Ferromagnetic nanoparticle-supported copper complex: A highly efficient and reusable catalyst for three-component syntheses of 1,4-disubstituted 1,2,3-triazoles and C–S coupling of aryl halides

Article abstract of DOI:10.1002/aoc.3714

A new nanocatalyst was synthesized by immobilization of 4′-(4-hydroxyphenyl)-2,2′:6′,2″-terpyridine/CuI complex on ferromagnetic nanoparticles through a surface modification (FMNPs@SiO₂-TPy-Cu). This heterogeneous catalyst was characterized using various techniques including Fourier transform infrared and energy-dispersive X-ray spectroscopies, transmission and scanning electron microscopies, X-ray diffraction, vibrating sample magnetometry and thermogravimetric analysis. The resulting nanocatalyst presented excellent catalytic activity for the regioselective syntheses of 1,4-disubstituted 1,2,3-triazoles and thioethers. The thermally and chemically stable, benign and economical catalyst was easily recovered using an external magnet and reused in at least five successive runs without an appreciable loss of activity.

Full text of DOI:10.1002/aoc.3714

Received: 23 October 2016
DOI 10.1002/aoc.3714
Revised: 16 November 2016
Accepted: 27 November 2016
F U L L PA P E R
Ferromagnetic nanoparticle‐supported copper complex: A highly
efficient and reusable catalyst for three‐component syntheses of
1,4‐disubstituted 1,2,3‐triazoles and C–S coupling of aryl halides
Mohammad Mehdi Khodaei | Kiumars Bahrami | Farhat Sadat Meibodi
Department of Organic Chemistry, Faculty of
A new nanocatalyst was synthesized by immobilization of 4′‐(4‐hydroxyphenyl)‐
2,2′:6′,2″‐terpyridine/CuI complex on ferromagnetic nanoparticles through a
surface modification (FMNPs@SiO2‐TPy‐Cu). This heterogeneous catalyst was
characterized using various techniques including Fourier transform infrared and
Chemistry, Razi University, Kermanshah 67149‐
67346, Iran
Correspondence
Mohammad Mehdi Khodaei and Kiumars
Bahrami, Department of Organic Chemistry,
energy‐dispersive X‐ray spectroscopies, transmission and scanning electron micros-
Faculty of Chemistry, Razi University,
Kermanshah 67149‐67346, Iran.
Email: mmkhoda@razi.ac.ir;
kbahrami2@hotmail.com
copies, X‐ray diffraction, vibrating sample magnetometry and thermogravimetric
analysis. The resulting nanocatalyst presented excellent catalytic activity for the
regioselective syntheses of 1,4‐disubstituted 1,2,3‐triazoles and thioethers. The
thermally and chemically stable, benign and economical catalyst was easily recov-
ered using an external magnet and reused in at least five successive runs without an
appreciable loss of activity.
KEYWORDS
1,2,3‐triazole, C–S coupling reaction, immobilized copper catalyst, magnetic
nanoparticles, terpyridines
1
|
INTRODUCTION
materials.[3] Despite these advantages for heterogeneous cat-
alysts, expensive ultracentrifugation is often the only way to
separate product and catalyst.[4] Magnetization of catalysts
can solve this problem since they can be easily separated
from the reaction mixture using an external permanent
magnet.[5]
The most important industrial disadvantages of performing
homogeneously catalysed reactions are the difficulties of sep-
arating the catalyst from the product and reusing the expen-
sive catalyst. These problems could be solved by
heterogenation of existing homogeneous catalysts. Thus,
many attempts have been made to develop heterogenation
of catalysts using various types of support such as polymeric,
organic and inorganic supports.[1] Even though heteroge-
neous catalytic systems can be recovered and reused, the
active sites in heterogeneous catalysts are not as accessible
as in homogeneous catalysts, so the activity of the catalysts
are usually decreased. As a result, we need a catalyst system
to have high activity and selectivity in addition to being easy
to separate and recover. Nanocatalysts can bridge the gap
between homogeneous and heterogeneous systems, keeping
the desirable attributes of both systems.[2] With the advent
of nanotechnology in the manufacture of catalysts,
nanocatalysts can be produced with high economic effi-
ciency, high safety and optimal use of chemicals and raw
Huisgen cycloaddition reactions of organic azides with
alkynes are promoted by copper catalysts with excellent effi-
ciency and selectivity.[6] This reaction has found many appli-
cations in various research areas including bioorganic
chemistry, medicinal chemistry and material science.[7] For
example, the 1,2,3‐triazole core is a key structural motif in
many bioactive compounds, exhibiting a wide range of activ-
ities, such as anti‐inflammatory, anti‐tubercular, anticancer,
antibacterial, antimicrobial, anti‐allergic and anticonvulsant
activities.[8] The reaction proceeds with high regioselectivity
when using terminal alkynes and produces 1,4‐disubstituated
1,2,3‐triazines as sole product.[9] The use of Cu(I)[10] and
Cu(II)/reducing agent (often sodium ascorbate or metallic
copper)[11] and metallic copper[12] has been reported in many
articles. However, due to the advantages of heterogeneous
Appl Organometal Chem 2017;e3714.
wileyonlinelibrary.com/journal/aoc
Copyright © 2017 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.3714

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KHODAEI ET AL.
catalysts, such as recovery and reusability, various supported
copper catalysts have been applied.[13] Although there are
many reports on this topic, there is still a need to develop
methods for the synthesis of 1,4‐disubstituated 1,2,3‐triazoles
which has received less attention.
The C─S bond formation of aryl halides with thiols is a
valuable step in the synthesis of many compounds that are
of biological, pharmaceutical and materials interest.[14] For
example, sulfide is a common functionality found in many
drugs in use for the treatment of diabetes, inflammation and
Parkinson's and Alzheimer's diseases.[15] Transition metal‐
catalysed cross‐coupling reactions between aryl halides and
thiols suggest a strong strategy for the construction of C─S
bonds. Despite the importance of this reaction protocol in
organic synthesis, less attention has been paid to transition
metal‐catalysed thioetherification, compared to other car-
bon–heteroatom bond forming reactions.
ThefirstreportofC─ScouplingreactionwasbyMigitaand
co‐workers[16] inwhichtheyusedPd(PPh3)4 asacatalystfor the
reaction of aryl iodides and bromides with thiols. Many other
palladium‐based catalyst systems with bidentate phosphines
or diverse organophosphate derivatives have also been
reported[17] but these systems have disadvantages such as the
use of the prepared PR3 ligands which are not eco‐friendly.
Other transition metal catalysts based on nickel[18] and
cobalt[19] have also been investigated for the formation of
C─S bonds. These catalysts have certain disadvantages such
as metal toxicity. Consequently, further development of cop-
per‐based catalytic systems is still required because of the low
costofcopper,despitemanyreportsusingcopperascatalyst.[20]
In continuation of our previous efforts to develop new
organic–inorganic hybrid materials as heterogeneous cata-
lysts,[21] a new reusable and efficient heterogeneous ferro-
SCHEME
2
Preparation of thioethers through carbon (aryl)–sulfur
coupling reaction in the presence of FMNPs@TPy‐Cu as nanocatalyst
were monitored by TLC. Melting points were determined
using a Stuart Scientific SMP2 apparatus. Fourier transform
infrared (FT‐IR) spectra were obtained with a Perkin Elmer
683 instrument. 1H NMR and 13C NMR spectra were
recorded with a Bruker (300 MHz) spectrometer using
CDCl3 as solvent. Powder X‐ray diffraction (XRD) patterns
were obtained with a SE1FERT‐3003TT. Scans were taken
with a 2θ step size of 0.02° from 3° to 70° and a counting
time of 1.0 s using a Cu Kα radiation source (λ = 1.542 Å)
and a nickel filter. Thermogravimetric analysis (TGA) was
carried out with a PL‐STA‐1640 in the range 30–600 °C with
a heating rate of 10 °C min−1. Scanning electron microscopy
(SEM) was performed with a VEGA 20 TESCAN micro-
scope. Transmission electron microscopy (TEM) measure-
ments were carried out with a Zeiss‐EM10C (Germany)
operating at 80 kV and using formvar carbon‐coated grid
Cu mesh 300. Energy‐dispersive X‐ray (EDX) spectroscopy
patterns were measured using a Seron model AIS2300C.
Magnetic measurements were carried out using vibrating
sample magnetometry (VSM; BHV‐55 and Riken, Japan) at
room temperature. All of the known products were character-
ized by comparison of their spectral data and physical proper-
ties with those reported in the literature.
magnetic
nanoparticle‐supported
copper(I)
iodide
2.2 | Preparation of catalyst
(FMNPs@TPy‐Cu) catalyst is introduced for the synthesis
of 1,4‐disubstituted 1,2,3‐triazoles from organic halides,
sodium azide and terminal alkynes in water and ethanol at
room temperature (Scheme 1) and for C─S bond formation
in cross‐coupling reactions of aryl halides and thiols in
dimethylformamide (DMF) (Scheme 2).
2.2.1
| Preparation of ferromagnetic nanoparticles (FMNPs)
FMNPs modified with citrate groups were prepared accord-
ing to a reported procedure.[22] Iron(III) chloride hexahydrate
(5.40 g, 20 mmol) and iron(II) chloride tetrahydrate (2 g,
10 mmol) were dissolved in deionized water (120 ml) under
nitrogen atmosphere. Then, 10 ml of ammonium hydroxide
(25%) was quickly added into the solution under rapid
mechanical stirring (500 rpm) and the mixture was heated
to 60 °C, while being stirred vigorously with a mechanical
stirrer for 1 h under nitrogen atmosphere. After cooling to
room temperature, the resultant nanoparticles were gathered
using a magnet and the collected magnetic solid was dis-
persed in 200 ml of trisodium citrate solution (0.3 M) and
heated at 80 °C for 1 h. Finally, the precipitates were col-
lected using an external magnet and washed with acetone to
eliminate remaining trisodium citrate.
2
| EXPERIMENTAL
2.1 | Materials and physical measurements
The materials were purchased from Merck and Fluka and
were used without any additional purification. All reactions
2.2.2
| Preparation of silica‐coated FMNPs (FMNPs@SiO2)
The surface‐modified FMNPs (1 g) were dispersed in deion-
ized water (40 ml) and ethanol by the ultrasonic treatment for
SCHEME
1
Preparation of 1,4‐disubstituated 1,2,3‐triazoles in the
presence of FMNPs@TPy‐Cu as nanocatalyst

KHODAEI ET AL.
3 of 10
25 min. Then NH3⋅H2O (5 ml) and a solution of tetraethyl
orthosilicate (TEOS; 1 ml) in ethanol (10 ml) were added in
a dropwise manner into the dispersed solution under continu-
ous mechanical stirring. Finally, FMNPs@SiO2 was obtained
by magnetic separation, and washed with ethanol and deion-
ized water.[23]
2.3 | General procedure for synthesis of triazoles
A round‐bottom flask was charged with FMNPs@TPy‐Cu
(0.08 g, containing 0.032 mmol of Cu), potassium carbonate
(0.1 g), alkyne (0.5 mmol), sodium azide (0.6 mmol) and
alkyl halide (0.5 mmol) in water (2 ml) and ethanol (2 ml).
The mixture was stirred at room temperature for 8–24 h, dur-
ing which the desired 1,4‐disubstituted 1,2,3‐triazole precip-
itated out. After completion of the reaction (as monitored
by TLC, eluting with n‐hexane–ethyl acetate, 3:1), the cata-
lyst was separated using an external magnet. The mixture
was condensed to evaporate ethanol and diluted with water
and EtOAc. The organic layer was separated and the aqueous
layer was extracted with EtOAc (3 × 2 ml). The combined
organic layers were dried over MgSO4 and evaporated to
afford pure 1,4‐disubstituted 1,2,3‐triazole in most cases. If
necessary, the product was purified by recrystallization from
n‐hexane–EtOAc.
2.2.3
| Preparation of FMNPs@SiO2‐Cl (1)
FMNPs@SiO2 (1 g) was dispersed in 100 ml of dried
toluene, and then 3‐chloropropyltrimethoxysilane (CPTS;
5 mmol, 1 ml) was added to this mixture. After vigorous
stirring for 18 h at 60 °C, the resultant magnetic
FMNPs@SiO2‐Cl nanoparticles were separated using an
external magnet and dried at 60 °C for 3 h.[24]
2.2.4
terpyridine (TPy)
| Preparation of 4′‐(4‐hydroxyphenyl)‐2,2′:6′,2″‐
To a solution of 4‐anisaldehyde (0.12 ml, 1 mmol) in ethanol
(10 ml) were added 2‐acetylpyridine (0.22 ml, 2 mmol) and
potassium hydroxide (0.15 g, 2 mmol). After stirring at room
temperature, to the mixture was added ammonium hydroxide
(2.9 ml, 2.5 mmol) and stirring was continued for 8 h. The
resulting precipitate was filtered and recrystallized from eth-
anol to produce 4′‐(4‐methoxyphenyl)‐2,2′:6′,2″‐terpyridine
as white crystals in 85% yield. Then 4′‐(4‐methoxyphenyl)‐
2,2′:6′,2″‐terpyridine (0.676 g, 2 mmol) was treated with
30% HBr in acetic acid (4 ml) under reflux condition for
4 h. The mixture was allowed to cool to room temperature.
The resultant solution was then basified to pH = 10 by adding
aqueous NaOH (20%) dropwise and extracted repeatedly
with CH2Cl2. The pH of the alkaline solution was then
lowered with HCl (20%). The addition of HCl converted the
soluble salt back into water‐insoluble TPy as white crystals.
The precipitated product was then filtered and collected in
60% yield.[25]
2.4 | General procedure for Cu‐catalysed coupling of
thiophenols with aryl halides
A mixture of aryl halide (0.5 mmol), thiophenol (0.6 mmol),
FMNPs@TPy‐Cu catalyst (80 mg containing 0.032 mmol of
Cu) and potassium carbonate (0.1 g) was stirred at 110 °C in
DMF (1 ml). The progress of the reaction was monitored by
TLC (ethyl acetate–hexane). When the reaction was com-
plete, the reaction mixture was cooled to room temperature
and the catalyst was separated using an external magnet.
The reaction mixture was treated with water (3 ml) and ethyl
acetate (10 ml). The organic and aqueous layers were then
separated and the aqueous layer was extracted with ethyl ace-
tate (5 ml). The combined organic solutions were washed
with water (5 ml) and dried with Na2SO4. The solvent was
evaporated under vacuum to afford a colourless liquid of
diaryl sulfide. The spectra and physical properties of known
products were compared to those reported in the literature.
2.2.5
| Preparation of FMNPs@TPy (2)
To 0.2 g of FMNPs@SiO2‐Cl in DMF (3 ml) were added
TPy (0.0325 g, 0.1 mmol), K2CO3 (0.05 g, 0.4 mmol) and
KI (0.05 g, 0.3 mmol). The reaction mixture was stirred at
60 °C for 24 h and then deionized water was added to the
mixture. The magnetic nanoparticles were separated with an
external magnet. Finally, the precipitate was dried at 50 °C
for 2 h to afford FMNPs@TPy in 99% yield.
3
| RESULTS AND DISCUSSION
3.1 | Synthesis and characterization of FMNPs@TPy‐
Cu Catalyst
In the first phase of the investigation, FMNPs were prepared
using a co‐precipitation method. In the second stage, the
nanoparticles were coated with silica using TEOS. Silica pre-
vents the iron oxide nanoparticles from aggregation or oxida-
tion, but somewhat decreases the saturation magnetization of
FMNPs. To stabilize the ligand on the magnetic nanoparticles
through a covalent bond linkage, CPTS was used to modify
the surface of the nanoparticles.
2.2.6
| Synthesis of FMNPs@TPy‐Cu catalyst (3)
FMNPs@TPy‐Cu catalyst was prepared in a typical proce-
dure as follows. FMNPs@TPy (0.2325 g) and CuI (0.
019 g, 0.1 mmol) were refluxed in ethanol (5 ml) for 24 h.
The magnetic nanocatalyst was separated with an external
magnet and washed with deionized water to remove the
excess Cu+ and dried at 50 °C for 2 h. The catalyst can be
used directly in catalytic reactions.
The ligand TPy was readily prepared and reacted with
FMNPs@SiO2‐Cl (1) in the presence of K2CO3 to afford
FMNP@TPy (2). The ligand has nitrogen atoms in the rings

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KHODAEI ET AL.
serving as multiple interaction sites and forms stable coordi-
nated complex with Cu+ (3) as indicated in Scheme 3.
After the successful preparation of immobilized ligand on
the surface of shell (FMNPs@TPy), the optimal loading
amount of CuI was investigated. It is found that a 1:1 mole
ratio of ligand to copper iodide is the best choice. The
obtained catalyst was fully characterized using FT‐IR spec-
troscopy, XRD, SEM, TEM, EDX and VSM.[26]
3.1.1
| FT‐IR spectroscopy
The successful synthesis of the Fe3O4 nanoparticles was con-
firmed from the FT‐IR spectra (Figure 1). The signal
observed at 579 cm−1 is attributed to the Fe─O bond vibra-
tion. The broad peaks at around 3200–3500 cm−1 are
ascribed to the stretching vibrations of hydrogen‐bonded sur-
face water molecules in atmosphere and hydroxyl groups,
which are located on the surface of the iron oxide nanoparti-
cles. These broad peaks may also indicate the presence of
some amount of ferric hydroxide in Fe3O4 (Figure 1a). In
the case of FMNPs@SiO2 (Figure 1b), the sharp band at
1087 cm−1 corresponds to Si─O─Si antisymmetric
stretching. The peak at 807 cm−1 is due to the symmetric
stretching vibration of Si─O─Si. These results indicate the
coating of silica on the surface of FMNPs. The band observed
at 1661 cm−1 could be attributed to the C═N (pyridine ring)
stretching frequency (Figure 1c). The C═N band of the
FMNPs@TPy‐Cu complex is shifted to a lower frequency
(1594 cm−1) compared to that of FMNPs@TPy (Figure 1d).
The lowering in frequency of the C═N peak is indicative of
the formation of a metal–ligand bond. Also the peak at
1228 cm−1 is assigned to the C─O stretching vibration of
phenolic group.
FIGURE
1
FT‐IR spectra: (a) FMNPs; (b) FMNPs@SiO2; (c)
FMNPs@TPy; (d) FMNPs@TPy‐Cu
3.1.2
| X‐ray diffraction
FIGURE
2
XRD patterns: (a) FMNPs@SiO2; (b) TPy‐Cu; (c)
In this work, the crystalline structures of FMNPs@SiO2
(Figure 2a), TPy‐Cu (Figure 2b) and FMNPs@TPy‐Cu
FMNPs@TPy‐Cu
(Figure 2c) were analysed using XRD. The XRD pattern of
Fe3O4 exhibits peaks at 2θ = 30.2°, 35.6°, 43.3°, 53.6°,
57.3° and 62.8° corresponding to diffraction lines (220),
(311), (400), (422), (511) and (440), respectively, which con-
form well to the reported values.[27] The XRD patterns
(Figure 2) show that no change occurs in the crystalline struc-
ture of Fe3O4 after silica modification with TEOS and CPTS.
Also, the XRD pattern shows the sharp peaks of copper com-
plex with terpyridine (Figure 2b). In Figure 2(c), the appear-
ance of peaks at lower than 30° confirms the presence of
copper in the catalyst. The data relating to XRD pattern of
the catalyst are summarized in Table 1. The signal appearing
at 2θ = 25.5° corresponds to the (111) plane of copper.[28]
The average crystallite size (D) for the designed
FMNPs@TPy‐Cu catalyst was calculated using the Debye–
Scherrer equation: D= Kλ/(β cos θ), with λ being the X‐ray
wavelength (0.154 nm), K the Scherrer constant (0.9), β the
SCHEME 3 Preparation of FMNPs@TPy‐Cu (3)

KHODAEI ET AL.
5 of 10
TABLE 1 Analysis of XRD patterns relating to FMNPs@TPy‐Cu
TABLE 2 TGA results
Position, 2θ (°)
Height (cts)
Reduced weight at
600 °C (wt%)a
Organic weight
(%)b
Yield
(%)
Sample
11.9
20.3
25.5
27.0
30.2
35.7
43.2
53.7
57.3
62.9
113
52
FMNPs@SiO2‐Cl
FMNPs@TPy‐Cu
6.87
—
—
19.93
13.98
93.4
54
73
aExperimental ligand part in the catalyst =19.93–6.87 = 13.06.
bTheoritical ligand part in the catalyst =13.98.
148
619
91
3.1.4
| EDX spectroscopy
44
The EDX spectrum of the obtained nanocatalyst indicates the
presence of iron, oxygen, nitrogen, carbon, silicon and cop-
per elements in its structure (Figure 4). The signal of Fe is
attributed to Fe3O4, Si and O correspond to SiO2, C and N
are related to TPy and Cu is assigned to CuI. The spectrum
confirms that FMNPs are coated with silica, modified with
TPy and complexed with CuI.
127
191
peak width of half maximum and θ the Bragg diffraction
angle.[29] The crystallite size of the catalyst (D), obtained at
a peak of say 2θ = 35.731° (θ = 17.8655°, cos θ = 0.554),
is found to be about 22 nm.
3.1.5
| Transmission electron microscopy
3.1.3
| Thermogravimetric analysis
TEM images of FMNPs@TPy‐Cu catalyst are presented in
Figure 5. The dark coloured regions or black spots in the
image of the core–shell correspond to the nano‐Fe3O4, while
the colourless parts represent silica. Figure 5(c) shows that
two small spots might indicate the presence of copper
The thermal behaviour of FMNPs@SiO2‐Cl and the catalyst
is shown in Figure 3. The amount of organic moieties
attached to FMNPs was measured using TGA. The TGA
plots of FMNPs@SiO2 and FMNPs@TPy‐Cu show that ther-
mal decomposition occurs in two steps. The first step weight
loss up to 200–220 °C corresponds to removal of physically
and chemically adsorbed water, whereas, at temperature
higher than 220 °C, the main weight loss (second step) is
due to removal of organic moieties from the surface. Also,
the TGA results indicate that the catalyst has very high ther-
mal stability (about 600 °C).
The TGA results are summarized in Table 2. The
observed total weight loss based on theoretical calculation
corresponds to 93.4% in conversion for the stage of
FMNPs@SiO2‐Cl to FMNPs@TPy‐Cu.
FIGURE 3 TGA curves: (a) FMNPs@SiO2‐Cl; (b) FMNPs@TPy‐Cu
FIGURE 4 EDX patterns: (a) FMNPs@TPy; (b) FMNPs@TPy‐Cu

6 of 10
KHODAEI ET AL.
FIGURE 6 SEM image of FMNPs@TPy‐Cu
composition and shell–core structure. The magnetization
curves for FMNPs@SiO2‐Cl and the obtained nanocatalyst
are depicted in Figure 7. The saturation magnetizations are
found to be 25.5 and 19.7 emu g−1 for FMNPs@SiO2‐Cl
and FMNPs@TPy‐Cu, respectively, which are much lower
than that of bare FMNPs. This can be attributed to the coating
of silica on the magnetic nanoparticles.[30]
3.2 | Catalytic studies of Fe3O4@TPy‐Cu nanocatalyst
3.2.1
| Synthesis of triazoles from sodium azide and terminal
acetylenes
The catalytic activity of the Fe3O4@TPy‐Cu nanocatalyst
was examined in an efficient and convenient preparation of
1,4‐disubstituated 1,2,3‐triazoles using a simple one‐pot
three‐component reaction of primary halides, sodium azide
and terminal acetylenes at room temperature (Scheme 1).
The catalyst was easily recovered using an external magnet
and was reused in at least five successive runs without an
appreciable loss of activity (Figure 8).
FIGURE 5 TEM images: (a) FMNPs@SiO2‐Cl; (b, c) FMNPs@TPy‐Cu
nanoparticles on the surface of the silica shell in the structure
of the catalyst.
3.1.6
| Scanning electron microscopy
The SEM image (Figure 6) shows that FMNPs@TPy‐Cu has
a mean diameter of about 40 nm and a nearly spherical shape.
The nanoparticles are well dispersed and uniform in shape
and size, which is consistent with XRD results and TEM
images.
3.1.7
| Magnetic properties
The magnetic properties of FMNPs@SiO2‐Cl and
FMNPs@TPy‐Cu were characterized using VSM. The satu-
ration magnetization (Ms) of FMNPs is 62.8 emu g−1. This
Ms is affected by various factors including size, shape,
FIGURE
7
VSM magnetization curves: (a) FMNPs@SiO2; (b)
FMNPs@TPy‐Cu

KHODAEI ET AL.
7 of 10
To evaluate the generality of this reaction, we investi-
gated the reactions using n‐butylacetylene and
hydroxymethylacetylene instead of phenylacetylene. Also,
the reactions of phenylacetylene, sodium azide and ring‐
substituted benzyl bromides, bromoacetophenones and allyl
bromide were carried out under the optimized reaction con-
ditions. The results are collected in Table 4. The results
show that the nature of the substituent does not have a con-
siderable effect on the yield and the time of the reaction.
However, the reactions with alkylacetylenes compared with
phenylacetylene proceed in longer reaction times and with
lower yields of products (Table 4, entries 3 and 4). Presum-
ably in the case of phenylacetylene, the aromatic ring pro-
motes the reaction.
In addition, it must be noted that negligible Cu leaching is
found in the reaction in a similar way as already reported in
the literature.[31] To test for leaching, the catalyst in the reac-
tion of benzyl bromide, phenylacetylene and sodium azide
was removed after 3 h and the reaction was permitted to con-
tinue under the same reaction conditions in the absence of the
catalyst. We observed that the reaction without the catalyst
was not completed.
FIGURE 8 Catalytic activity and reusability of magnetically separable Cu‐
based catalyst
We chose benzyl bromide and phenyl acetylene as
model substrates, and their reaction was investigated with
sodium azide in the presence of FMNPs@TPy‐Cu under
various aerobic conditions (Table 3). The reaction rates
are markedly dependent on the amount of catalyst, base
and solvent. Therefore, the application of FMNPs@TPy‐
Cu was examined with the optimization of the reaction
conditions. It is evident from Table 3 (entry 12) that the
best result is obtained when K2CO3 is used as a base,
0.032 mmol of Cu loaded and a mixture of water and eth-
anol (1:1) applied as a solvent. The presence of ethanol as
a co‐solvent leads to an improved solubility of the sub-
strates. Water, dimethylsulfoxide (DMSO), DMF, tetrahy-
drofuran (THF), ethanol and water with co‐solvents such
as DMSO, DMF and ethanol were evaluated as a solvent
and bases such as NEt3, K2CO3, Na2CO3, NaHCO3, NaOH
and KOH were examined in this reaction (Table 3).
3.2.2
| C─S cross‐coupling reaction
In recent years, a series of synthetic protocols have been
reported for the formation of C─S bonds and especially the
preparation of arylalkyl and diaryl sulfides through cross‐
coupling reactions using copper nanoparticles as catalyst.
TABLE 3 Optimization of reaction conditions for synthesis of 1,4‐disubstituted 1,2,3‐triazolesa
Entry
FMNPs@TD‐Cu (g)
Base
Solvent
Yield (%)b
1
—
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
NaHCO3
NaOH
KOH
H2O–EtOH (1:1)
H2O
Trace
35
67
78
78
74
85
80
83
88
92
97
64
78
80
79
2
0.04
0.06
0.08
0.1
3
H2O
4
H2O
5
H2O
6
0.06
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
DMSO
7
DMF
8
THF
9
EtOH
10
11
12
13
14
15
16
H2O–DMSO (1:1)
H2O–DMF (1:1)
H2O–EtOH (1:1)
H2O–EtOH (1:1)
H2O–EtOH (1:1)
H2O–EtOH (1:1)
H2O–EtOH (1:1)
NEt3
aReaction conditions: phenylacetylene (1.2 mmol), NaN3 (1 mmol), benzyl bromide (1 mmol), catalyst (80 mg), solvent (4 ml), 25 °C.
bIsolated yield.

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KHODAEI ET AL.
TABLE 4 One‐pot synthesis of 1,4‐disubstituted 1,2,3‐triazolesa
Entry
R1
X
R2
Time (h)
Yield (%)b
1
C6H5
C6H5
Br
Cl
Br
Cl
Br
Br
Br
Br
Cl
Br
Br
Br
C6H5CH2
C6H5CH2
C6H5CH2
C6H5CH2
C6H5CH2
8
8
97
96
85
83
89
93
90
91
90
87
85
94
2
3
CH2OH
CH2OH
n‐C4H9
C6H5
13
13
16
8
4
5
6
O2NC6H4CH2
MeC6H4CH2
PhC6H4CH2
7
C6H5
9
8
C6H5
9
9
C6H5
MeOC6H4CH2
C6H5COCH2
4‐BrC6H4COCH2
CH2═CHCH2
10
9
10
11
12
C6H5
C6H5
10
8
C6H5
aThree‐component reaction conditions: alkyne (1.2 mmol), NaN3 (1 mmol), alkyl halide (1 mmol), catalyst (80 mg), H2O–EtOH (4 ml), 25 °C.
bIsolated yield.
TABLE 5 Optimization of reaction conditions for synthesis of diphenyl
sulfide
The magnetic nanocatalysts of copper are efficient catalysts
for C─S coupling reactions. In this work, copper(I) supported
on functionalized FMNPs was used as an efficient and mag-
netically recoverable catalyst for C─S cross‐coupling reac-
tions of aryl halides with thiols (Scheme 2). It is notable
that after completion of the reaction, the catalyst was sepa-
rated from the mixture using an external magnet, washed
with deionized water and ethanol, and then dried. It can be
reused up to five times without significant decrease in effi-
ciency (Figure 8).
Initially, we examined the coupling of iodobenzene with
thiophenol as a model reaction in the presence of various
amounts of catalysts, and with a variety of bases and solvents.
It is found that using iodobenzene (1 mmol), thiophenol
(1 mmol) and K2CO3 (0.1 g) in the presence of nanocatalyst
(0.08 g, 0.032 mmol Cu) in DMF at 110 °C affords the
desired product in 94% yield (Table 5). It is seen that DMF/
K2CO3 system has a good compatibility in the product yield.
To define the scope of the FMNPs@TPy‐Cu‐catalysed
coupling reaction, we investigated the reactivity of
thiophenol, p‐nitrothiophenol and p‐methylthiophenol with
various substituted aryl halides under optimized conditions.
In general, all reactions are very clean and this protocol gives
the corresponding thioethers in good to excellent yields
(Table 6, entries 1–16). The reactions with aryl bromides
afford slightly lower yields and require longer reaction
times (Table 6, entries 7–9). The small decrease in the yield
of o‐product (Table 6, entries 3 and 5) can be ascribed to steric
hindrance at the substrates. It must be noted that when 2‐
iodothiophene is used, the desired product is obtained in
90% yield and no poisoning of the catalyst is observed. Aryl
chlorides are not reactive under these reaction conditions
Entry
FMNPs@TPy‐Cu (g)
Base
Solvent
Yield (%)b
1
0.04
0.06
0.08
0.1
K2CO3
K2CO3
K2CO3
K2CO3
Na2CO3
KOH
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
Toluene
DMSO
THF
35
67
94
94
74
82
80
53
86
69
83
53
50
2
3
4
5
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
0.08
6
7
NaOH
8
Et3N
9
NaOBut
K2CO3
K2CO3
K2CO3
K2CO3
10
11
12
13
EtOH
aReaction conditions: iodobenzene (1 mmol), thiophenol (1.2 mmol), base
(3.0 mmol), solvent (3 ml), FMNPs@Tpy‐Cu (80 mg), 6 h.
bIsolated yield.
(Table 6, entry 17). Unfortunately, an attempt to couple an
aliphatic thiol (Table 6, entry 18) with aryl halides failed.
3.2.3
| Reusability of catalyst
The reusability of the catalyst was studied during the prepara-
tion of 1,4‐disubstituted 1,2,3‐triazoles and thioethers. After
completion of the reaction, the catalyst was easily removed

KHODAEI ET AL.
9 of 10
TABLE 6 C─S cross‐coupling reactions of aryl halides and thiolsa
Entry
Ar
X
Ar′
Time (h)
Yield (%)b
1
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
C6H5
I
I
C6H5
5
5
94
92
2
4‐MeC6H4
2‐MeC6H4
4‐MeOC6H4
2‐MeOC6H4
C4H3S
3
I
6
90
4
I
5
91
5
I
7
89
6
I
5
90
7
Br
Br
Br
Br
Br
Br
I
C6H5
10
10
8
87
8
4‐MeC6H4
4‐O2NC6H4
C6H5CH2
4‐BrC6H4
4‐MeC6H4CH2
C6H5
86
9
90
10
11
12
13
14
15
16
17
18
5
95
5
90
5
92
4‐MeC6H4
4‐MeC6H4
4‐MeC6H4
4‐NO2C6H4
C6H5
5
95
I
4‐MeC6H4
4‐MeOC6H4
C6H5
5
91
I
6
89
I
7
85
Cl
I
C6H5
24
24
Trace
Trace
n‐C4H9
C6H5
aReaction conditions: aryl halide (0.5 mmol), ArSH (0.5 mmol), DMF (1 ml), K2CO3 (0.1 g), catalyst (80 mg), 110 °C.
bIsolated yield.
using an external magnet. It was simply recovered by succes-
sively washing with organic solvent (ethanol) and vacuum
drying. The catalyst was tested for five consecutive runs
and, through each run, no fresh catalyst was added. For
example, the reaction of phenylacetylene, benzyl bromide
and sodium azide affords the corresponding 1,4‐disubstituted
1,2,3‐triazole five times in sequence (Figure 8). As the results
in Figure 8 show, the catalyst can be used several times with-
out any appreciable loss of its initial catalytic activity. To
determine the catalyst leaching into solution, atomic absorp-
tion spectroscopy (AAS) was used to measure the amount
of copper before and after five successive runs using
FMNPs@TPy‐Cu. The amount of copper attached on fresh
catalyst is 2.16% based on the AAS results, while the amount
of copper decreases to 2.15% after five sequential reuses.
Hence, the amount of copper leached from the catalyst is
0.01% after five runs, which is negligible, and this is due to
strong interaction between copper and catalyst.
and the synthesis of thioethers from C─S cross‐coupling
reactions of thiols and aryl halides.
This highly active heterogeneous nanocatalyst has a very
high surface area, and its thermal and chemical stabilities
were confirmed using various characterization techniques.
This recoverable and reusable catalyst is benign, of low cost
and can be handled easily.
ACKNOWLEDGEMENT
The authors thank the Razi University Council for support of
this work.
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How to cite this article: Khodaei MM, Bahrami K,
Meibodi FS. Ferromagnetic nanoparticle‐supported
copper complex: A highly efficient and reusable cata-
lyst for three‐component syntheses of 1,4‐disubstituted
1,2,3‐triazoles and C–S coupling of aryl halides. Appl
Organometal Chem. 2017;e3714. https://doi.org/
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