Functionalization of fullerene (C60) with metformine to immobilized palladium as a novel heterogeneous and reusable nanocatalyst in the Suzuki-Miyaura coupling reaction at room temperature

Article abstract of DOI:10.1016/j.molcata.2014.01.007

Pd supported on biguanide(metformine)-functionalized fullerene (C ₆₀-Met/Pd²⁺) hybrid materials was fabricated for the first time. The catalyst prepared was characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The catalyst showed excellent activity Suzuki-Miyaura coupling reaction of different aryl iodides and bromides with phenylboronic acid at room temperature in the EtOH:H₂O (1:1) mixture as solvent. The yields of the products were in the range from 85% to 98%. The catalyst can be readily recovered and reused at least 6 consecutive cycles without significant loss in its catalytic activity. This is the new example for the development of fullerene (C₆₀-Met-Pd) complexes which can be used as efficient recyclable catalysts without palladium leaching.

Full text of DOI:10.1016/j.molcata.2014.01.007

Journal of Molecular Catalysis A: Chemical 385 (2014) 61–67
Contents lists available at ScienceDirect
Journal of Molecular Catalysis A: Chemical
journal homepage: www.elsevier.com/locate/molcata
Functionalization of fullerene (C ) with metformine to immobilized
60
palladium as a novel heterogeneous and reusable nanocatalyst in the
Suzuki–Miyaura coupling reaction at room temperature
a,∗
a
a
Hojat Veisi , Ramin Masti , Davood Kordestani ,
a
b
Maryam Safaei , Onur Sahin
Department of Chemistry, Payame Noor University, Tehran 19395-4697, Iran
a
b
Department of Chemistry, Faculty of Science, Istanbul Technical University, Maslak, Istanbul 34469, Turkey
a r t i c l e i n f o
a b s t r a c t
Pd supported on biguanide(metformine)-functionalized fullerene (C60-Met/Pd2+) hybrid materials was
fabricated for the first time. The catalyst prepared was characterized by X-ray diffraction spectroscopy
Article history:
Received 19 November 2013
Received in revised form 8 January 2014
Accepted 10 January 2014
Available online 22 January 2014
(XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), and transmission electron
microscopy (TEM). The catalyst showed excellent activity Suzuki–Miyaura coupling reaction of different
aryl iodides and bromides with phenylboronic acid at room temperature in the EtOH:H2O (1:1) mixture
as solvent. The yields of the products were in the range from 85% to 98%. The catalyst can be readily
recovered and reused at least 6 consecutive cycles without significant loss in its catalytic activity. This is
the new example for the development of fullerene (C60-Met-Pd) complexes which can be used as efficient
recyclable catalysts without palladium leaching.
Keywords:
Biguanide-functionalized C60
Metformine
Pd catalyst
Suzuki–Miyaura coupling
© 2014 Elsevier B.V. All rights reserved.
1
. Introduction
Fullerenes, the new molecular allotrope of carbon, were discov-
the development of covalent chemistry of C60 has opened the pos-
sibility to attach this spherical structure with several groups, which
allows increment in the material science.
ered in 1985 by H. W. Kroto, R. F. Curl and R. E. Smalley [1], who were
awarded the Nobel Prize in Chemistry in 1996 due to this seminal
scientific finding. The novel and promising fullerene (C60)-based
carbon nanomaterial has attracted tremendous attentions over the
recent years due to its exceptional properties, such as excellent
mechanical, thermal, optical, high specific surface area, electronic,
structural properties and also their promising preliminary biolog-
ical activities, such as DNA photocleavage, HIV-protease (HIV-P)
inhibition, neuroprotection and apoptosis [2–5]. The chemical ver-
satility and tunability combined with solution processability make
fullerene-based materials attractive for a wide range of applica-
tions in many field including catalysis, drug delivery, bioimaging,
adsorption, electronic and photonic devices [6–10]. Since its large
specific surface area and the large delocalized ꢀ-electron sys-
tem of fullerene-related material can form strong hydrophobic
and ꢀ-stacking interactions with organic molecules, it might be a
promising candidate for a catalyst or a catalyst support. However,
Recently, immobilization of Pd nanoparticles on solid supports
have received considerable attention as a new generation of het-
erogeneous catalysts in various scientific fields because of their
superior catalytic performance, good stability, ease of separa-
tion and satisfactory reusability in comparison to the traditional
homogeneous Pd(OAc) , PdCl catalysts [11–17]. However, the
2
+
2
catalytic activity of Pd2 -supported decrease gradually when the
catalyst was used repeatedly. This could be ascribed to the weak
interaction between palladium and the support material, as well
as the agglomeration and accumulation of Pd nanoparticles on
the surface of the material [18,19]. Therefore, it is desirable to
improve the stability, recyclability, and catalytic activity of hetero-
geneous Pd nanocatalysts. Owing to these interests and also as a
part of our ongoing research program on the application of cata-
lysts for the development of useful new synthetic methodologies
[20], herein, we report the synthesis of a heterogeneous pal-
ladium nanocatalyst supported on metformine-grafted-fullerene
(C60-Met/Pd(II)) and its catalytic activity of the catalyst pre-
pared 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
∗ Corresponding author. Tel.: +98 838 4227463.
E-mail address: hojatveisi@yahoo.com (H. Veisi).
1
381-1169/$ – see front matter © 2014 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.molcata.2014.01.007

6
2
H. Veisi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 61–67
Fig. 1. FTIR spectra of (a) C60, (b) C60-COOH, (c) C60-COCl, (d) C60-CO-Met, and (e) C60-CO-Met/Pd(II).
catalyst but at the same time it was easy to separate off and
reuse.
then separated from solution by centrifugation. The solid prod-
ucts were then washed with a limited amount of deionized water
and centrifuged several times to remove residual HCl until this
product started to dissolve. The yield of chestnut brown solid of
2
. Experimental
C60-(COOH) was 56%. It is soluble in water and other polar organic
6
solvents, such as DMF, DMSO, THF. The carboxylated C
(C60
-
2.1. Materials
60
◦
(
COOH) ) thus obtained were dried at 60 C for 1 day under reduced
6
pressure and reacted with excess of SOCl2 at room temperature
All the reagents were purchased from Aldrich and Merck used
for 24 h. The product (fullerene having carbonyl chloride, (C60
-
without any purification. The pure fullerene without functional
groups was purchased from Petrol Co. (Tehran, Iran) (Fig. 1). SOCl2,
HCl, H SO , HNO , deionized water, anhydrous dimethyl formam-
COCl) ) was purified by centrifugation and subsequently washed
6
◦
with THF, which was then dried at 50 C for 12 h. The final prod-
2
4
3
uct was then subjected to functionalization with metformine. Free
metformine (metformine-to-fullerene weight ratio was 10:1) were
ide (DMF), CaH , and metformin hydrochloride were obtained from
2
Sigma–Aldrich and Merck.
mixed with 1 mL solution of DMF and Et N (1 mL) and then stirred
3
for 1 h. The obtained acyl chloride fullerene in 20 mL DMF was then
added to the suspension. The reaction mixture was kept at 120 C
2.2. Preparation of free metformin
◦
for 3 days. The solid was then separated by filtration and washed
1
.65 g of metformin hydrochloride (10 mmol) and 0.40 g of
with CH Cl2 and deionized water for several times and dried in
2
NaOH (10 mmol) were added to 100 ml of ethanol and the result-
ing suspension was stirred for 5 h. Then, the suspension was filtered
and ethanol was removed with rotary evaporation leading to free
metformine in 99% yield. The obtained free metformin was freshly
used in the next experiments.
vacuum.
2.4. Preparation of C60-Met/Pd2+and C60-Met/Pd0 nanocatalysts
2
.3. Covalent grafting of metformine to C60
The C60-Met (1 g) was dispersed in 30 mL deionized water by
sonication for 10 min and a aqueous solution of PdCl2 (10 mL,
0.7 mmol) was added to dispersion of C60-Met. The mixture was
stirred for 24 h in room temperature to complete attainment of
coordination. Thus yielded C60-Met/Pd2+ nanocatalyst was sub-
jected to centrifugation, washed with deionized water and dried
Hexa(carboxyl)fullerene was synthesized following a well-
known procedure [22–24]. C60 (400 mg, 0.556 mmol) was added
to dry degassed 1,2-dimethoxyethane (DME) (250 mL). After stir-
ring for 6 h, sodium naphthalenide (11.5 mmol) in DME (50 mL)
was added and stirred until the color of this mixture was changed
from dark green to dark brown. Purified carbon dioxide gas was
then introduced into the reaction container continuously, accom-
panied by vigorous stirring for 3 days, to afford a brown suspension.
The precipitates were separated from solution by the centrifu-
gation. They were then dissolved in DMF, and the insoluble side
products and unreacted C60 were separated from the DMF solu-
tion by centrifugation. The dark brown sodium salt solution was
added dropwise to 4 M HCl with vigorous stirring to induce the
precipitation of a chestnut brown product. The precipitates were
◦
2+
in vacuum at 40 C for 12 h. The overall synthesis of C60-Met/Pd
nanocatalyst is schematically demonstrated in Scheme 1.
The reduction of C60-Met/Pd2+ by hydrazine hydrate was per-
formed as follows: 30 mg of C60-Met/Pd2+ was dispersed in 60 mL
of water, and then 100 ␮L 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 C60-Met/Pd0 was washed with water and dried in
◦
vacuum at 50 C. Scheme 1 depicted the synthetic procedure of
C60-Met/Pd2+ and C60-Met/Pd . The concentration of palladium in
0

H. Veisi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 61–67
63
H
O
C
H
O
C Cl
OH
6
6
SOCl
2
1
)Na naphthalemide
o
6
5 C, 24h
2
) excess CO
2
+
3
) H
NH NH
H C
3
NH2 DMF, Et
N
3
N
N
H
H C
3
Cl
Cl
Pd
H
O
C
HN
NH
H
O
C
NH NH
CH3
CH
3
N
N
N
N
H
N
H
N
H
H
CH
3
CH
3
PdCl
2
H O
2
N
H
2
N
H
2
Pd0
H
O
C
HN
NH
CH3
N
N
N
H
H
CH
3
Scheme 1. Schematic diagram of C60-Met/Pd(II) and C60-Met/Pd(0) fabrication.
C60-Met/Pd2+ and C60-Met/Pd0 were 18 and 16 wt.%, respectively,
which were determined by ICP-AES and TGA.
The metformine-functionalized fullerene anchored palladium(II)
complex (C60-Met/Pd2+) was conveniently synthesized from com-
mercially available and cheap materials via immobilization on
fullerene. The pathways of C60-Met/Pd2+ fabrication are shown in
Scheme 1.
2.5. Catalytic activity
2
.5.1. Suzuki–Miyaura coupling reaction
In a typical reaction, 10 mg of the catalyst (1 mol%) was placed
The surface structure of the materials was confirmed using
Fourier transform infrared (FTIR) spectroscopy. Fig. 1 shows the
FT-IR spectra obtained for (a) C60, (b) C60-COOH, (c) C60-COCl,
(d) C60-CO-Met, (e) C60-CO-Met/Pd(II). Comparison of the FT-IR
spectra of C60-COOH (curve b) with C60 (curve a), a new band
in a 25 mL Schlenk tube, 1 mmol of the aryl halide in 5 mL
of water/ethanol (1:1) was added 0.134 g (1.2 mmol) of phenyl
boronic acid, 0.276 mg of K CO3 (2 mmol). The mixture was then
stirred for the desired time at room temperature. The reaction was
monitored by thin layer chromatography (TLC). After completion of
reaction, the catalyst was recovered by centrifuge and washed with
ethyl acetate and ethanol. The combined organic layer was dried
over anhydrous sodium sulfate and evaporated in a rotary evapo-
rator under reduced pressure. The crude product was purified by
column chromatography.
2
−
1
(1701 cm ) appeared in C60-COOH due to C O stretching vibra-
tion of the carboxylic acid group, which indicated the carboxylic
derivative of C60 was prepared successfully. The converting of the
carboxylic acid groups (C60-COOH) into the acyl chloride interme-
diate (C60-COCl) by treatment with thionyl chloride was confirmed
−
1
by the appearance of peak near 1778 cm
stretching in curve
c. Curve d shows the spectrum of C60-Met and the absorption
−
1
band at 1658 cm
was attributed to the carbonyl stretching of
3
. Results and discussion
the amide groups ( CONH ). Also, the band in the spectral region
−
1
of 1671 cm
can be assigned to the imine (C NH) bond of the
3
.1. Catalyst characterization
attached metformine. These results indicated that the metformine
was bonded to the surface of fullerene through amidation reac-
tion. The signals appeared at 1671 and 1658 cm in curve d for the
−
1
The synthesis of metformine-functionalized fullerene anchored
palladium catalyst consists in: (i) surface modification of fullerene
with nitric acid and sulfuric acid to introduce carboxyl group (ii)
conversion of the surface carboxylic acid groups into acid chlo-
ride groups by reaction with thionyl chloride, (iii) attachment of
metformine to the fullerene surface through reaction with the acid
chloride groups and (iv) complexation of the metformine ligand
to Pd by reaction with palladium chloride and then reduction
with hydrazine hydrate and ammonium hydroxide (Scheme 1).
metal-ligand co-ordination [25,26] presumably leads to a shift of
−
1
these two peaks to lower frequencies (1671–1658 cm ). This shift
can be observed comparing curve e. These peaks at curves d and
e displayed the successful attachment of metformine organic lig-
ands and subsequent coordination of Pd2+ ions within the hybride
material.
Transmission electron microscopy (TEM) investigations are car-
ried out to observe the morphology and distribution of palladium

6
4
H. Veisi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 61–67
Fig. 2. TEM images of C60-Met/Pd.
Fig. 3. XRD spectra of (a) C60 and (b) C60-Met-Pd.
◦
particles supported on C60-Met/Pd. The existence of Pd nanoparti-
cles, deposited on modified-fullerene was clearly distinguishable
as dark spots in Fig. 2. The TEM images of C60-Met/Pd (Fig. 2)
show a uniform diameter distribution of palladium particles with
near spherical morphology supported on C60-Met. The diameters
of palladium particles range from 3 to 5 nm and there is no large
agglomerate of the palladium particles. The results indicated that
metformine play an important role to improve the dispersibility
of Pd. The different size aggregation of functionalized fullerenes is
observable from the TEM that shown the self-assembly behavior of
substituted water-soluble C60-containing metformines ligand [21].
The metal loading was determined using ICP-AES, and the
occurred at a temperature range of 100–650 C and was moder-
ate. Another weight loss was observed the temperature range of
660–780 C. The results shown that solvent loss such as water
start at 100 C and carbon cage and amorphous carbon decom-
pose start at 650 C. [20] Curve “b” showsthat several weight losses
were observed for C60-Pd(II) complex. The first mass loss occurs at
temperature range of 100–310 C that is related to the loss of sol-
vent trap in complex. The second mass loss occurs at temperature
◦
◦
◦
◦
◦
range of 310–450 C that is related to the loss of ligand in com-
◦
plex and third mass losses occur at 600–800 C and that related
−1
results showed Pd loading of 1 mmol g (18%). Thus for the sup-
ported Pd catalyst approximately 20% of the ligand are occupied by
metal.
The X-ray diffraction spectroscopy (XRD) pattern of pure
fullerene C60 (curve “a” in Fig. 3) is clear and appears at 2ꢁ = 10.8,
1
7.6, and 20.7. Solid C60 forms a face-centered-cubic structure at
room temperature [27,28]. The XRD pattern of C60-Met/Pd complex
curve “b” in Fig. 3) confirmed the presence of C60 in catalysts. This
(
means that the crystallinity and morphology of C60 were preserved
during the functionalized method. XRD pattern of Pd(0) complex
◦
as shown four major peaks at a 2ꢁ of 39.9, 47.4, 68.7 and 82.0 can
be assigned to the diffraction from the four reflection indexes of
(
1 0 0), (2 0 0), (2 2 0) and (3 1 1), respectively (card 05-0681 in the
JCPDS file).
The thermogravimetric analysis (TGA) in inert atmosphere (N2)
is shown in Fig. 4. These curves are related to C60 (curve “a” in
Fig. 4), C60-Met-Pd(II) (curve b) and C60-Met-Pd(II) (curve c). Two
main mass loss regions are observed for C60. The first weight loss
Fig. 4. TGA spectra of (a) C60, (b) C60-Met-Pd(II), and (c) C60-Met-Pd(0).

H. Veisi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 61–67
65
Table 1
Optimization of the conditions for the Suzuki–Miyaura reaction of bromobenzene with phenylboronic acid.
Cl
Cl
Pd
H
O
C
HN
NH
CH3
N
N
N
H
H
CH
3
Br
B(OH)2
K CO , H O, EtOH, r.t.
2
3
2
.
Entry
Solvent
Pd catalyst (mg)
Base
Time (min)
Yield (%)a
1
2
3
4
5
6
7
8
9
DMF
Toluene
EtOH
10
10
10
10
10
10
10
5
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
NaOAc
Et3N
K2CO3
K2CO3
K2CO3
K2CO3
60
60
80
120
45
60
60
60
60
60
88
70
75
55
98
70
85
85
98
75
85
H2O
b
EtOH/H2O
EtOH/H2Ob
b
EtOH/H2O
EtOH/H2Ob
b
EtOH/H2O
15
10
10
1
1
0
1
EtOH/H2Oc
d
EtOH/H2O
120
Reaction conditions: bromobenzene (1 mmol), PhB(OH)2 (1.2 mmol), C60-Met/Pd(II) (10 mg, 1 mol%), solvent (4 ml).
a
Isolated yield.
EtOH/H2O = 1:1.
EtOH/H2O = 2:1.
EtOH/H2O = 1:2.
b
c
d
◦
to the decomposition of C60. This part of the thermogram reveals
the amounts of supported ligand on fullerene which is estimated
to be ∼20% (w/w). Curve “c” that related to C60-Pd(0) complex, is
similar to curve “b”. The remaining weight percent up to the tem-
H O/EtOH (4 mL, 1:1), K CO (2 mmol) and 25 C as the reaction
temperature.
2
2
3
To generalize the application of the C60-Met/Pd+2catalyst, the
coupling reactions of various substituted aryl halides and phenyl-
boronic acids were carried out using 1 mol% C60-Met/Pd
◦
+2
perature of 800 C is equal to 0, 18 and 19 are related to curves
as
“
a”, “b” and “c”, respectively. The remaining weight of C60 is zero
catalyst at room temperature (Table 2). The reactions proceeded
well with a wide range of aryl iodides and bromides. For most of
the substrates, the reaction could be completed in 0.75–4 h with
moderate or excellent yields, with the substrates having either
electron-donating groups or electron-withdrawing groups.
As it is seen, under optimized conditions, phenyl iodide and
bromide was reacted efficiently with phenylboronic acid (Table 2,
entries 1, 2). Both electron-withdrawing and releasing groups with
phenylboronic acid afforded the corresponding products in high
yields (Table 2, entries 3–14). It was found that the yield of reaction
ortho-position aryl bromide is lower (Table 2, entry 13) than those
of para- or meta-substituted aryl bromides (Table 2, entries 3–12).
Notably, when 2-iodothiophene was used as coupling partner, the
desired product was obtained and no poisoning of palladium cata-
lyst occurred (Table 2, entry 14).
◦
because all fullerene carbons, at a temperature of 800 C, burned
and converted to carbon dioxide. The remaining weights percent
of complexes (18 and 19) show the presence of metal palladium
installed on the fullerene. These results confirm that our applied
strategy can be considered as a good and practical method for the
modification of the C60 substrate by various functional groups such
as amines.
3
.2. Catalytic testing
3
.2.1. Suzuki–Miyaura coupling reaction
In order to evaluate the catalytic performance of C60-Met/Pd(II),
the Suzuki–Miyaura reactions of aryl halides and phenylboronic
acid were studied. Initially, we explored the catalyst ability for the
reaction mentioned and the conditions optimized of coupling reac-
tion between bromobenzene and phenylboronic acid as a model
reaction with different amounts of the catalyst, solvents and bases
Finally, to assess the present protocol with respect to other
reported methods for the preparation of biaryls, the catalytic per-
+2
formance of the C60-Met/Pd was compared with some of the
reported catalysts. From Table 3, it can be seen that present cata-
lyst exhibited higher conversions and yields compared to the other
reported system [17,29–32].
(
Table 1).
The influences of various reaction parameters such as base
Et N, AcONa and K CO ), solvent (nonpolar, protic and aprotic),
(
3
2
3
and catalyst amount on the reaction were tested (Table 1). Among
the bases evaluated, K CO3 was found to be the most effective and
3.3. Recycling of the catalyst
2
other bases were substantially less effective. We also investigated
the effect of solvents on the Suzuki–Miyaura cross-coupling reac-
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 C60-Met/Pd+2 was
chosen as a model reaction. The results indicated that C60-Met/Pd+2
can be reused 6 times without significant loss of catalytic activ-
ity (Fig. 5). The result indicated that the palladium leaching of the
tion and found that H O/EtOH (1:1) was the best media. It was
2
found that C60-Met/Pd(II) (10 mg, 1 mol% Pd) gave the optimum
results using H O/EtOH (1:1) as solvent at room temperature. Thus,
2
the optimum conditions selected are: bromobenzene (1 mmol),
phenylboronic acid (1.2 mmol), C60-Met/Pd(II) (10 mg, 1 mol% Pd),

6
6
H. Veisi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 61–67
Table 2
Suzuki cross-coupling reaction of aryl halides with phenylboronic acid.
B(OH)2
X
+2
C -Met/Pd (10 mg)
6
0
+
G
H O/EtOH, K CO , r.t.
2
2
3
G .
Entry
1
Aryl halide
Time (min)
45
Yield (%)a
98
I
Br
2
3
80
45
95
96
I
MeO
MeO
Br
4
5
6
7
8
80
50
92
98
95
92
93
I
OMe
I
60
O N
2
I
60
OHC
Br
120
H C
3
Br
9
75
80
90
95
O N
2
Br
1
0
1
2
OHC
Me
Br
1
180
80
92
90
O
1
1
O N
2
Br
Br
3
240
60
70
93
CHO
I
1
4
S
a
Isolated yield.

H. Veisi et al. / Journal of Molecular Catalysis A: Chemical 385 (2014) 61–67
67
Table 3
Comparison of the activity of different catalysts in the Suzuki cross-coupling reaction.
Reaction
Catalyst
Reaction conditions
Yield (%)
Refs.
C60-Met/Pd+2
Graphene oxide-NH2-Pd
Cell-OPPh2-Pd0
Pd-ZnFe2O4
K2CO3, H2O/EtOH (1:1), 25 C, 45 min
◦
◦
98
87
85
92
34
90
80
80
This study
29
31
32
Iodobenzene + phenylboronic acid
2
+
K2CO3, H2O/EtOH (1:1), 60 C, 30 min
◦
◦
K2CO3, EtOH, 78 C, 20 min
K2CO3, EtOH, 78 C, 4 h
◦
Chitosan-Schiff base-Pd(II)
K2CO3, xylene, 130 C, 6 h
17
C60-Met/Pd+2
K2CO3, H2O/EtOH (1:1), 25 C, 75 min
◦
◦
This study
29
30
p-Nitrobromobenzene + phenylboronic acid
2
+
Graphene oxide-NH2-Pd
Polystyrene-supported
K2CO3, H2O/EtOH (1:1), 60 C, 4 h
◦
K2CO3, H2O, 70 C, 5 h
palladium(II) dithizone complex
Chitosan-Schiff base-Pd(II)
◦
K2CO3, xylene, 130 C, 6 h
76
31
(C60-Met-Pd) complexes which can be used as efficient recyclable
catalysts without palladium leaching.
Acknowledgement
We are thankful to Payame Noor University (PNU), Iran and
Istanbul Technical University, Turkey for partial support of this
work.
References
[
1] H.W. Kroto, J.R. Heath, S.C. O’Brien, R.F. Curl, R.E. Smalley, Nature 318 (1985)
62.
1
[
[
2] A.W. Jensen, S.R. Wilson, D.I. Schuster, Bioorg. Med. Chem. 4 (1996) 767.
3] T. Da Ros, M. Prato, Chem. Commun. (1999) 663.
Fig. 5. The recycling of the C60-Met/Pd+2 for the Suzuki coupling reaction.
[4] S.R. Wilson, K. Kadish, R. Ruoff (Eds.), The Fullerene Handbook, Wiley, New
York, 2000, pp. 437–465.
[
5] J.E. Fischer, P.A. Heiney, A.B. Smith, Acc. Chem. Res. 25 (1992) 112.
catalyst was low. The results demonstrated that metformine play
[6] N. Martin, Chem. Commun. (2006) 2093.
[7] A.F. Hebard, Annu. Rev. Mater. Sci. 23 (1993) 159.
[
a key role to improve the stability of the C6 -Met/Pd+2 catalyst.
0
8] (a) P.M. Allemand, K.C. Khemani, A. Koch, F. Wudl, K. Holczer, S. Donovan, G.
Grüner, J.D. Thompson, Science 253 (1991) 301;
(b) E. Dagotto, Science 293 (2001) 2410;
Also, it is notably, after using C60-Met/Pd+2, no palladium ion could
be detected in the liquid reaction mixtures by atomic absorption
spectroscopy.
(
c) P. Grant, Nature 413 (2001) 264.
9] (a) Q. Xie, E. Pérez-Cordero, L. Echegoyen, J. Am. Chem. Soc. 114 (1992) 3978;
b) L. Echegoyen, L.E. Echegoyen, Acc. Chem. Res. 31 (1998) 593.
[10] D.M. Guldi, Chem. Commun. (2000) 321.
[
(
3.4. Leaching test
[
11] M. Lamblin, L. Nassar-Hardy, J.C. Hierso, E. Fouquet, F.X. Felpin, Adv. Synth.
Catal. 352 (2010) 33.
12] L. Yin, J. Liebscher, Chem. Rev. 107 (2007) 133.
In order to investigate the leaching of Pd during the reaction in
our catalytic system, we conducted a filtration test for the Suzuki
[
[
13] J.Y. Kim, Y. Jo, S.K. Kook, S. Lee, H.C. Choi, J. Mol. Catal. A: Chem. 323 (2010) 28.
reaction between iodobenzene and phenylboronic acid using C60-
[14] S.A. Patel, K.N. Patel, S. Sinha, B.V. Kamath, A.V. Bedekar, J. Mol. Catal. A: Chem.
332 (2010) 70.
Met/Pd+2 as catalyst. After 15 min (the reaction was completed in
[
15] N. Shang, C. Feng, H. Zhang, S. Gao, R. Tang, C. Wang, Z. Wang, Catal. Commun.
0 (2013) 111.
[16] M.R. Nabid, Y. Bide, S.J. Tabatabaei Rezaei, Appl. Catal. A: Gen. 406 (2011) 124.
4
5 min), the reaction was stopped and the reaction mixture was
4
centrifuged at 10000 rpm for 10 min. Then the mixture without the
solid catalyst was allowed to continue under the same conditions
for another 30 min, and the conversation did not proceed signifi-
cantly. This suggests that the leaching of Pd species from the solid
support is low and the prepared catalyst is stable. On the other
hand, atomic absorption spectroscopy of the filtrate also confirmed
that the Pd content in the solution was below the detection limit
[
[
17] B.C.E. Makhubela, A. Jardine, G.S. Smith, Appl. Catal. A: Gen. 393 (2011) 231.
18] G.M. Scheuermann, L. Rumi, P. Steurer, W. Bannwarth, R. Mülhaupt, J. Am.
Chem. Soc. 131 (2009) 8262.
[19] L. Rumi, G.M. Scheuermann, R. Mülhaupt, W. Bannwarth, Helv. Chim. Acta 94
2011) 966.
20] (a) H. Veisi, Synthesis 2631 (2010);
b) H. Veisi, Tetrahedron Lett. 51 (2010) 2109;
(
[
(
(c) H. Veisi, Curr. Org. Chem. 15 (2011) 2438.
[
[
21] P. Ravi, S. Dai, K.M. Hong, K.C. Tam, L.H. Gan, Polymer 46 (2005) 4714.
22] Y. Chi, J.B. Bhonsle, T. Canteenwala, J.P. Huang, J. Shiea, B.J. Chen, L.Y. Chiang,
Chem. Lett. 465 (1998).
(
0.1 ppm).
4
. Conclusion
[23] B.P. Sullivan, K. Krist, H.E. Guard, Electrochemical and Electrocatalytic Reactions
of Carbon Dioxide, Elsevier Science Publishers, Amsterdam, 1993.
[
[
24] D.J. Cram, G.S. Hammond, Organic Chemistry, McGraw-Hill, Inc., U. S. A., 1964.
25] J. Guerra, M.A. Herrero, Nanoscale 2 (2010) 1390.
In conclusion, a novel and recyclable palladium catalyst sup-
ported on metformine modified fullerene was fabricated for the
[26] H. Veisi, A. Khazaei, M. Safaeu, D. Kordestani, J. Mol. Catal. A: Chem. 382 (2014)
first time. The results indicated that the stability of the catalyst was
106.
much improved and C60-Met/Pd+2 were an efficient and recyclable
[27] P.W. Steven, P. Thomas, L. Jamey, A.W. Michele, S.F. Christopher, J. Chem. Educ.
7
4 (1997) 311.
28] W. Zhu, D.E. Miser, W.G. Chan, M.R. Hajaligol, Carbon 42 (2014) 1463.
[29] N. Shang, C. Feng, H. Zhang, S. Gao, R. Tang, C. Wang, Z. Wang, Catal. Commun.
0 (2013) 111.
catalyst for the Suzuki–Miyaura cross-coupling reaction. The cat-
alyst can be readily recovered and reused without significant loss
of its catalytic activity. The proposed method can be a promising
alternative approach for the preparation of biphenyl compounds.
This is the new example for the development of fullerene
[
4
[
[
30] M. Bazherad, S. Jajarmi, J. Mol. Catal. A: Chem. 370 (2013) 152.
31] Q. Du, Y. Li. Beilstein, J. Org. Chem 7 (2011) 378.
[32] A.S. Singh, U.B. Patil, J.M. Nagarkar, Catal. Commun. 35 (2013) 11.