Suzuki-Miyaura reaction catalyzed by graphene oxide supported palladium nanoparticles

Article abstract of DOI:10.1016/j.catcom.2013.06.006

Pd supported on polyamine modified graphene oxide (GO-NH ₂-Pd^{2 +}) was fabricated for the first time. The prepared catalyst was characterized by transmission electron microscopy, X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy and infrared spectroscopy. The catalytic activity of the prepared catalyst was investigated by employing Suzuki-Miyaura coupling reaction as a model reaction. A series of biphenyl compounds were synthesized through the Suzuki-Miyaura reaction using GO-NH₂-Pd^{2 +} as catalyst. The yields of the products were in the range from 71% to 95%. The catalyst can be readily recovered and reused at least 10 consecutive cycles without significant loss its catalytic activity.

Full text of DOI:10.1016/j.catcom.2013.06.006

Catalysis Communications 40 (2013) 111–115
Contents lists available at SciVerse ScienceDirect
Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short Communication
Suzuki–Miyaura reaction catalyzed by graphene oxide supported
palladium nanoparticles
⁎
⁎
Ningzhao Shang, Cheng Feng, Haiyan Zhang, Shutao Gao, Ranxiao Tang, Chun Wang , Zhi Wang
College of Science, Agricultural University of Hebei, Baoding 071001, China
a r t i c l e i n f o
a b s t r a c t
Pd supported on polyamine modified graphene oxide (GO-NH2-Pd2+) was fabricated for the first time. The
prepared catalyst was characterized by transmission electron microscopy, X-ray diffraction spectroscopy,
X-ray photoelectron spectroscopy and infrared spectroscopy. The catalytic activity of the prepared catalyst
was investigated by employing Suzuki–Miyaura coupling reaction as a model reaction. A series of biphenyl
compounds were synthesized through the Suzuki–Miyaura reaction using GO-NH2-Pd2+ as catalyst. The
yields of the products were in the range from 71% to 95%. The catalyst can be readily recovered and reused
at least 10 consecutive cycles without significant loss its catalytic activity.
Article history:
Received 17 March 2013
Received in revised form 26 May 2013
Accepted 7 June 2013
Available online 14 June 2013
Keywords:
Suzuki–Miyaura coupling reaction
Pd catalyst
© 2013 Elsevier B.V. All rights reserved.
Polyamine modified graphene oxide
1. Introduction
The palladium-catalyzed C–C cross-coupling reaction plays a key
role in the synthesis of many important chemicals including pharma-
The novel and promising graphene (G)-based carbon nanomaterial
has attracted tremendous attentions over the recent years due to
its exceptional properties, such as excellent mechanical, electrical,
thermal, optical properties and very high specific surface area
[1–3]. The chemical versatility and tunability combined with solu-
tion processibility make graphene-based materials attractive for a
wide range of applications in many field including catalysis, drug
delivery, bioimaging, adsorption, electronic and photonic devices
[4–9]. Since its large specific surface area and the large delocalized
π-electron system of graphene-related material can form strong
hydrophobic and π-stacking interactions with organic molecules,
it might be a promising candidate for a catalyst or a catalyst sup-
port. Recently, various of organic reactions catalyzed by G-based
nanomaterial have been reported in the documents [9–11]. The re-
sults indicated that G-based nanomaterial exhibited a high catalytic
activity for different reactions.
ceuticals, herbicides, polymers and so on. Usually, the cross-coupling
reactions were performed under homogeneous condition employing
soluble palladium organic complex as catalyst [12]. However, the
high cost, low efficiency in separation, and subsequent recycling of
homogeneous transition metal catalysts remains a scientific chal-
lenge. To overcome the problems mentioned above, more and
more attentions have been paid to the development of heteroge-
neous catalyst [13]. The solid materials, such as activated carbon
[14–16], zeolites [17–19] and nanoparticles [20–22], have been
used as support for heterogeneous palladium catalyst. Although het-
erogeneous catalysts can be recycled efficiently, a decrease in the
activity of the immobilized catalysts is often observed [23]. Up to
now, only a few papers using G or GO as a solid support for palladi-
um ions and/or palladium particles catalyst for C–C cross-coupling
reaction have been reported [24–26]. However, the catalytic activity
of Pd2+-graphene oxide or graphene decreased gradually when the
catalyst was used repeatedly. This could be ascribed to the weak inter-
action between palladium and the support material, as well as the ag-
glomeration and accumulation of Pd nanoparticles on the surface of
the material [24,25]. Therefore, it is desirable to improve the stability,
recyclability, and catalytic activity of heterogeneous Pd nanocatalysts.
In continuation of our interest in exploring efficient catalyst for or-
ganic transformations [27–31], herein, Pd supported on polyamine
modified graphene oxide was fabricated for the first time. The catalyt-
ic activity of the prepared catalyst was investigated by employing
Suzuki–Miyaura coupling reaction as a model reaction. The result
showed that the new catalyst retains the reactivity characteristic of
a homogeneous catalyst but at the same time it was easy to separate
off and reuse.
⁎
Corresponding authors at: Chun Wang, College of Science, Agricultural University of
Hebei, Baoding 071001, Hebei Province, P. R. China. Tel.: +86 312 7528291; fax: +86 312
7528292.
E-mail addresses: wangchun@hebau.edu.cn (C. Wang), wangzhi@hebau.edu.cn
(Z. Wang).
1566-7367/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.catcom.2013.06.006

112
N. Shang et al. / Catalysis Communications 40 (2013) 111–115
NH2
HN
H2N
NH
NH
HO
O
HN
O
HO
HO
HO
EDC, NHS
DMF
O
O
H2N
NH2
+
N
H
O
N
H
HO
HO
HN
N
O
HO
HN
H2N
O
HO
H
NH2
GO-NH2
GO
NH2
NH2
HN
H2N
HN
Pd0
H2N
NH
NH
Pd2+
NH
NH
Pd2+
Pd0
HN
HN
HO
HO
NH2NH2
PdCl2
O
O
O
O
N
HO
N
HN
Pd2+
HO
H
HN
H
N
N
HN
O
HO
H
NH2
Pd0
HN
O
HO
H
NH2
Pd2+
Pd0
H2N
H2N
GO-NH2-Pd2+
G-NH2-Pd0
Scheme 1. Preparation of GO-NH2-Pd2+ and G-NH2-Pd0.
2. Experimental
2.1. Materials and methods
For the preparation of GO-NH2-Pd2+ and G-NH2-Pd0, 30 mg of
GO-NH2 was dispersed in 50 mL water. After the solution was sonicated
(200 W, 40 kHz) for 10 min, 3.1 mg PdCl2 (0.018 mmol) was added
and the mixture was sonicated for 5 min. Then the solution was stirred
overnight. After filtration, the solid was washed with water and ace-
tone, respectively. The obtained GO-NH2-Pd2+ was dried in vacuo at
room temperature.
Graphite powder (320 mesh) was provided by the Boaixin
Co., Ltd. (Baoding, China). Hydrazine hydrate (80%), 1-(3-
dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC),
n-hydroxysuccinimide (NHS), dimethylformamide (DMF), potassi-
um carbonate and ethanol were all obtained from Chengxin Chem-
ical Reagents Company (Baoding, China). Arylboronics, aryl halides,
diethylenetriamine and palladium chloride (PdCl2) were purchased
from Aladdin Reagent Limited Company and used as received.
The size and morphology of the magnetic nanoparticles were ob-
served by transmission electron microscopy (TEM) using a JEOL
The reduction of GO-NH2-Pd2+ by hydrazine hydrate was
performed as follows: 20 mg of GO-NH2-Pd2+ was dispersed in 50 mL
of water, and then 90 μL of hydrazine hydrate (80%) was added. The
pH of the mixture was adjusted to 10 with 25% ammonium hydroxide
and the reaction was carried out at 95 °C for 2 h. The final product
G-NH2-Pd0 was washed with water and dried in vacuo at 50 °C.
2+
Scheme 1 depicted the synthetic procedure of GO-NH2-Pd
and
model JEM-2011(HR) at 200 kV. The infrared (IR) spectra (cm−1
)
G-NH2-Pd0.
were measured with a WQF-510 spectrometer. The XRD patterns
of the samples were recorded with a Rigaku D/max 2500 X-ray
diffractometer using Cu Kα radiation (40 kV, 150 mA) in the range
2θ = 5o–90o. The Pd content was determined by means of inductively
coupled plasma atomic emission spectroscopy (ICP-AES) on Thermo
Elemental IRIS Intrepid II. X-ray photoelectron spectroscopy (XPS)
was performed with a PHI 1600 spectroscope using Mg Kα X-ray source
for excitation.
GO-Pd2+ and G-Pd0 were fabricated according to the procedure
mentioned above except that 30 mg GO-NH2 was replace by 30 mg
GO. The concentration of palladium in GO-NH2-Pd2+, G-NH2-Pd0,
GO-Pd2+ and G-Pd0 were 6.1, 5.8, 6.2 and 6.0 wt%, respectively,
which were determined by ICP-AES.
2.2. Synthesis of GO-NH2-Pd2+ and G-NH2-Pd0
Table 1
Suzuki–Miyaura coupling reaction catalyzed by different catalysts.
GO was prepared according to the procedure reported by us [32].
Polyamine modified GO (GO-NH2) was synthesized by the condensa-
tion reaction of GO and polyamine. Briefly, 30 mg GO was dispersed
in 50 mL DMF. After ultrasonication for 1 h, the GO solution was cooled
to 0 °C and then 6 mmol EDC and 6 mmol NHS were added. The mix-
ture was stirred for 2 h at 0 °C. Then 12 mmol diethylenetriamine
was added and stirred at room temperature over night. The obtained
amino-functionalized GO (GO-NH2) was separated by filtration and
washed with acetone and H2O, respectively. GO-NH2 was dried at
room temperature under reduced pressure.
Catalysts
Reaction time/h
Yield/%
Pd0/G
7
57
81
64
87
Pd2+/GO
0.5
5.5
0.5
G-NH2-Pd0
GO-NH2-Pd2+
n
(K2CO3):
n (Aryl iodide): n (Phenylboronic acid) = 4: 1: 1.3; solvent: 2 mL
ethanol + 1 mL H2O; the quantity of catalyst was 1 mol %; 60 °C.

N. Shang et al. / Catalysis Communications 40 (2013) 111–115
113
at 60 °C for 0.5 h (shown in Table 1). Upon the completion of the reaction
(monitored by thin layer chromatography), the reaction mixture was di-
luted with 20 mL H2O and extracted with ether (3 × 10 mL). The organic
phase were combined together and dried over anhydrous Na2SO4. The
solvent was evaporated under vacuum. The pure products were obtained
by flash chromatography using hexane: ethylacetate (4:1) as the eluent.
a
b
3. Results and discussion
c
3.1. Characterization of the nanoparticle catalysts
The corresponding IR spectra of GO, GO-NH2 and G-NH2-Pd0 were
depicted in Fig. 1. For the GO-NH2 sample, the bands observed at
2920 and 2850 cm−1 were assigned to the bending vibration of
CH2. The prominent IR bands at 3328 and 1579 cm−1 were ascribed
to the NH2 stretching vibrations. These results indicated that the
diethylenetriamine was bonded to the surface of GO through amidation
reaction. The typical XPS image of GO-NH2-Pd2+ was shown in Fig. 2. As
shown in Fig. 2, the N1s band appears at 399.2 eV, which obviously
confirming the diethylenetriamine was bonded to the surface of GO.
The IR scanning patterns of G-NH2-Pd0 and GO-NH2 samples were
almost similar indicated that the structure of diethylenetriamine bonded
to GO was preserved in the process of coordination and reduction. The
peak at 2360 cm−1 in the three samples was attributed to CO2, which
was formed from the decomposition of labile functional groups [33].
The typical TEM image of GO-Pd2+ and GO-NH2-Pd2+ were
shown in Fig. 3 A and B, respectively. As can be seen from Fig. 3A, a
poor distribution of Pd on the GO sheets was observed. From
Fig. 3B, we can see that Pd was well dispersed on the surface of poly-
amine modified GO. The results indicated that polyamine play an im-
portant role to improve the dispersibility of Pd.
4000 3500 3000 2500 2000 1500 1000 500
Wavenumbers ( cm-1)
Fig. 1. FT-IR spectra of (a) GO, (b) GO-NH2, (c) G-NH2-Pd0.
N 1s
Energy: 399.2
Fig.
4
showed the XRD patterns of (a) G-NH2-Pd0, (b)
GO-NH2-Pd2+, (c) G-Pd0, (d) GO-Pd2+. As shown in Fig. 4a and c,
the wide diffraction peak at 2θ = 25° can be indexed to disorderedly
stacked graphene [26]. The broad peak between 20° and 25° could be
attributed to the diffraction peak of disorderedly stacked graphene
oxide (Fig. 4b and d). A new wide peak at 2θ = 10° (Fig. 4d) could
be indexed to graphite oxide [26]. The well-defined peaks around
40°, 47°, 68° and 83° can be assigned to (111), (200), (220) and
(311) crystal planes of Pd0 [26]. Comparing the XRD pattern of the
G-NH2-Pd0 with GO-NH2-Pd2+, the peaks representing the Pd0 crys-
talline phase (marked with *) were found (Fig. 4a) and the ones
representing the stacked graphene oxide crystalline phase (Fig. 4b)
were shifted to the right, which demonstrated that the graphene
oxide and Pd2+ were reduced to graphene and Pd0 by hydrazine
hydrate, respectively.
394 396 398 400 402 404 406 408 410 412
Binding Energy (eV)
Fig. 2. The XPS image of GO-NH2-Pd2+
.
2.3. General procedure for Suzuki–Miyaura reactions
In a 25 mL round bottom flask, aryl halide (0.5 mmol, 1 eq.) was
dissolved in a mixture of 3 mL H2O-EtOH (1:2, v/v). Then, aryl boronic
acid (0.65 mmol, 1.3 eq.), potassium carbonate (2 mmol, 4 eq.) and
GO-NH2-Pd2+ (10 mg, 1 mol %) were added. The mixture was stirred
A
B
100 nm
100 nm
Fig. 3. TEM image of GO-Pd2+ (A) and GO-NH2-Pd2+ (B).

114
N. Shang et al. / Catalysis Communications 40 (2013) 111–115
GO-NH2-Pd2+ catalyst, which suggested that the polyamine modi-
fied graphene oxide was helpful to increase the dispersion of the ac-
tive species. Additional, a high dispersion of the catalyst in the
reaction media was expected to increase the activity of a heteroge-
neous catalyst. The Pd2+-GO and GO-NH2-Pd2+ catalyst could be
dispersed well in the reaction media but the Pd0-G and G-NH2-Pd0
catalyst could not.
*
# Graphite Oxide
% Stack Graphene
& Stack Graphene Oxide
Pd0
*
%
%
*
a
*
*
*
&
b
To generalize the application of the GO-NH2-Pd2+ catalyst, the cou-
pling reactions of various substituted aryl halides and phenylboronic
acids were carried out using 1 mol% GO-NH2-Pd2+ as catalyst at 60 °C
(Table 2). The reactions proceeded well with a wide range of aryl io-
dides and aryl bromides except aryl chloride. For most of the substrates,
the reaction could be completed in 0.5–4 h with moderate or excellent
yields, with the substrates having either electron-donating groups or
electron-withdrawing groups.
*
*
c
*
*
*
*
d
#
&
*
10
20
30
40
50
60
70
80
90
In order to investigate the recycling of the catalyst, the Suzuki–
Miyaura cross-coupling reaction between iodobenzene and
phenylboronic acid catalyzed by 1 mol% of GO-NH2-Pd2+ was cho-
sen as a model reaction. The results indicated that GO-NH2-Pd2+
can be reused 10 times without significant loss of catalytic activity.
However, when the reaction was catalyzed by GO-Pd2+, the yield
of biphenyl decreased drastically from 81% to 40% from the third
cycle. The concentration of palladium in GO-NH2-Pd2+ after 10
runs was 5.9 wt%. The result indicated that the palladium leaching
of the catalyst was low. The results demonstrated that polyamine
play a key role to improve the stability of the GO-NH2-Pd2+ catalyst.
Two-Theta (degree)
Fig. 4. XRD patterns of the catalysts. (a) G-NH2-Pd0, (b) GO-NH2-Pd2+, (c) G-Pd0, (d)
GO-Pd2+
.
3.2. Suzuki–Miyaura reactions catalyzed by the prepared catalysts
In order to investigate the catalytic activity of different catalysts
for the C–C coupling reaction, the coupling of phenyl iodide and phe-
nyl boronic acid was selected as a model reaction. As shown in
Table 1, among the catalysts tested, GO-NH2-Pd2+ was found to be
the most effective catalyst since it gave the highest yield of product.
Good dispersion of the active species (Pd2+ or Pd0) on the support is
a key factor for the catalytic activity of the catalyst. The crystalline
phase of the Pd2+ or Pd0 were not detectable in the XRD pattern of
4. Conclusions
In conclusion, a novel and recyclable palladium catalyst supported
on polyamine modified GO was fabricated for the first time. The
Table 2
Suzuki–Miyaura coupling of arylboronic acids and aryl halides catalyzed by GO-NH2-Pd2+
.
Entry
1
Aryl halides
Arylboronic acids
t/h
0.5
Yield/%
87
2
0.6
87
3
4
0.6
0.5
90
90
5
0.5
89
6
7
0.5
0.5
90
85
8
1.5
89
9
0.5
4
95
73
10
11
12
13
4
80
71
15
4
24
n (K2CO3): n (Aryl halides): n (Phenylboronic acid) = 4: 1: 1.3; solvent: 2 mL ethanol + 1 mL H2O; the quantity of catalyst was 1 mol %; 60 °C.

N. Shang et al. / Catalysis Communications 40 (2013) 111–115
115
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