Synthesis of Pd@graphene oxide framework nanocatalyst with enhanced activity in Heck-Mizoroki cross-coupling reaction

Article abstract of DOI:10.1002/aoc.5775

A new method was developed for producing a catalyst involving a Pd nanoparticle (NP) embedded in a graphene oxide framework (Pd@GOF) with ordered macro- and mesoporous structures. First, 5,5′-diamino-2,2′-bipyridine was selected as cross-linking for covalent modification of GO nanosheets to prepare a three-dimensional (3D) framework with interlayer spaces in which well-dispersed and ultra-small Pd NPs in situ grew and embedded the framework. The synthesized nanopores 3D Pd@GOF can act as nanoreactors to help the reaction substrates thoroughly come into contact with the surface of Pd NPs, thereby exhibiting high activity toward the Heck reaction, rarely reported concerning Pd NPs supported on one-side functionalized graphene. The Pd@GOF catalyst can be used 10 times without any significant loss in the catalytic activity, confirming the long-term stability of this catalyst. Therefore, the covalently assembled GOF was proposed as a universal platform for hosting noble metal NPs to construct the desired metal@GOF nanocatalyst with improved activity and stability that can be used in a broad range of practical applications.

Full text of DOI:10.1002/aoc.5775

Received: 19 December 2019
DOI: 10.1002/aoc.5775
Revised: 13 March 2020
Accepted: 12 April 2020
F U L L P A P E R
Synthesis of Pd@graphene oxide framework nanocatalyst
with enhanced activity in Heck-Mizoroki cross-coupling
reaction
Arezoo Shekarizadeh | Roya Azadi
Chemistry Department, College of
A new method was developed for producing a catalyst involving a Pd nanopar-
ticle (NP) embedded in a graphene oxide framework (Pd@GOF) with ordered
macro- and mesoporous structures. First, 5,50-diamino-2,20-bipyridine was
selected as cross-linking for covalent modification of GO nanosheets to prepare
a three-dimensional (3D) framework with interlayer spaces in which well-
dispersed and ultra-small Pd NPs in situ grew and embedded the framework.
The synthesized nanopores 3D Pd@GOF can act as nanoreactors to help the
reaction substrates thoroughly come into contact with the surface of Pd NPs,
thereby exhibiting high activity toward the Heck reaction, rarely reported con-
cerning Pd NPs supported on one-side functionalized graphene. The Pd@GOF
catalyst can be used 10 times without any significant loss in the catalytic activ-
ity, confirming the long-term stability of this catalyst. Therefore, the covalently
assembled GOF was proposed as a universal platform for hosting noble metal
NPs to construct the desired metal@GOF nanocatalyst with improved activity
and stability that can be used in a broad range of practical applications.
Science, Shahid Chamran University of
Ahvaz, Ahvaz, 61357-43169, Iran
Correspondence
Roya Azadi, Chemistry Department,
College of Science, Shahid Chamran
University of Ahvaz, Ahvaz 61357-43169,
Iran.
Email: razadi@scu.ac.ir
Funding information
Shahid Chamran University of Ahvaz,
Grant/Award Number: 1398
K E Y W O R D S
graphene oxide frameworks, Heck reaction, heterogeneous catalyst, palladium nanoparticles
1 | INTRODUCTION
electrostatic, hydrogen bonding, and Van der Waals
interactions, which are insufficiently durable during the
Three-dimensional graphene materials (3DGMs) with
porous structures have a large specific surface area, tun-
able porosity, low density, and excellent mechanical
strength.[1–3] These materials have shown promising sup-
port in the preparation of heterogeneous catalysts. Specif-
ically, their structures are conducive to stabilizing metal
nanoparticles (NPs) and restricting their growth, which
are the basic features of heterogeneous catalysts.
The past several years have witnessed the develop-
ment of various synthetic strategies toward 3DGMs with
diverse morphologies, structures, and properties, includ-
ing self-assembly, template-assisted preparation, and
direct deposition.[2,3] Structures of 3DGMs are often
formed based on noncovalent interactions such as
catalytic process.[4–8] An important strategy for improv-
ing the stability of 3DGMs is the covalent construction of
frameworks in stabilizers as linkers.[9] Among the stabi-
lizers, monomers with two functional groups such as
polyethylenimine
and
ethylenediamine,[10]
p-
phenylenediamine,[11] poly(oxypropylene)diamines,[12]
triethylenetetramine,[2] benzene-1,4-diboronic acid or
its
derivatives,[13]
1,4-phenylenediisocyanate,[14]n-
alkylamines,[15] and 1,2,4,5-benzenetetraamine[16] have
been recently reported for cross-linking to the prepara-
tion of graphene oxide frameworks (GOFs). However, to
our knowledge, only a few studies have reported a
coordination-assisted synthetic approach toward encap-
sulated NPs inside the space of GOFs.[2,13] Most recently,
Appl Organomet Chem. 2020;e5775.
wileyonlinelibrary.com/journal/aoc
© 2020 John Wiley & Sons, Ltd.
1 of 8
https://doi.org/10.1002/aoc.5775

2 of 8
SHEKARIZADEH AND AZADI
Tran et al.[13] reported a new synthetic method compris-
ing Pd NPs encapsulated in GOF (Pd@GOF) prepared
through the cross-linking of GO with benzene-1,-
4-diboronic acid. The catalytic activity of the nanocatalyst
was investigated in the Suzuki-Miyaura cross-coupling
reaction.
Next, 5,50-diamino-2,20-bipyridine was reacted with GO–
COCl layers for the synthesis of GOF. After GOF was
washed and dried, the structures were analyzed using
Fourier-transform
(Figure 1).
infrared
(FT-IR)
spectroscopy
The IR spectrum of GO revealed the characteristic
Herein, we demonstrate a novel and facile method for
confining Pd NPs inside the space of a new GOF. In this
fabrication process, GO layers are primarily intercalated
by two-side covalent linkers with 5,50-diamino-2,20-
bipyridine to form a new GOF. The porous structures of
the GOF are utilized for the in situ growth of Pd NPs.
Therefore, the formed Pd NPs are dispersed with a nar-
row particle-size distribution. Pd@GOF can effectively
prevent the direct exposure of trapped Pd NPs and pre-
serve their stabilization. The coordination effect between
the N atom of bipyridine and Pd can further suppress the
accumulation of the Pd NP. The catalytic activity of the
well-defined nanocatalyst is then investigated in the
Heck-Mizoroki cross-coupling reaction.
stretching vibrations corresponding to O–H at
3300–3500 cm−1, C=O at 1736 cm−1, C=C at 1624 cm−1
,
and C–O at 1054 cm−1. After cross-linking with 5,50-dia-
mino-2,20-bipyridine, the peak at 1736 cm−1 almost dis-
appeared, and a new peak appeared at about 1700 cm−1
,
which represents C=O in the amide group. To synthesize
Pd@GOF, PdCl2 was added to the ethanol solution of the
GOF. Palladium was coordinated with the N atom of
bipyridine present in the GOF. The chemical structure,
framework, and morphology of the catalyst were charac-
terized using FT-IR, X-ray diffraction (XRD), atomic
absorption spectrometry (AAS), and transmission elec-
tron microscopy (TEM) spectroscopy. In the IR spectrum
of Pd@GOF, a new peak emerged at 528 cm−1
corresponding to the N–Pd band.
Figure 2 represents the XRD spectra of Pd@GOF
where GOF showed a characteristic peak at 2Ɵ = 26ꢀ,
which is the same as that of GO,[18] confirming that the
composite preserves the structure of GO. A significant Pd
characteristic peak was obtained at 40.1ꢀ, indicating a
successful reduction in palladium ion to Pd(0). The other
two peaks at 47ꢀ and 68ꢀ are attributed to crystalline
plane diffraction peaks of Pd(0). The particle size was cal-
culated at 20.25 nm for the Pd@GOF catalyst based on
the Scherrer equation.
2 | RESULTS AND DISCUSSION
Regarding the synthesis and use of metal NPs in organic
reactions,[17] we report here the synthesis of Pd@GOF
nanocatalyst to use in the Heck reaction of various aryl
iodides, bromides, and chlorides with styrene.
The synthesis of Pd@GOF is shown in Scheme 1. The
framework was generated by the covalent linking of car-
boxyl (–COOH) groups of GO with the amino (–NH2)
groups of bipyridine. As shown, the first graphene oxide
refluxed in SOCl2 generated intermediate GO–COCl.
Figure 3 shows the energy-dispersive X-ray spectros-
copy (EDS), which verifies the presence of a large
SCHEME 1 Synthesis of Pd@GOF (GO,
graphene oxide; GOF, graphene oxide
framework)

SHEKARIZADEH AND AZADI
3 of 8
FIGURE 1 Fourier-transform infrared
spectra of graphene oxide (GO), graphene oxide
framework (GOF), and palladium nanoparticle
embedded in a graphene oxide framework
(Pd@GOF)
Figure 4b that the sizes of Pd NPs are 15.5 nm that are
consistent with those estimated by XRD.
The catalytic activity of the prepared catalyst was sys-
tematically tested through the Heck-Mizoroki cross-
coupling reaction. For this purpose, the coupling reaction
of bromobenzene with styrene was chosen as the model
reaction, and the effects of several solvents were also
examined to specify the most optimal solvent. According
to the results summarized in Table 2, the best conversion
was observed for H2O–EtOH (1:1) in the presence of
Pd@GOF (1 mg, 0.2 mol% Pd) (Table 2, entry 3). K2CO3
(1.5 mmol) was used as a base for optimizing the reaction
conditions. In the next step, the optimum amount of the
catalyst was monitored to achieve the maximum yield of
the product, and 1 mg (0.2 mol% Pd) of the catalyst was
selected as the optimum amount (Table 3, entry 2).
FIGURE 2 X-ray diffraction pattern of Pd@GOF
number of Pd NPs on graphene. The figure also shows
the presence of nitrogen, therefore the existence of 5,50-
diamino-2,20-bipyridine in the Pd@GOF. The amounts of
elements detected by EDS analysis are summarized in
Table 1. The amount of Pd in the catalyst measured using
the AAS was 21.68 wt%.
Figure 4 shows the TEM image of Pd@GOF catalyst,
based on which dispersed Pd NPs were trapped by the
graphene network and homogeneously embedded
between the sheets of GO. Further, it is also clear from
TABLE 1
EDS analysis
Elemental composition of Pd@GOF determined by
C
O
N
Pd
32.27
28.42
6.63
32.67
Abbreviations:
EDS,
energy-dispersiveX-ray
spectroscopy;
Pd@GOF, palladium nanoparticle embedded in a graphene oxide
framework.
FIGURE 3 Energy-dispersiveX-ray
spectroscopy analysis of Pd@GOF

4 of 8
SHEKARIZADEH AND AZADI
FIGURE 4 (a) Transmission
electron microscopy image of Pd@GOF
and (b) histogram of particle-size
distribution of Pd@GOF catalyst
TABLE 2 Heck reaction in various solventsa
aryl
bromides
including
4-bromotoluene,
4-bromoanisole, 4-bromophenol, and 4-bromoaniline also
provided 90%, 85%, 83%, and 85% yields, respectively, but
over longer reaction times and lower TOF (2.25, 2.13,
Entry
Solvent
H2O
Yield (%)b
1
2
3
4
5
85
93
98
30
78
EtOH
1.38, and 1.42 h−1
, respectively) compared with
H2O–EtOH
Toluene
DMF
deactivated aryl bromides (Table 4, entries 2–5). More-
over, iodobenzene reacted much faster than
bromobenzene with higher TOF (Table 4, entry 12). The
catalytic system was less effective on the reaction of aryl
chlorides (Table 4, entries 14, 15).
Abbreviation: DMF, dimethylformamide.
aReaction was carried out with 1 mmol of bromobenzene, 1.2 mmol
of styrene, 1.5 mmol of K2CO3, 1 mg (0.2 mol% Pd) of Pd@GOF,
and 5 ml of the solvent at 80ꢀC for 20 min.
To investigate the reusability of the heterogeneous
palladium catalyst, a set of experiments were performed
under optimized conditions for the reaction of
bromobenzene with styrene. After each catalytic cycle
was completed, the reaction mixture was primarily
cooled down to the room temperature, then filtered and
washed with ethanol and acetone, and dried under vac-
uum for the next run. Finally, the reuse of Pd@GOF was
investigated in the Heck reaction of bromobenzene with
styrene. Table 5 shows that the Pd@GOF catalyst was
recycled 10 times with a minor loss of catalytic activity,
which clearly indicates the high catalytic activity and sta-
bility of Pd@GOF. Comparison of the Pd concentrations
before the catalytic reaction (21.68 wt%) and after 10 runs
(19.02 wt%) measured by atomic absorption shows that
palladium leaching was negligible, probably due to the
excellent binding of the N atom with Pd.
bIsolated yield.
To study the catalytic activity of Pd@GOF under opti-
mal conditions, the coupling reactions of various
substituted aryl halides with styrene were accomplished
in the presence of Pd@GOF catalyst, using K2CO3 as a
base and H2O–EtOH (1:1) as an environmentally benign
solvent, and the results are summarized in Table 4.
The results show that the catalyst system is efficient
and the stilbene derivatives are obtained in a short time
with high yields. Heck reactions of the deactivated aryl
bromides proceeded with high yields over a short reac-
tion period and high turnover frequencies (TOF)
(Table 4, entries 6–11). The Heck reaction of the activated
TABLE 3 Influence of amount of catalyst on Heck reactiona
To investigate whether the catalytically active species
is really heterogeneous, the hot filtration[19] experiment
was carried out to get insight into Heck reaction cata-
lyzed with apparently a heterogeneous Pd@GOF catalyst.
The catalytically active nanocomposite was removed
from the reaction of bromobenzene with styrene by filtra-
tion after 5 min using a hot frit, and the filtrate was mon-
itored for continued activity. The hot filtrates were then
transferred into another flask containing 1.5 mmol of
K2CO3 and 5 ml of H2O–EtOH (1:1) at 80ꢀC. Upon fur-
ther continuation of the catalyst-free reaction for 5 h, no
Amount of catalyst
Entry (mg)
Pd content
(mol%)
Yield
(%)b
1
2
3
0.5
1
0.1
0.2
0.4
60
98
98
2
aReaction was carried out with 1 mmol of bromobenzene, 1.2 mmol
of styrene, 1.5 mmol of K2CO3, and 5 ml of the solvent H2O–EtOH
(1:1) at 80ꢀC for 20 min.
bIsolated yield.

SHEKARIZADEH AND AZADI
5 of 8
TABLE 4
Heck reaction of aryl halides with styrene catalyzed by Pd@GOFa
Entry
R
X
Time (h)
Yield (%)b
TONc
4.85
4.50
4.25
4.15
4.25
4.45
4.70
4.50
4.25
4.25
4.40
4.75
4.50
3.25
3.50
TOF (h−1 d
)
1
H
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
Br
I
15 min
97
90
85
83
85
89
94
90
85
85
88
95
90
65
70
19.40
2.25
2.13
1.38
1.42
4.45
4.70
2.25
2.13
4.25
4.40
57.00
9.00
0.46
0.50
2
CH3
OCH3
OH
2
3
2
4
3
5
NH2
CN
3
6
1
7
NO2
CO2H
COH
COCH3
Cl
1
8
2
9
2
10
11
12
13
14
15
1
1
H
5 min
OCH3
H
I
0.5
7
Cl
Cl
COH
7
aReaction conditions: aryl halides (1.0 mmol), styrene (1.2 mmol), K2CO3 (1.5 mmol), Pd@GOF (1 mg, 0.2 mol% Pd), and H2O–EtOH (1:1)
(5 ml) at 80ꢀC.
bIsolated yield.
cTON, turnover number, moles of aryl halides converted per mole of Pd.
dTOF, turnover frequencies, TON/time of reaction.
TABLE 5
Reusability of the Pd@GOF in Heck reactiona
Run
1
2
3
4
5
6
7
8
9
10
Yield (%)b
90
90
89
89
87
86
86
86
85
85
aReaction conditions: bromobenzene (1.0 mmol), styrene (1.2 mmol), K2CO3 (1.5 mmol), Pd@GOF (1 mg, 0.2 mol% Pd), and H2O–EtOH
(1:1) (5 ml) at 80ꢀC.
bIsolated yield.
TABLE 6
Comparison of efficiency of Pd@GOF with one-side functionalized graphene in Heck reaction of bromobenzene with styrene
Entry
Catalyst [ref]
Solvent
DMF
Base
Temp. (ꢀC)
Time (h)
Yield (%)a
TOF (h−1
0.73
)
1
2
3
4
5
6
ERGO-Pd (0.3 mol%)[20]
Pd/Met/GO (0.1 mol%)[21]
Pd/GO (0.16 mol%)[22]
TRGO-NPy-Pd (0.3 mol%)[23]
PCA-GNS-Pd (0.2 mol%)[24]
Pd@GOF (0.2 mol%) [this work]
Et3N
120
110
110
140
90
4
88
96
63
97
85
97
DMF
Et3N
3
3.2
Toluene
DMF
Et3N
5
0.78
Na2CO3
Na2CO3
K2CO3
5
0.65
H2O
12
0.35
H2O–EtOH
80
15 min
19.40
Abbreviations: DMF, dimethylformamide; TOF, turnover frequencies.
aIsolated yield.

6 of 8
SHEKARIZADEH AND AZADI
substantial progress (by GC analysis) was observed. Fur-
thermore, AAS of the same reaction solution at the mid-
point of completion indicated that no significant
quantities of palladium were lost to the reaction liquors
during the process.
KBr pellets using a Spectrum One FT-IR spectrometer
(PerkinElmer, Waltham, MA). High-field nuclear mag-
netic resonance (NMR) spectra were obtained using a
Bruker 250 MHz Avance Ultrashield instrument
1
(Germany). H NMR and 13C NMR chemical shifts are
The catalytic performance of Pd@GOF was compared
with the certain Pd NPs supported on one-side
functionalized graphene reported in the literature for the
reaction of bromobenzene with styrene (Table 6).[20–24]
Table 6 shows that the high loading of palladium on
Pd@GOF effectively made it possible to perform the reac-
tion with only a small catalyst amount with higher reac-
tion yield over shorter reaction times and higher TOF.
The high catalytic activity is attributed to the small size
and identical dispersion of Pd NPs on ordered pores that
could be considered as nanoreactors to increase the con-
tact area between the substrate and the catalyst.
quoted relative to solvent resonance(s) as the internal
standard. TEM images were acquired using a Zeiss-
EM10C transmission electron microscope with an
acceleration voltage of 80 kV. Samples were prepared
by dispersing Pd@GOF in water via ultrasonication.
One drop of the suspension was applied to a formvar
carbon-coated grid Cu mesh 300 and left dry in air.
An Analytik Jena (Germany) flame AAS instrument
was used for the determination of Pd. In addition,
investigations using scanning electron microscopy were
carried out by applying an EDS detector. The measure-
ments were conducted using a Rontec scanning elec-
tron microscope (Bruker, Germany).
3 | CONCLUSION
4.2 | Synthesis of GO
In summary, the GOF was successfully prepared by
cross-linking of 5,50-diamino-2,20-bipyridine with GO as
well-defined porous support in heterogeneous catalysis.
The reaction of two amino groups of linker with the car-
boxylic group of GO sheets provided a GOF structure
with a regularly expanded interlayer spacing. In situ dis-
persed Pd NPs were grown and encapsulated in the
framework due to the strong coordination between the
Pd atoms and bipyridine’s N atom of 5,50-diamino-2,20-
bipyridine, a process facilitating the immobilization and
stabilization of Pd NP in the GOF matrix. The Pd@GOF
catalyst exhibited a superior performance toward the
Heck cross-coupling reaction. Also, the formed ordered
pores were considered as nanoreactors to increase the
contact area between the substrate and the catalyst.
Accordingly, such a catalyst exhibits high activity, syner-
gistic catalysis, and stable cycling toward the Heck
reaction.
GO was synthesized from graphite using a modified
Hummers method.[25]
4.3 | Synthesis of GO–COCl
GO–COCl was synthesized according to our previous
procedure.[17b] GO (0.1 g) was dispersed in 15 ml SOCl2
by sonication for 30 min. Subsequently, the suspension
was refluxed at 70ꢀC for 24 h. The product (GO–COCl)
was gathered by filtration, washed with anhydrous tetra-
hydrofuran (THF), and dried at room temperature.
4.4 | Synthesis of 5,50-diamino-2,20-
bipyridine by homocoupling of 5-amino-
2-bromopyridine
The linker was prepared using a modification of the pro-
cedure described in Wang et al.[26] A mixture of 5-amino-
2-bromopyridine (1.73 g, 10 mmol), PdCl2 (17.7 mg,
0.1 mmol), K2CO3 (1.38 g, 10 mmol), and PEG 4000
(10 g) was stirred at 120ꢀC for 24 h at which time the
starting material could not be detected anymore by thin-
layer chromatography (eluent ethyl acetate). After the
reaction, the solution was cooled to room temperature,
and the resulting solid was extracted with dic-
hloromethane (4 × 35 ml). Further purification of the
product was achieved using flash chromatography on a
silica gel column. The product 5,50-diamino-2,20-
bipyridine was separated as a yellowish solid and was
4 | EXPERIMENTAL
4.1 | Materials and methods
Graphite powder, sulfuric acid (H2SO4), potassium per-
manganate (KMnO4), hydrogen peroxide (H2O2), vari-
ous aryl halides, styrene, potassium carbonate (K2CO3),
5-amino-2-bromopyridine, PEG 4000, and palladium(II)
chloride were purchased from Merck Chemical Com-
pany (Kenilworth, NJ 07033, USA), without further
purification. Double-distilled water was used through-
out the experiments. FT-IR spectra were recorded in

SHEKARIZADEH AND AZADI
7 of 8
sublimed as described earlier to yield a colorless powder
over anhydrous Na2SO4, and the crude product was puri-
fied using column chromatography (n-hexane–ethyl ace-
tate). The evaporation of the solvent generated pure
desired products, all of which are known compounds
whose NMR spectra are in accordance with those
reported in the literature.[20–24]
(yield, 1.75 g; 85%). m.p. 206ꢀC (Janiak et al.[27]205–206-
1
ꢀC). H NMR (300 MHz, DMSO-d6): δ = 7.94 (d, 2H,
J = 2.8 Hz, H6, H60), 7.85 (d, 2H, J = 8.5 Hz, H3, H30),
6.90 (dd, 2H, J1 = 8.5 Hz, J2 = 2.5 Hz, H4, H40), 5.38
[s (br.), 4H, NH2]. 13C NMR (75 MHz, DMSO-d6):
δ = 147.3 (C2, C20), 145.3 (C5, C50), 135.7 (C6, C60), 124.2
(C3, C30), 121.8 (C4, C40).
ACKNOWLEDGMENT
We thank Shahid Chamran University of Ahvaz Research
Council, Ahvaz, for financial support of this study (Grant
Number 1398).
4.5 | Synthesis of GOFs
The GOF was prepared with the reaction between 5,50-
diamino-2,20-bipyridine and GO–COCl according to the
following procedure. At first, GO–COCl (0.1 g) was mixed
in dimethylformamide (DMF) (30 ml) and sonicated for
30 min. Then, 5,50-diamino-2,20-bipyridine was added to
20 ml of DMF and stirred; the achieved solution was then
slowly added to GO–COCl suspension. Consequently, the
reaction temperature was raised to 100ꢀC and the mix-
ture was stirred for 24 h. Finally, the reaction tempera-
ture was reduced down to 80ꢀC, and the mixture was
kept under static conditions for 24 h. The resulting solid
was filtered and washed several times with deionized
water. Next, it was dried at room temperature before
characterization.
ORCID
Roya Azadi https://orcid.org/0000-0002-8580-0810
REFERENCES
[1] Y. Ma, Y. Chen, Natl. Sci. Rev. 2015, 2, 40.
[2] J. Liu, G. Hu, Y. Yang, H. Zhang, W. Zuo, W. Liu, B. Wang,
Nanoscale 2016, 8, 2787.
[3] C. Li, G. Shi, Nanoscale 2012, 4, 5549.
[4] L. Zhang, G. Shi, J. Phys. Chem. C 2011, 115, 17206.
[5] X. Yang, J. Zhu, L. Qiu, D. Li, Adv. Mater. 2011, 23, 2833.
[6] Z. Tang, S. Shen, J. Zhuang, X. Wang, Angew. Chem. Int. Ed.
2010, 49, 4603.
[7] C. Hu, X. Zhai, Y. Zhao, K. Bian, J. Zhang, L. Qu, H. Zhang,
H. Luo, Nanoscale 2014, 6, 2768.
[8] X. Wang, L. L. Lu, Z. L. Yu, X. W. Xu, Y. R. Zheng, S. H. Yu,
Angew. Chem. Int. Ed. 2015, 54, 2397.
4.6 | Synthesis of GOF-embedded Pd NPs
(Pd@GOF)
[9] (a) J. W. Burress, S. Gadipelli, J. Ford, J. M. Simmons,
W. Zhou, T. Yildirim, Angew. Chem. Int. Ed. 2010, 49, 8902. (b)
R. Kumar, V. M. Suresh, T. K. Maji, C. N. R. Rao, Chem.
Commun. 2014, 50, 2015.
[10] (a) H. Hu, Z. Zhao, W. Wan, Y. Gogotsi, J. Qiu, Adv. Mater.
2013, 25, 2219. (b) Y. Zhang, S. Zhang, J. Gao, T. S. Chung,
J. Membr. Sci. 2016, 515, 230.
[11] (a) G. Tang, Z. G. Jiang, X. Li, H. B. Zhang, A. Dasari,
Z. Z. Yu, Carbon 2014, 77, 592. (b) Y. Lu, L. Zhang, K. Leng,
Y. Huang, X. Yang, M. Zhang, F. Zhang, T. Zhang, Y. Chen,
Chin. Sci. Bull. 2014, 59, 1809.
The GOF (50 mg) was dispersed in 20 ml of ethanol by
sonication for 30 min. Subsequently, PdCl2 (0.25 mmol,
44.3 mg) was added, and the mixture was subjected to
sonication for 5 min. The reaction was then stirred for
24 h at room temperature. The final product was filtered
and washed with distilled water five times, and the cata-
lyst (Pd@GOF) was air-dried.
[12] W. Wan, L. Li, Z. Zhao, H. Hu, X. Hao, D. A. Winkler, L. Xi,
T. C. Hughes, J. Qiu, Adv. Funct. Mater. 2014, 24, 4915.
[13] (a) T. P. N. Tran, A. Thakur, D. X. Trinh, A. T. N. Dao,
T. Taniike, Appl. Catal. A. Gen. 2018, 549, 60. (b)
J. W. Burress, S. Gadipelli, J. Ford, J. M. Simmons, W. Zhou,
T. Yildirim, Angew. Chem. Int. Ed. 2010, 49, 8902.
[14] B. Feng, K. Xu, A. Huangm, Desalination 2016, 394, 123.
[15] H. P. Mungse, R. Singh, H. Sugimura, N. Kumar, O. P. Khatri,
Phys. Chem. Chem. Phys. 2015, 17, 20822.
4.7 | General procedure for the Heck
reaction
In a 25 ml round-bottom flask, 1 mg of Pd@GOF catalyst
(0.2 mol% Pd) was dispersed in 5 ml of H2O–EtOH (1:1)
by sonication for 20 min at room temperature. To this
suspension, aryl halides (1 mmol), styrene (1.2 mmol),
and K2CO3 (1.5 mmol) were added, and the reaction mix-
ture was stirred at 80ꢀC for the required time. After the
completion of the reaction (monitored by TLC), the reac-
tion mixture was cooled down to room temperature, fil-
tered, and then washed with dichloromethane
(3 ×10 ml). The organic phase was separated and dried
[16] Y. Cui, Q. Y. Cheng, H. Wu, Z. Wei, B. H. Han, Nanoscale
2013, 5, 8367.
[17] (a) M. Sarvestani, R. Azadi, Appl. Organomet. Chem. 2017, 31,
e3667. (b) M. Sarvestani, R. Azadi, Appl. Organomet. Chem.
2018, 32, e3906. (c) M. Sarvestani, R. Azadi, Can. J. Chem.
2019, 97, 191. (d) A. Ahmadi, T. Sedaghat, R. Azadi,
H. Motamedi, Catal. Lett. 150, 112. https://doi.org/10.1007/
s10562-019-02913-5

8 of 8
SHEKARIZADEH AND AZADI
[18] Y. Wang, Y. Li, L. Tang, J. Lu, J. Li, Electrochem. Commun.
2009, 11, 889.
[26] L. Wang, Y. Zhang, L. Liu, Y. Wang, J. Org. Chem. 2006, 71,
1284.
[19] R. A. Sheldon, M. Wallau, I. Arends, U. Schuchardt, Acc.
Chem. Res. 1998, 31, 485.
[27] C. Janiak, S. Deblon, H.-P. Wu, M. J. Kolm, P. Klüfers,
H. Piotrowski, P. Mayer, Eur. J. Inorg. Chem. 1999, 1999, 1507.
[20] S. S. Shendage, J. M. Nagarkar, Colloids Interface Sci.
Commun. 2014, 1, 47.
[21] H. Veisi, N. Mirzaee, Appl. Organomet. Chem. 2018, 32, e4067.
[22] Y. V. Ioni, S. E. Lyubimov, V. A. Davankov, S. P. Gubin, Russ.
J. Inorg. Chem. 2013, 58, 392.
How to cite this article: Shekarizadeh A,
Azadi R. Synthesis of Pd@graphene oxide
framework nanocatalyst with enhanced activity in
Heck-Mizoroki cross-coupling reaction. Appl
Organomet Chem. 2020;e5775. https://doi.org/10.
1002/aoc.5775
ꢀ
[23] L. Fernández-García, M. Blanco, C. Blanco, P. Alvarez,
M. Granda, R. Santamaría, R. Menéndez, J. Mol. Catal. A-
Chem. 2016, 416, 140.
[24] V. Sharavath, S. Ghosh, RSC Adv. 2014, 4, 48322.
[25] W. S. Hummers, R. E. Offemann, J. Am. Chem. Soc. 1958, 80,
1339.