Synthesis and characterization of DETA/Cu(NO3)2 supported on magnetic nanoparticles: a highly active and recyclable catalyst for the solvent-free synthesis of polyhydroquinolines

Article abstract of DOI:10.1007/s00706-016-1906-4

Abstract: A new magnetically separable catalyst consisting of Cu(II) complex immobilized on Fe₃O₄ nanoparticles functionalized with diethylenetriamine (Fe₃O₄–DETA–Cu(II)) was successfully synthesized and charact

Full text of DOI:10.1007/s00706-016-1906-4

Monatsh Chem
DOI 10.1007/s00706-016-1906-4
ORIGINAL PAPER
Synthesis and characterization of DETA/Cu(NO ) supported
3
2
on magnetic nanoparticles: a highly active and recyclable catalyst
for the solvent-free synthesis of polyhydroquinolines
1
1
1
Lotfi Shiri
•
Arash Ghorbani-Choghamarani
•
Mosstafa Kazemi
Received: 6 August 2016 / Accepted: 30 December 2016
Ó Springer-Verlag Wien 2017
Abstract A new magnetically separable catalyst consist-
ing of Cu(II) complex immobilized on Fe O nanoparticles
Introduction
3
4
functionalized with diethylenetriamine (Fe O –DETA–
4
Nowadays, search for finding separable and reusable cat-
alysts become a hot research topic in chemistry, especially
in modern catalysis research. The immobilization of
homogeneous catalysts on heterogeneous supports is in fact
an efficient strategy to reach this goal [1]. In recent times,
compared to the conventional separation, magnetic sepa-
ration has emerged as a robust, highly efficient, easy, and
rapid separation technique for products and catalysts [2].
The catalyst supported on magnetic nanoparticles (MNPs)
can be readily separated from the reaction media using an
external magnet, without the need for filtration, centrifu-
gation, or other tedious workup processes [3, 4]. In
addition, magnetic-supported catalysts can be reused many
times while keeping their initial activity. Among the vari-
ous employed magnetic NPs as the core magnetic support,
Fe O nanoparticles have been widely studied both for
3
Cu(II)) was successfully synthesized and characterized by
FT-IR, SEM, EDS, VSM, TGA, XRD, and AAS tech-
niques. This synthesized nanosolid was shown to be an
efficient heterogeneous catalyst for the solvent-free syn-
thesis of polyhydroquinoline derivatives. The catalyst was
readily separated from the final product solution by mag-
netic decantation and reused for subsequent reactions for at
least seven runs with less deterioration in catalytic activity.
Graphical abstract
O
X
H
O
O
O
X
O
Fe3O4-DETA-Cu(II)
O
O
+
Solvent free, 90 o
20-65 min
C
O
N
H
O
NH4OAC
3
4
X = Cl, F, Br, NO2, Me, OMe, NMe2,OEt, OH, H
1
9 Examples
88-98%)
their scientific interests and technological applications [5].
The designing and developing of copper-catalyzed
routes for organic reactions is a hot research topic in
modern catalysis research, because compared to other
transition metals, copper is less toxic, available, and
inexpensive [6]. In recent times, copper complex immo-
bilized on magnetic Fe O nanoparticles has been
(
Keywords Heterogeneous catalysis Á
Magnetically separable catalyst Á Polyhydroquinoline Á
3
4
Solvent-free
recognized as an efficient catalytic strategy for a range of
organic reactions, such as carbon–carbon and carbon–het-
eroatom bonds formation, oxidation and multi-component
reactions [4–7].
Electronic supplementary material The online version of this
article (doi:10.1007/s00706-016-1906-4) contains supplementary
material, which is available to authorized users.
Heterocyclic compounds, especially nitrogen-containing
heterocycles, have attracted profound attention in modern
chemistry science because they play a key role in the fields of
natural products, medicinal chemistry and materials chem-
istry. In recent times, a lot of attention has been focused on
the synthesis of polyhydroquinoline derivatives, because
&
Lotfi Shiri
lshiri47@gmail.com
1
Department of Chemistry, Faculty of Basic Sciences, Ilam
University, P.O. Box 69315-516, Ilam, Iran
123

L. Shiri et al.
2
?
they are well-known as Ca channel blockers, and have
emerged as an important class of drugs for the treatment of
cardiovascular diseases [8]. In fact, cardiovascular agents,
such as nifedipine, nicardipine, amlodipine (Fig. 1) are
effective dihydropyridine drugs for the treatment of hyper-
tension [9]. Polyhydroquinolines and their derivatives also
possess a variety of biological and pharmaceutical activities,
such as antidiabetic, hepatoprotective, vasodilator, gero-
protective, antiatherosclerotic, bronchodilator, anticancer,
and antitumor activities [10–12]. In chemistry, the dihy-
dropyridine skeleton has been widely utilized as a hydride
source for reductive amination [9]. The classical procedure
for the synthesis of polyhydroquinolines is the one-pot
condensation of aldehydes with 1,3-dicarbonyl compounds
and ammonia either in acetic acid or refluxing in alcohol
report a highly efficient and eco-friendly multi-component
protocol for the synthesis of polyhydroquinolines using
Fe O –DETA–Cu(II) as a magnetically recoverable catalyst
3
4
under solvent-free conditions.
Result and discussion
Preparation and characterization of Fe O –DETA–
3
4
Cu(II)
Magnetic Fe O nanoparticles supported-DETA/Cu(II) was
3
4
successfully synthesized using the surface modification
strategy as depicted in Scheme 1. The magnetic nanopar-
ticles (Fe O MNPs) were prepared by chemical co-
[
13]. In general, traditional procedures are unpleasant from
3
4
the economic and environment points of view. In this
respect, during the last decade, new strategies toward the
synthesis of dihydroquinolines have been focused on a cat-
alytic version. For example, for the synthesis of
polyhydroquinolines, a variety of catalysts, such as ionic
liquid [14], TMSCl-NaI [15], heteropoly acid [16], sulfamic
precipitation method [21] and coated with 3-chloropropy-
ltrimethoxysilane (CPTMS) by covalent bonds [22]. The
reaction of the supported CPTMS with diethylenetriamine
(DETA) in toluene under reflux conditions for 42 h pro-
duced the DETA functionalized Fe O nanoparticles
3
4
(Fe O –DETA). Finally, the Fe O –DETA treated with
3 4
3
4
acid [2], nickel nanoparticle [17], MCM-41 [18], ZrCl [19],
4
Cu(NO ) Á3H O in ethanol at reflux temperature for 24 h to
3 2
2
and p-TSA [20] have been recently reported in the literature.
Most of these protocols suffer from some drawbacks, such as
requiring large amount of the catalyst and toxic solvents,
product contamination, formation of by-products, long
reaction times, difficulty in catalyst separation from the
reaction media and recycling which is a serious problem in
the pharmaceutical industry. Therefore, the search for
improving reaction conditions for the synthesis of polyhy-
droquinoline derivatives using efficient and reusable
catalysts under solvent-free conditions is a prime and real
challenge for synthetic chemists. Now, in this paper, we
provide magnetic nanoparticles supported-DETA/Cu(II).
The prepared magnetic nanocatalyst was comprehen-
sively characterized by FT-IR, TGA, XRD, SEM, EDS,
AAS, and VSM analysis techniques. The FT-IR spectra for
the Fe O MNPs (a), Fe O –CPTMS (b), Fe O –DETA
3
4
3
4
3 4
(c), and Fe O –DETA–Cu(II) (d) are displayed in Fig. 2.
3
4
The FT-IR analysis of the Fe O MNPs exhibits a char-
3
4
-
1
acteristic peak at 579 cm , which is attributed to the Fe–O
stretching vibration. Also, the broad band at around
-
3400 cm is attributed to bound water O–H stretching
1
vibration adsorption. The anchored CPTMS on Fe O
3
4
-
1
MNPs is confirmed by a characteristic peak at 996 cm
,
which is attributed to Fe–O–Si stretching vibration. In the
curve of Fe O –DETA, three obvious peaks at 1040, 1119,
3
4
-
1
and 1203 cm are proved the existence of C–N bonds and
their vibration. FT-IR spectrum of the Fe O –DETA–
Cl
CO Et
NO2
3
4
MeO C
2
2
MeO C
CO Me
2
2
Cu(II) catalyst showed two characteristic peaks at 1621 and
-
432 cm , which are corresponded to N–H bending and
1
O
3
N
H
NH2
N
H
stretching mode, respectively. Therefore, it can be con-
cluded that Cu(II) complex was immobilized successfully
on the surface of Fe O –DETA nanoparticles.
Amlodipine
Nifedipine
NO2
3 4
The morphology and size of the catalyst was studied by
scanning electron microscope (SEM) as shown in Fig. 3.
The SEM image of Fe O –DETA–Cu(II) shows that the
O
O
3
4
MeO C
N
2
catalyst was formed of nanometer-sized particles. The
components of Fe O –DETA–Cu(II) were analyzed using
3
4
N
H
energy-dispersive X-ray spectroscopy (EDS) (Fig. 4). As
shown in Fig. 4, characteristic peaks of Fe, O, Si, C, N, and
Cu demonstrated clearly that the copper(II) complex suc-
cessfully immobilized on the surface of Fe O –DETA
Nicardipine
Fig. 1 Typical dihydropyridine drugs
3
4
1
23

Synthesis and characterization of DETA/Cu(NO
3
)
2
supported on magnetic nanoparticles…
Scheme 1
NH OH
Fe O
4
MNPs
CPTMS
4
3
.
.
FeCl 6H O + FeCl 4H O
3
2
2
2
N , rt, 30 min
o
2
EtOH/H O, 40 C, 8 h
2
H N
NH2
2
O
O
N
H
Fe O
3
4
Si
Cl
MNPs
O
toluene, reflux, 42 h
O
O
O
.
Fe O
MNPs
H
Cu(NO ) 3H O
3
4
3 2
2
Si
N
NH2
N
H
o
EtOH, 80 C
O
O
O
H
N
Fe O
MNPs
3
4
HN
Si
NH2
Cu
O N
3
NO3
can be seen that the saturation of the obtained catalyst
-
1
decreases from 55.1 to 38.25 emu g
for the Fe O
3 4
MNPs. The decrease of the saturation magnetization can be
related to the presence of amine groups on the surface of
the Fe O nanoparticles supports. As a result of this anal-
3
4
ysis, the superparamagnetic properties of the prepared
Fe O –DETA–Cu(II) are attractive for their application.
3
4
The TGA was used to determine the percent of func-
tional groups chemisorbed onto the surface of magnetic
nanoparticles. Figure 6 shows the TGA curves for bare
Fe O MNPs (red line), DETA-Fe O (green line), and
3
4
3 4
Fe O –DETA–Cu(II) (blue line). The TGA curve of the all
3
4
samples shows the small amount of weight loss below
200 °C is due to desorption of physically adsorbed solvents
and surface hydroxyl groups. Organic groups have been
reported to desorb at temperatures above 260 °C. The
organic groups on the DETA-Fe O are found to have a
3
4
mass percentage loss about 9%, while the Fe O –DETA–
3
4
Cu(II) catalyst have greater mass loss, at about 32.5%. As a
result of this analysis, it can be concluded that the well
grafting of Cu(II) complex on the Fe O –DETA is verified.
3
4
X-ray diffraction (XRD) is an effective spectra tech-
nique to the better reorganization of the major properties of
the magnetite structures. In fact, the formation of magnetite
crystal phase in the nano-magnetic catalyst in aggregate
powder form can be as well identified by the X-ray
diffraction (XRD). The XRD-diffraction patterns of
Fe O –DETA (green line or a), Fe O –DETA–Cu(II) (red
Fig. 2 FT-IR spectra of Fe
Fe O –DETA (c), and Fe O –DETA–Cu(II) (d)
3
O
4
MNPs (a), Fe
3 4
O –CPTMS (b),
3 4 3 4
nanoparticles. As a result of this analysis, the Fe O –
3
4
DETA–Cu(II) catalyst has been successfully synthesized.
The magnetic property of the nano-magnetic catalyst
was investigated by vibrating sample magnetometer (VSM)
at ambient temperature. Figure 5 exhibits the magnetiza-
tion curves of Fe O MNPs and Fe O –DETA–Cu(II). It
3
4
3 4
line or b) and the recovered catalyst after seven cycles
blue line or c) are presented in Fig. 7. As seen in Fig. 7,
(
3
4
3 4
123

L. Shiri et al.
FeKα
1
1
500
000
O Kα
N Kα
5
00
0
FeKβ
FeLα
C KαCuLα SiKα
CuKα
CuKβ
keV
0
10.00
3 4
Fig. 4 EDS spectrum of the Fe O –DETA–Cu(II)
8
6
4
2
0
0
0
0
0
-10000
-5000
0
5000
10000
-
-
-
-
20
40
60
80
Applied field /Oe
3 4 3 4
Fig. 5 Magnetization curves for Fe O NPs (blue line) and Fe O –
DETA–Cu(II) (green line) at room temperature
1
10
00
90
80
70
9
8.92970195
1
9
%
3 4
Fig. 3 SEM images of the Fe O –DETA–Cu(II)
9
0.96203876
2.5%
several characteristic peaks at 2h = 34.5°, 41.2°, 50.7°,
3.2°, 67.3°, and 74.5° were observed in all samples
3
6
(
Fig. 6a–c), which are related to the (220), (311), (400),
422), (511), and (440) planes of Fe O nanoparticles with
(
3
4
6
7.54401581
6
5
0
cubic phase (in good agreement with the standard Fe O
3
4
XRD spectrum reported in the literature) [6]. As shown in
Fig. 6b, c, XRD-diffraction pattern of the recovered cata-
lyst after seven times was nearly similar to the fresh
catalyst. As a result of this analysis, the Fe O –DETA–
0
2
5
125
225
325
425
525
625
725
Temperature /°C
3
4
Cu(II) catalyst had been synthesized successfully without
damaging the crystal structure of Fe O core.
Fig. 6 TGA curves of Fe
line), and Fe O –DETA–Cu(II) (blue line)
3
O
4
MNPs (red line), Fe
3 4
O –DETA (green
3 4
3
4
1
23

Synthesis and characterization of DETA/Cu(NO
3
)
2
supported on magnetic nanoparticles…
-
.25 9 10 mol% of the catalyst was considered as an
1
2
optimum catalyst concentration.
To identify the ideal solvent, the reaction furnishing 5a
was studied in several solvent (such as CH CN, THF,
3
acetone, H O, EtOH, and H O/EtOH) at reflux temperature
2
2
(Table 1, entries 6–11). The reaction in THF and water
only gave product in low yields of 65 and 35%, respec-
tively (entries 7 and 9). When the reaction was performed
in CH CN, acetone, and H O/EtOH (entries 6, 8, and 11),
3
2
respectively, the yields were slightly inferior to the results
in EtOH (entry 10). Although the obtained results for EtOH
were satisfactory and venerable, but the solvent-free
method was found to be superior in terms of reaction time
and product yield. Next, to evaluate the effect of temper-
ature on the reactivity, the model reaction was carried out
at various temperatures (Table 1, entries 12–14). As shown
in Table 1, reaction times and yields of product 5a were
improved as the reaction temperature increased. However,
no significant improvement on the yield was observed
when the reaction performed at 100 °C (entry 14).
Finally, control experiments show that only a trace
amount of the product was obtained in the absence of the
copper catalyst after 120 min (Table 1, entry 15).
Accordingly, as evident from Table 1, the best results for
3 4
Fig. 7 The XRD patterns of Fe O –DETA (a), the fresh copper
catalyst (b), the recovered copper catalyst after seven times (c)
-
1
Atomic absorption spectroscopy (AAS) of the fresh
catalyst showed that the amount of copper loaded on the
the product 5a were obtained with 2.25 9 10 mol% of
the catalyst under solvent-free conditions at 90 °C (entry
4).
-
1
surface of Fe O nanoparticles was about 0.15 mmol g
4
.
3
All together, these analyses are indicative of the suc-
cessful immobilization of Cu(NO3)2 groups onto the
amino-functionalized magnetite Fe O nanoparticles.
To evaluate the scope and generality of this catalytic
system, various aldehydes were used and converted to the
polyhydroquinolines under the optimum conditions
3
4
(Scheme 2). The results of this study are listed in Table 2.
Catalytic study
As shown in Table 2, a broad spectrum of aromatic alde-
hydes bearing electron-deficient or electron-rich
substituents on the aromatic ring in the ortho, meta, and
para positions were successfully subjected to the same
reaction and the corresponding 1,4-DHP derivatives were
obtained in admirable yields in satisfactory times. It is
noteworthy that the kind of aldehyde has no significant
effect on the reaction, because the desired products were
obtained in high yields in relatively short reaction times.
To show the merits of this catalytic system in compar-
ison with other reported protocols in the literature, we
summarized the results for the preparation of product 5a
(as a model substrate) in Table 3. As shown in Table 3, this
synthetic protocol is superior to some of the previously
reported procedures in terms of product yield and reaction
time. Furthermore, this new nano-magnetic catalyst is also
comparable in terms of price, non-toxicity, stability, and
easy separation.
After successful characterization of the catalyst, we deci-
ded to evaluate the efficiency of the Fe O –DETA–Cu(II)
3
4
in the synthesis of polyhydroquinolines. The control
experiment and the optimization of the reaction condition
were tested by choosing the reaction of 4-choloroben-
zaldehyde (1 mmol), with ethyl acetoacetate (1 mmol),
dimedone (1 mmol), and ammonium acetate (1.2 mmol) as
model reaction. The reaction conditions were optimized by
evaluating various parameters, such as catalyst concentra-
tion, solvent type, and temperature. The collected results
from these experiments are listed in Table 1. In initial
investigation, the effect of catalyst loading (from
-
2
-1
4
.5 9 10
reaction was screened in the absence of solvent at 90 °C
Table 1, entries 1–5). As can be seen from the summa-
rized results in Table 1, the excellent yield of 98% was
mol% to 3 9 10
mol%) on the model
(
-
1
obtained when only 2.25 9 10 mol% of the copper
The recovery and reusability of catalyst is an important
aspect in catalytic processes. In this respect, the reusability
of the Fe O –DETA–Cu(II) as catalyst in the model reac-
catalyst was used. Further increase in catalyst concentra-
-
tion (3 9 10 mol%) does not show any significant effect
1
3
4
on reaction time and yield of product (entry 5). Hence,
tion was checked. After completion of the reaction, the
123

L. Shiri et al.
Table 1 Optimization of the reaction conditions
a
Entry
Catalyst/mol%
Solvent
Temperature/°C
Time/min
Yield/%
-
-
-
2
2
1
1
2
3
4
5
6
7
8
9
4.5 9 10
7.5 9 10
1.5 9 10
2.25 9 10
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Solvent-free
90
70
50
78
90
84
90
35
95
-
1
90
20
98*
98
-
1
3 9 10
90
20
-
-
-
-
-
-
-
-
-
1
1
1
1
1
1
1
1
1
2.25 9 10
2.25 9 10
2.25 9 10
2.25 9 10
2.25 9 10
2.25 9 10
2.25 9 10
2.25 9 10
2.25 9 10
–
CH
3
CN
Reflux
Reflux
Reflux
Reflux
Reflux
80
180
220
190
240
150
165
60
85
THF
65
Acetone
80
2
H O
35
10
11
12
13
14
15
EtOH
O/EtOH(1:1)
90
H
2
82
Solvent-free
Solvent-free
Solvent-free
Solvent-free
70
92
80
35
95
100
90
20
97
120
Trace
Reactions conditions: aldehyde (1 mmol), dimedone (1 mmol), ethyl acetoacetate (1 mmol), and ammonium acetate (1.2 mmol)
*
a
Best reaction condition
Isolated yield
Scheme 2
O
X
H
O
O
O
X
O
2
Cu(II)/ Fe O -DETA
3
4
O
O
o
+
Solvent free, 90 C
20-65 min
O
N
H
5
O
1
3
NH OAC
4
X = Cl, F, Br, NO , Me, OMe, NMe , OEt, OH, H
19 Examples
88-98%)
4
2
2
(
catalyst was separated easily and rapidly from the product
by exposure to an external magnet, and the reaction solu-
tion was decanted magnetically. The remaining nano-
magnetic catalyst was washed several times with ethyl
acetate and dried to remove residual product, and subjected
to the next run. The convenient separation using this
strategy minimizes the loss of catalyst during separation.
The recovered catalyst was used for seven successive times
without any significant loss of its catalytic efficiency
catalyst did not show significant leaching and the reaction
was truly heterogeneous in nature.
Also, the SEM image of the recovered catalyst is shown
in Fig. 9. From the comparison of Fig. 9 with Fig. 3, it can
be concluded that there is no significance difference in the
morphologies of freshly prepared catalyst and the recov-
ered catalyst after operation for seven consecutive reaction
cycles.
(
Fig. 8). This reusability exhibits the high stability of the
catalyst under the operating conditions.
Conclusion
To investigate the copper leaching in this reaction, the
recovered catalyst was analyzed by AAS technique. The
elemental analysis of the recovered catalyst after seven
times by AAS indicated that the content of copper is about
In summary, DETA/Cu(II) immobilized on Fe O
3
4
nanoparticles was found to be an efficient and recoverable
heterogeneous catalyst for the thermal solvent-free syn-
thesis of polyhydroquinolines via the four-component
-
1
0
.13 mmol g . AAS analysis revealed that the recovered
1
23

Synthesis and characterization of DETA/Cu(NO
3
)
2
supported on magnetic nanoparticles…
Table 2 Fe O
3 4
–DETA–Cu(II) catalyzed the synthesis of polyhydroquinolines at 90 °C under solvent-free conditions
a
Entry
Aldehyde
Product
Time/min
Yield/%
M.p./°C [References]
1
2
3
4
5
6
7
8
9
4-ClC
4-MeOC
4-MeC
4-FC
4-O NC
4-BrC
4-HOC
6
H
4
CHO
CHO
CHO
CHO
CHO
CHO
CHO
NC CHO
CHO
5a
5b
5c
5d
5e
5f
20
30
35
30
40
30
55
45
35
50
30
40
35
65
40
35
30
25
35
98
94
90
92
91
98
93
97
95
96
94
92
95
88
89
92
93
94
92
238–240 [23]
250–252 [24]
253–255 [23]
181–183 [25]
240–242 [24]
250–253 [23]
232–234 [25]
232–234 [25]
178–180 [26]
216–218 [25]
232–234 [27]
175–177 [24]
233–235 [25]
217–219 [27]
209–211 [28]
207–209 [29]
255–257 [30]
203–205 [24]
241–242 [23]
6
H
4
6 4
H
6 4
H
2
6 4
H
6 4
H
6
H
4
5g
5h
5i
4-(Me)
2
6 4
H
4-EtOC
6 4
H
10
11
12
13
14
15
16
17
18
19
a
6
C H
5
CHO
3-ClC CHO
3-O NC CHO
3-BrC CHO
3-OHC CHO
2-O NC CHO
2-ClC CHO
2-MeOC CHO
5j
H
6 4
5k
5l
2
6 4
H
6
H
4
5m
5n
5o
5p
5q
5r
5s
6 4
H
2
6 4
H
H
6 4
H
6 4
3,4-(MeO)
2,4-(Cl)
2 6
C H
3
CHO
2
6
C H
3
CHO
Isolated yield
Table 3 Comparison of the activity of various catalysts in the synthesis of product 5a
Entry
Catalyst
Condition
Time/min
Yield/%
References
1
2
3
4
5
6
7
GSA@MNPs
EtOH, reflux
THF, reflux
200
240
30
94
87
80
96
98
95
98
[31]
PdCl
[PW11CoO40
Hf(NPf
Cu-SPATB/Fe
[TBA] [W
Fe –DETA–Cu(II)
2
[10]
K
7
]
CH
3
CN, reflux
[32]
2
)
4
C
10
F
18, 60 °C
120
65
[33]
3
O
4
PEG-400, 80 °C
Solvent-free, 110 °C
Solvent-free, 90 °C
[21]
2
O
6 19
]
20
[34]
3
O
4
20
This work
reaction of aromatic aldehydes with ethyl acetoacetate,
dimedone, and ammonium acetate. Notably, a broad
spectrum of polyhydroquinoline derivatives was obtained
in admirable yields. The nanosolid catalyst was readily
separated from the final product solution by magnetic
decantation and reused for seven times with only minimal
reduction in the catalytic activity. This catalytic system
suggests a series of significant advantages, such as easy
separation by external magnetic field, solvent-free condi-
tions, high product yields and simplicity of operation. As a
result of this study, this catalytic system can act as an
efficient strategy for the synthesis of biologically and
pharmaceutically active molecules.
Experimental
Chemicals were purchased from Fisher and Merck. The
reagents and solvents used in this work were obtained from
Sigma-Aldrich, Fluka, or Merck and used without further
purification. The particles size and morphology were
investigated by a JEOL JEM-2010 scanning electron
microscopy (SEM), on an accelerating voltage of 200 kV.
IR spectra were recorded as KBr pellets on a VRTEX 70
model BRUKER FT-IR spectrophotometer. Powder XRD
was collected with a Rigaku-Dmax 2500 diffractometer
´
˚
with nickel filtered Cu Ka radiation (k = 1.5418 A,
40 kV). Thermogravimetric analysis (TGA) curves were
123

L. Shiri et al.
magnetic decantation, washed with double-distilled water
until neutrality, and further washed twice with ethanol and
dried at room temperature.
1
9
8
7
6
5
4
00
0
0
Preparation Fe O –CPTMS
3
4
0
0
The obtained Fe O nanoparticles (1.5 g) was dispersed in
3 4
3
50 cm ethanol/water (volume ratio, 1:1) by sonication
2
0
3
for 30 min, and then 2 cm CPTMS was added to the
mixture reaction. The reaction mixture was stirred using
0
7
6
5
4
3
2
1
mechanically stirring under N atmosphere at 40 °C for
2
Run
8
h. Then, the nanoparticles was re-dispersed in ethanol by
sonication for 5 times and separated through magnetic
decantation. The nanoparticles product (Fe O –CPTMS)
3 4
Fig. 8 Reusability of Fe O –DETA–Cu(II) in the synthesis of
product 5a
3
4
was dried at room temperature.
Preparation of Fe O –DETA
3
4
The N-propylcholoro-functionalized Fe O (1.5 g) was
3
4
3
dispersed in 50 cm toluene by ultrasonic bath for 10 min.
3
DETA (2 cm ) was added and stirred at 100 °C for 30 h
under N atmosphere. Then, the prepared functionalized
2
magnetic nanoparticles were separated by magnetic
decantation and washed three times with ethanol to remove
the unattached substrates. The resulting product was dried
at room temperature.
Preparation of the Fe O –DETA–Cu(II)
3
4
In the last step, 0.25 g Cu(NO ) Á3H O was added to 0. 5 g
3
2
2
3
Fe O –DETA in 30 cm absolute ethanol and the resultant
3
4
3 4 3
Fig. 9 SEM image of the recovered catalyst (Fe O –TBA–Br ) after
seven runs
mixture was under reflux for 24 h. Finally, the synthesized
nanosolid (Fe O –DETA–Cu(II)) was separated by mag-
3
4
netic decantation. The nano-magnetic catalyst washed
several times with absolute ethanol, and dried under vac-
uum at room temperature (Scheme 1).
recorded using a PL-STA 1500 device manufactured by
Thermal Sciences. The magnetic property of Fe O4
3
nanoparticles and the catalyst was characterized by
vibrating sample magnetometer (VSM, MDKFD, Iran).
The concentration of the copper in the catalyst was mea-
sured using an atomic absorption spectrophotometer (AAS)
General procedure for the synthesis
of polyhydroquinolines
(
UV/Vis, Analytikjena, nova-400p, Germany).
A mixture of aldehyde (1 mmol), dimedone (1 mmol), ethyl
acetoacetate (1 mmol), ammonium acetate (1.2 mmol) and
Preparation of the magnetic Fe O -nanoparticles
4
3
-
Fe O –DETA–Cu(II) (2.25 9 10 mol%) was stirred at
1
3
4
The mixture of 5.838 g FeCl Á6H O (0.0216 mol) and
90 °C under solvent-free conditions. Reaction progress was
monitored by TLC (acetone:n-hexane 3:7). After completion
of the reaction, the catalyst was separated using an external
magnet and washed with ethyl acetate. Then, the solvent was
evaporated and all products were recrystallized from etha-
nol. The pure polyhydroquinoline derivatives were obtained
in good to excellent yields (88–98%). All the products
reported here are known compounds and the spectroscopic
data was matched literature values.
3
2
2
1
.147 g FeCl Á4H O (0.0108 mol) was dissolved in
2
2
3
00 cm of deionized water in a three-necked flask
3
(
250 cm ) under N atmosphere. After that, under rapid
2
3
mechanically stirring, 10 cm of ammonia solution was
added into the solution within 30 min with vigorous
mechanical stirring. After being rapidly stirred for 30 min,
the resultant black dispersion was heated to 80 °C for
3
0 min. The black precipitate formed was isolated by
1
23

Synthesis and characterization of DETA/Cu(NO
3
)
2
supported on magnetic nanoparticles…
Acknowledgements This work was supported by the research
facilities of Ilam University, Ilam, Iran.
16. Heravi MM, Bakhtiari K, Zadsirjan V, Saeedi M, Bamoharram
FF (2010) Iran J Org Chem 2:298
1
7. Sapkal SB, Shelke KF, Shingate BB, Shingare MS (2009)
Tetrahedron Lett 50:1754
1
8. Nagarapu L, Kumari MD, Kumari NV, Kantaveri S (2007) Catal
Commun 8:1871
References
1
2
2
9. Reddy CS, Raghu M (2008) Ind J Chem 47:1578
0. Kumar A, Maurya RA (2008) Synlett 883
1. Ghorbani-Choghamarani A, Tahmasbi B, Moradi P, Havasi N
1
2
3
. Niknam K, Saberi D (2009) Tetrahedron Lett 50:5210
. Liu X, Zhao X, Lu M (2015) Catal Lett 145:1549
. Hosseini-Sarvari M, Khanivar A, Moeini F (2016) J Iran Chem
Soc 13:45
. Shiri L, Ghorbani-Choghamarani A, Kazemi M (2016) Aust J
Chem 69:585
. Shiri L, Ghorbani-Choghamarani A, Kazemi M (2016) Aust J
Chem. doi:10.1071/CH16318
. Ghorbani-Choghamarani A, Norouzi M (2014) J Mol Catal A:
Chem 395:172
. Ghorbani-Choghamarani A, Shiri L, Azadi G (2016) RSC Adv
(
2016) Appl Organomet Chem 30:619
2. Rostami A, Navasi Y, Moradi D, Ghorbani-Choghamarani A
2014) Catal Commun 43:16
2
4
5
6
7
8
9
(
2
2
3. Mosaddegh E, Hassankhani A (2012) Arab J Chem 5:315
4. Surasani R, Kalita D, Dhanunjaya-Rao AV, Yarbagi K, Chan-
drasekhar KB (2012) J Fluorine Chem 135:91
5. Sheik-Mansoor S, Aswin K, Logaiya K, Sudhan SPN (2012) Arab
J Chem. doi:10.1016/j.arabjc.2012.10.017
6. Ghorbani-Choghamarani A, Azadi G (2015) RSC Adv 5:9752
7. Das S, Santra S, Roy A, Urinda S, Majee A, Hajra A (2012)
Green Chem Lett Rev 5:97
8. Raghuvanshi DS, Singh KN (2014) Ind J Chem Sect B 52B:1218
9. Kumar S, Sharma P, Kapoor KK, Hundal MS (2008) Tetrahedron
2
2
2
6
:32653
. Donelson JL, Gibbs RA, De SK (2006) J Mol Catal A Chem
56:309
2
2
2
. Heydari A, Khaksar S, Tajbakhsh M, Bijanzadeh HR (2009) J
Fluorine Chem 130:609
0. Saha M, Pal AK (2011) Tetrahedron Lett 52:4872
6
4:536
1
1
3
3
3
0. Mamaghani M, Kazemi-Rad R (2009) Iran J Org Chem 4:248
1. Hajjami M, Tahmasbi B (2015) RSC Adv 5:59194
2. Heravi MM, Bakhtiari K, Javadi NM, Bamoharram FF, Saeedi M
1. Undale KA, Shaikh TS, Gaikwad DS, Pore DM (2011) C R Chim
1
4:511
1
1
1
1
2. Sirisha K, Achaiah G, Reddy VM (2010) Arch Pharm 343:342
3. Zolfigol MA, Safaiee M (2004) Synlett 827
4. Ji SJ, Jiang ZQ, Lu J, Loh TP (2004) Synlett 831
5. Sabitha G, Reddy GSKK, Reddy CS, Yadav JS (2003) Tetrahe-
dron Lett 44:4129
(
3. Hong M, Cai C, Yi WB (2010) J Fluorine Chem 131:111
2007) J Mol Catal A Chem 264:50
3
3
4. Davoodnia A, Khashi M, Tavakoli-Hoseini N (2013) Chin J Catal
3
4:1173
123