Palladium nanoparticles immobilized on EDTA-modified Fe3O4@SiO2 nanospheres as an efficient and magnetically separable catalyst for Suzuki and Sonogashira cross-coupling reactions

Article abstract of DOI:10.1002/aoc.4302

In this study, a novel heterogeneous palladium catalyst was synthesized by anchoring palladium onto ethylenediaminetetraacetic acid (EDTA)-coated Fe₃O₄@SiO₂ magnetic nanocomposite and used for the Suzuki and Sonogashira cross-coupling reactions. The properties of the magnetic catalyst were characterized by FT-IR, XRD, TEM, FE-SEM, DLS EDX, XPS, N₂ adsorption-desorption isotherm analysis, TGA, VSM, elemental analysis and the loading level of Pd in catalyst was measured to be 0.51?mmol/g by ICP. The catalyst was used in Suzuki cross-coupling reactions of various aryl halides, including less reactive chlorobenzenes with phenylboronic acid without any additive or ligand under green conditions. Furthermore, we have reported this recyclable catalytic system for Sonogashira cross-coupling reactions of various aryl halides (I, Br, Cl) under copper and ligand-free conditions in the presence of DMF/H₂O (1:2/v:v) as a solvent. The magnetic catalyst could also be separated by an external magnet and reused six times without any significant loss of activity.

Full text of DOI:10.1002/aoc.4302

Received: 22 October 2017
DOI: 10.1002/aoc.4302
Revised: 3 January 2018
Accepted: 3 January 2018
F U L L P A P E R
Palladium nanoparticles immobilized on EDTA‐modified
Fe3O4@SiO2 nanospheres as an efficient and magnetically
separable catalyst for Suzuki and Sonogashira cross‐coupling
reactions
Mohsen Esmaeilpour1 | Saeed Zahmatkesh2
| Nafiseh Fahimi1 | Mehran Nosratabadi3
1 Chemistry Department, College of
In this study, a novel heterogeneous palladium catalyst was synthesized by
anchoring palladium onto ethylenediaminetetraacetic acid (EDTA)‐coated
Fe3O4@SiO2 magnetic nanocomposite and used for the Suzuki and Sonogashira
cross‐coupling reactions. The properties of the magnetic catalyst were charac-
terized by FT‐IR, XRD, TEM, FE‐SEM, DLS EDX, XPS, N2 adsorption‐desorp-
tion isotherm analysis, TGA, VSM, elemental analysis and the loading level of
Pd in catalyst was measured to be 0.51 mmol/g by ICP. The catalyst was used
in Suzuki cross‐coupling reactions of various aryl halides, including less reac-
tive chlorobenzenes with phenylboronic acid without any additive or ligand
under green conditions. Furthermore, we have reported this recyclable catalytic
system for Sonogashira cross‐coupling reactions of various aryl halides (I, Br,
Cl) under copper and ligand‐free conditions in the presence of DMF/H2O
(1:2/v:v) as a solvent. The magnetic catalyst could also be separated by an exter-
nal magnet and reused six times without any significant loss of activity.
Science, Shiraz University, Shiraz, Iran
2 Department of Science, Payame Noor
University (PNU), 19395‐4697 Tehran,
Islamic Republic of Iran
3 Department of Chemistry, Payame Noor
University, PO Box 74515‐161,
Estahban, Iran
Correspondence
Mohsen Esmaeilpour, Chemistry
Department, College of Science, Shiraz
University, Shiraz, Iran
Email: m1250m551085@yahoo.com
Saeed Zahmatkesh, Department of
Science, Payame Noor University (PNU),
19395‐4697, Tehran, Islamic Republic of
Iran.
Email: zahmatkesh1355@yahoo.com
KEYWORDS
aryl halides, magnetic heterogeneous catalyst, palladium, sonogashira‐hagihara reaction, uzuki‐
Miyaura reaction
1 | INTRODUCTION
catalysis with merits of magnetic separation is using
magnetic materials as stable supports.[9,11,12]
Homogeneous catalysts are commonly more active
than their heterogeneous analogs because of their
homogeneous distribution of active sites in reaction
media, but it has some problems such as separating
and reusing.[1–4] Therefore, the design of stable hetero-
geneous metal catalysts with easy separation from the
reaction mixtures and high surface‐to‐volume ratio of
the active phase is significant. To solve these problems,
metals are typically dispersed onto resistant supports
with high surface area such as zirconia, alumina,
zeolites, silica, activated carbon, titania, or mixed
oxides.[5–10] One of the aspects of heterogeneous
Having specific characteristics including biocompati-
bility, large surface‐to‐volume ratio, low toxicity and
superparamagnetism, Fe3O4 nanoparticles have recently
applied extensively as unique magnetic supports.[13,14]
Fe3O4 magnetic nanoparticles have been used not only
in catalysts but also in the wide range of aspects such as
biosensors, ion exchange separation, magnetic fluids,
magnetic data storage, magnetic inks for jet printing,
environmental remediation, targeted gene therapy, drug
delivery systems, detoxification of biological fluids,
cell separation and biomedicine.[15–19] However, due to
magnetic dipolar attractions, magnetic particles are liable
Appl Organometal Chem. 2018;e4302.
wileyonlinelibrary.com/journal/aoc
Copyright © 2018 John Wiley & Sons, Ltd.
1 of 15
https://doi.org/10.1002/aoc.4302

2 of 15
ESMAEILPOUR ET AL.
to aggregation, alter magnetic properties, and rapid
biodegradation when they expose directly to the biological
system.[20] Therefore, a protection layer is required as the
stabilizer, which prevents direct contact between
the nanoparticles.[21] Among different kinds of coating
materials like metal oxide, noble metals and polymer
materials, silica is extensively used as a protective
layer.[22,23] Therefore, magnetic core‐shell nanostructures,
which are consist of Fe3O4 magnetic nanoparticles, are
being coated with a silica layer as a stabilizer to create
an interesting scaffold with attractive properties such as
chemically stability, unique magnetic properties, and
uniform size to prevent their aggregation.[24,25] Further-
more, the silica layer provides large amount of hydroxyl
groups on the surface of composite particles and as a
result, provides the opportunity to link different func-
tional molecules for many particular applications.[26]
Transition metal‐catalyzed organic transformations
are among the most important approaches in organic
synthesis.[27,28] Among transition metals, palladium is
powerfull in catalyzing of Suzuki‐Miyaura and
Sonogashira cross‐coupling reactions as two strong and
expanded procedures for the C‐C bonds formation in
organic synthesis.[29–31] Synthetic method of Suzuki‐
Miyaura with the construction of biaryl units as
molecular portions in pharmaceuticals, alkaloids like
ancistrocladine, herbicides, engineering materials such
as liquid crystals, conducting polymers and molecular
wires is highlighted.[32–34] Sonogashira reaction provides
a brilliant pathway to generate a broad variety of organic
compounds amongst natural products, biologically active
molecules and pharmaceuticals, conjugated oligomers
and polymers, and materials for nonlinear optical and
molecular electronics.[35,36] Nevertheless, the arbitrary
Suzuki‐Miyaura and Sonogashira reactions suffer from
phosphorus‐containing ligands.[37,38] Phosphorus ligands
are so sensitive to air and moisture, are toxic and have a
destructive effect on the natural environment.[39] Further-
more, these ligands are made hardly and this preparing
approach costs a lot. They often decompose the Pd
catalyst through the P‐C bond cleavage of a coordinated
phosphine ligand.[39] The other common drawback of
Sonogashira reaction is the application of environmen-
tally unfriendly copper salts as co‐catalyst which are
inducing Glaser‐type homocoupling reactions of the ter-
minal alkynes.[40] Herein, designing and introduction of
effective phosphine ligand‐free Pd complex catalysts and
copper‐free conditions have been placed in high impor-
tance for many researchers.[41,42]
and magnetically separable catalyst for Suzuki and
copper‐free Sonogashira cross‐coupling reactions.
2 | EXPERIMENTAL
2.1 | Materials and physical
measurements
Reagents and solvents were obtained from commercial
suppliers and used without further purification. The
purity determinations of the products were accomplished
by TLC on silica gel polygram STL G/UV 254 plates. The
1H NMR and 13C NMR spectra were recorded with a
Bruker Avance DPX 250 spectrometer. Fourier transform
infrared (FT‐IR) spectra were run on a Shimadzu FTIR‐
8300 spectrophotometer, and the sample and KBr were
pressed to form a tablet.
The powder XRD patterns were recorded on a
Bruker AXS D8‐advance X‐ray diffractometer using a
Cu Kα radiation (λ= 1.5418). Transmission electron
microscopy (TEM, Philips EM208) was used to charac-
terize the size and morphology of the samples. Field
emission scanning electron microscopy (FE‐SEM) was
obtained using a Hitachi S‐4160 electron microscope.
Dynamic light scattering (DLS) was recorded on a
HORIBA‐LB550. The elements in the samples were
probed by energy‐dispersive X‐ray (EDX) spectroscopy
accessory to the Philips scanning electron microscopy
(SEM). XPS measurements were made on a XR3E2
(VG Microtech) spectrometer with Al mono Kα X‐ray
source (1486.6 eV photons). The thermogravimetric
analysis (TGA) was carried out on a Perkin Elmer
instrument at a heating rate of 10 °Cmin‐1 under nitro-
gen. The magnetization curves of MNPs were measured
as a function of applied magnetic field H with a BHV‐55
vibrating sample magnetometer (VSM). The hysteresis of
the magnetization was obtained by changing H between
+7000 and ‐7000 Oe at 300 K. The BET surface area of
the nanocomposites were tested using a Micromeritics
ASAP 2000 surface area analyzer. The content of palla-
dium were recorded using inductively coupled plasma
(ICP) analysis (Varian, Vista‐pro). Elemental analysis
was carried out on a Thermofinigan Flash EA‐1112
CHNSO elemental analyzer. Mass spectrometric data
were acquired by using the electron spray ionization
(ESI) technique in a Micromass Q‐tof‐Micro Quadruple
mass spectrophotometer. The melting points of products
were determined with a Buchi 510 melting point appa-
ratus. The products were characterized by their melting
Therefore, in this study, we reported the synthesis and
characterizations of palladium nanoparticles supported
on EDTA‐modified Fe3O4@SiO2 nanospheres that is
illustrated in scheme 1 as an efficient, phosphine free
1
points and H NMR and 13C NMR spectra and compar-
ison with literature values. All yields refer to isolated
products after purification.

ESMAEILPOUR ET AL.
3 of 15
SCHEME 1 Schematic representation of the synthesis of Fe3O4@SiO2‐EDTA‐Pd NPs
(TEOS) (0.20 ml). Afterward, 5 ml of NaOH (10 wt%)
was added dropwise. After being stirring for 30 min
at room temperature, the magnetic nanoparticles were
collected by magnetic separation and washed with
ethanol and deionized water three times and then
dried at 80 °C for further uses.
2.2 | General procedure
2.2.1 | Preparation of Fe3O4@SiO2 core‐
shell
Magnetic Fe3O4 particles were synthesized based on a
modified co‐precipitation method.[43–45] Briefly, the
mixture of FeCl3.6H2O (1.3 g, 4.8 mmol), FeCl2.4H2O
(0.9 g, 4.5 mmol) and polyvinyl alcohol (PVA 15000)
(1 g) as a surfactant was dissolved in water (30 ml)
with vigorous stirring. Afterwards, as the temperature
of the mixture was elevated to 80 °C, a proper amount
of hexamethylenetetramine (HMTA) (1.0 mol/l) was
added dropwise until reaction media reaches pH 10.
The black magnetic particles were collected with the
help of a magnet filed, followed by washing with etha-
nol and deionized water three times. The product was
then dried at 80 °C for 10 h. The Fe3O4@SiO2 MNPs
were prepared through a modified Stober method.[46]
2.2.2 | Preparation of Fe3O4@SiO2‐NH2
MNPs (1)
The Fe3O4@SiO2 MNPs (1 g) obtained from the above step
were ultrasonically dispersed in 10 ml ethanol followed by
the addition of 0.25 ml of 3‐aminopropyl(triethoxy)silane
(1 mmol). The mixture was stirred under reflux conditions
for 12 h to obtain amino‐functionalized Fe3O4@SiO2
NPs. Subsequently, the suspensions were separated
with the external magnetic field and washed with ethanol
and deionized water to remove no reacted species.
Finally the obtained composite particles were dried at
80 °C for 6 h.
In
(0.5 g) were dispersed in
(50 ml), deionized water (5 ml), and tetraethoxysilane
a
typical procedure, prepared Fe3O4 particles
a
mixture of ethanol

4 of 15
ESMAEILPOUR ET AL.
(3.0 ml) were mixed in a reaction flask and stirred under
aerobic conditions at 70 °C. After completion of the reac-
tion and separation of catalyst using a magnetic field, the
mixture was diluted with ethyl acetate (5 ml) and water
(3×5 ml) and extracted. The organic layer was dried over
anhydrous MgSO4, filtrate, solvent was removed on a
rotary evaporator. The crude product was purified by flash
column chromatography over silica gel.
2.2.3 | Preparation of cyanuric chloride
functionalized Fe3O4@SiO2‐NH2 MNPs
(Fe3O4@SiO2‐TCT (2))
1 g of Fe3O4@SiO2‐NH2 NPs were dispersed into 10 ml of
THF, then cyanuric chloride (TCT, 1.0 mmol, 0.185 g) and
diisopropylethylamine (DIPEA) (1 mmol, 0.17 ml) were
added. The mixture was mechanically stirred at room
temperature for 16 h. The obtained cyanuric chloride
group immobilized Fe3O4@SiO2‐NH2 particles (as
Fe3O4@SiO2‐TCT) were collected with a magnet, washed
with hot ethanol and deionized water, and finally dried at
60 °C for 4 h.
2.2.7 | General procedure for Sonogashira
reaction using Fe3O4@SiO2‐EDTA‐Pd NPs
Aryl halide (1 mmol) and alkyne (1.1 mmol) were added
to a flask containing Pd catalyst (0.007 g, 0.35 mol% Pd)
and K2CO3 (2.0 mmol) in DMF/H2O (1:2/v:v) (3.0 ml)
and stirred at 90 °C. After completion of the reaction
(monitored by TLC), the catalyst was easily recovered by
using magnetic field. The organic compound was
extracted with ethyl acetate (2×10 ml) and dried over
anhydrous MgSO4, filtered, and concentrated under
reduced pressure to provide the crude product. The crude
product was purified by flash chromatography by n‐hex-
ane/ethyl acetate as eluent to give the pure desired
cross‐coupling products in high to excellent yields.
2.2.4 | Preparation of Fe3O4@SiO2‐TCT‐
NH2 MNPs (3)
The prepared Fe3O4@SiO2‐TCT (1 g) were suspended in
DMF (5 ml). After addition of bis(3‐aminopropyl)amine
(2 mmol, 0.25 mL) and DIPEA (2 mmol, 0.35 ml), the mix-
ture was stirred at 80 °C for 12 h. Then, the product
(Fe3O4@SiO2‐TCT‐NH2) was magnetically collected and
sequentially washed with distilled water and ethanol sev-
eral times, and finally dried at 70 °C for 4 h.
2.2.5 | Preparation of Fe3O4@SiO2‐EDTA‐
Pd NPs
3 | RESULTS AND DISCUSSION
To conjugate EDTA to Fe3O4@SiO2‐TCT‐NH2 (3), first,
EDTA (2 mmol) was mixed with 20 ml of DMSO and thi-
onyl chloride (SOCl2) (2 mmol) was then slowly added to
the mixture through a constant pressure drop funnel.
Immediately after the SOCl2 was completely dropped,
1.5 g of Fe3O4@SiO2‐TCT‐NH2 was quickly added to the
mixture. The mixture was stirred at room temperature
for 2 h. Finally, the Fe3O4@SiO2‐EDTA NPs were sepa-
rated with a magnet and washed with acetone, sodium
carbonate solution (0.1 mol L‐1) and deionized water
and dried at 60 °C. Then, Pd(OAc)2 (1 mmol, 0.225 g) in
THF (5 ml) added to the Fe3O4@SiO2‐EDTA (1.5 g) and
refluxed for 4 h. The obtained palladium nanoparticles
supported on EDTA‐modified Fe3O4@SiO2 NPs (as
Fe3O4@SiO2‐EDTA‐Pd NPs) were collected with a mag-
net, washed with THF (10 ml) and ethanol (10 ml) and
then dried at 60 °C for 3 h.
The FTIR spectra of bare Fe3O4, Fe3O4@SiO2,
Fe3O4@SiO2‐NH2, Fe3O4@SiO2‐TCT, Fe3O4@SiO2‐TCT‐
NH2, Fe3O4@SiO2‐EDTA and Fe3O4@SiO2‐EDTA‐Pd
MNPs are presented in Figure S1 (see in ESI). The peaks
at 3400 cm‐1 and 570‐580 cm‐1 appear in all the IR spectra
are assigned to the ‐OH groups and the Fe‐O groups,
respectively.[47] The absorption bands of 801 cm‐1 and
1090 cm‐1 are assigned to symmetric and asymmetric
stretching of Si‐O‐Si (Figure S1b) (see in ESI), indicating
that the magnetite NPs are successfully coated with silica
layer. The FT‐IR spectrum of Fe3O4@SiO2‐NH2 (Figure
S1c) (see in ESI) emerged absorption peaks at 576 (Fe‐
O), 1123 (Si‐O‐Si), and 2810‐2986 cm‐1 (C‐H). Also, the
obvious bands with medium intensity in 3303 and
3351 cm‐1 regions are assigned to the N‐H stretching from
the successful immobilization of (3‐aminopropyl)
triethoxysilane on the surface of the Fe3O4@SiO2 NPs.
According to Figure S1d (see in ESI), the successful
Fe3O4@SiO2‐NH2 surface modification with cyanuric
chloride moieties has been verified. The presence of peaks
at around 1511, 1564 and 1711 cm‐1 and approximately
1264 cm‐1 also correspond to the stretching vibration of
C=N groups and the stretching vibration of the C‐N band.
Also, it was not possible to assign the C‐Cl band in the FT‐
IR spectrum, due to interference from the core‐shell Si‐O‐
2.2.6 | General procedure for Suzuki‐
Miyaura reaction using Fe3O4@SiO2‐EDTA‐
Pd NPs
A mixture of Fe3O4@SiO2‐EDTA‐Pd catalyst (0.005 g,
0.25 mol%), aryl halide (1.0 mmol), K2CO3 (2.0 mmol),
arylboronic acid (1.1 mmol) and EtOH:H2O (1:2/v:v)

ESMAEILPOUR ET AL.
5 of 15
TABLE 1 Selected properties of Fe3O4, Fe3O4@SiO2 and
Fe3O4@SiO2‐EDTA‐Pd NPs
shown in Figure S1f,g (see in ESI). The FTIR spectra of
both samples reveal characteristic bands of species, i.e.,
Fe3O4 NPs (Fe‐O stretching vibration; ~580 cm‐1), SiO2
(Si‐O‐Si asymmetric stretching vibration; ~1100 cm‐1) as
well as EDTA (C=O amide stretching vibration;
~1630 cm‐1). It is also clear that the strong C=O band of
the carboxyl group, which is generally present at
1736 cm‐1, is appear in the lower frequency at 1721 cm‐1
due to the coordination of the oxygen with the palladium
(Figure S1g) (see in ESI). All the characteristic bands in
the FT‐IR spectra demonstrate that the Fe3O4@SiO2‐
EDTA‐Pd NPs catalyst was successfully prepared.
Fe3O4
crystal
structure
Specific
surface area
(m2/g)a
Magnetite
particle size
(nm)b
Sample
Fe3O4
Cubic spinel
480
11.33
12.64
14.86
Fe3O4@SiO2 Cubic spinel
430.3
352.8
Fe3O4@SiO2‐ Cubic spinel
EDTA‐Pd
aCalculated by the BJH method.
bCalculated by the Scherrer equation based on powder X‐ray diffraction
(XRD) patterns.
Figure S2 (see in ESI) shows the XRD patterns for pure
Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2‐EDTA‐Pd magne-
tite nanoparticles. From Figure S2a (see in ESI), the initial
synthesized product can be indexed to Fe3O4 according to
standard data (JCPDS19‐0629), indicating the highly crys-
talline cubic spinel structure.[48] The characteristic peaks
at 2θ= 30.1°, 35.4°, 43.1°, 53.4°, 57° and 62.6° for pure
Fe3O4 nanoparticles, which were marked respectively by
their indices (220), (311), (400), (422), (511), and (440),
were also observed for Fe3O4@SiO2 and Fe3O4@SiO2‐
EDTA‐Pd nanoparticles. After being coated by silica and
Si band. The new bands at 1257, 1451 and 2871‐3057 cm‐1
can be attributed to the C‐N (stretching vibration), CH2
(bending) and C‐H (symmetric and asymmetric stretching
vibrations) in the Fe3O4@SiO2‐TCT‐NH2 NPs, respec-
tively. Due to the presence of strong O‐H stretching vibra-
tion bond, the N‐H bond of bis(3‐aminopropyl)‐amine
group has been mashed (Figure S1e) (see in ESI). Also,
the FTIR transmission spectra of Fe3O4@SiO2‐EDTA
and Fe3O4@SiO2‐EDTA‐Pd NPs were recorded and
FIGURE 1 TEM images of a) Fe3O4, b) Fe3O4@SiO2, and c) Fe3O4@SiO2‐EDTA‐Pd; FE‐SEM images of d) Fe3O4, e) Fe3O4@SiO2, f)
Fe3O4@SiO2‐EDTA‐Pd and the size distributions of g) Fe3O4, h) Fe3O4@SiO2 and i) Fe3O4@SiO2‐EDTA‐Pd, respectively

6 of 15
ESMAEILPOUR ET AL.
surface functionalization, the diffraction intensity of the
iron oxide phase decreased obviously and a wide diffrac-
tion of amorphous silica could be found between 10 and
20o of 2θ, as shown in Figure S2b,c (see in ESI). For
Fe3O4@SiO2‐EDTA‐Pd nanoparticles, the broad peak
was transferred to lower angles due to the synergetic
effect of amorphous silica and organic compounds. In
Figure S2c (see in ESI), palladium nanoparticles deposited
onto Fe3O4@SiO2‐EDTA surface can be confirmed from
the corresponding XRD data. In addition to the character-
istic diffraction peaks that correspond to Fe3O4 (labeled
with the symbol *), there also exist other diffraction peaks.
The two peaks positioned at 2θ values of 40.02o and
46.56°, which can be attributed to the reflections of the
(111) and (200) crystalline planes of palladium, indicating
that Pd element exists in the form of Pd(0) (Figure S2c)
(see in ESI).
The average crystal size of each of the Fe3O4 cores
was calculated from the full width at half‐maximum
(FWHM) of the (311) reflection of Fe3O4, using the
Scherrer equation:
D ¼ kλ=β cosðθÞ
where D is the average crystal size of the Fe3O4 cores, k is
the form factor (k= 0.9), λ is the wavelength of X‐ray used,
β is the FWHM of diffraction peak, and θ is the Bragg
diffraction angle. The particle sizes of the magnetite
calculated using the Scherrer equation were 11.33, 12.64,
and 14.86 nm for Fe3O4, Fe3O4@SiO2, and Fe3O4@SiO2‐
EDTA‐Pd, respectively (Table 1).
The structures and morphologies of the nanoparti-
cles were characterized using transmission electron
microscopy (TEM) (Figure 1a‐c). The TEM image shows
that the diameter of the pure Fe3O4 is uniform in a
spherical morphology at the range of 10‐15 nm
(Figure 1a). The Fe3O4 nanoparticles coated with SiO2
revealed the increased diameter nearly to 20 nm in
TEM image, which emphasize that Fe3O4 particles were
completely covered with a uniform thin silica layer with
about 10 nm thick (Figure 1b). As shown in Figure 1c, a
basically core‐shell structure (dark colored core for
Fe3O4@SiO2 nanoparticles and light‐colored shell
for EDTA) was obtained. The nanoparticles still
remained monodisperse, and diameter of the nanoparti-
cles is found to be nearly 30 nm.
The morphology of Fe3O4, Fe3O4@SiO2 and
Fe3O4@SiO2‐EDTA‐Pd NPs was also observed using
FE‐SEM (Figure 1d‐f). The FE‐SEM images are another
evidence on successful coating of the magnetic Fe3O4 par-
ticles. Figure 1f reveal that particles stay on their spherical
TABLE 2 TGA and elemental analysis (EA) results for the syn-
thesis of Fe3O4@SiO2‐EDTA‐Pd NPs
Entry Sample
C%
H% N%
1
2
3
4
Fe3O4@SiO2‐NH2
EA
(wt%)
TGA
(wt%)
6.614 1.475 2.532
6.746 1.501 2.627
Fe3O4@SiO2‐TCT
EA
(wt%)
TGA
(wt%)
7.464 0.752 5.614
7.377 0.717 5.736
Fe3O4@SiO2‐TCT‐NH2 EA
(wt%)
TGA
(wt%)
15.946 2.871 10.377
16.172 2.918 10.564
Fe3O4@SiO2‐EDTA‐Pd EA
(wt%)
TGA
(wt%)
29.838 3.516 10.941
30.014 3.404 10.866
FIGURE 2 (a) EDX spectra of Fe3O4@SiO2‐EDTA‐Pd MNPs and
(b) XPS spectra of fresh Fe3O4@SiO2‐EDTA‐Pd MNPs and after six
reaction cycles

ESMAEILPOUR ET AL.
7 of 15
SCHEME 2 Sonogashira and Suzuki
coupling reactions catalyzed by
Fe3O4@SiO2‐EDTA‐Pd NPs
shape well even after Pd absorbance and forming
Fe3O4@SiO2‐EDTA‐Pd NPs. Figure 1g‐i show the particle
size distributions of the magnetic nanoparticles. The
average size distribution is shown in DLS diagrams at a
value of 12, 20 and 31 nm for Fe3O4, Fe3O4@SiO2 and
Fe3O4@SiO2‐EDTA‐Pd NPs, respectively.
The specific surface area was calculated based on
standard Brunauer‐Emmett‐Teller (BET) methods,
TABLE 3 Optimization of Suzuki coupling reaction between bromobenzene and phenylboronic acida
Entry
Catalyst (mol% Pd)
Solvent
Base
Temp. (°C)
Time (h)
Yieldb (%)
1
None
0.0025
0.025
0.05
0.1
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
DMF
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Na2CO3
K3PO4
Et3N
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
70
12
10
8
6
6
6
2
3
3
2
2
4
2
3
2
2
4
5
3
6
4
2
None
14
28
37
56
74
94
89
88
91
82
77
92
73
85
82
86
88
81
35
71
92
2
3
4
5
6
0.2
7
0.25
0.35
0.4
8
70
9
70
10
11
12
13
14
15
16
17
18
19
20
21
22
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
100
100
Reflux
70
DMSO
EtOH
EtOH:H2O (1:1/v:v)
Peg (200)
70
H2O
70
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
EtOH:H2O (1:2/v:v)
70
70
70
NaOH
K2CO3
K2CO3
K2CO3
70
Rt
60
80
aReaction conditions: bromobenzene (1.0 mmol), phenylboronic acid (1.1 mmol), base (2 mmol), Fe3O4@SiO2‐EDTA‐Pd catalyst, Solvent (3.0 ml).
bIsolated yield.

8 of 15
ESMAEILPOUR ET AL.
respectively (Table 1). The BET surface area of Fe3O4,
Fe3O4@SiO2 and Fe3O4@SiO2‐EDTA‐Pd MNPs are 480,
430.3 and 352.8 m2/g, respectively. As compared with bare
Fe3O4, Fe3O4@SiO2‐EDTA‐Pd MNPs exhibit smaller BET
surface area. The decrease of the surface area could be
ascribed to the presence of silica shell and ethylenedi-
aminetetraacetic acid on the particle surface.
Furthermore, in order to confirm the presence of
the palladium nanoparticles, the energy dispersive
X‐ray (EDX) spectrum of the Fe3O4@SiO2‐EDTA‐Pd
catalyst was recorded (Figure 2a). The spectrum proves
the presence of Pd and also C, N, O, Fe and Si in the
matrix.
(Figure 2b). The metal 3d5/2 and 3d3/2 electronic states
for the fresh catalyst were observed at 338.1 and
343.2 eV, suggesting that the palladium species were
present in a +2 oxidation state.[49] Except for the peaks
of Pd(II), two new peaks appear at the binding energy of
340.2 eV and 334.9 eV are assigned to 3d3/2 and 3d5/2
of Pd(0), respectively.[50] The XPS spectrum of the used
catalyst clearly shows the presence of Pd(0) species
(Figure 2b). The formation of Pd(0) species in the recov-
ered catalyst is acquired via the reduction of Pd(II) to
Pd(0); solvent (EtOH or DMF) acts as a reducing agent
during the synthesis procedure.[51]
Thermogravimetric
analysis
(TGA)
of
the
X‐ray photoelectron spectroscopy (XPS) is one of
powerful surface analysis technologies that measure
the chemical composition, chemical state and electronic
state of the elements. Therefore, XPS was conducted to
investigate the chemical oxidation state of palladium in
the fresh and the used Fe3O4@SiO2‐EDTA‐Pd catalyst
Fe3O4@SiO2‐NH2, Fe3O4@SiO2‐TCT, Fe3O4@SiO2‐TCT‐
NH2 and Fe3O4@SiO2‐EDTA‐Pd MNPs were performed
over the temperature range of 50‐700 °C (Figure S3A)
(see in ESI). The magnetic nanoparticles show two weight
loss steps over the temperature range of TGA analysis.
The first weight loss for all the samples, which occurred
TABLE 4 Suzuki reaction of aryl halides with arylboronic acids catalyzed by Fe3O4@SiO2‐EDTA‐Pd nanoparticles under optimal
conditionsa,b
X=I, 3a: 0.5 h, 96%b, TON: 384
X=I, 3d: 1 h, 95%, TON: 380
X=I, 3b: 1 h, 94%, TON: 376
X=I, 3e: 2 h, 93%, TON: 372
X=I, 3c: 0.5 h, 97%, TON: 388
X=I, 3f: 0.5 h, 96%, TON: 384
X=I, 3i: 1 h, 93%, TON: 372
X=I, 3 h: 0.75 h, 92%, TON: 368
X=I, 3 g: 1.5 h, 95%, TON: 380
X=I, 3j: 2 h, 91%, TON: 364
X=Br, 3 m: 2 h, 96%, TON: 384
X=Br, 3 l: 2 h, 97%, TON: 388
X=I, 3 k: 2.5 h, 89%, TON: 356
X=Br, 3n: 5 h, 93%, TON: 372
X=Br, 3o: 2.5 h, 89%, TON: 356
X=cl, 3r: 8 h, 78%, TON: 312
X=cl, 3u: 10 h, 71%, TON: 284
X=Br, 3q: 2 h, 94%, TON: 376
X=Br, 3p: 4 h, 91%, TON: 364
X=cl, 3 s: 5 h, 83%, TON: 332
X=cl, 3 t: 8 h, 74%, TON: 296
aReaction conditions: aryl halide (1.0 mmol), arylboronic acid (1.1 mmol), K2CO3 (2.0 mmol), Fe3O4@SiO2‐EDTA‐Pd catalyst (0.25 mol%), EtOH:H2O (1:2/v:v)
(3 ml), 70 oC, under aerobic conditions.
bIsolated yield.

ESMAEILPOUR ET AL.
9 of 15
below 150 °C was probably because of the loss of adsorbed
solvent or trapped water on the surface.[52] As shown in
Figure S3A (see in ESI), a significant second weight loss
step appeared at temperatures higher than 150 °C, which
was attributed to the decomposition of organic material.
The weight loss of Fe3O4@SiO2‐EDTA‐Pd nanoparticles
is about 42.4% at 150‐600 °C, corresponding to the
thermal decomposition of organic compounds over
Fe3O4@SiO2 NPs (Figure S3Ad) (see in ESI). The mag-
netic properties of the Fe3O4 and Fe3O4@SiO2‐EDTA‐Pd
nanocomposites were measured via a vibrating sample
magnetometer (VSM) (Figure S3B) (see in ESI).
Room temperature specific magnetization (M) versus
applied magnetic field (H) curve measurements of the
Fe3O4@SiO2‐EDTA‐Pd MNPs indicate
a saturation
magnetization value (Ms) of 31.2 emu g‐1 (Figure S3Bb)
(see in ESI), lower than that of the bare magnetic
nanoparticles (64.8 emu g‐1) (Figure S3Ba) (see in ESI)
due to the silica coating and the layer of organic
compounds. Moreover, the magnetization curves showed
TABLE 5 Optimization of the conditions for Sonogashira‐Hagihara reaction of phenylacetylene with p‐bromoacetophenonea
Temp.
(°C)
Time
(h)
Yieldb
(%)
Entry
Catalyst (mol% Pd)
Solvent
EtOH
Base
K2CO3
1
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
‐
Reflux
Reflux
Reflux
90
10
10
10
3
68
43
65
93
77
23
41
46
90
‐
2
MeOH
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Et3N
3
EtOH/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMSO
4
5
100
Reflux
Reflux
Reflux
90
6
6
CH3CN
12
16
24
5
7
THF
8
Toluene
9
DMF/H2O (1:1/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
DMF/H2O (1:2/v:v)
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
120
120
100
100
90
24
24
16
16
14
12
8
0.0025
0.025
0.05
0.1
9
33
48
59
73
91
83
85
76
90
62
47
34
91
84
17
56
85
90
0.2
90
0.3
90
0.4
90
6
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
0.35
90
8
Na2CO3
Cs2CO3
NaOAc
K3PO4
NaOH
Piperidine
DBU
90
8
90
6
90
8
90
10
10
8
90
90
90
8
K2CO3
K2CO3
K2CO3
K2CO3
Rt
24
12
6
60
80
100
6
aReactions conditions: p‐bromoacetophenone (1.0 mmol), phenylacetylene (1.1 mmol), Base (2.0 mmol), Fe3O4@SiO2‐EDTA‐Pd catalyst, Solvent (3.0 ml).
bYields are isolated.

10 of 15
ESMAEILPOUR ET AL.
no remanence or coercivity in both samples, suggesting
their superparamagnetic character. Nevertheless, the
Fe3O4@SiO2‐EDTA‐Pd NPs dispersed in EtOH:H2O can
easily separate by an external magnetic field in less than
30 second, and then with a slight shake they can promptly
be re‐dispersed (Figure S3C) (see in ESI).
As shown in Table 2, the content of carbon, hydrogen,
and nitrogen matched well with TGA results and
proposed structures. According to the above‐mentioned
results, elemental analysis for these nanoparticles
confirmed successful grafting of organic groups on
Fe3O4@SiO2 surface.
TABLE 6 Sonogashira‐Hagihara coupling reaction of different aryl halides and alkynes under the optimized conditionsa
X=I, 5a: 1 h, 96%b, TON: 274
X=I, 5d: 0.75, 94%, TON: 269
X=I, 5 g: 2 h, 90%, TON: 257
X=I, 5j: 2 h, 92%, TON: 263
X=I, 5b: 1 h, 90%, TON: 257
X=I, 5e: 1 h, 93%, TON: 266
X=I, 5 h: 2 h, 88%, TON: 251
X=I, 5c: 1 h, 92%, TON: 263
X=I, 5f: 0.75 h, 95%, TON: 271
X=I, 5i: 1.5 h, 94%, TON: 269
X=Br, 5 l: 3 h, 92%, TON: 263
X=I, 5 k: 2.5 h, 93%, TON: 266
X= Br, 5n: 3 h, 93%, TON: 266
X= Br, 5q: 2 h, 93%, TON: 266
X= Br, 5 m: 3 h, 90%, TON: 257
X= Br, 5o: 5 h, 92%, TON: 263
X= Br, 5r: 7 h, 88%, TON: 251
X= Br, 5p: 6 h, 85%, TON: 243
X= Br, 5 s: 7 h, 90%, TON: 257
X= cl, 5v: 18 h, 84%, TON: 240
X= Br, 5 t: 6 h, 92%, TON: 263
X= cl, 5w: 12 h, 87%, TON: 249
X= cl, 5z: 20 h, 76%, TON: 217
X= cl, 5u: 16 h, 80%, TON: 229
X= cl, 5x: 20 h, 81%, TON: 231
X= I, 5aa: 2 h, 90%, TON: 257
X= cl, 5y: 24 h, 71%, TON: 203
X= I, 5ab: 1.5 h, 93%, TON: 266
X= Br, 5ae: 10 h, 82%, TON: 234
X= I, 5 ac: 3 h, 85%, TON: 243
X= Br, 5ad: 6 h, 86%, TON: 246
X= cl, 5ag: 24 h, 79%, TON: 226
X= Br, 5af: 8 h, 87%, TON: 249
X= cl, 5ai: 24 h, 76%, TON: 217
X= cl, 5ah: 24 h, 82%, TON: 234
X= cl, 5aj: 24 h, 69%, TON: 197
aReactions conditions: aryl halides (1.0 mmol), alkyne (1.1 mmol), K2CO3 (2.0 mmol), DMF/H2O (1:2/v:v) (3.0 ml), Fe3O4@SiO2‐EDTA‐Pd catalyst (0.35 mol%
Pd), 90oC.
bIsolated yields.

ESMAEILPOUR ET AL.
11 of 15
Also, the Pd loading of catalyst was confirmed by
Inductively Coupled Plasma (ICP) analyzer. The catalyst
was stirred in aq. HCl (37%), then the magnetic nanocom-
posite was separated by external magnetic field and the
remaining solution was analyzed by inductively coupled
plasma (ICP) to determine the content of palladium. The
obtained results reveal that 0.51 mmol per gram of Pd is
immobilized on Fe3O4@SiO2‐EDTA NPs.
The efficiency of this nanomagnetic composite in
organic synthesis is revealed by applying it as the catalyst
in the Suzuki and Sonogashira cross‐coupling reactions
(Scheme 2). First studies were performed upon the reac-
tion of bromobenzene (1 mmol) with phenylboronic acid
(1.1 mmol) as a model reaction and the effects of amount
of catalyst, solvents, bases and different temperatures
were studied for this reaction. Change in the amount of
used nanocatalyst is influenced on the reaction time and
yield. As you see in Table 3 0.25 mol% of Fe3O4@SiO2‐
EDTA‐Pd is the best selected amount (entry 7) and the
higher amounts decrease yield obviously and increase
time of the reaction (Table 3, entries 8, 9). On the other
hand, this model reaction was carried out with low
amounts of Fe3O4@SiO2‐EDTA‐Pd and the corresponding
products were obtained in longer reaction times and
lower yields (Table 3, entries 2‐6). The effect of different
solvents on the model reaction in the presence of
0.25 mol% catalyst, K2CO3 as base at 70 °C was studied.
We have presented the results of this study in Table 3,
which indicates that EtOH:H2O (1:2/v:v) is the most suit-
able solvent among the different cases studied for this
purpose (Table 3, entry 7) which advance the reaction in
shorter reaction time and higher yield. Also the effect of
different bases was surveyed by carrying out the reaction
of bromobenzene (1 mmol) with phenylboronic acid
(1.1 mmol), 0.25 mol% of Fe3O4@SiO2‐EDTA‐Pd in
EtOH:H2O (1:2/v:v) at 70 °C. Among K2CO3, Et3N,
NaOH, Na2CO3 and K3PO4 is observed that K2CO3 act
more effective with mention to results obtained and
collected in Table 3 (Entry 7, 16‐19). Furthermore, the
reaction in the presence of Fe3O4@SiO2‐EDTA‐Pd was
carried out at different temperatures to assess the effect
of temperature on the reaction yield (Table 3, entries 7,
20‐22). The yield increased as the reaction temperature
was raised. At 70 °C, product was obtained in excellent
yield within 120 min. A further increase in temperature
did not improve the product yield. Therefore, we
TABLE 7 Catalytic activity of Fe3O4@SiO2‐EDTA‐Pd compared with some catalysts reported for the Sonogashira‐ Hagihara
(phenylacetylene with bromobenzene) and Suzuki (phenylboronic acid with bromobenzene) coupling reactions
Coupling
Entry reaction
Time Yield TOF
Catalyst
Conditions
DMF, hexamine, 100oC
(h)
(%)
(h‐1)
Ref.
[53]
1
Sonogashira
Sonogashira
Sonogashira
Pd‐TPOP‐1 (5 mol%)
Si‐PVI‐Pd (0.5 mol%)
12
52
77
73
85
64
75
76
56
92
100
85
98
90
92
89
95
65
88
0.87
[54]
[55]
[56]
[57]
[58]
[59]
[60]
2
DMF/K2CO3/120 °C
DMSO/K3PO4/100 °C
1.5
102.7
73.0
28.3
1.8
3
NHC‐palladium complex (1 mol%)
1
6
4
Sonogashira Fe3O4@SiO2/Schiff base/Pd(II) (0.5 mol%)
DMF/K2CO3/90 °C
5
Sonogashira
Sonogashira
Sonogashira
Sonogashira
Sonogashira
Suzuki
Pd/MgLa (1.5 mol% Pd)
MNP‐CD‐Pd (0.15 mol%)
DMF/Et3N/80 °C
24
9
6
H2O/DMF (3:1/v:v), K2CO3, 100oC
55.5
6.3
7
CPS‐MNPs‐NNN‐Pd (0.5 mol%)
MCM‐41‐Pd (0.1 mol%)
H2O/DMF (2:1/v:v), K2CO3, 90 °C 24
8
Toluene/Bu3N, 100oC
DMF/H2O (1:2/v:v), K2CO3, 90 °C
DMF/H2O (1:1/v:v), K2CO3, 100oC
EtOH, K2CO3, reflux
24
3
23.3
9
Fe3O4@SiO2‐EDTA‐Pd (0.35 mol%)
(SMNPs‐Salen Pd (II) (0.5 mol%)
Pd–ZnFe2O4 (4.62 mol%)
87.6 This work
[61]
10
11
12
13
14
15
16
17
18
19
20
3
66.7
[62]
Suzuki
9
2.04
[63]
Suzuki
Pd/MFC (0.308 mol %)
EtOH, K2CO3,Reflux
1
16.33
[64]
Suzuki
Pd(II)‐isatin‐ɣ‐Fe2O3 (1.5 mol%)
Pd‐BIP‐γ‐Fe2O3@SiO2 (0.5 mol%)
Ru‐MPTAT‐1 (2 mol%)
Solvent‐free, Et3N, 100oC
DMF, Et3N, 100oC
0.75
80
[65]
Suzuki
3
6
61.3
[66]
Suzuki
DMF, K2CO3, 80oC
7.4
[67]
Suzuki
Silica‐APTS‐Pd (1 mol%)
DMA, K2CO3, 100oC
4
23.6
[68]
Suzuki
Bis(oxamato)palladate(Π) (5 mol%)
SiO2‐pa‐cyan‐Cys‐Pd (0.5 mol%)
Pd3(dba) (1 mol%)
n‐Bu4NBr, Et3N, 120oC
H2O, K2CO3, 100oC
2
6.5
[69]
Suzuki
5
35.2
[70]
Suzuki
THF, K3PO4, 80oC
EtOH:H2O (1:2/v:v), K2CO3, 70oC
24
2
78.5
97
3.27
Suzuki
Fe3O4@SiO2‐EDTA‐Pd (0.25 mol%)
194
This work

12 of 15
ESMAEILPOUR ET AL.
continued the reactions under optimum conditions
(Table 3, entry 7). We applied these optimized conditions
to investigate the merit of catalyst in the Suzuki reaction
involving cross‐coupling of an aryl halide with aryl
boronic acid (Table 4). A wide range of functional groups
on the aryl iodides, aryl bromides, and aryl chlorides were
studied and the reaction was effective for them and give
excellent conversions to the desired products. As shown,
the Suzuki couplings of arylboronic acids with aryl
iodides and bromides bearing various electron‐donating
or electron‐attracting groups afford the desired biaryls in
excellent yields (Table 4, entries 3a‐3q). On the base of
these data, aryl iodides act as the most powerful compared
with aryl bromides and aryl chlorides with the least times
and the best yields and aryl chlorides act the weakest.
Electron‐releasing substituents on aryl bronic acid coop-
erate in advancing reaction in lower time (Table 4, entries
3f and 3 h) and the electron‐withdrawing groups make
the reaction time longer (entries 3e and 3 t). Steric effect
is another factor impress the reactivity of aryl halides.
For example, the presence of methoxy group in the ortho
position in entries 3n and 3u in Table 4 made the corre-
sponding substrates less reactive towards Suzuki reaction
in the presence of the catalyst. Furthermore, the catalytic
system was able to affect the Suzuki coupling reaction of
aryl chlorides, and good conversions and yields could be
obtained after 5‐10 h (Table 4, entries 3r‐3u).
Then, the utility of this Fe3O4@SiO2‐EDTA‐Pd
NPs was explored for Sonogashira reaction using a variety
of substrates. Firstly, the reaction conditions were opti-
mized using p‐bromoacetophenone (1.0 mmol) and
phenylacetylene (1.1 mmol) as substrate. As shown in
Table 5, the best results for this reaction were obtained
with 0.35 mol% of catalyst in presence of K2CO3 as a base
and DMF/H2O (1:2/v:v) as a solvent at 90 °C (Entry 3).
Using the best selected reaction conditions according to
Table 5, a range of aryl halides (I, Br, Cl) were chosen
to examine their reactivity in the Sonogashira coupling
reaction in the presence of Fe3O4@SiO2‐EDTA‐Pd
catalyst. As it is summarized in Table 6, all of aryl halides
(I, Br) were active in the Sonogashira reaction efficiently
and afforded the desired products in high to excellent
FIGURE 3 (a) Recyclability of Fe3O4@SiO2‐EDTA‐Pd in the synthesis of 3 l and 5n under the optimized conditions; (b) and (c) FE‐SEM
and DLS images of Fe3O4@SiO2‐EDTA‐Pd nanoparticles after six reaction cycles

ESMAEILPOUR ET AL.
13 of 15
yields, but aryl chlorides were not as reactive as the iodide
and bromide counterparts. Different factors like elec-
tronic behavior of substitutions and also their position
on the aromatic ring of aryl halides (I, Br, Cl) showed to
be effective on the time and yield. According to the data
achieved, as predicted, the reaction of aryl iodides bearing
electron‐withdrawing groups went to completion in
shorter reaction times (Table 6, entries 5b‐5f and 5ab)
than those with electron‐ donating groups (Table 6,
entries 5 g‐5j and 5 ac). Also, the Sonogashira reactions
of a variety of aryl bromides with alkynes could go on
smoothly at 90 °C to give the resultant coupling products
in excellent yields on longer reaction times (entries 5 l‐5 t
and 5ad‐5af). The coupling reaction of sterically hindered
substrates, like 1‐iodonaphthalene, 2‐bromobenzaldehyde
and 2‐chlrotoluene with phenylacetylene led to the corre-
sponding products in high yields (Table 6, entries 5 k, 5p,
5y). Also, heterocyclic compounds of 3‐bromo‐thiophene,
3‐bromopyridine and 5‐bromopyrimidine provided the
title products in excellent yields (Table 6, entries 5r‐5 t).
Moreover, aliphatic alkynes such as 1‐octyne and
2‐ethynylcyclohexan‐1‐ol were also successfully coupled
with aryl halides and provided high yield of the
desired product (Table 6, entries 5aa‐5aj).
A comparison between the results of the proposed
catalyst and some of the recently used catalysts for the
Sonogashira‐Hagihara and Suzuki‐Miyaura coupling
reactions is summarized in Table 7. According to these
results, Fe3O4@SiO2‐EDTA‐Pd NPs performed its cata-
lytic activity effectively in a lower amount of Pd and a
shorter reaction time to produce the desired product in
excellent yield, with higher turnover frequency (TOF)
(Table 7, entries 9 and 20). Also Fe3O4@SiO2‐EDTA‐Pd
MNPs are superior in terms of stability, bio‐compatibility
and easy separation than the previously reported works.
In addition, the recoverability and recyclability of catalyst
is more rapid and easier than the other catalysts.
The Fe3O4@SiO2‐EDTA‐Pd catalyst in Suzuki and
Sonogashira coupling model reactions was conveniently
recovered from the both reaction mixtures by using
magnetic field and reused ten times without observation
of appreciable loss in its catalytic activity (Figure 3a).
To determine the degree of leaching of the palladium
from the heterogeneous catalyst, we used the hot
filtration test.[71] In a typical experiment, bromobenzene
(1.0 mmol), phenylboronic acid (1.1 mmol), K2CO3
(2.0 mmol), Fe3O4@SiO2‐EDTA‐Pd catalyst (0.25 mol%)
and EtOH:H2O (1:2/v:v) (3 ml) were placed in a round
bottom flask and stirred at 70 °C for 1 h. Then, the catalyst
was separated by an external magnet and allowed to the
residue solution to be stirred at 70 °C for further 2 h. This
experiment appeared only a little progress in the reaction
yield (GC) in the absence of nanocatalyst, which confirms
FIGURE 4 The FT‐IR spectrum of the fresh and reused catalyst
little leaching of palladium and proves responsibility of
the nanomagnetic heterogeneous palladium catalyst in
catalyzing the C‐C coupling reaction.
Furthermore, the amount of palladium leaching after
the first run was determined by ICP analysis to be only
0.17% and 0.28% for Suzuki and Sonogashira reaction
and after tenth run was 1.92% and 4.34%, respectively,
which suggests the heterogeneous nature of the prepared
catalyst. The FE‐SEM image of the catalyst taken after
the six cycle of the reaction did not show significant
change in the morphology of the catalyst (Figure 3b),
which indicates the retention of the catalytic activity
after recycling. Also, the particle size distribution of
Fe3O4@SiO2‐EDTA‐Pd after the six recycle was evaluated
using DLS technique and showed that the average
diameter of the particles was 38 nm (Figure 3c).
Figure 4 shows the FT‐IR spectra of the fresh and
reused catalyst after tenth run. The reused catalyst had
no obvious change in structure, as shown by comparison
of the FT‐IR spectra to that of fresh catalyst (Figure 4).
Therefore, the consistent structure and also the activity
of recovered and reused Fe3O4@SiO2‐EDTA‐Pd NPs indi-
cates that the reused catalyst shows excellent performance
in both studied reactions.
4 | CONCLUSION
In summary, we have developed palladium nanoparticles
supported on EDTA‐modified Fe3O4@SiO2 nanoparticles
as a robust, efficient and magnetically recoverable hetero-
geneous catalyst for Suzuki and Sonogashira cross‐cou-
pling reactions. The use of magnetically recoverable and
reusable catalyst, lower loading of catalyst compared with
the other methods, use of environmentally benign proce-
dure for Suzuki‐Miyaura reactions, short reaction periods,

14 of 15
ESMAEILPOUR ET AL.
[19] L. Zhang, P. Li, C. Liu, J. Yang, M. Wang, L. Wang, Cat. Sci.
Technol. 2014, 4, 1979.
excellent product yields and wide substrate scope makes
this an improved and superior catalyst to the existing
ones. Also, leaching test indicates that the catalytic reac-
tion is mainly heterogeneous in nature. Furthermore,
the magnetic catalyst also showed a high thermal stability
and can be reused six times without significant loss of
activity.
[20] H. Zhang, X. Zhong, J. J. Xu, H. Y. Chen, Langmuir 2008, 24,
13748.
[21] X. Du, J. He, J. Zhu, L. Sun, S. An, Appl. Surf. Sci. 2012, 258,
2717.
[22] J. Javidi, M. Esmaeilpour, Mater. Res. Bull. 2016, 73, 409.
[23] L. Zhang, P. Li, J. Yang, M. Wang, L. Wang, Chem. Plus. Chem
2014, 79, 217.
ACKNOWLEDGEMENTS
[24] J. Ji, P. Zeng, S. Ji, W. Yang, H. Liu, Y. Li, Catal. Today 2010,
158, 305.
This work was supported by council of Iran National
Science Foundation and University of Shiraz from the
Iran Society for the Promotion of Science.
[25] Z. Markova, K. Siskova, J. Filip, K. Safarova, R. Prucek, A.
Panacek, M. Kolar, R. Zboril, Green Chem. 2012, 14, 2550.
[26] M. Esmaeilpour, J. Javidi, M. Zandi, New J. Chem. 2015, 39,
3388.
ORCID
[27] D. K. Dumbre, P. N. Yadav, S. K. Bhargava, V. R. Choudhary,
J. Catal. 2013, 301, 134.
Saeed Zahmatkesh http://orcid.org/0000-0002-3054-2842
[28] L. Zhang, P. Li, H. Li, L. Wang, Cat. Sci. Technol. 2012, 2, 1859.
[29] N. T. S. Phan, M. Van Der Sluys, C. W. Jones, Adv. Synth. Catal.
2006, 348, 609.
REFERENCES
[1] K. W. Anderson, S. L. Buchwald, Angew. Chem. Int. Ed. 2005,
44, 6173.
[30] M. Esmaeilpour, J. Javidi, M. Mokhtari Abarghoui, F. Nowroozi
Dodeji, J. Iran, Chem. Soc. 2014, 11, 499.
[2] B. Saito, G. C. Fu, J. Am. Chem. Soc. 2007, 129, 9602.
[3] C. E. Garrett, K. Prasad, Adv. Synth. Catal. 2004, 346, 889.
[31] S. J. Hoseini, B. Habib Agahi, Z. Samadi Fard, R. Hashemi Fath,
M. Bahrami, Appl. Organomet. Chem. 2017, 31, e3607.
[32] A. Kumbhar, S. Kamble, S. Jadhav, G. Rashinkar, R. Salunkhe,
[4] M. Esmaeilpour, J. Javidi, M. Divar, J.Magn. Magn. Mater 2017,
423, 232.
Catal. Lett. 2012, 142, 1388.
[33] B. J. Reizman, Y. M. Wang, S. L. Buchwald, K. F. Jensen, React.
Chem. Eng. 2016, 1, 658.
[5] K. Wilson, A. F. Lee, Heterogeneous catalysts for clean technol-
ogy: spectroscopy, design, and monitoring, John Wiley & Sons,
Weinheim, Germany 2013.
[34] X. Zhang, P. Li, Y. Ji, L. Zhang, L. Wang, Synthesis 2011, 18,
2975.
[6] Y. M. A. Yamada, K. Takeda, H. Takahashi, S. Ikegami, J. Org.
Chem. 2003, 68, 7733.
[35] E. Negishi, L. Anastasia, Chem. Rev. 2003, 103, 1979.
[36] H. Doucet, J. C. Hierso, Angew. Chem. Int. Ed. 2007, 46, 834.
[37] A. Elangovan, Y. H. Wang, T. I. Ho, Org. Lett. 2003, 5, 1841.
[38] J. H. Li, Y. Liang, X. D. Zhang, Tetrahedron 2005, 61, 1903.
[7] M. Esmaeilpour, J. Javidi, F. Dehghani, J. Iran. Chem. Soc. 2016,
13, 695.
[8] M. Cai, J. Peng, W. Hao, G. Ding, Green Chem. 2011, 13, 190.
[9] S. J. Hoseini, N. Aramesh, M. Bahrami, Appl. Organomet.
Chem. 2017, 31, e3675.
[39] M. Esmaeilpour, A. Sardarian, J. Javidi, Catal. Sci. Technol.
2016, 6, 4005.
[10] K. S. Shin, Y. K. Cho, J. Y. Choi, K. Kim, Appl. Catal. Gen. 2012,
413‐414, 170.
[40] C. N. Chinchilla, Chem. Rev. 2007, 107, 874.
[41] P. Srinivas, K. Srinivas, P. R. Likhar, B. Sridhar, K. V. Mohan, S.
[11] Y. Chi, Q. Yuan, Y. Li, J. Tu, L. Zhao, N. Li, X. Li, J. Colloid
Interface Sci. 2012, 383, 96.
Bhargava, M. L. Kantam, J. Organomet. Chem. 2011, 696, 795.
[42] P. Sharma, A. P. Singh, Cat. Sci. Technol. 2014, 4, 2978.
[12] R. K. Sharma, M. Yadav, R. Gaur, Y. Monga, A. Adholeya, Cat.
Sci. Technol. 2015, 5, 2728.
[43] M. Esmaeilpour, J. Javidi, S. Zahmatkesh, Appl. Organomet.
Chem. 2016, 30, 897.
[13] A. Schatz, M. Hager, O. Reiser, Adv. Funct. Mater. 2009, 19,
[44] M. Esmaeilpour, J. Javidi, J. Chin. Chem. Soc. 2015, 62, 614.
[45] M. Esmaeilpour, J. Javidi, J. Chin. Chem. Soc. 2015, 62, 328.
2109.
[14] M. Esmaeilpour, J. Javidi, F. Dehghani, S. Zahmatkesh, Res.
Chem. Intermed. 2017, 43, 163.
[46] M. Esmaeilpour, A. R. Sardarian, Green Chem. Lett. Rev. 2014, 7,
301.
[15] T. T. Baby, S. Ramaprabhu, Talanta 2010, 80, 2016.
[47] M. Esmaeilpour, J. Javidi, F. Nowroozi Dodeji, H.
[16] S. Sun, C. B. Murray, D. Weller, L. Folks, A. Moser, Science
2000, 287, 1989.
Hassannezhad, J. Iran. Chem. Soc. 2014, 11, 1703.
[48] J. Javidi, M. Esmaeilpour, M. Rajabnia Khansari, RSC Adv.
2015, 5, 73268.
[17] J. Javidi, M. Esmaeilpour, Colloid. Surface B. 2013, 102, 265.
[18] S. Zahmatkesh, M. Esmaeilpour, J. Javidi, RSC Adv. 2016, 6,
[49] J. Huang, F. Zhu, W. He, F. Zhang, W. Wang, H. Li, J. Am.
Chem. Soc. 2010, 132, 1492.
90154.

ESMAEILPOUR ET AL.
15 of 15
[50] P. Li, L. Wang, L. Zhang, G. W. Wang, Adv. Synth. Catal. 2012,
354, 1307.
[65] S. Sobhani, Z. Zeraatkar, F. Zarifi, New J. Chem. 2015, 39, 7076.
[66] N. Salam, S. K. Kundu, A. S. Roy, P. Mondal, K. Ghosh, A.
[51] A. K. Rathi, M. B. Gawande, J. Pechousek, J. Tucek, C.
Aparicio, M. Petr, O. Tomanec, R. Krikavova, Z. Travnicek, R.
S. Varma, Green Chem. 2016, 18, 2363.
Bhaumik, S. M. Islam, Dalton Trans. 2014, 43, 7057.
[67] L. Zhang, L. Wang, H. Li, P. Li, Synth. Commun. 2008, 38, 1498.
[68] F. R. Fortea‐Pérez, I. Schlegel, M. Julve, D. Armentano, G. De
Munno, S. E. Stiriba, J. Organomet. Chem. 2013, 743, 102.
[52] M. Esmaeilpour, A. R. Sardarian, A. Jarrahpour, E. Ebrahimi, J.
Javidi, RSC Adv. 2016, 6, 43376.
[69] M. Ghiaci, M. Zargani, F. Moeinpour, A. Khojastehnezhad,
[53] A. Modak, M. Pramanik, S. Inagaki, A. Bhaumik, J. Mater.
Chem. A 2014, 2, 11642.
Appl. Organomet. Chem. 2014, 28, 589.
[70] V. I. De Paula, C. A. Sato, R. Buffon, J. Braz. Chem. Soc. 2012,
23, 258.
[54] B. Tamami, F. Farjadian, S. Ghasemi, H. Allahyari, New J.
Chem. 2013, 37, 2011.
[71] R. H. Crabtree, Chem. Rev. 2012, 112, 1536.
[55] L. Yang, Y. Li, Q. Chen, Y. Du, C. Cao, Y. Shi, G. Pang, Tetrahe-
dron 2013, 69, 5178.
SUPPORTING INFORMATION
[56] M. Esmaeilpour, J. Javidi, F. Nowroozi Dodeji, M. M.
Abarghoui, Transition Met. Chem. 2014, 39, 797.
Additional Supporting Information may be found online
in the supporting information tab for this article.
[57] A. Cwik, Z. Hell, F. Figueras, Tetrahedron Lett. 2006, 47, 3023.
[58] H. Salemi, B. Kaboudin, F. Kazemi, T. Yokomatsu, RSC Adv.
2016, 6, 52656.
[59] F. Dehghani Firuzabadi, Z. Asadi, F. Panahi, RSC Adv. 2016, 6,
How to cite this article: Esmaeilpour M,
Zahmatkesh S, Fahimi N, Nosratabadi M.
Palladium nanoparticles immobilized on EDTA‐
modified Fe3O4@SiO2 nanospheres as an efficient
and magnetically separable catalyst for Suzuki and
Sonogashira cross‐coupling reactions. Appl
Organometal Chem. 2018;e4302. https://doi.org/
10.1002/aoc.4302
101061.
[60] B. N. Lin, S. H. Huang, W. Y. Wu, C. Y. Mou, F. Y. Tsai, Mole-
cules 2010, 15, 9157.
[61] X. Jin, K. Zhang, J. Sun, J. Wang, Z. Dong, R. Li, Cat. Com.
2012, 26, 199.
[62] A. S. Singh, U. B. Patil, J. M. Nagarkar, Cat. Com. 2013, 35, 11.
[63] M. Zhu, G. Diao, J. Phys. Chem. C 2011, 115, 24743.
[64] S. Sobhani, F. Zarifi, Chin. J. Catal. 2015, 36, 555.