Magnetic (chitosan/laponite)-immobilized copper(II) ions: an efficient heterogeneous catalyst for azide-alkyne cycloaddition

Article abstract of DOI:10.1039/c6nj03862j

Cu²⁺ ions immobilized on a novel magnetic chitosan-based catalytic system were prepared in combination with laponite RD. The Cu^II-magnetic chitosan/laponite RD (Cu-mCSLap) nanocomposite was characterized via X-ray diffraction, energy dispersive X-ray, scanning electron microscopy, and transmission electron microscopy. Further, the catalytic activity of this well-defined material was investigated in three-component CuAAC reactions to obtain 1,4-disubstituted-1,2,3-triazoles in good to excellent yields from an organic halide, sodium azide, and an alkyne using air-in-water as a green solvent.

Full text of DOI:10.1039/c6nj03862j

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: G. R. Mahdavinia,
M. Soleymani, M. Nikkhoo, S. M. F. Farnia and M. Amini, New J. Chem., 2017, DOI: 10.1039/C6NJ03862J.
Volume 40 Number
1
January 2016 Pages 1–846
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
NJC
New Journal of Chemistry
www.rsc.org/njc
A journal for new directions in chemistry
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1144-0546
PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
rsc.li/njc

Page 1 of 17
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03862J
Magnetic (Chitosan/Laponite)-Immobilized Copper (II) Ions: An Efficient
Heterogeneous Catalyst for the Azide–alkyne Cycloaddition
a*
b
c
Gholam Reza Mahdavinia, Moslem Soleymani, Mohammad Nikkhoo, Sayed Morteza F.
Farnia, Mojtaba Amini
c
a*
a
Polymer Research Laboratory, Department of Chemistry, Faculty of Science, University of
Maragheh, Maragheh, 55181ꢀ83111, Iran.
b
Department of Polymer Engineering, Faculty of Engineering, University of Maragheh,
55181ꢀ83111, Maragheh, Iran.
c
Department of Chemistry, University of Tehran, Tehran, Iran.
*
Corresponding Author: grmnia@maragheh.ac.ir
Telephone: +984137273068; Fax:+984137276060
Abstract
2
+
The Cu ions immobilized on a novel magnetic chitosanꢀbased catalytic system by
II
combination laponite RD was prepared. Cu ꢀmagnetic chitosan/laponite RD (CuꢀmCSLap)
nanocomposite was characterized by Xꢀray diffraction analysis, energy dispersive Xꢀray
Analysis, scanning electron microscope and transmission electron microscope. Further, we
tested the catalytic activity of this wellꢀdefined material in threeꢀcomponent CuAAC
reactions to obtain 1,4ꢀdisubstitutedꢀ1,2,3ꢀtriazoles in good to excellent yields from an
organic halide, sodium azide and alkyne under air in water as a green solvent.
Keywords: Chitosan; Laponite RD; Magnetic Catalysis; Copper (II); Azide–Alkyne
Cycloaddition
1
. Introduction
,2,3ꢀtriazole derivatives have gained significant amount of attention due to their wide
application in various fields, such as material science and biology, agricultural and
1
1
ꢀ3
pharmaceutical. One of the most interesting synthetic tools for comfortable and trusty
construction of 1,2,3ꢀtriazole derivatives is the 1,3ꢀdipolar cycloaddition of organic azides
4
and terminal alkynes in the presence of copperꢀcontaining catalysts. Although Cu(I)ꢀ
1

New Journal of Chemistry
Page 2 of 17
View Article Online
DOI: 10.1039/C6NJ03862J
catalyzed cycloaddition of azides and alkynes has been extensively reported, but in recent
years, due to higher stability of Cu(II)ꢀcontaining compounds and also their easy synthetic
5
ꢀ7
methods, they has characterized as a catalyst for the azide–alkyne cycloaddition.
In order to prepare heterogeneous catalytic systems based on copper (II), an easy and
2+
8
efficient method is the immobilizing Cu ion on solid supports ions on a solid support. In
this regard, various solid supports including clays, polymers, magnetic nanoparticles, and
2
+
9ꢀ12
alumina have been used for immobilizing Cu ions.
From standpoints of nonꢀtoxicity,
biodegradability, and natural origin, the polysaccharides such as chitosan and alginate with
2
+
different functionalities are suitable candidates in designing Cu ꢀloaded solid catalytic
13, 14
systems.
Chitosan is known as a basic polysaccharide carrying primary amine pendants.
This biopolymer is derived from chitin (with a wide distribution in living organisms) by
15
2+
deacetylation method. The high affinity of amine groups to complex with Cu ions makes
1
6
the chitosan as a green candidate to fabricate solid catalytic systems. In spite of the high
2+
tendency of chitosan to bind with Cu ions, the low mechanical and thermal properties
1
7
restrict its applications in some catalytic systems. To overcome these disadvantages the
nanoclays with high surface area can be used. The hydroxyl and amine functional groups on
chitosan are interacted physically with hydroxyl groups of nanoclays such as
18
montmorillonite. From a recovery and reusability standpoint, magnetic catalytic systems are
recommended. Magnetic Fe nanoparticles are combined with the catalytic supports;
therefore the magnetic materials can be easily separated from reaction media without needing
3
O
4
10
filtration and centrifugation processes. The magnetic nanoparticles with homogeneous
dispersing in catalytic systems without any aggregation are desirable. In this regard,
magnetite nanoparticles can be immobilized on the laponite RD nanoclay with disc forming
ability in water. Magnetic laponite RD discs are uniformly dispersed in the media due to the
1
9
anionic centers on its structure.
2

Page 3 of 17
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03862J
The main objective of this work was to fabricate a novel magnetic chitosanꢀbased catalytic
system by combination laponite RD. The magnetic nanocomposite was prepared through in
2+
situ method. The Cu ions were immobilized on the obtained nanocomposite. The 1,3ꢀ
II
dipolar azide–alkyne cycloaddition reaction proceeds with Cu ꢀmagnetic chitosan/laponite
RD nanocomposite with excellent yields.
2
. Materials and Methods
.1. Materials
2
Chitosan with ~85% of degree of deacetylation and molecular weight of 2500±30 kDa was
obtained from SigmaꢀAldrich and used without any purification. Laponite RD nanoclay was
2
supplied from Southern Clay Products, USA (surface area: 370 m /g, bulk density:
3
1
000kg/m , chemical composition: SiO
2
59.5%, MgO 27.5%, Li
2
O 0.8%, Na
2
O 2.8%, loss on
ignition: 8.2%).FeCl .6H O, FeCl .4H O, and CuSO .5H O chemicals were purchased from
3
2
2
2
4
2
Merck (Germany) and used as received. Ammonia solution (NH
4
OH, 25 %wt, Merck,
Germnay) and sodium tripolyphosphate (TPP, SigmaꢀAldrich, USA) were used as received.
2.2. In situ preparation of magnetic chitosan/laponite RD and its catalytic system
The aqueous dispersion of nanoclay with 1 %wt was prepared by adding 1 g of laponite RD
in 100 mL distilled water, and then stirring the clayꢀdispersed solution for overnight with a
magnetic stirrer (500 rpm). To ensure homogeneous dispersion of laponite RD, the solution
was sonicated for 10 min (power: 70 W and frequency: 50 kHz; Bandelin, Sonoplus, HD
2
200, Germany). Before adding the iron salts, the laponite solution was degassed by bubbling
atmosphere for 30 min. Then, 2.22 g of ferric salt (FeCl ) and 0.87 g of ferrous salt
FeCl ) were dissolved in 20 mL distilled water and added immediately to the laponite
N
2
3
(
2
2
solution. The solution was allowed to stir under N gas for 10 min.
Chitosan solution was individually prepared by dissolving 1 g of its powder in 100 mL of 1
2
+
3+
%
wt of acetic acid solution. The obtained solution was added to the Fe /Fe ꢀloaded laponite
3

New Journal of Chemistry
Page 4 of 17
View Article Online
DOI: 10.1039/C6NJ03862J
o
RD solution. The temperature of the mixture was adjusted at 60 C under N atmosphere
2
4
condition and magnetic stirring at 500 rpm. The ammonia solution (NH OH, 3 M) was slowly
added to the reaction mixture until the pH of the solution reached to 11. The produced dark
o
magnetic nanocomposite was stirred at 60 C for 1 h. In order to purify and neutralize the
product, magnetic chitosan/laponite RD was thoroughly washed with excess distilled water.
The purified magnetic nanocomposite was dispersed under ultrasound condition in water and
the TPP (2 %wt, 5mL) was slowly added into magnetic solution in order to crosslink the
magnetic chitosan/laponite RD (mCSLap) nanocomposite. The pH of resulting solution was
reached to 5.5 by adding 0.1 M of HCl solution. The TPPꢀcrosslinked nanocomposite was
sonicated as above and the magnetic solution was divided into two parts. The first part was
filtered and dried at room temperature and the dried product was kept in order to compare
with the structure of catalyst. The second part was used for the preparation of the magnetic
catalyst. The final volume of magnetic solution was 50 mL. For the preparation of catalyst,
4 2
the 0.39 g of CuSO .5H O was dissolved in 50 mL distilled water and was added dropwise
into magnetic chitosan/laponite RD solution at ambient temperature. The mixture was stirred
2+
on a shaker (120 rpm) for 5 h to reach equilibrium adsorption of Cu ions on magnetic
nanocomposite. Finally, the Cuꢀadsorbed nanocomposite was removed by a magnet and dried
2
+
at room temperature. The supernatant was used for estimating the content of Cu ions loaded
in the magnetic sample. Therefore, 1 mL of supernatant was added to the 3 M of ammonia
2
+
solution and the unꢀadsorbed concentration of Cu ions was investigated at λmax=600 nm by
UVꢀvisible spectrophotometer (UVꢀ1800, Shimadzu, Japan). The amount of adsorbed copper
(II) on magnetic nanocomposite was calculated from the difference between the initial
2
+
concentration of the used copper (II) ions and the remained concentration of Cu in the
supernatant.
2.3. Characterization
4

Page 5 of 17
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03862J
Fourier infrared (FTIR) spectra of dried samples were recorded by Bruker 113V FTꢀ
IR spectrometer (in KBr pellets). Xꢀray diffraction (XRD) patterns of dried and finely
powdered samples were made on a Siemens Dꢀ500 Xꢀray diffractometer (CuꢀKα, λ= 1.54 A˚,
Voltage: 35 kV, current: 30 mA). After a thin layer coating of gold on dried samples, the
surface morphology of magnetic nanocomposites was imaged on a scanning electron
microscopy energy dispersive Xꢀray instrument (SEM/EDX, VEGAII, XMU, Czech
Republic). The wet nanocomposites were dispersed in ethanol and transmission electron
microscopy (TEM) images were studied on a Philips CM10 operating at 60 kV tension. The
magnetic properties of the magnetic samples were recorded on a vibrating sample
magnetometer (VSM) (model 7400, Lakeshare Company, USA).
3
3
. Results and Discussion
.1.Synthesis and characterization
Fig. 1 shows the preparation of magnetic catalyst by combination of chitosan and laponite
2+
3+
RD. A solution of Fe /Fe ions was added to the dispersed laponite RD solution and was
allowed to interact the iron ions electrostatically with laponite RD discs. The exchange
+
20
between the interlayer Na ions of laponite RD and the iron ions can be occurred easily. The
chitosan solution was poured to the ironꢀloaded clay solution and subsequently, by adjusting
the pH of mixture at 11 by the ammonia solution the magnetic nanocomposite was obtained.
The TPP, a common crosslinker in the preparation of chitosanꢀbased materials, was used to
21
obtain the crosslinked magnetic nanocomposite. Because of the high tendency of chitosan
2
+
and laponite RD to complex with Cu ion, copper (II) solution was added to the magnetic
2
+
nanocomposite and allowed to reach equilibrium adsorption of Cu
ions on
22, 23
2+
nanocomposite.
A greenish Cu ꢀloaded magnetic chitosan/laponite RD catalyst was
2
+
gained. The adsorption capacity of magnetic nanocomposite for Cu ions was calculated and
ꢀ1
2+
found to be 365 mgg .The resulting catalyst was loaded with the high contents of Cu ions
5

New Journal of Chemistry
Page 6 of 17
View Article Online
DOI: 10.1039/C6NJ03862J
2+
and was comparable with the other supports used for the preparation of Cu ꢀloaded
10, 11
catalysts.
2+
Fig. 1 A simple scheme showing the steps used for the preparation of Cu ꢀchitosan/laponite
RD (CuꢀmCSLap) catalytic system.
6

Page 7 of 17
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03862J
TEM micrographs of the mCSLap and CuꢀmCSLap were used to investigate the formation of
nanoparticles in nanocomposites. Discꢀlike nanoplates can be formed by dispersing and
24
swelling the laponite RD in water (thickness: 1 nm and diameter: 25ꢀ40 nm). The main
advantage of the synthesis of magnetic nanoparticles in the presence of laponite RD disc is
the formation of magnetite embedded within the laponite discs. This phenomenon prevents
19
the aggregation and clustering of magnetic nanoparticles. As shown in Fig.2a, in the
2+
absence of Cu , the magnetic laponite RD showed diskꢀlike nanoplates in shape with an
average size of 29±4 nm. A similar observation has been reported in the preparation of clayꢀ
25
based hydrogels using laponite diskꢀlike nanoplates. Additionally, the nanoparticles with the
size of less than 20 nm are visible in the polymer matrix that can be assigned to the formed
3 4
magnetic Fe O nanoparticles freely. The CuꢀmCSLap indicated no deformation or
aggregation in the magnetic nanoparticles and the morphology was obtained similar to the
mCSLap nanocomposite (Fig. 2b).
(a)
(b)
2+
2+
Fig. 2 TEM images of (a) Cu ꢀunloaded (mCSLap) and (b) Cu –loaded (CuꢀCSLap)
nanocomposites.
The surface morphology of mCSLap and CuꢀmCSLap catalyst was studied by SEM
technique. The results revealed a coarse and undulant structure for mCSLap and no spherical
discs or nanoparticles due to the magnetic laponite RD was observed; indicating uniform
2
+
dispersion of magnetic clay in nanocomposite matrix (Fig. 3a). By loading the Cu ions, the
surface structure of nanocomposite was changed slightly, and a noduleꢀlike surface was
7

New Journal of Chemistry
Page 8 of 17
View Article Online
DOI: 10.1039/C6NJ03862J
obtained (Fig. 3b). Compared to the mCSLap nanocomposite, the variation in surface of
catalyst can be attributed to the crosslinking of the chitosan backbones through adsorption of
2
+
Cu ions. The energy dispersive Xꢀray spectroscopy (EDX) analysis of mCSLap indicated
Fe and Si confirming the magnetic laponite RD (Fig. 3a). In the EDX spectrum of magnetic
catalyst the Cu characteristic peak was appeared and confirmed the presence of copper ions in
the catalyst (Fig. 3b).
Fig. 3 SEM/EDX of (a)mCSLap and (b) CuꢀCSLap nanocomposites.
The d001 peak in XRD diffractograms is indicative the interaction/exfoliation structure of
nanoclays in polymer matrix. From the XRD pattern, a distinctive diffraction peak for native
laponite RD with dꢀspacing of 12.77Å (2θ=6.4º) was clearly observed (Fig. 4a). The XRD
8

Page 9 of 17
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03862J
º
pattern of neat chitosan showed a characteristic peak at 2θ=20 that is attributed to the partial
º
crystalline structure of chitosan. Moreover, chitosan showed a broad peak at 2θ=10.5 ,
originating from the hydrated crystals of αꢀchitin chains remaining in raw chitosan. The XRD
diffractograms of nanocomposites mCSLap and CuꢀmCSLap were studied and shown in
Fig.4a. Both of them indicated similar patterns. By synthesizing magnetite in the presence of
laponite RD and chitosan, the intensive peak of clay at 2θ=6.4º was disappeared, showing
exfoliation of clay nanoparticles as confirmed in TEM micrographs. Also, the characteristic
º
peak of chitosan at 2θ=20 was vanished, showing the amorphous structure of chitosan in
nanocomposite matrix. The existence of the magnetite in the nanocomposites was evidenced
26
by the distinctive peaks at about 2θ=30.4º, 35.6º, 43.5º, 53.2º, 57.4 and 63.3º. The Xꢀray
diffractions of mCSLap and CuꢀmCSLap revealed that the produced magnetite nanoparticles
2+
have high crystalline and spinel structures. After loading the Cu ions, the intensity of
distinctive peaks of CuꢀmCSLap was slightly reduced in compared to the mCSLap, in which
can be attributed to the nonꢀmagnetic behavior of copper (II) ions.
The magnetic behavior of magnetic mCSLap and CuꢀmCSLap nanocomposites were
investigated with a VSM technique at 298 K and in a range of applied field of ±8 kOe
(Fig.4b). The hysteresis loops of mCSLap and CuꢀmCSLap nanocomposites showed
superparamagnetic behavior that is obvious from zero value for the coercivity and remanence
on the magnetization curves. The saturation magnetization was reduced from 3.8 emu/g for
mCSLap to 2.7 emu/g for CuꢀmCSLap. The corresponding reduction in the magnetization of
catalyst in compared to the neat nanocomposite can be assigned to the antimagnetic behavior
of loaded copper (II). As illustrated in insert of Fig. 4b, the magnetization of catalyst was
sufficient to remove it from aqueous solution by a permanent magnet.
9

New Journal of Chemistry
Page 10 of 17
View Article Online
DOI: 10.1039/C6NJ03862J
Figure 4 (a) XRD patterns of chitosan, neat laponite RD, mCSLap, and CuꢀmCSLap
nanocomposites; (b) roomꢀtemperature magnetization curves of mCSLap and CuꢀCSLap
nanocomposites; (c) FTIR spectra of initial materials, mCSLap, and CuꢀCSLap.
The FTIR spectra of chitosan, pristine laponite RD, magnetic laponite RD, mCSLap, and Cuꢀ
mCSLap were investigated and shown in Fig.4c. In chitosan spectrum, the absorption bands
ꢀ1
at 1658, 1560, and 1084 cm correspond to the amide I, amide II, and glycosidic bonds,
respectively. The characteristic peaks of pristine clay are as follow: the hydroxyl groups and
2
the adsorbed H O on the laponite RD displayed a broadband, visible in the range of 3000ꢀ
ꢀ1
ꢀ1
ꢀ1
3
700 cm ;3643cm (stretching vibration of SiꢀOH), 3687 cm (stretching vibration of Mgꢀ
ꢀ1
ꢀ1
OH bonds), 998 cm due to the stretching vibration of SiꢀO and SiꢀOꢀSi bonds, and 464 cm
owing to the vibration stretching of MgꢀO. For a detailed comparison, the FTIR spectrum of
magnetic laponite RD was shown in figure. The magnetic laponite RD showed almost all
characteristic bands of the pristine laponite RD, with slight peak shifts to the lower
1
0

Page 11 of 17
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03862J
ꢀ1
frequencies. The distinctive peaks of FeꢀO in Fe O /laponite RD (450 and 470 cm ) were not
3
4
ꢀ1
distinguishable due to the overlap with characteristic peak of laponite RD at around 466 cm .
In the mCSLap nanocomposite, the absorption bands of the amide I, amide II, and glycosidic
ꢀ1
bonds related to the chitosan were appeared at 1625, 1535, and 1065 cm , respectively. In
comparison to the neat chitosan, the peaks showed a shifting to the lower frequencies,
confirming the interaction between chitosan and magnetic laponite RD. The presence of
ꢀ1
magnetic clay in mCSLap is evident by the bands at 1006 cm (stretching vibration of SiꢀO
ꢀ1
3 4
and SiꢀOꢀSi bonds) and 444 cm (FeꢀO in Fe O /laponite RD). The Cuꢀloaded catalyst, Cuꢀ
CSLap, showed almost the characteristic peaks of mCSLap nanocomposite with a slightly
shifting to the higher frequencies.
3
.2.Catalytic effects
II
The Cu ꢀmagnetic chitosan/laponite RD nanocomposite demonstrated to be very efficient in
the multicomponent 1,3ꢀdipolar cycloaddition of terminal alkynes and organic azides yielded
in situ from different organic halides and sodium azide. Phenylactelylene and benzyl chloride
were chosen as model starting compounds for the optimization of the reaction conditions
(Table 1). Initially optimization of the cycloaddition reaction was performed by varying the
catalyst amount. As shown in Table 1, after 12 h no product was obtained in the absence of a
catalyst (entry 1). The best result was achieved with0.004 g of the catalyst (entry 4). With a
further increase of the catalyst amount to 0.005 g showed adverse effect on the product yield
(
entry 5). The yield of cycloaddition product 1ꢀ benzylꢀ4ꢀphenylꢀ1Hꢀ1,2,3ꢀtriazole,
monotonously increased with increasing reaction temperature to 70 °C (entries 6ꢀ
).Interestingly, from the different solvents checked, H O as was found to be more effective
8
2
3 3 3
for this reaction than CH OH, CH Cl, ethyl acetate, CH CN and acetone (entries 4 and 9ꢀ13).
The cycloaddition reaction of phenyl acetylene with benzyl chloride and sodium azide gave
product almost quantitatively in 4 hour of reaction time (entry 15).
1
1

New Journal of Chemistry
Page 12 of 17
View Article Online
DOI: 10.1039/C6NJ03862J
Table 1. The Effect of various conditions on the azide–alkyne cycloaddition
Entry
Amount of
catalyst
Solvent Temperature Time Yield
a
(°C)
(h)
(%)
(
g)
1
2
3
4
5
6
7
8
9
ꢀ
H
2
O
70
70
70
70
70
rt
50
60
70
70
70
70
70
70
70
12
12
12
12
12
12
12
12
12
12
12
12
12
2
0
70
80
97
76
15
69
94
81
trace
trace
trace
58
94
97
0.002
0.003
0.004
0.005
0.004
0.004
0.004
0.004
0.004
0.004
0.004
0.004
0.004
0.004
H O
2
H
H
2
O
O
2
H2O
H
2
H
2
H
2
O
O
O
OH
CN
CH
CH
3
10
11
12
13
14
15
3
EtOAc
CHCl
acetone
3
H
2
O
H O
2
4
a
Isolated yield
In order to produce the 1,4ꢀdisubstitutedꢀ1,2,3ꢀtriazoles, the same process was successfully
applied to a wide range of diversely substituted phenyl acetylenes and a mixture of benzyl
bromides/chlorides with sodium azide. The results of cycloaddition reaction are summarized
in Table 2. With substitution of electron withdrawing or electron donating groups on the
phenyl ring of the phenyl acetylenes and benzyl halides, no significant influence on the yield
of the reaction was observed. But ortho substituents on the benzyl chloride in compared to the
para derivative showed minor steric hindrance (entries 2 and 3). Aliphatic alkynes required
longer reaction times than aromatic alkynes to give high yields of the corresponding
cycloaddition reactions (entries 7 and 8). Replacement of benzyl bromide with benzyl
chloride showed a conclusive effect on the catalytic activity, as benzyl bromide reacted to
give the corresponding 1,2,3ꢀtriazole products in essentially quantitative yields (entries 9ꢀ11),
except for aliphatic alkynes containing ꢀOH group (entries 12 and 13).
1
2

Page 13 of 17
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03862J
II
Table 2 Cycloaddition of alkyl halides with terminal alkynes in the presence of Cu ꢀ
magnetic chitosan/laponite RD nanocomposite
R1
N
nanocomposite
N
R1
+
NaN3
+
R2
N
0
H O, 70 C
2
X
R2
Yield (%)
a
Entry
Aliphatic halide
Alkyne
1
Cl
9
7
2
3
Cl
9
0
H C
3
Cl
CH3
7
6
4
5
Cl
9
9
3
1
O N
2
Cl
MeO
6
7
Cl
Cl
H C
3
9
5
3
4
H3C
HO
H C
3
8
9
Cl
Cl
Br
Br
Br
HO
6
0
97
1
1
1
0
1
2
9
9
9
7
5
2
MeO
H C
3
1
3

New Journal of Chemistry
Page 14 of 17
View Article Online
DOI: 10.1039/C6NJ03862J
1
1
3
4
H3C
Br
6
7
5
1
HO
H C
3
Br
HO
a
Isolated yield
The worthiness and efficiency of the present CuꢀCSLap nanocomposites are shown by
the comparison of the catalytic behavior of CuꢀCSLap nanocomposites with
previously reported copper catalysts (Table 3). The catalytic reactivity of CuꢀCSLap
nanocomposites is superior to the reaction conditions, such as much amount of catalyst
(
entries 2 and 4), using of hazardous solvents (entry 3) and addition of an additive
agent (entries 3 and 5). Also, easy separation and recoverability of catalyst and in situ
generation of organic azides are other advantages of our catalytic system.
Table 3. Comparison of the catalytic reactivity of CuꢀCSLap nanocomposites with other
reported catalysts
Entry
Catalyst
Conditions
Yield
%)
Ref.
(
1
2
3
CuꢀCSLap nanocomposites
POSS–SAL–Cu
Cu NPs/aminopropylꢀsilica
0.004 g catalyst/ H
2
O/12 h/70 ºC
97
95
38
Present work
0.01 g catalyst/ H O/12 h/70 ºC
27
28
2
0.004 g catalyst/PhNHNH
5 °C
0.006 g catalyst/H
0.001 catalyst/H O/sodium
2
/THF/2h/
2
4
5
Cu/CeO
Kenaf cellulose supported
2
2
O/4 h/70 °C
96
94
29
30
g
2
II
poly(hydroxamic acid) Cu ꢀ ascorbate (5 mol%)/ 4 h/70 ºC
complex
4. Conclusion
II
In summary, the present study illustrates the feasibility and applicability of utilizing the Cu ꢀ
magnetic chitosan/laponite RD nanocomposite to catalyze the 1,3ꢀdipolar cycloaddition of
terminal alkynes with organic azides generated in situ from sodium azide and different
organic halides for the synthesis of the corresponding 1,2,3ꢀtriazoles. The process is
environmentally friendly and uses an easily available solvent to produce excellent yields.
References
1
4

Page 15 of 17
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03862J
1
2
R. Huisgen, 1,3ꢀDipolar Cycloaddition Chemistry; Padwa, A., Ed.; Wiley: New York,
1984).
(
M. Amini, H. Naslhajian, S.M.F. Farnia, H.K. Kang, S. Gautam and K.H. Chae, New
J. Chem., 2016,40,5313ꢀ5317.
3
4
5
K.F. Donnelly, A. Petronilho and M. Albrecht, Chem. Commun.,2013, 49, 1145ꢀ1159.
P. Thirumurugan, D. Matosiuk and K. Jozwiak, Chem. Rev.,2013, 113, 4905ꢀ4979.
M. Amini, A. Bayrami, M. NazariMarashi, A. Arab, A. Ellern and L.K. Woo, Inorg.
Chim. Acta, 2016,443, 22–27.
6
7
8
9
I. Jlaliaa, F. Gallier, N. BrodieꢀLinder, J. Uziel, J. Augé and N. LubinꢀGermain, J.
Mol. Catal. A: Chem.,2014, 393, 56–61.
S. Mohammed, A. K. Padala, B. A. Dar, B. Singh, B. Sreedhar, R. A. Vishwakarma
and S B. Bharate, Tetrahedron,2012, 68, 8156−8162.
L.V. L.Lupano, J.M. L.Martínez, L.L. Piehl, E.R. de Celis, R.M. T. Sanchez and V.C.
D.Orto,Langmuir, 2014, 30, 2903–2913.
M. Ghadiri, F. Farzaneh, M. Ghandi and M. Alizadeh, J. Mol. Catal. A-Chem.,2005,
2
33, 127ꢀ131.
0 A. Pourjavadi, A. Motamedi, S.H. Hosseini and M. Nazari, RSC Adv., 2016,6, 19128ꢀ
9135.
1 A. Pourjavad, M. Tajbakhsh, M. Farhang and S.H. Hosseini, New J. Chem.,2015, 39,
591ꢀ4600.
2 N. Mukherjee, S. Ahammed, S. Bhadra and B. C. Ranu, Green Chem., 2013,15, 389ꢀ
97.
1
1
1
1
1
1
1
1
4
3
3A. Shaabani, M.B. Boroujeni and M.S. Laeini, RSC Adv., 2016, 6,27706ꢀ27713.
4K.R. Reddy, K. Rajgopal and M. Lakshmi Kantam, Catal.Lett., 2007, 114, 36ꢀ40.
5 G.R. Mahdavinia, A. Pourjavadi, H. Hosseinzadeh and M.J. Zohuriaan, Eur. Polym. J.
,
2
004,40, 1399ꢀ1407.
6 N. Horzum, E. Boyacı, A.E. Eroglu, T. Shahwan and M.M. Demir,
Biomacromolecules,2010, 11,3301–3308.
1
1
7 AlꢀSagheer and S. Muslim, J. Nanomater.,2010, 2010, Article ID 490679.
8S.F. Wang, L. Shen, Y.J. Tong, L. Chen, I.Y. Phang, P.Q. Lim and T.X. Liu, Polym.
Degrad. Stab.,2005, 90, 123ꢀ131.
1
5

New Journal of Chemistry
Page 16 of 17
View Article Online
DOI: 10.1039/C6NJ03862J
1
2
9V. Tzitzios, G. Basina, A. Bakandritsos, C.G. Hadjipanayis, H. Mao,
D. Niarchos, G.C. Hadjipanayis, J. Tucek and R.Zboril, J. Mater. Chem.,2010, 20,
5
418–5428.
0 L.L. Yang, G.Z. Liang, Z.P. Zhang, S.B. He and J.H. Wang, J. Appl. Polym. Sci.
009,114, 1235–1240.
1 Y. Huang and Y. Lapitsky, Langmuir, 2011, 27, 10392–10399.
2 E.S. Dragan, D.F.A. Loghin and A.I. Cocarta, ACS Appl. Mater. Interfaces, 2014, 6,
6577–16592.
,
2
2
2
1
2
2
2
2
3 K. Esumi, K. Yoshida, K. Torigoe, Y. Koide, Colloid. Surface. A, 1999, 160, 247ꢀ250.
4P. A. Wheeler, J. Wang, J. Baker and L.J. Mathias, Chem. Mater., 2005,17, 3012ꢀ3018.
5 C. Lorthioir, M. Khalil, V. Wintgens, C. Amiel, Langmuir, 2012, 28, 7859ꢀ7871.
6P.Sun, H. Zhang, C. Liu, J. Fang, M. Wang, J. Chen, J. Zhang, C. Mao and S.Xu,
Langmuir, 2010, 26, 1278ꢀ1284.
2
2
2
3
7 A. Akbari, N. Arsalani, M. Amini and E. Jabbari, J. Mol. Catal. A: Chem., 2016, 414,
4
7ꢀ54.
8 R.P. Jumde, C. Evangelisti, A. Mandoli, N. Scotti and R. Psaro, J. Catal. 2015, 324,
5ꢀ31.
2
9 M. Amini, R. Hassandoost, M. Bagherzadeh, S. Gautam and K. H. Chae, Catal.
Commun., 2016, 85,13ꢀ16.
0 B. H. Mandal, M. L. Rahman, M. H. A. Rahim and S. M. Sarkar, ChemistrySelect,
2
016, 1, 2750ꢀ2756.
1
6

Page 17 of 17
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03862J
2+
The present work reports the synthesis and characterization of Cu -loaded magnetic
chitosan/laponite catalytic system. Under green protocol and using water as a solvent,
CuAAC reactions were successfully performed to obtain 1,4-disubstituted-1,2,3-triazoles in
good to excellent yields.