Magnetically recoverable copper nanorods and their catalytic activity in Ullmann cross-coupling reaction

Article abstract of DOI:10.1002/aoc.3647

A novel polydentate ligand supported on Fe₃O₄@SiO₂ was designed and demonstrated for the synthesis of Cu nanorods. The Fe₃O₄@SiO₂/EP.EN.EG@Cu was characterized using X-ray diffraction, ther

Full text of DOI:10.1002/aoc.3647

Received: 17 August 2016
DOI 10.1002/aoc.3647
Revised: 31 August 2016
Accepted: 3 September 2016
F U L L PA P E R
Magnetically recoverable copper nanorods and their catalytic
activity in Ullmann cross‐coupling reaction
Maryam Rajabzadeh1 | Hossein Eshghi1 | Reza Khalifeh2 | Mehdi Bakavoli1
1 Department of Chemistry, Faculty of Sciences,
A novel polydentate ligand supported on Fe3O4@SiO2 was designed and demon-
Ferdowsi University of Mashhad, Mashhad
91775‐1436, Iran
2 Department of Chemistry, Shiraz University of
strated for the synthesis of Cu nanorods. The Fe3O4@SiO2/EP.EN.EG@Cu was
characterized using X‐ray diffraction, thermogravimetric analysis, transmission elec-
tron microscopy, energy‐dispersive X‐ray spectroscopy and vibrating sample mag-
netometry. The Fe3O4@SiO2/EP.EN.EG@Cu showed excellent catalytic efficiency
Technology, 71555‐313 Shiraz, Iran
Correspondence
Hossein Eshghi, Department of Chemistry, Faculty
for the cross‐coupling reaction of nitrogen‐containing heterocycles with aryl halides.
of Sciences, Ferdowsi University of Mashhad,
Mashhad 9177948974, Iran.
Email: heshghi@um.ac.ir
The catalyst could be effectively separated from the reaction mixture by simply
applying an external magnetic field and reused at least five times without loss of
activity.
KEYWORDS
Cu nanorods, Fe3O4@SiO2/EP.EN.EG, nanocatalyst, Ullmann reaction
1
|
INTRODUCTION
have different properties compared to their bulk counter-
parts.[13–17] Recently, the synthesis of metal nanorods, espe-
The C─N bond formation reaction is one of the most impor-
tant reactions and has proved to be challenging in industrial
and medicinal settings.[1] Ullmann and Goldberg first devel-
oped the introduction of an amino group via copper‐catalysed
cross‐coupling reactions (stoichiometric amounts of copper
salts were used to activate aryl halides) that have been exten-
sively investigated by many researchers.[2,3] Many efforts
have been directed at achieving mild and inexpensive reac-
tion conditions for C─N bond formation reactions. Most of
these processes are carried out in the presence of metal com-
plexes. Numerous copper‐containing complexes with new
ligands have been designed which allow the formation of
cially with metallic copper, of various sizes in high yield
and of monodispersity has been developed.[18–20] But only a
few papers have been published related to their applications
in organic syntheses. Various methods such as the thermal,
photochemical and sonochemical reduction of Cu(II)
complexes for the synthesis of Cu NPs of various shapes
have been reported.[21,22] Anionic surfactants such as
C11–17COOH and sodium dodecylsulfate were used for stabi-
lizing Cu(II) ions through electrostatic interactions and further
in situ reduction promotes the formation of Cu NPs of different
sizes and shapes.[23] Bhaumik and co‐workers reported a
method for the preparation of Cu nanospheres and nanorods
via a hydrothermal process utilizing the templating property
important products via C─N bond cross‐coupling.[4–6]
A
complex of CuBr with N,N′‐dimethylethylenediamine
(DMEDA) was reported for the cyclization of ortho‐gem‐
dibromovinyl anilines and benzoyl chloride.[7] Also,
complexes of copper salts and various ligands such as 2‐
acetylcyclohexanone,[8] 2,2′‐bipyridine,[9] 2‐(2,6‐dimethyl-
phenylamino)‐2‐oxoacetic acid[10] and DMEDA[11] were
investigated for C─N bond cross‐coupling reactions. The
catalytic reactions occur on the surface of metal
nanoparticles (NPs), and are mainly dependent on their size
and shape.[12] Design of metal NPs with various sizes and
shapes is a major research area due to the fact that metals
of
a fatty acid with or without the addition of
ethylenediamine.[24] Also, dispersion of NPs onto supports
for increasing availability and avoiding of NP agglomeration
is effective. Furthermore, surface modification with various
functional groups such as ─NHn and ─OH groups via strong
interaction between Cu NPs affects the catalytic properties.
Fe3O4 magnetic NPs have been employed as an excellent
choice for catalyst supports, due to their easy recovery using
an external magnetic field. Their insoluble and
superparamagnetic natures make it possible to realize various
reactions and reduce capital and operational costs.[25,26]
Appl Organometal Chem 2016; 1–7
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
1

2
RAJABZADEH ET AL.
In this article, we demonstrate the efficiency of a newly
designed polydentate ligand (EP.EN.EG) for the synthesis
of Cu nanorods. In fact, our designed ligand can control the
shape of Cu NPs. So that, without any stabilizing agent, this
ligand can act as a templating agent. The efficiency of
Fe3O4@SiO2@EP.EN.EG@Cu in the Ullmann reaction was
evaluated.
2
| RESULTS AND DISCUSSION
The Fe3O4 magnetic NPs were prepared via a co‐precipitation
method and then were coated with silica via the Stober
method.[27] The Fe3O4@SiO2@EP.EN.EP was prepared in a
three‐step procedure.[28] The Cu nanorods were then obtained
by mixing Cu(II) acetate and Fe3O4@SiO2@EP.EN.EP in a
refluxing ethanol solution in the presence of NaOH in 12 h.
Finally, NaBH4 was added to mixture reaction for synthesis
of Fe3O4@SiO2/EP.EN.EG@Cu (Scheme 1). This
nanocatalyst was characterized using X‐ray diffraction
(XRD), thermogravimetric analysis (TGA), transmission
electron microscopy (TEM), energy‐dispersive X‐ray spec-
troscopy (EDS) and vibrating sample magnetometry (VSM).
The crystal structures of Fe3O4, Fe3O4@SiO2 and
Fe3O4@SiO2/EP.EN.EG@Cu were identified using XRD
characterization (Figure 1). The peaks located at 30.31°,
35.64°, 43.31°, 53.86°, 57.24° and 62.83° could be attributed
to (220), (311), (400), (422), (511) and (440) crystal planes,
which, as observed, were in agreement with the standard data
for Fe3O4 (cubic phase) (Figure 1a). The broad peak observed
at 2θ = 23° could be allocated to the amorphous silica shell
(Figure 1b). As the XRD pattern of Fe3O4@SiO2/EP.EN.
EG@Cu shows (Figure 1c), there was a decline in peak inten-
sity compared to that of Fe3O4@SiO2 which generally indi-
cates retained crystal structure of the Fe3O4 core after
modification. Additionally, new peaks were observed at
2θ = 51.52° and 74.24° which could be attributed to the Cu
nanorods in the catalysis matrix.
FIGURE
1
XRD patterns: (a) Fe3O4; (b) Fe3O4@SiO2; (c)
Fe3O4@SiO2@EP.EN.EG@Cu
(Figure 2). A significant weight decrease observed around
100 °C was due to desorption of water molecules on the sup-
port. A weight loss of 13% appearing at 190–600 °C was a
result of decomposition of organic groups loaded on the
Fe3O4@SiO2 surface. TGA curves confirm that the amount
of the organic part grafted on the surface of the catalyst was
about 0.6 mmol g−1
.
In addition, TEM images were used to examine the mor-
phology and size of Fe3O4@SiO2 and Fe3O4@SiO2/EP.EN.
EG@Cu (Figure 3). It was observed that Fe3O4@SiO2
consisted of spherical structures and that the average size of
the magnetic NPs was about 20 nm (Figure 3a). Figure 3(b)
shows a TEM image of the Fe3O4@SiO2/EP.EN.EG@Cu.
The Cu nanorods with an average size of about 10 nm are
uniformly distributed on the surfaces of the catalyst. More-
over, the presence of Cu, Fe and Si was confirmed through
the EDS spectrum (Figure 4). The amount of Cu loaded on
the magnetic nanoparticles was estimated to be
2.59 mmol g−1 based on inductively coupled plasma atomic
emission spectroscopy (ICP) results.
The magnetic responsivity plays a very significant role
for magnetic materials. Thus, the magnetic properties of
Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2/EP.EN.EG@Cu were
analysed using VSM at room temperature (Figure 5). The
The thermal behaviour of organic functional groups
anchored on Fe3O4@SiO2 was investigated using TGA
SCHEME 1 Synthetic route to Fe3O4@SiO2/EP.EN.EG@Cu
FIGURE 2 TGA thermogram of Fe3O4@SiO2@EP.EN.EG

RAJABZADEH ET AL.
3
FIGURE
5
Magnetization curves: (a) Fe3O4; (b) Fe3O4@SiO2; (c)
Fe3O4@SiO2/EP.EN.EG@Cu
the uncoated Fe3O4. These decreases occur as a result of
the increase in mass and size after the SiO2 shell coating
and the anchoring of Cu nanorods. Also, there was found
no noticeable remanence or coercivity in the magnetization
curves, showing superparamagnetic character. Thus, an exter-
nal magnet can readily separate the new magnetic material.
One of the goals of the research reported here was to
estimate the activity of Fe3O4@SiO2/EP.EN.EG@Cu as a
catalyst for the cross‐coupling reactions of N‐heterocyclic
compounds with aryl halides. The reaction of 1H–pyrazole
and p‐methoxyanisole in the presence of Fe3O4@SiO2/EP.
EN.EG@Cu was chosen as a model and its behaviour was
studied under a variety of conditions via TLC and NMR
spectroscopy (Table 1). Initially, the effect of solvent was
studied based on isolated yield. These results indicated that
dimethylformamide (DMF) was the best choice for this
reaction (Table 1, entry 7), while other solvents such as
dimethylsulfoxide (DMSO), water, toluene and CH3CN gave
lower yields (Table 1, entries 1–4). In order to determine the
best base, the model reaction was carried out in the presence
of K2CO3, NaHCO3 and KOH (Table 1, entries 7, 8 and 9).
Among them, K2CO3 was found to be highly efficient for
the cross‐coupling reaction. In addition, temperature is also
important for the progress of the reaction. At temperatures
below 110 °C, the desired product was detected in lower
yield (Table 1, entries 5 and 6). The influence of the amount
of catalyst was evaluated using the model reaction. No reac-
tion was observed in the absence of the catalyst (Table 1,
entry 10). The best result was achieved when the amount
of catalyst was increased from 1.3 to 8 mol% (Table 1,
entries 10–13).
FIGURE
3
TEM images: (a) Fe3O4@SiO2; (b) Fe3O4@SiO2/EP.EN.
EG@Cu
With these optimal conditions, we investigated the cou-
pling of nitrogen‐containing heterocycles with a variety of
aryl halides bearing either an electron‐donating group or an
electron‐withdrawing group (Table 2). We found that the
arylation of pyrazole, benzimidazole and triazole with aryl
iodide provided higher yields in shorter reaction times than
with aryl bromide (Table 2, entries 1, 2, 9, 10, 14 and 15).
In the case of 1‐iodo‐4‐bromobenzene, substitution occurs
in C─I bond as a main product, but C─Br product
FIGURE 4 EDS spectrum of Fe3O4@SiO2/EP.EN.EG@Cu
saturation magnetization (Ms) values of these magnetic sam-
ples are 63.6, 37.8 and 29.4 emu g−1, respectively. The
results showed that Ms values for Fe3O4@SiO2 and
Fe3O4@SiO2/EP.EN.EG@Cu have decreased, compared to

4
RAJABZADEH ET AL.
TABLE 1 Optimization of reaction conditions for N‐arylation of
1H–pyrazolea
benzimidazole (Table 2, entries 1 and 5), electron‐withdraw-
ing groups (Table 2, entries 3, 6 and 7) led to higher yields.
In addition, the reactions of heterocyclic compounds such as
pyrazole, triazole, indole and 1H–benzo[d] [1–3]triazole with
aryl iodide were examined. The results show excellent yields
of the corresponding products (Table 2, entries 8, 9, 11, 14
and 17).
The reusability of the catalyst was tested in the model
reaction (Table 3). After the completion of the reaction, the
catalyst was separated from the product using an external
magnet. To remove all organic compounds, the catalyst was
washed with ethanol, dried at 50 °C under vacuum and
reused for five times without a significant decline in its cata-
lytic activity.
Entry
Base
Solvent
Amount of catalyst (mol%)
Yield (%)
1
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
NaHCO3
KOH
H2O
8
8
20
60
2
CH3CN
Toluene
DMSO
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
3
8
40
4
8
60
5b
6c
7
8
60
8
30
The Fe3O4@SiO2/EP.EN.EG@Cu recovered after the
fifth run was characterized using TEM and ICP. As shown in
Figure 6, the TEM image of the reused catalyst did not por-
tray a significant change compared to the fresh catalyst. The
amount of Cu loaded in the catalyst used for five times was
8
98
8
8
Trace
50
9
8
10
11
12
13
K2CO3
K2CO3
K2CO3
K2CO3
—
1.3
2
0
30
determined using elemental analysis (ICP) as 1.82 mmol g−1
.
50
Therefore, these results indicated that the morphology and
2.6
75
aReaction conditions: p‐methoxyiodobenzene (1 mmol), 1H–pyrazole (1.2 mmol),
catalyst (8 mol%), base(2 mmol) and solvent (5 ml) at 110°C.
bReaction carried out at 90°C.
cReaction carried out at 70°C.
TABLE 3 Reusability of catalyst for N‐arylation of nitrogen‐containing
heterocycles
Run
Yield (%)
1
2
3
4
5
98
98
95
90
90
substitution was also observed (Table 2, entries 12 and 16).
However, for 2‐iodo‐5‐bromopyridine, N‐arylation occurs
selectively only at C‐5 (Table 2, entries 4 and 13). Com-
pared with electron‐donating groups on aryl iodide or
TABLE 2 Fe3O4@SiO2/EP.EN.EG@Cu‐catalysed N‐arylation of various nitrogen‐containing heterocycles with aryl halidesa
Entry
Aryl halide
Heterocycle
Benzimidazole
Time (h)
Yield (%)
1
p‐Methoxyiodobenzene
p‐Methoxybromobenzene
1‐Iodo‐2‐methyl‐4‐nitrobenzene
5‐Bromo‐2‐iodopyridine
p‐Methoxyiodobenzene
p‐Methoxyiodobenzene
1‐Iodo‐4‐nitrobenzene
18
20
16
14
20
16
16
18
12
18
16
12
14
14
16
12
16
85
70
90
95
80
90
95
90
98
85
98
80
95
98
90
85
90
2
Benzimidazole
3
Benzimidazole
4
Benzimidazole
5
2‐Methyl‐1H‐benzimidazole
5‐Nitro‐1H‐benzimidazole
5‐Nitro‐1H‐benzimidazole
Indole
6
7
8
p‐Methoxyiodobenzene
p‐Methoxyiodobenzene
p‐Methoxybromobenzene
1‐Iodo‐2‐methyl‐4‐nitrobenzene
1‐Bromo‐4‐iodobenzene
5‐Bromo‐2‐iodopyridine
p‐Methoxyiodobenzene
p‐Methoxybromobenzene
1‐Bromo‐4‐iodobenzene
p‐Methoxyiodobenzene
9
1H–pyrazole
10
11
12
13
14
15
16
17
1H–pyrazole
1H–pyrazole
1H–pyrazole
1H–pyrazole
1H‐1,2,4‐triazole
1H‐1,2,4‐triazole
1H‐1,2,4‐triazole
1H–benzo[d] [1–3]triazole
aAryl halides (1 mmol), nitrogen‐containing heterocycles (1.2 mmol), catalyst (8 mol%) and K2CO3 (2 mmol) in DMF (5 ml) as solvent at 110°C.

RAJABZADEH ET AL.
5
X‐ray diffractometer with Ni‐filtered Cu Kα radiation
(40 kV, 30 mA).
3.1 | General procedure for preparation of
Fe3O4@SiO2/EP.EN.EP
In the first step, the synthesis of core–shell Fe3O4@SiO2
microspheres was carried out using the Stober sol–gel
method.[27] In the second step, a mixture of epibromohydrin
(10 mmol, 1.36 g) and Fe3O4@SiO2 (0.5 g) in ethanol
(3 ml) was stirred for 5 h at 60 °C. Fe3O4@SiO2/EP was sep-
arated using an external magnet, washed with ethanol and
dried at 80 °C. Ethylenediamine (5 ml) was added to dried
Fe3O4@SiO2/EP and stirred at 60 °C. After 24 h, the solid
was collected, washed with methanol and dried at 80 °C to
afford Fe3O4@SiO2/EP.EN. Then the dried precipitate was
added to a solution of epibromohydrin (10 mmol, 1.36 g) in
ethanol (3 ml) at 60 °C for 5 h. Finally, the product was sep-
arated using an external magnet, washed with methanol and
dried at 80 °C.[28]
FIGURE 6 TEM image of Fe3O4@SiO2/EP.EN.EG@Cu after five recycles
3.2 | General procedure for preparation of Cu
nanorods loaded on magnetic core (Fe3O4@SiO2/EP.EN.
EG@Cu)
structure of the catalyst were the same, and the leaching of Cu
was low, after the fifth run.
The catalytic activity of Fe3O4@SiO2/EP.EN.EG@Cu
was compared with that of systems previously reported
(Table 4) as applied in the cross‐coupling reactions of
nitrogen‐containing heterocycles with aryl halides. It is clear
that Fe3O4@SiO2/EP.EN.EG@Cu is the most effective cata-
lyst for N‐arylation of nitrogen‐containing heterocycles, lead-
ing to the formation of products in high yield.
Cu(OAc)2 (0.25 g) and Fe3O4@SiO2/EP.EN.EP (0.5 g) were
dissolved in absolute ethanol (5 ml) and then NaOH solution
was added to mixture under vigorous stirring until a pH of
12–13 was achieved. After reaction under reflux for 12 h, a
solution of sodium borohydride (10 ml, 0.15 mol l−1) was
added dropwise to the mixture and stirred under nitrogen
atmosphere for 2 h. The product (Fe3O4@SiO2/EP.EN.
EG@Cu)wascollectedusingamagnet. Washedwithmethanol
and dried under vacuum at room temperature for 8 h.
3
| EXPERIMENTAL
3.3 | General procedure for n‐arylation of n‐
heterocyclic compounds with aryl halides
Mass spectra were recorded with a 5973 Network mass selec-
tive detector. H NMR spectra were recorded with a Bruker
1
AC 300 MHz instrument in DMSO‐d6 or CDCl3. TGA was
performed with a Shimadzu TG‐50 thermogravimetric
analyser. TEM images were acquired using a Leo 912 AB
120 kV TEM microscope (Zeiss, Germany). Elemental
compositions were determined using an EDS instrument
with 133 eV resolution (7353, Oxford, UK). ICP analysis
was conducted obtained using a Varian VISTAPRO CCD
(Australia). XRD patterns were collected using a Bruker D4
Fe3O4@SiO2/EP.EN.EG@Cu (0.03 g) as a catalyst was
added to a mixture of aryl halide (1 mmol), N‐heterocyclic
compound (1.2 mmol) and K2CO3 (2 mmol) in DMF at
110 °C. After completion of the reaction, the catalyst was
separated using an external magnet and washed with ethyl
acetate. The product was extracted with ethyl acetate and
purified using column chromatography with hexane–ethyl
acetate as a solvent system.
TABLE 4 Comparison of various catalysts for N‐arylation of 1H–pyrazole
Entry
Catalyst
Cu(OAC)2⋅H2O
Temp (°C)
Time (h)
Yield (%)
Ref.
1
2
3
4
5
110
80
24
18
10
12
12
95
95
70
75
95
[29]
[30]
Cu2O
Copper decorated OMMT
[Cu(Im12)2]CuCl2
Fe3O4@SiO2/EP.EN.EG@Cu
130
80
[31]
[32]
110
This work

6
RAJABZADEH ET AL.
3.3.1
entry 1)
|
1‐(4‐Methoxyphenyl)‐1H–benzo[d]imidazole (Table 2,
(d, 1H, J = 1.2 Hz), 7.75 (d, 1H, J = 2.4 Hz). 13C NMR
(75 MHz, CDCl3, δ, ppm): 55.58, 107.17, 114.51, 120.92,
126.83, 134.04, 140.63, 158.24. MS (EI): m/z (%) 174 [M+].
1H NMR (DMSO, 300 MHz, δ, ppm): 3.85 (s, 3H), 7.17 (d,
2H, J = 8.7 Hz), 7.27–7.79 (m, 4H), 7.59 (d, 2H, J = 9 Hz),
8.47 (s, 1H). 13C NMR (75 MHz, DMSO, δ, ppm): 56.00,
110.92, 115.60, 120.31, 122.69, 123.75, 125.90, 129.26,
134.07, 143.98, 159.16. MS (EI): m/z (%) 224 [M+].
3.3.8
entry 11)
| 1‐(2‐Methyl‐4‐nitrophenyl)‐1H–pyrazole (Table 2,
1H NMR (CDCl3, 300 MHz, δ, ppm): 2.46 (s, 3H), 6.53 (t,
1H), 7.54 (d, 1H, J = 8.7 Hz), 7.73 (d, 1H, J = 2.4 Hz),
7.79 (d, 1H, J = 1.5 Hz), 8.14 (dd, 1H, J1 = 8.7 Hz,
J2 = 2.4 Hz), 8.22 (d, 1H, J = 2.4 Hz). 13C NMR
(75 MHz, CDCl3, δ, ppm): 19.10, 107.58, 122.02, 126.27,
126.82, 130.50, 134.35, 141.56, 144.67, 146.61.MS (EI):
m/z (%) 203 [M+].
3.3.2
(Table 2, entry 3)
| 1‐(2‐Methyl‐4‐nitrophenyl)‐1H–benzo[d]imidazole
1H NMR (CDCl3, 300 MHz, δ, ppm): 2.30 (s, 3H), 7.16 (dd,
1H, J1 = 6.6 Hz, J2 = 1.5 Hz), 7.34–7.43 (m, 2H), 7.55 (d,
1H, J = 8.7 Hz), 7.94 (d.d, 1H, J1 = 6 Hz, J2 = 2.1 Hz),
8.21 (s, 1H), 8.27 (d.d, 1H, J1 = 8.4 Hz, J2 = 2.4 Hz), 8.36
(d, 1H, J = 2.1 Hz). 13C NMR (75 MHz, CDCl3, δ, ppm):
18.17, 110.16, 120.90, 122.54, 123.23, 124.25, 126.78,
128.51, 134.04, 137.10, 140.34, 142.11, 143.48, 147.71.
MS (EI): m/z (%) 253 [M+].
3.3.9
| 1‐(4‐Bromophenyl)‐1H–pyrazole (Table 2, entry 12)
1H NMR (CDCl3, 300 MHz, δ, ppm): 6.49 (t, 1H), 7.59 (AB
q, 4H), 7.74 (d, 1H, J = 2.4 Hz), 7.90 (d, 1H, J = 2.4 Hz). 13C
NMR (75 MHz, CDCl3, δ, ppm): 108.06, 119.63, 120.58,
126.65, 132.47, 138.41, 141.42. MS (EI): m/z (%) 221 [M+].
3.3.3
entry 4)
| 1‐(6‐Iodopyridin‐3‐yl)‐1H–benzo[d]imidazole (Table 2,
1H NMR (CDCl3, 300 MHz, δ, ppm): 7.34–7.39 (m, 2H),
7.76 (d, 1H, J = 6.6 Hz), 7.96 (d, 1H, J = 8.7 Hz), 8.26–
8.33 (m, 1H), 8.76 (d, 1H, J = 2.4 Hz), 8.85 (d, 1H,
J = 1.8 Hz), 8.98 (s, 1H). 13C NMR (75 MHz, CDCl3, δ,
ppm): 113.51, 115.72, 119.36, 123.52, 131.14, 141.39,
143.63, 146.69, 148.22, 148.87, 153.84. MS (EI): m/z (%)
320 [M+].
3.3.10
entry 14)
| 1‐(4‐Methoxyphenyl)‐1H‐1,2,4‐triazole (Table 2,
1H NMR (CDCl3, 300 MHz, δ, ppm): 3.79 (s, 3H), 6.93 (d,
2H, J = 8.7 Hz), 7.50 (d, 2H, J = 8.7 Hz), 8.01 (s, 1H),
8.38 (s, 1H). 13C NMR (75 MHz, CDCl3, δ, ppm): 55.64,
114.83, 121.99, 130.47, 152.41, 159.47. MS (EI): m/z (%)
175 [M+].
3.3.4
(Table 2, entry 5)
| 1‐(4‐Methoxyphenyl)‐2‐methyl‐1H‐benzo[d]imidazole
3.3.11
| 1‐(4‐Bromophenyl)‐1H‐1,2,4‐triazole (Table 2, entry 16)
1H NMR (CDCl3, 300 MHz, δ, ppm): 7.59 (q, 4H). 8.10 (s,
1H), 8.55 (s, 1H). 13C NMR (75 MHz, CDCl3, δ, ppm):
121.43, 132.86, 135.98, 138.83, 140.80, 152.76. MS (EI):
m/z (%) 223 [M+].
1H NMR (DMSO, 300 MHz, δ, ppm): 2.51 (s, 3H), 3.93 (s,
3H), 7.09–7.31 (m, 7H), 7.65 (d, 1H, J = 7.2 Hz). 13C
NMR (75 MHz, DMSO, δ, ppm): 14.33, 55.63, 109.92,
115.05, 118.92, 122.35, 128.34, 128.66, 136.84, 142.50,
151.95, 159.75. MS (EI): m/z (%) 238 [M+].
3.3.12
(Table 2, entry 17)
|
1‐(4‐Methoxyphenyl)‐1H–benzo[d] [1–3]triazole
3.3.5
(Table 2, entry 6)
| 1‐(4‐Methoxyphenyl)‐5‐nitro‐1H‐benzo[d]imidazole
1H NMR (CDCl3, 300 MHz, δ, ppm): 3.93 (s, 3H), 7.14
(d, 2H, J = 8.4 Hz), 7.45 (t, 1H), 7.55 (t, 1H), 7.6 (d, 1H,
J = 8.1 Hz), 8.16 (d, 1H, J = 8.1 Hz). 13C NMR (75 MHz,
CDCl3, δ, ppm): 55.68, 110.26, 114.98, 120.22, 124.43,
128.03, 130.00, 132.65, 146.32, 159.84. MS (EI): m/z (%)
225 [M+].
1H NMR (CDCl3, 300 MHz, δ, ppm): 3.88 (s, 3H), 7.23–8.87
(m, 8H). MS (EI): m/z (%) 269 [M+].
3.3.6
(Table 2, entry 7)
| 5‐Nitro‐1‐(4‐nitrophenyl)‐1H–benzo[d]imidazole
1H NMR (CDCl3, 300 MHz, δ, ppm): 7.68 (1H, d, J = 9 Hz),
7.79 (d, 2H, J = 9 Hz), 8.37 (dd, 1H, J1 = 9 Hz, J2 = 2.1 Hz),
8.38 (s, 1H), 8.56 (d, 2H, J = 9 Hz), 8.86 (d, 1H, J = 2.1 Hz).
13C NMR (75 MHz, CDCl3, δ, ppm): 110.41, 117.86,
120.24, 124.42, 126.13, 136.89, 140.46, 143.91, 144.80,
147.44. MS (EI): m/z (%) 284 [M+].
4
| CONCLUSIONS
In summary, we have reported an efficient procedure for the
synthesis of Cu nanorods using a polydentate ligand. The
application of the Fe3O4@SiO2/EP.EN.EG@Cu catalyst in
N‐arylation of nitrogen‐containing heterocycles has been
examined, and high yields of the products were achieved. In
addition, the catalyst could be easily recovered and reused
for at least five cycles.
3.3.7
| 1‐(4‐Methoxyphenyl)‐1H–pyrazole (Table 2, entry 9)
1H NMR (CDCl3, 300 MHz, δ, ppm): 3.77 (s, 3H), 6.36 (t,
1H), 6.89 (d, 2H, J = 9 Hz), 7.51 (d, 2H, J = 9 Hz), 7.62

RAJABZADEH ET AL.
7
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