Synthesis of magnetically separable catalyst Cu-ACP-Am-Fe3O4@SiO2 for Huisgen 1,3-dipolar cycloaddition

Article abstract of DOI:10.1016/j.tetlet.2018.08.045

The present manuscript elicits the use of novel magnetically separable silica coated copper (Cu-ACP-Am-Fe₃O₄@SiO₂) as a heterogeneous nanocatalyst for the Huisgen 1,3-dipolar cycloaddition reaction of alkyl or aryl halide,

Full text of DOI:10.1016/j.tetlet.2018.08.045

Accepted Manuscript
Synthesis of magnetically separable catalyst Cu-ACP-Am-Fe3O4@SiO2 for
Huisgen 1,3-dipolar cycloaddition
S.P. Vibhute, P.M. Mhaldar, S.N. Korade, D.S. Gaikwad, R.V. Shejawal, D.M.
Pore
PII:
S0040-4039(18)31046-3
https://doi.org/10.1016/j.tetlet.2018.08.045
TETL 50220
DOI:
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
14 July 2018
18 August 2018
22 August 2018
Please cite this article as: Vibhute, S.P., Mhaldar, P.M., Korade, S.N., Gaikwad, D.S., Shejawal, R.V., Pore, D.M.,
Synthesis of magnetically separable catalyst Cu-ACP-Am-Fe3O4@SiO2 for Huisgen 1,3-dipolar cycloaddition,
Tetrahedron Letters (2018), doi: https://doi.org/10.1016/j.tetlet.2018.08.045
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Synthesis of magnetically separable catalyst Cu-ACP-Am-Fe3O4@SiO2 for
Huisgen 1,3-dipolar cycloaddition
S. P. Vibhutea, c, P.M. Mhaldara, S. N. Koradea, D. S. Gaikwada, R. V. Shejawalb, D. M. Porea*
aDepartment of Chemistry, Shivaji University, Kolhapur- 416004, India
*E-mail: p_dattaprasad@rediffmail.com
bLal Bahadur Shastri College of Arts, Science and Commerce, Satara
cShrimant Babasaheb Deshmukh Mahavidyalaya, Atpadi.
Abstract: The present manuscript elicits the use of novel magnetically separable silica coated copper (Cu-
ACP-Am-Fe3O4@SiO2) as a heterogeneous nanocatalyst for the Huisgen 1,3-dipolar cycloaddition reaction of
alkyl or aryl halide, sodium azide and terminal alkyne, which provide a series of 1,4-disubstituted-1,2,3-
triazoles. The catalyst was characterized by various physicochemical techniques such as Powder X-ray
Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM),
Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray Spectroscopy(EDS), Thermogravimetric
analysis (TGA-DSC), X-ray Photoelectron spectroscopy (XPS) and Vibrational sampling magnetometer
(VSM). The acquisition of this nanocatalyst is also exemplified by employing reusability test and recycling of
synthesized catalyst was achieved multiple times just by sequestering with an external magnet. It is
noteworthy that the key-features like mild reaction conditions, simple work-up, High turnover number (TON),
high turnover frequency (TOF), no use of hazardous organic solvents, easy recovery and reusability of the
catalyst makes the present protocol more fascinating from an environmental and economic point of view.
Keywords: Magnetic Nanoparticles, Acetyl Pyridine, Heterogeneous catalyst, Reusability, Cycloaddition.
Thus, in last decade magnetically separable nano material as a
heterogeneous catalyst became a choice of catalyst from the organic
synthetic viewpoint.
Introduction:
In this context, iron oxides and relevant iron containing
nanoparticles have gained considerable attention and several
In current scenario due to environmental legislation, the
society’s driving force is to search for an ecofriendly catalyst which
chemical methods have been reported in the literature for their
can be utilized in eco-benign solvents (e.g., water, ethanol). Nano
synthesis.14-19 However, a major demerit for most of the methods is
metal catalysts are being widely used for promoting organic
the instability of the nanoparticles rooted from their high tendency
reactions owing to their superior catalytic activity over bulk metal
for aggregation and possible degradation on exposure to harsh
environments. The best way to improve their dispersibility and to
and cost effectiveness, most of the times the separation of nano
overcome these limitations is coating them with protective layers,
catalysts. In spite of having advantages such as enhanced activity
catalyst becomes expensive due to need of filtration, solvent
forming core-shell type nanocomposites, organic (surfactants or
extraction or centrifugation of the final reaction mixture. Sometimes,
polymers) or inorganic (silica, carbon, precious metals or
product and catalyst are insoluble in common solvents lead to
oxides).1,4a,8,12 Remarkably, silica coating has been proved as a
difficulty in work-up. Scientific community put forward remedy to
promising tool to shield the magnetic dipolar interactions between
overcome the isolation issues of nano materials by discovery of
magnetic nanoparticles. Furthermore, chemical stability of silica
coating offers additional advantages viz. biocompatibility and easy
highly paramagnetic nano materials1. Magnetic separation is an
attractive alternative to filtration or centrifugation as it prevents loss
surface alteration which allows grafting of new functionalities onto
1,4,8
of the catalyst results in remarkable catalyst recovery and increases
the surface of nanoparticles.
efficient synthesis of
Herein, we report a simple and
nano-ferrite-supported, magnetically
reusability. Their insoluble and paramagnetic nature enables easy
and efficient separation of the catalysts from the reaction mixture
with an external magnet. This makes the catalyst cost-effective and
promising for industrial applications.2 The use of magnetic nano
particles has been studied extensively for various biological
applications such as magnetic resonance imaging, drug delivery, and
bio molecular sensors.3 Recently, research in the super paramagnetic
nanoparticles have been boosted to a large extent owing to their
extraordinary physicochemical properties and wide range
applications in various fields such as biomedicine/biotechnology,4-7
catalysis,8 magnetic sensors,9 magnetic fluids,10 data storage
devices,11 magneto-optical devices12 and magnetic refrigeration.13
a
recyclable, and inexpensive Cu catalyst and its application in
Huisgen 1,3-dipolar cycloaddition reaction to synthesize 1,2,3-
triazoles via one of the most powerful click reaction.
Over the past few years click reaction for synthesis of 1,2,3-
Triazoles have dragged immense attention of synthetic chemists due
to their multifarious applications in pharmaceuticals, agro chemicals,
dyes, photographic materials, corrosion inhibition20, etc. They are
found to exhibit wide range of bioactivities such as antiviral21,
antiallergic22, anticancer23, anti HIV24 and antimicrobial activities25
against gram positive bacteria which reflects their versatility and
significance in drug chemistry. In this context, the researchers are in

O
O
FeCl3.6H2O
TEOS, EtOH
APTES, EtOH
24 h, RT
Urea, NaOH
O
Si
Fe3O4
Fe3O4
Fe3O4
H
2N
+
FeSO4.7H2O
85-90oC, 2 h
NH4OH, RT, 24 h
Am-Fe O @SiO
2
3
4
Fe3O4@SiO2
Acetyl Pyridine
EtOH
RT, 24 h
O
O
Copper Acetate Monohydrate,
Acetone
Fe3O4
Fe3O4
O
N
Si
O
N
Si
RT, 6 h
O
O
N
N
Cu-
OAc
ACP-Am-Fe O @SiO
3
4
2
AcO
Cu-ACP-Am-Fe O @SiO
2
3
4
Scheme 1: Synthesis of silica coated ferrite supported organic–inorganic hybrid copper catalyst (Cu-ACP-Am-Fe3O4@SiO2)
quest of development of greener and economical synthetic strategies of silica around the magnetic core as corroborated by the appearance
for synthesis of 1,2,3-triazoles by click approach.
of Si–O–Si asymmetric, Si–O–Si symmetric, stretching vibrations at
1080, 799 cm−1 respectively.27
Moreover, on consequently moving towards the Amine
Results and discussion:
An initial attempt in the accomplishment of this goal was the functionalized Fe3O4@SiO2, two new bands at 1641 cm−1 and 2927
synthesis and functionalization of magnetic nanoparticles (Scheme cm−1 are observed corresponds to the NH2 and CH2 the groups of the
1). The catalyst was characterized by diverse physicochemical amino-propyl moiety, respectively. The characteristic C=N band at
techniques such as Powder X-ray Diffraction (XRD), Fourier 1644 cm−1 confirms the immobilization of the ligand over the amine
Transform Infrared Spectroscopy (FT-IR), Scanning Electron functionalized magnetite nanoparticles. Remarkably, an alteration in
Microscopy (SEM), Transmission Electron Microscopy (TEM) this value in the final Cu-ACP-Am-Fe3O4@SiO2 nanocatalyst
Energy Dispersive X-Ray Spectroscopy (EDS), Thermogravimetric suggests the formation of a co-ordinative linkage between the
Analysis (TGA-DSC) X-ray Photoelectron Spectroscopy (XPS) and nitrogen atom of the ligand and the metal. These results signify that
Vibrating Sample Magnetometer (VSM).
the copper species effectively bind onto the surface of the modified
magnetite nanoparticles (MNPs) as a ACP-copper complex.
Phase and structural characterization of the catalyst was done by
powder X-ray diffraction (XRD) (Fig. 2).
The XRD analysis exhibited the information about the
crystallographic structure, chemical composition, and physical
properties of the nanocomposites. The positions and the relative
intensities in the diffractogram matched well with the standard XRD
data of Joint Committee on Powder Diffraction Standards (JCPDS)
card number (19-0629) for Fe3O4, which is consistent with the TEM
result.
Fig. 1 FTIR analysis
The FTIR spectroscopic analysis was done in order to confirm
the structures of the Fe3O4, Fe3O4@SiO2, Am-Fe3O4@SiO2, ACP-
Am-Fe3O4@SiO2 and Cu-ACP-Am-Fe3O4@SiO2 nanoparticles. The
FTIR spectrum of Fe3O4 displays an intense absorption band at 588
cm−1 which is attributed to the typical Fe–O vibrations of the
magnetite structure whereas a broad band at 3114 cm−1 is relevant to
the presence of surface OH groups26. On the contrary, the IR
spectrum of Fe3O4@SiO2 provides strong evidence of the occurrence
Fig. 2 XRD analysis
The broadening of XRD peaks could be attributed to the decrease
in crystalline size of the Fe3O428. The XRD pattern for Fe3O4@SiO2
showed a weak broad band at 2θ = 20–24◦ which is due to the
coating of amorphous silane shell formed around the magnetic

core29. Other than this, there is no any other appreciable shift in the
peak positions, which indicates that the extreme chemical and
physical conditions created during silica coating process have no
significant effect on crystallographic structural characteristic of
magnetite nanoparticles.
e
The morphology and particle size of the catalyst was determined
by Scanning Electron Microscopy (SEM) and Transmission Electron
Microscopy (TEM) analysis, respectively.
Fig.4 TEM images of prepared catalyst
a
c
b
ꢀ
ꢀ
Before reaction (a) 20nm (b) 50nm;
After reaction (c) 20nm (d) 50nm (e) SAED
EDS analysis of an prepared catalyst indicates the presence of Cu
with its respective energy position at 0.92 KeV, 8.10 KeV and 8.90
KeV.
d
Fig.3 SEM images of Cu-ACP-Am-Fe3O4@SiO2
ꢀ
ꢀ
before reaction (a) 100nm (b) 1µm ;
after reaction (c) 100nm (d) 1µm.
SEM images (Fig. 3) exhibits that MNPs are roughly in
spherical shape possessing average size less than 60 nm. Another
important aspect that needs to be highlighted is that there is no
separate aggregation of silica that predicts the precipitation of the
primary nanoparticles occurs on the surface of magnetic core.
Besides SEM, Transmission Electron Microscopy (TEM)
analysis of the MNPs, reveals a roughly spherical morphology with
an average size 21 nm. The presence of silica coating around the
magnetic core can be visualized in the TEM images (Fig.4).
Furthermore, from the TEM image of the recovered catalyst after
reaction can be interpreted that the structural morphology of
nanocatalyst remains unchanged even after 6 consecutive cycles,
demonstrating its high catalytic efficiency. From selected area
electron diffraction (SAED) pattern of MNPs, crystallinity was
confirmed by the presence of diffraction rings, which originates from
the different planes of magnetite. (Fig.4e)
Fig. 5 EDS analysis of prepared catalyst
X-ray photoelectron spectroscopy (XPS) analysis of the catalyst
is shown in Fig. 6a &6b.
a
b
Fig. 6a XPS analysis
The binding energy values 933.15 and 953.01 eV corresponding
to the spin orbit splitting components of Cu 2P3/2 and Cu 2P1/2 in the
+2 oxidation state of copper agrees well with the reported literature
values30. A satellite peak observed at 942.58 eV in the XPS spectrum
(Fig. 6b), which is a feature of 2P/3d satellite peak of Cu in +2
oxidation state. Hence based on the XPS output, the Cu species in
the catalyst is in the +2 oxidation state.
d
c

out in presence of catalyst and sodium ascorbate at room temperature
(Scheme 2). Timely analysis of the reaction mixture (TLC) did not
indicate any appreciable progress. Hence reaction was carried out at
reflux condition and it was truly gratifying to notice that, the
corresponding 1,2,3 triazole was obtained with 71% yield. Further,
screening of solvents was done to obtain standard reaction
conditions. Pleasingly, in ethanol corresponding 1,2,3 triazole was
obtained in excellent yield (95%) within a short time duration.
Reaction was also screened in terms of temperature and catalyst
loading. Best result was obtained using 40 mg of catalyst in ethanol at
80 0C (Table 1, Entry 1). There was no difference in yield and reaction
time when catalyst loading was increased to 50 mg (Table 1, Entry 12).
However, it took longer time for completion of the reaction and inferior
yield obtained when catalyst loading was reduced to 20 mg, 15 mg or 10
mg (Table 1, Entry 13-15). To check the effect of the catalyst and
sodium ascorbate, a click reaction was performed without catalyst and
without sodium ascorbate, in both cases no product was obtained. Hence
after achieving the best reaction condition next decided to probe the
generality of the method.
Next, we turned our attention to examine generality of the
reaction conditions. Accordingly benzyl bromide component in the
model reaction was replaced with fluoro, methoxy, nitro, cyano etc.
In each case, corresponding 1,2,3-triazole was obtained in excellent
yield (Table 2), and most gratifyingly, the resultant product did not
require any further purification by conventional methods. During the
extension of the protocol towards aliphatic bromides it was observed
that, in case of alkyl halides like n-butyl bromide as well as ethyl
chloroacetate, the reaction required longer reaction time and
furnished corresponding triazoles in lower yields (Table 2 entries
5,9,10,15).
Fig. 6b XPS analysis
After this initial success in the synthesis of designed catalyst,
Cu-ACP-Am-Fe3O4@SiO2, we focused our attention towards
exploring its catalytic activity in click reaction. A model reaction of
benzyl bromide, phenylacetylene and sodium azide was chosen and
screening of solvents, effect of temperature and effect of different
amount of catalyst was studied. (Table 1)
Table 1: Optimization of reaction condition for synthesis of 1,4-
disustituted 1,2,3-triazole
Br
N
Cu-ACP-Am-Fe3O4@SiO2
N
In addition to this instead of phenylacetylene substituted isatin
alkynes were also employed to check the effect on protocol. It was
found that reaction proceeds smoothly furnished excellent output in
terms of yield with different kind of isatin alkynes (Table 3).
It’s an added advantage of magnetically separable
heterogeneous catalyst that it can be easily recovered after
completion of the reaction without any significant loss. The
reusability of the catalyst Cu-ACP-Am-Fe3O4@SiO2 was also
studied for reaction between benzyl bromide and phenylacetylene.
N
+
Sodium ascorbate
Ethanol, 80 oC
NaN3
Entry
Solvent
Time
( min)
20
Yield
b
%
1
2
Ethanol
Ethanol
Methanol
Water
96
75
92
71
75
81
86
79
89
57
76
96
75
63
51
40*
20
3
4
30
96
92
89
100
80
60
40
20
0
85
81
5
Ethanol :Water (7:3)
Ethanol:Water (6:4)
Ethanol:Water (1:1)
Acetonitrile
30
78
6
30
7
30
8
30
9
Dimethylformamide
Tetrahydrofuran
30
10
11
12
13
14
15
30
1
2
3
4
5
6
Dichloromethane
30
Number of cycles
Ethanol (catalyst: 40mg)
Ethanol (catalyst: 20mg)
Ethanol (catalyst: 15mg)
Ethanol (catalyst: 10mg)
20
Fig.7: Reusability study of Cu-ACP-Am- Fe3O4@SiO2
30
50
After completion of the reaction the catalyst was separated from
reaction mixture by using bar magnet, washed thoroughly with water
and ethanol, dried in air and reused for next run. It was noticed that
catalyst could be recycled six times without any noticeable loss in
yield (Fig.7). After sixth run we analyzed the catalyst by SEM and
TEM analysis, and it was found that no significant change in
morphology as well as particle size of the nano catalyst.
Fig. 8 shows the magnetization curve of catalyst obtained by
VSM at room temperature. The saturation magnetization of catalyst
was 57.09 emu/g. Neither coercivity nor remanence were observed.
Nanoparticle exhibited typical superparamagnetic behaviour. The
magnetization of catalyst is not far from the actual magnetization of
80
Reaction conditions: Benzyl bromide (1 mmol), phenylacetylene (1
mmol), sodium azide (1.1 mmol), Sodium ascorbate (0.015 mmol)
catalyst : 40 mg, temperature: 80 C; Isolated yield * Reaction at
toom temperature.
0
b
Initially a model reaction for Huisgen 1,3 dipolar cycloaddition of
benzyl bromide, phenylacetylene and sodium azide in water was carried

the Fe3O4 is 92 emu/g31. The excellent magnetic responsivity was atmosphere (Fig. 9). In the beginning, the slight weight loss of
necessary for magnetic separation of the catalyst.
2.49% observed in the temperature range of 35.40-84.86 0C was due
to evaporation of physically adsorbed water molecules in the
catalyst. The second weight loss in the temperature range of 182.72-
266.45 OC (5.37 %) is attributed to decomposition of organic ligand
moiety along with copper acetate group. The aminopropyl spacer in
the catalyst decomposes in the thermal range of 266.45- 431.90 OC
which is reflected in the weight loss of 2.75 %. An abrupt weight
loss of 2.52 % in the thermal range 431.90-719.43 indicates the
decomposition of silica coating on ferrite. Finally the largest residual
weight 83.44 % after thermal degradation of catalyst is in
accordance with the non-volatile oxides of iron.
The catalytic activity of Cu-ACP-Am-Fe3O4@SiO2 was
compared with other synthesized MNPs complex of Cu(I), Cu(II)
ions (Table 4). It is noteworthy that the use of Cu-ACP- Am-
Fe3O4@SiO2 as new heterogeneous and reusable catalyst for 1,3-
dipolar cycloaddition has an excellent activity as compared to earlier
reported copper catalytic systems. The use of ethanol as eco-benign
solvent system, easy isolation of product from the reaction mixture,
operational simplicity, and reusability of catalyst are the merits of
present method.
Fig. 8 Saturation Magnetization of catalyst
Conclusion
We have developed a highly selective, economical, efficient
method for one pot muliticomponent 1,4 disubstituted 1,2,3 –
triazoles. The reactions were achieved under relatively mild
experimental condition with high yield. Moreover the broad
substrate scope, short reaction time, high yield, easy recovery of
catalyst and reusability without any appreciable loss of activity make
it a favourable protocol for the reaction
Acknowledgement
We are grateful to acknowledge, The Atpadi Education Society’s
Shrimant Babasaheb Deshmukh Mahavidyalaya, Atpadi for their
encouragement and help. One of the authers PMM gratefully
acknowledge the Council of Scientific and Industrial Research
(CSIR), New Delhi, for financial assistance [File No.
09/816(0040)/2017-EMR-I.
Fig 9. TGA-DTA analysis of the catalyst
Catalyst is thermally stable and it was investigated by
Thermogravimetric Analysis (TGA) and Differential Thermal
Analysis (DTA) from the temperature range of 35-1000OC in an air
Table 2: Substrate scope for 1,2,3-triazoles
N
N
Cu-ACP-Am-Fe3O4@SiO2
R'
N
R'
R
Sodium ascorbate
Ethanol, 80 oC
+
NaN3
R
X
Scheme 2 Synthesis of 1,2,3-triazoles by click approach
Entry
Alky/Aryl Halide
(R)
Alkyne
(R’)
Product
Time Yieldb
TON
TOF
Min
%
N
N
Cl
N
1
20
91
5055
252

N
N
N
Br
2
15
95
5257
351
OCH
N
3
N
F
F
N
Br
3
15
93
5166
344
OCH3
Br
N
N
4
5
20
20
91
85
5055
4722
252
236
N
F
F
F
F
N
N
Br
N
F
NC
Br
N
N
6
20
87
4833
241
NC
N
F
NC
Br
N
N
7
20
87
4833
241
NC
N
N
N
N
N
Br
N
N
N
N
8
20
86
4777
238
O N
O2N
2
N
N
9
Br
20
82
4555
227
N
N

N
N
Br
N
10
11
20
15
82
92
4555
5111
227
340
OMe
OMe
OMe
OMe
F
OCH
N
3
Br
N
F
N
OCH3
OMe
NC
Br
N
N
12
13
14
20
15
20
91
93
90
5055
5166
5000
252
344
250
NC
N
OMe
F
OCH
N
Br
3
N
F
N
OCH3
Br
N
N
O2N
N
O N
2
O
N
N
O
HO
Cl
O
N
O
15
20
85
4722
236
HO
Br
N
N
HO
N
16
20
89
4944
247
HO
O2N
O N
2
Reaction conditions: Alkyl/Aryl halide (1.0 mmol), alkyne (1.0 mmol), sodium azide (1.1 mmol), Sodium ascorbate (0.015mmol), Catalyst
40mg ethanol (5mL) , Temp.80 0C; b Isolated yield TON = Turn Over Number, TOF = Turn Over Frequency

Table 3: Synthesis of 1,2,3-triazoles by using substituted isatin alkyes
O
O
R1
R1
X
Cu-ACP-Am-Fe3O4@SiO2
O
O
+
R
N
N
Sodium ascorbate
o
Ethanol, 80 C
NaN3
N
R
N
N
Entry
Aryl/Alkyl
Halide (R)
R1
Product
Time
(min)
Yieldb
(%)
TON
TOF
O
O
O
Cl
N
O
O
1
H
20
89
4944
235
N
O
N
N
O
Br
O
O
Cl
N
O
O
2
Br
22
85
4722
214
N
O
N
N
O
Br
F
O
Br
N
OCH3
3
Br
24
96
5333
222
OCH3
N
N
N
F
O
O
H3CO
Cl
O
O
O
4
OCH3
21
92
5112
243
O
N
N
N
N
O
H3CO
O
N
5
OCH3
20
86
5777
289
Br
N
N
N

O
O
O
Cl
N
O
O
6
CH3
22
92
5445
247
N
O
N
N
Reaction conditions: Alkyl/ aryl halide (1.0 mmol), alkyne (1.0 mmol), sodium azide (1.1 mmol), ethanol (5 mL), Temp.80 0C; b Isolated
yield of pure product.
Table 4: Comparison of catalytic activity of the Cu-ACP-Am-Fe3O4@SiO2 catalyst with literature precedents using Cu based homogeneous
and heterogeneous catalysts for Click reaction.
Sr.
No.
1
Catalyst
Temp
0C
Solvent
Time
(h)
Yield
%
Ref.
Cu-ACP-Am-Fe3O4@SiO2
80
Ethanol
20a
96
Present work
2
Cu-ACP-Am-Fe3O4@SiO2
RT
70
Ethanol
Water
40a
3
75
93
98
98
98,
98
98
92
Present work
3
CuFe2O4 NPs, 5 mol %
32
33
34
35
4
Cu NPs on activated carbon (0.5 mol %)
Clay supported Cu(II)
70
Water
3
5
RT
80
ACN: H2O
Water,
8
6
CuBr on graphene oxide / Fe3O4
(benzyl chloride), 5 mol %
8,
10a
6
microwave
Water
7
8
Silica immobilised NHC-Cu(I), 0.5 mol %
Polymer supported Ionic liquid
MR-IMZ-As, CuSO4.5H2O
Cu–Al2O3 NPs, 10 mg
80
36
37
RT
Water
2
9
RT
70
Water
3
92
93
99
80
90
38
39
40
41
42
10
11
12
13
Cu/SiO2 composite (10 mol %)
Cu NPs
Water
12
7
RT
RT
Methanol
Water
µ-Hydroxyl trinuclear copper(II) compounds (1% equiv)
6
Dicationic
1,3-bis(1-methyl-1H-imidazol-3-ium) 80
Ethanol:Water
(6:4)
2
propanecopper(I) dibromate catalyst [bis-(MIM)] (CuBr2)]
aTime in min.
Experimental:
Materials:
Ferric chloride hexahydrate (FeCl3.6H2O), Ferrous sulphate determined by X-ray Photoelectron Spectroscopy PHI 5000 Versa
heptahydrate (FeSO4.7H2O) (Loba Chemie), Sodium hydroxide Probe-II.
(Sigma-Aldrich),
Tetraethyl
orthosilicate
(TEOS),
3-
Preparation of Catalyst:
aminopropyltriethoxysilane (APTES) (Alfa Aesar), Copper acetate
monohydrate (S. D.fine), Sodium hydroxide (NaOH) (Sigma-
Aldrich), Urea (Thomas Baker)and all other reagents and solvents
Preparation of Magnetic Nanoparticles (MNPs):
Magnetite nanoparticles (MNPs) were synthesized by simple co-
precipitation method. Typically FeCl3.6H2O(5.41g) and Urea(3.6 g)
were commercially obtained and used without any further were dissolved in 200mL water. The resulting mixture was heated at
0
purification.
85 to 90 C for 2hrs.The solution turned into brown colour. The
IR spectra were recorded on Bruker FT-IR Spectrometer. 1H resultant reaction mixture was cooled to room temperature and to
(400 MHz) and 13C (100 MHz) NMR spectra were recorded using this solution FeSO4.7H2O ( 2.78 g) and 0.1M NaOH was added until
Bruker Avance spectrometer. Phase transformation and structural pH=10. The obtained black coloured precipitate was dispersed by
changes
were
determined
by
X-Ray
Powder ultrasonicator in a sealed flask at 30 to 35 0C for 30 min. The
Diffractometer(XRD)D2 PHASER, Bruker. Scanning electron prepared magnetic nanoparticles of Fe3O4 was washed with ethanol
micrographs were obtained using Field Emission Gun-Scanning and dried under vacuum.
Electron Microscope (FEG-SEM) with Energy Dispersive Preparation of Silica Coated magnetic Nanoparticles:
Spectrometer (EDS) using JEOL JSM-7600F instrument.
The coating of silica layer on the surface of nano Fe3O4 (1.0 g)
Transmission electron Microscopy (TEM) analysis of the sample was achieved by dispersion of MNPs in ethanol (200 mL) for 30
was carried out using Philips CM 200 operated at 200 kV. Magnetic min. at room temp. Then conc. NH4OH (12 mL) and TEOS (2 mL)
properties of the sample was analyzed by using the Vibrating Sample was added successively. After stirring for 24 h the brownish black
Magnetometer (VSM) lakeshore 7410, Oxidation state of Copper

coloured precipitate of Fe3O4@SiO2was formed. The resultant
product was washed three times with ethanol and dried in vacuum.
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Functionalization
aminopropyltriethoxysilane(APTES):
of
Fe3O4@SiO2
with
3-
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Preaparation of Acetyl pyridine immobilized on amine
functionalized silica coated magnetite nanoparticles (Cu-ACP-
Am-Fe3O4@SiO2):-
The final synthesis of Cu-ACP-Am-Fe3O4@SiO2 nonocatalyst
was carried out in two steps. First, a mixture of Am-Fe3O4@SiO2
(1.0 g) and acetyl pyridine (2 mL) was stirred in ethanol (200 mL) at
room temperature for 24 h. Thereafter ACP-Am-Fe3O4@SiO2 (1.0 g)
was added to a solution containing 1.5 mmol copper acetate and
resultant mixture was stirred for 6 h at room temperature. The
resulting nonocomposites were removed magnetically, washed
thoroughly with acetone and dried in oven to generate Cu-ACP-Am-
Fe3O4@SiO2.
General procedure for synthesis of 1,4-disubstituted 1,2,3-
triazoles:
In a 50 mL round bottom flask alkyl/ aryl halide (1.0 mmol),
sodium azide (1.2 mmol), alkyne (1.0 mmol), Cu-AcP-Am-
Fe3O4@SiO2 (40 mg) and sodium ascorbate (29 mg, 0.15 mmol)
were mixed and stirred in 5 mL ethanol. The reaction was allowed to
proceed for 20 min at 800C. Reactions were monitored by Thin Layer
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ꢀ The catalyst could be recycled and reused up to
six consecutive runs without significant loss in
yield.
Graphical Abstract
Synthesis of magnetically separable
catalyst Cu-ACP-Am-Fe3O4@SiO2
for Huisgen 1,3-dipolar
cycloaddtion
aDepartment of Chemistry, Shivaji University,
Kolhapur- 416004, India
*E-mail: p_dattaprasad@rediffmail.com
bLal Bahadur Shastri College of Arts, Science and
Commerce, Satara
cShrimant Babasaheb Deshmukh Mahavidyalaya,
Atpadi..
Highlights
ꢀ Magnetically separable amine functionalized
Copper complex was synthesized.
ꢀ The catalyst was employed efficiently for
Huigsen 1,3 dipolar cycloaddition reaction.