47 (s, 3H, CH3), 7.10 (d,
J = 8.2 Hz, 2H, Ar-H), 7.42 (d, J = 8.2 Hz, 2H, Ar-H),
7.74 (s, 1H, CH), 8.02 (d, J = 8.2 Hz, 2H, Ar-H), 8.02
(d, J = 8.2 Hz, 2H, Ar-H), 8.12 (d, J = 8.4 Hz, 2H,
Py-H), 8.26 (d, J = 8.2 Hz, 2H, Ar-H), 8.84 (d, J = 8.4
Hz, 2H, Py-H), 9.45 (s, 1H, NH);13C NMR (DMSO-d6,
75 MHz): δ 20.72, 116.30, 117.74, 120.31, 120.65,
127.01, 128.98, 129.86, 132.31, 132.83, 139.59,
142.01, 150.62, 151.34, 162.86, 164.80; IR (KBr):
3434 (br, NH), 1610 (m, C O), 1566, 1518, 1495,
1432 cm−1; FABMS m/z (relative intensity): 397 (M +
2, 5), 396 (M + 1, 18), 395 (M+, 10), 155 (23), 155
(23), 154 (100), 138 (35), 137 (60), 136 (96). Anal.
Calcd for C22H17N7O: C, 66.83; H, 4.33; N, 24.80.
Found: C, 66.78; H, 4.34; N, 24.83.
[1] For reports of 1,3,4-oxadiazole–heterocycle hybrids,
see: (a) Wang, C.; Jung, G..-Y.; Batsanov, A. S.; Bryce,
M. R.; Petty, M. C. J Mater Chem 2002, 12, 173; (b)
Guan, M.; Bian, Z. Q.; Zhou, F. Y.; Li, Z. J.; Li, Z. J.;
Haung, C. H. Chem Commun 2003, 2708; (c) Zhang,
Q.; Chen, J.; Cheng, Y.; Wang, L.; Ma, D.; Jing, X.;
Wang, F. J Mater Chem 2004, 14, 895; (d) Chien, Y.;
Wong, K.; Chou, P.; Cheng, Y. Chem Commun 2002,
2874.
[2] For reviews, see: (a) Kraft, A. C.; Holmes, A. B.
Angew Chem Int Ed Engl 1998, 37, 402; (b) Segura,
J. L. Acta Polym 1998, 49, 319; (c) Thelakkat, M.;
Schidt, H.-W. Polym Adv Technol 1998, 9, 429;
(d) Mitschke, U.; Ba¨uerle, P. J. Mater Chem 2000, 10,
1471.
[3] The present results were submitted for publication.
[4] Wang, C.; Jung, G.-Y.; Hua, Y.; Pearson, C.; Bryce,
M. R.; Petty, M. C.; Batsanov, A. S.; Goeta, A. R.;
Howard, J. A. Chem Mater 2001, 13, 1167.
[5] (a) Yeh, M.-Y.; Tien, H.-J.; Huang, L.-Y.; Chen,
M.-H. J Chin Chem Soc 1983, 30, 29; (b) Thoman,
C. J.; Voaden, D. J.; Hunsberger, I. M. J Org
Chem 1964, 29, 2044; (c) Dallacker, F.; Kern, J.
Ber 1966, 99, 3830; (d) Kuo, W.-F.; Lin, I.-T.;
Sun, S.-W.; Yeh, M.-Y. J Chin Chem Soc 2001, 48,
769.
[6] Thelakkat, M.; Schmidt, H.-W. Adv Mater 1998, 10,
219.
[7] Masuda, K.; Kikuchi, K. Imajo, Y. Chem Abstr 1973,
78, 124597e.
[8] Eade, A.; Earl, J. C. J Chem Soc 1946, 591.
[9] Shinohafa, H.; Ichimiya, Y.; Yoshimura, T.; Okawara,
M. Chem Abstr 1960, 54, 22636i.
[10] Wang, C.; Jung, G.-Y.; Hua, Y.; Pearson, C.; Bryce,
M. R.; Petty, M. C.; Batsanov, A. S.; Goeta, A. R.;
Howard, J. A. Chem Mater 2001, 13, 1167.
[11] Hwu, J. R.; Chuang, K.-S.; Chuang, S. H.; Tsay, S.-C.
Org Lett 2005, 7, 1545.
N-(4-Bromophenyl)-2-(4-(5-(pyridin-4-yl)-1,3,4-
oxadiazol-2-yl)phenyl)-2H-1,2,3-triazol-4-amine 7d.
The standard procedure was followed to prepare
7d as white powder in 84% yield; mp 287–289◦C.
1H NMR (DMSO-d6, 300 MHz): δ 7.34–7.64 (m,
4H, Ar-H), 7.76 (s, 1H, CH), 8.03 (d, J = 8.2 Hz,
2H, Ar-H), 8.12 (d, J = 8.8 Hz, 2H, Py-H), 8.26 (d,
J = 8.8 Hz, 2H, Ar-H), 8.84 (d, J = 8.8 Hz, 2H, Py-H),
9.62 (s, 1H, NH); 13C NMR (DMSO-d6, 75 MHz):
δ 111.44, 118.19, 119.37, 120.63, 127.14, 128.96,
130.82, 132.13, 132.83, 141.32, 141.90, 150.62,
151.33, 162.89, 164.75; IR (KBr): 3428 (br, NH),
1606 (m, C O), 1556, 1489, 1415 cm−1; FABMS m/z
(relative intensity): 462 (M + 2, 7), 461 (M + 1, 28),
460 (M+, 29), 155 (25), 154 (100), 138 (33), 137 (55),
136 (80). Anal. Calcd for C21H14BrN7O: C, 54.80; H,
3.07; N, 21.30. Found: C, 54.88; H, 3.03; N, 21.25.
[12] Demas, J. N.; Crosby, G. A. J Phys Chem 1971, 75,
991.
[13] Wu, F.-I.; Shu, C.-F.; Chien, C.-H.; Tao, Y.-T. Synth Met
2005, 148, 133.
Heteroatom Chemistry DOI 10.1002/hc