Palladium nanoparticles decorated into a biguanidine modified-KIT-5 mesoporous structure: A recoverable nanocatalyst for ultrasound-assisted Suzuki-Miyaura cross-coupling

Article abstract of DOI:10.1039/c9ra08809a

In the current research work, a new KIT-5-biguanidine-Pd(0) catalyst was prepared and applied to ultrasound-assisted Suzuki-Miyaura cross-coupling reactions using ultrasound waves at ambient temperature. The ultrasound-assisted method is a green and efficient method for C-C coupling. Many parameters of the Suzuki coupling reaction were examined, such as the irradiation time, the types of organic and inorganic bases, the types of aprotic and protic solvents, and the dosage (mol%) of catalyst. Also, the results showed that the yields from the ultrasound-assisted coupling reactions were higher than from non-irradiated reactions. The prepared catalyst was characterized via HR-TEM, SEM-EDX-mapping, FT-IR, ICP-AAS, BET-BJH, and XRD studies. The stability and catalytic performance of the prepared catalyst were good, and it could be reused 6 times without catalytic activity loss for the Suzuki-Miyaura cross-coupling reaction.

Full text of DOI:10.1039/c9ra08809a

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Palladium nanoparticles decorated into
a biguanidine modified-KIT-5 mesoporous
structure: a recoverable nanocatalyst for
ultrasound-assisted Suzuki–Miyaura cross-
coupling
Cite this: RSC Adv., 2019, 9, 41581
Hojat Veisi, * Amin Mirzaei and Pourya Mohammadi*
In the current research work, a new KIT-5-biguanidine-Pd(0) catalyst was prepared and applied to
ultrasound-assisted Suzuki–Miyaura cross-coupling reactions using ultrasound waves at ambient
temperature. The ultrasound-assisted method is a green and efficient method for C–C coupling. Many
parameters of the Suzuki coupling reaction were examined, such as the irradiation time, the types of
organic and inorganic bases, the types of aprotic and protic solvents, and the dosage (mol%) of catalyst.
Also, the results showed that the yields from the ultrasound-assisted coupling reactions were higher
than from non-irradiated reactions. The prepared catalyst was characterized via HR-TEM, SEM-EDX-
mapping, FT-IR, ICP-AAS, BET-BJH, and XRD studies. The stability and catalytic performance of the
prepared catalyst were good, and it could be reused 6 times without catalytic activity loss for the
Suzuki–Miyaura cross-coupling reaction.
Received 26th October 2019
Accepted 3rd December 2019
DOI: 10.1039/c9ra08809a
rsc.li/rsc-advances
reactivity. Therefore, one useful strategy for solving these
problems involves the use of many different solid supports to
1
. Introduction
In the last few decades, the Pd-catalyzed Suzuki–Miyaura immobilize the Pd nanoparticles, which can modify the active
cross-coupling reaction, as one of the reactions for C–C bond site centers of the catalyst and improve the catalytic activity
8
–12
coupling, has attracted the attention of researchers. Different and reusability.
types of heterogeneous and homogeneous catalysts have been
To design an effective heterogeneous nanocatalyst, the
applied to this coupling reaction; for example, Pd complexes synthesis of a support with targeted functionalization to
with phosphine ligands as homogeneous catalysts have been maximize the immobilization and loading of Pd nanoparticles
widely used. Nevertheless, homogeneous catalysts have basic is necessary. One type of support used today is ordered mes-
defects, such as difficulties relating to isolation, which can oporous silica materials. These materials have unique prop-
cause contamination of the product; catalyst instability, erties, such as ordered porosity, considerably high pore
leading to leaching during product purication; and consid- volumes and high surface areas, good mechanical and chem-
erably higher costs relating to the separation of the catalyst. ical stability, and good surface functionalization; this means
On the other hand, Pd supported on a substrate, known as they have found use in sensing, separation, drug delivery,
1
3,14
a heterogeneous catalyst, has many advantages, such as easy adsorption, and catalysis
. Among the different types of
separation and good recovery from reaction mixtures, good silica ordered mesoporous materials, silica mesoporous
stability, and low leaching during the reaction. Therefore, materials that have cage-type and large-pore systems with
heterogeneous catalysts that involve a substrate can be sepa- grown porous structures in three-dimensions have been used
rated from the reaction mixture, can be recovered from reac- as efficient supports for many types of heterogeneous catalysis.
1
–7
tion mixtures and can be reused several times. Hence, from Also, 3D mesoporous materials have advantages vs. 2D mate-
green chemistry perspective, heterogeneous catalysts rials: (1) the blocking of pores is avoided; (2) they provide
a
focusing on the utilization of Pd nanostructures are well highly active sites for high absorption; (3) they have the ability
known. Nevertheless, the high activity of Pd nanoparticles and to absorb large molecules; and (4) they have high diffusion
1
5
their desire to agglomerate could lead to a decrease in their indices for the diffusion of reactants. Nanostructures such as
SBA-16, SBA-15, and KIT-5 are examples of silica mesoporous
1
6–18
materials that have pores with 3D cage-type structures.
Department of Chemistry, Payame Noor University, Tehran, Iran. E-mail: hojatveisi@
yahoo.com; pourya.mohammadi93@yahoo.com; Fax: +98 8343724748; Tel: +98
Among them, the KIT-5 mesoporous material, rst introduced
by Ryoo et al., has 3-D close-packed cage-type Fm3m cubic
8
343724748
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 41581–41590 | 41581

View Article Online
RSC Advances
Paper
symmetry, and it also has a high pore volume and surface area, conditions, leading to high reaction yields and lower levels of
1
8
26
and large pores. Therefore, given the reasons mentioned pollution.
above, KIT-5 can be used as an efficient support for the
immobilization of palladium nanoparticles. Today, it is development using nanocatalysis,
In continuation of our endeavors to support sustainable
27
we herein introduce
important to prepare chemical reactants under milder condi- (Scheme 1) an ultrasound-assisted method as a simple green
tions, such as using shorter time periods along with obtaining synthetic method using a new KIT-5-biguanidine-Pd(0) catalyst,
higher efficiencies at lower temperatures.
Ultrasound-assisted methods are efficient methods for the tion. The prepared nanocatalyst was used for the Suzuki–
and we applied it to the Suzuki–Miyaura cross-coupling reac-
19–22
acceleration of many organic and inorganic reactions.
Miyaura cross-coupling reaction of phenylboronic acid and
Ultrasound, due to cavitation effects, can generate effective various aryl halides (X ¼ Cl, Br, I) and the reactions were
intensity in the reaction process, causing physical and chemical successfully carried out in EtOH/H O as the reaction solvent at
2
effects. Ultrasound spreads via a chain of expansion and ambient temperature. This heterogeneous catalyst showed good
compression cycles induced in a liquid medium. Accordingly, catalytic activity and could be recovered easily via centrifuging;
cavities are created in the liquid. These cavities grow and it was also capable of being re-used six times for the afore-
collapse in different stages. Eventually, they collapse furiously, mentioned transformations, with no considerable loss of
producing high pressures and high local heating for very short activity.
lifetimes. The “hot spots” created have very high pressures
(
1000 atm) and very high temperatures (4500–5000 K); on the
2
. Experimental
other hand, these spots cool down in a very short time (>1010 K
s
ꢀ
1
23–25
2.1. The preparation of KIT-5
).
These physical effects cause the dispersion of nano-
particles and can prevent them from agglomerating. Also, the
separation of the materials (reactants) attached to the active
surface leads to an increase in the rate and efficiency of the
reaction. Given the reasons mentioned, ultrasound-assisted
methods are a green methodology for the preparation of
various organic and inorganic compounds under mild reaction
Firstly, 8.5 g of HCl (37%), 192 g of H
2
O and 19 g of the
copolymer F127 were added to a beaker, then the mixture was
ꢁ
heated at 45 C, 19 g of TEOS was added to it, and it was le
ꢁ
overnight. Aer further aging at 100 C for 24 h, the white
2
precipitate was ltered and washed with distilled H O and
dried, and, nally, to remove the copolymer F127, it was
ꢁ
calcined at 550 C for 5 h.
Scheme 1 The preparation of the KIT-5-biguanidine-Pd(0) catalyst.
41582 | RSC Adv., 2019, 9, 41581–41590
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
.2. The preparation of KIT-5-biguanidine
RSC Advances
2
2.3. The preparation of KIT-5-biguanidine-Pd(0)
First, 1.0 g of KIT-5 and 100 mL of toluene were added to In a typical reaction, 40 mg of PdCl and 50 mL of acetonitrile
2
a 150 mL round-bottom ask, and the mixture was stirred at was added to a 100 mL beaker and the mixture was then stirred
2
ambient temperature for 1 h. In the next step, 1 mL of 3-ami- and heated until PdCl completely dissolved (Solution A). 0.5 g
nopropyl trimethoxysilane (APTMS) was added dropwise to the of KIT-5-cyanoguanidine and 50 mL of acetonitrile was added to
reaction mixture and this was then reuxed overnight under N
2
a 150 mL round-bottom ask and this mixture was strongly
ꢁ
gas. Finally, the precipitate was ltered and washed several stirred at 50 C; then, Solution A was added dropwise to this
ꢁ
times with ethanol (70%). Subsequently, it was dried at 60 C mixture. Subsequently, it was reuxed for 5 h. In the next step,
overnight. Then, 0.5 g of the product from the previous step and 300 mL of hydrazine hydrate (N H $H O) was added dropwise,
2
2
2
1

00 mL of acetonitrile were added to a 100 mL round-bottom and this mixture was then reuxed for 24 h. Aer the end of the
ꢁ
ask and stirred at 40 C for 30 min. Then, 3 mmol of cyano- reaction, the gray precipitate was ltered and washed several
ꢁ
guanidine was added to the reaction mixture and it was heated times with EtOH (70%) before being dried at 50 C overnight. To
at 60 C overnight. Aer the end of the cyanoguanidine addition determine the amount of Pd loaded on the catalyst, ICP-AAS
ꢁ
reaction, the precipitate was ltered and washed several times analysis was used, and the value was estimated to be
ꢁ
ꢀ1
with ethanol (70%), and it was dried at 60 C overnight.
0.3 mmol g .
Fig. 1 Small- (a) and wide- (b) angle XRD patterns of KIT-5-biguanidine-Pd(0).
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 41581–41590 | 41583

View Article Online
RSC Advances
.4. Suzuki–Miyaura coupling reactions
Paper
2
material like its KIT-5 parent. The ordered structure of KIT-5-
biguanidine-Pd(0) remained intact aer functionalization,
which was supported by the XRD results. The pattern features
distinct Bragg peaks in the 2q range of 0.8–2 , which can be
indexed as the (1 0 0), (1 1 0) and (2 0 0) reections of the two-
dimensional hexagonal structure of the KIT-5 material.
Wide-angle XRD analysis was used to conrm the presence
of Pd crystalline nanoparticles and their purity, and also the
presence of amorphous silica from KIT-5, in the prepared KIT-5-
biguanidine-Pd(0) catalyst (Fig. 1b). The XRD pattern shows
diffraction peaks at 2q values of 39.9 , 46.4 , and 67.5 , which
relate to the planes of the Pd nanoparticles with Miller indices
of (111), (200), and (220), respectively. A broad diffraction peak
The protocol for the Suzuki–Miyaura coupling reactions is
described as follows: 10 mg of the KIT-5-biguanidine-Pd(0)
nanocatalyst, phenylboronic acid (0.6 mmol), aryl halide (0.5
ꢁ
2 3
mmol) and K CO (0.5 mmol) were dissolved in 5 mL of solvent
under an air atmosphere. The reaction mixture was sonicated
using an ultrasonic bath and the reaction progress was
monitored via TLC. Aer the completion of the coupling
reaction, the nanocatalyst was separated via centrifugation.
The nal coupling product was puried via column
chromatography.
ꢁ
ꢁ
ꢁ
ꢁ
at about 2q ¼ 24 appeared, which is from the non-crystalline
3. Results and discussion
silica of KIT-5. Also, the lack of additional peaks showed that
the prepared nanocatalyst was of good purity.
3.1. Characterization of the catalyst
3.1.1. XRD. The small-angle XRD pattern of KIT-5-
3.1.2. FT-IR. FT-IR analysis was applied in order to conrm
biguanidine-Pd(0) is shown in Fig. 1a. Three well-resolved the successive synthesis steps for KIT-5-biguanidine-Pd(0)
ꢁ
ꢀ1
diffraction peaks in the 2q range of 0.8–2 are observed for (Fig. 2). The bands at about 471 and 802 cm were indicated
the prepared catalyst, which is an organic–inorganic hybrid
2
Fig. 2 The FTIR spectra of (a) KIT-5, (b) KIT-5-NH , (c) KIT-5-biguanidine, and (d) KIT-5-biguanidine-Pd(0).
41584 | RSC Adv., 2019, 9, 41581–41590
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
RSC Advances
to relate to the symmetric bending and stretching frequencies biguanidine. The presence of these peaks indicates that the
ꢀ
1
of Si–O–Si bonds and, also, the band at 1085 cm can be linked functionalization of KIT-5-NH with cyanoguanidine was done
2
to the asymmetric stretching frequency of Si–O–Si bonds successfully (Fig. 2c). The functional group signal of C]N
ꢀ
1
ꢀ1
(
Fig. 2a). The broad peak appearing at 3436 cm is related to bonds then shied from 1610 to 1605 cm ; this change can be
28,28a
the O–H stretching frequency of silanol groups (Si–OH).
attributed to the coordination of biguanidine with Pd nano-
Upon the functionalization of KIT-5 with APTES, new peaks particles. This result demonstrates that the Pd nanoparticles
ꢀ
1
28b
appear. The weak peaks shown at 2840 and 2945 cm corre- were successfully immobilized on KIT-5 (Fig. 2d).
spond to C–H symmetric and asymmetric stretching frequen- 3.1.3. SEM-EDX mapping. The morphology of the prepared
ꢀ1
cies, respectively. The broad peak at about 3450 cm can result catalyst was considered via SEM-EDX mapping (Fig. 3). This
from the stretching of SiO–H and N–H bonds (Fig. 2b). In displays that the Pd particles were aggregated and immobilized
ꢀ1
addition, the peaks that appear at 1480 and 1610 cm can be on the surface of KIT-5; as shown in the image, the Pd-NPs are
attributed to the stretching of C–N and C]N bonds in spherical and their average size is about 20 nm. To elementally
Fig. 3 SEM imaging and SEM-EDS mapping of the KIT-5-biguanidine-Pd(0) catalyst.
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 41581–41590 | 41585

View Article Online
RSC Advances
Paper
Fig. 4 HRTEM-EDX images and the SAED pattern of the KIT-5-biguanidine-Pd(0) catalyst.
conrm the formation of the KIT-5-biguanidine-Pd(0) catalyst, carbon, nitrogen, oxygen, silicon, and palladium, which
elemental mapping was carried out via energy-dispersive X-ray conrms the presence of biguanidine and palladium in the KIT-
absorption spectroscopy (EDS). Fig. 3 shows peaks from 5 support. From EDS analysis, the Pd content was calculated to
be 0.25 mol% in the nanocatalyst.
3.1.4. HRTEM-EDX studies. To observe and conrm the
mesoporous structure of KIT-5 and the presence of Pd nano-
particles on the KIT-5-biguanidine-Pd(0) catalyst, high-
resolution transmission electron microscopy-energy disper-
sive X-ray (HRTEM-EDX) analysis was done (Fig. 4). The mes-
oporous structure of KIT-5 is clearly observed with a good
2
Table 1 A summary of the N adsorption–desorption results for KIT-5
and KIT-5-biguanidine-Pd(0) samples
3
ꢀ1
2
ꢀ1
Sample
V
p
(cm g
)
A
p
(m g
)
p
D (nm)
KIT-5
117.14
80.71
578.23
351.31
5.84
4.24
Fig. 5
N
2
adsorption–desorption isotherms from KIT-5 and KIT-5- KIT-5-biguanidine-Pd(0)
biguanidine-Pd(0) samples.
41586 | RSC Adv., 2019, 9, 41581–41590
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
RSC Advances
Scheme 2 A schematic diagram of the role of the KIT-5-biguanidine-Pd(0) nanocatalyst in the Suzuki coupling reaction.
degree of long-range ordering. In addition, the good distri- 3.2. Evaluation of the catalytic performance of the KIT-5-
bution of Pd nanoparticles on the KIT-5-biguanidine-Pd(0) biguanidine-Pd(0) nanocatalyst towards C–C coupling
catalyst can be seen in the HRTEM image. In addition, the reactions
presence of Si, N, C, and O was shown via this analysis. Also,
Scheme 2 schematically illustrates the catalytic role of the KIT-5-
the SAED pattern of the Pd nanoparticles indicated the pres-
biguanidine-Pd(0) nanocatalyst for carrying out the Suzuki
ence of the (111), (200) and (220) lattice planes of face-centered
coupling reaction. To analyze the catalytic performance of the
cubic (fcc) structures, which relate to the crystalline structure
prepared catalyst, many parameters of the Suzuki coupling
of Pd-NPs.
reaction were examined, such as the types of organic and
inorganic bases, the types of aprotic and protic solvents, and the
3.1.5. N2 adsorption–desorption. N2 adsorption–desorp-
tion analysis of KIT-5 and KIT-5-biguanidine-Pd(0) samples is
shown in Fig. 5. The textural properties obtained from this
analysis are summarized in Table 1. The KIT-5 sample illus-
dosage (mol%) of catalyst. The C–C catalytic coupling was done
ꢁ
at room temperature (25 C) using a model reaction (the reac-
2
tion of Ph-B(OH) and Ph-Br) (Table 2). At rst, the effects of
2
trates a type-IV adsorption isotherm and a H -type hysteresis
ultrasound on the Suzuki–Miyaura cross-coupling reaction were
optimized. The obtained results show that in the presence of
ultrasound, the yield of the reaction was greater than under only
loop. The obtained results are in good agreement with the
successful synthesis of mesoporous KIT-5. The pore diameter
of KIT-5 is about 5.84 nm. Aer the functionalization of the
pores and the immobilization of Pd nanoparticles, the diam-
eter of the pores is reduced to 4.24 nm, which can be due to the

lling of the pores with biguanidine and Pd nanoparticles.
Table 3 Optimization of the solvent, base and catalyst amount when
using the KIT-5-biguanidine-Pd(0) catalyst for the Suzuki coupling
reaction
Also, the results show a reduction in the surface area from
2
ꢀ1
5
78.23 to 351.31 m g , conrming that the pores are lled.
Entry Pd (mol%) Solvent
Base
Time (min) Yield (%)
1
2
3
4
5
6
7
8
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.20
0.15
0.10
0.0
Toluene
DMF
EtOH
K
K
K
K
2
2
2
2
CO
CO
CO
CO
3
3
3
3
20
20
20
20
20
20
20
25
30
30
30
65
80
82
55
93
80
98
85
74
62
0
Table 2 Optimization of the sonication time when using the KIT-5-
biguanidine-Pd(0) catalyst in the Suzuki coupling reaction
2
H O
Entry
Sonication time (min)
Yield (%)
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
EtOH/H
2
2
2
2
2
2
2
2
O
O
O
O
O
O
O
O
Et
NaOAc
3
N
1
2
3
4
5
6
5
10
15
20
40
53
79
98
98
38
K
2
K
2
K
2
K
2
K
2
CO
CO
CO
CO
CO
3
3
3
3
3
9
10
11
12
25
Just stirring (20 min)
0.25
No base 20
Trace
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 41581–41590 | 41587

View Article Online
RSC Advances
Paper
Table 4 Investigation of the effects of functional groups when using the absence of nanocatalyst and no product was observed (Table
the KIT-5-biguanidine-Pd(0) catalyst for the Suzuki coupling reaction
3, entry 11). It was proved that the presence of nanocatalyst was
required for the coupling reaction to occur. Also, different
dosages of nanocatalyst from 0.1 to 0.2 mol% were tested. Table
3 indicates that an increase in the dosage of nanocatalyst leads
to an increase in the yield of the coupling reaction. Also, the
results showed that the progress of the reaction with more than
Entry
RC
6
H
4
X
R
2
C
6
H
4
B(OH)
2
X
Time (min)
Yield (%)
1
2
3
4
5
6
7
8
9
H
H
H
4-CH
4-CH
4-CH
4-COCH
4-COCH
4-NO
H
H
H
H
H
H
H
H
H
H
H
H
H
H
I
15
20
60
15
30
60
20
45
60
20
45
20
60
20
60
60
60
98
98
72
96
90
68
92
93
80
94
92
95
92
88
92
90
87
Br
Cl
I
Br
Cl
I
Br
Cl
I
Br
I
Br
I
I
Br
Br
3
0.2% mol nanocatalyst did not signicantly increase the yields.
3
3
So, this dosage of catalyst was selected for carrying out the
Suzuki coupling reaction under favored conditions (Table 3,
entry 8).
3
3
2
10
11
12
13
14
15
16
17
4-OCH
4-OCH
3
3
3.3. Investigation of functional group effects on C–C
4-NO
4-NO
4-CH
4-NO
H
2
2
3
2
coupling
The Suzuki C–C coupling reactions of variously substituted
aryl halides with electron-withdrawing and electron-donating
functional groups with phenylboronic acids was done in the
presence of 0.2 mol% of the nanocatalyst under optimized
conditions (Table 4). Also, under the optimized conditions, the
coupling reactions of phenylboronic acid with different
types of aryl halides, such as phenyl chlorides, phenyl
bromides, and phenyl iodides, were carried out (Table 4,
entries 1–17). The results illustrated that aryl halides with an
electron-withdrawing functional group showed more activity
than those with an electron-donating functional group in the
para-position. For a more accurate evaluation of the prepared
catalyst, a wide range of activated and deactivated aryl halides
was examined. According to the results obtained, medium
yields were observed under the optimized reaction conditions
due to the C–Cl bonds in aryl chlorides being stronger than the
C–Br bonds in aryl bromides, so the yields from the
coupling of aryl bromides were greater than those from aryl
chlorides (Table 4, entries 2–3, 5–6 and 8–9). As expected, on
the basis of the results obtained, aryl boronic acids with
electron-donating functional groups showed excellent yields
4-OCH
3-OCH
2-OCH
3
3
3
H
Fig. 6 Reusability of the KIT-5-biguanidine-Pd(0) catalyst.
stirring; also, with an increase in the ultrasound time, the yield
of the reaction increased and the optimized time was deemed to
be 20 min (Table 2). In the process of Suzuki C–C coupling
reactions, the nature of the solvent (protic and aprotic) has been
proven to play an important role. For this purpose, various
solvents were used, and the best solvent for this reaction was
seen to be a mixture of water and ethanol (1 : 1). This mixed
solvent has benets, such as being economical and eco-friendly.
(
Table 4, entries 16–17). To test the stability of the prepared
catalyst, recovery tests were carried out that showed that it
could be used efficiently for 6 runs without signicant loss of
activity (Fig. 6).
The activity and efficiency of the KIT-5-biguanidine-Pd(0)
catalyst were compared to various catalysts for the Suzuki
coupling reaction (Table 5). As shown, the prepared catalyst
Also, the most efficient base was seen to be K
selected and applied. The coupling reaction was examined in
2 3
CO , and it was
Table 5 Comparison of the KIT-5-biguanidine-Pd(0) catalyst with various catalysts for the Suzuki coupling reaction
ꢁ
Entry
Catalyst (mol%)
Conditions
X
Time (h)
T ( C)
Yield (%)
Ref.
1
2
3
4
5
6
7
8
9
PdCl
2
(MeCN)
2
(0.02 mmol)
K
K
K
Et
Et
2
2
2
CO
CO
CO
3
3
3
, H
, H
2
O/DMF
O
Br
I, Br
I
I, Br
I, Br
I, Br
I, Br
Br
5 min
5, 5.5
6
r.t.
100
70
120
100
40
100
80
r.t.
95
95, 88
100
78, 65
95, 90
98, 90
96, 96
77.7
29
30
31
32
33
34
35
36
SiO -pA-Cyan-Cys-Pd (0.5)
2
2
Pd–BOX (2)
Bis(oxamato)palladate(II) complex (5)
Pd-isatin Schiff base-g-Fe
NHC–Pd(II) complex (0.2)
, DMF
NBr
N, solvent-free
$3H O, H O, TBAB
N, DMF
PO , THF
CO , H O/EtOH
3
N, n-Bu
4
2
2
O
3
(0.5, 1.5)
3
0.5, 0.75
5, 6
0.5, 0.5
24
K
3
PO
4
2
2
g-Fe
Pd (dba) (1)
KIT-5-biguanidine-Pd(0)
2
O
3
–acetamidine–Pd (0.12)
Et
3
3
K
K
3
4
2
3
2
I, Br
15 min
This work
41588 | RSC Adv., 2019, 9, 41581–41590
This journal is © The Royal Society of Chemistry 2019

View Article Online
Paper
RSC Advances
demonstrated good yields and moderate conditions compared 13 B. J. Scott, G. Wirnsberger and G. D. Stucky, Chem. Mater.,
to other reported catalysts.
2001, 13, 3140–3150.
1
1
4 A. Taguchi and F. Schuth, Microporous Mesoporous Mater.,
2005, 77, 1–45.
4
. Conclusions
5 S. MacQuarrie, B. Nohair, J. H. Horton, S. Kaliaguine and
In this work, an ultrasound-assisted simple green synthetic
C. M. Crudden, J. Phys. Chem. C, 2010, 114, 57–64.
method was introduced, using a new KIT-5-biguanidine-Pd(0) 16 M.-C. Liu, C.-S. Chang, J. C. C. Chan, H.-S. Sheu and
catalyst, and it was applied to the Suzuki–Miyaura cross- S. Cheng, Microporous Mesoporous Mater., 2009, 121, 41–51.
coupling reaction. To analyze the catalytic performance of the 17 W. Cheng-Yu, H. Ya-Ting and Y. Chia-Min, Microporous
prepared catalyst, many parameters of the Suzuki coupling
Mesoporous Mater., 2009, 117, 249–256.
reaction were examined, such as the types of organic and 18 F. Kleitz, D. Liu, G. M. Anilkumar, I.-S. Park, L. A. Solovyov,
inorganic bases, the types of aprotic and protic solvents, and the
A. N. Shmakov and R. Ryoo, J. Phys. Chem. B, 2003, 107,
14296–14300.
dosage (mol%) of catalyst. On the basis of the results observed,
ꢁ
a temperature of 25 C, the use of ethanol/water (1 : 1) as the 19 G. Cravotto and P. Cintas, Angew. Chem., Int. Ed., 2007, 46,
solvent, and a nanocatalyst amount of 0.2 mol% were selected
for carrying out the Suzuki coupling reaction under favorable 20 J.-L. Luche, Synthetic Organic Sonochemistry, Plenum Press,
conditions. This heterogeneous catalyst system showed excel- New York, 1998.
lent catalytic performance and can be recovered easily via 21 M. Ashokkumar and T. Mason, ‘‘Sonochemistry’’ in Kirk-
5476.
centrifuging; it can also be reused 6 times for the aforemen-
tioned transformation with no considerable loss of activity.
Othmer Encyclopedia of Chemical Technology, John Wiley
and Sons, 2007.
2
2
2 T. J. Mason, Chem. Soc. Rev., 1997, 26, 443–451.
3 T. J. Mason and P. Cintas, Sonochemistry in Handbook of green
chemistry and technology, Blackwell Science Ltd., 1st edn,
2002, pp. 375–396.
Conflicts of interest
The authors report no conicts of interest related to this work.
2
4 P. Cintas, S. Tagliapietra, E. C. Gaudino, G. Palmisano and
G. Cravotto, Green Chem., 2014, 1056–1065.
5 G. Cravotto, E. Borretto, M. Oliverio, A. Procopio and
A. Penoni, Catal. Commun., 2015, 63, 2–9.
Acknowledgements
2
The authors are thankful to Payame Noor University for nan-
cial support.
26 F. Chang, J. Wang, J. Luo, J. Sun and X. Hu, J. Colloid
Interface Sci., 2016, 468, 284–291.
2
7 (a) S. Hemmati, L. Mehrazin, M. Pirhayati and H. Veisi,
Polyhedron, 2019, 158, 414–422; (b) H. Veisi, P. Safarimehr
and S. Hemmati, Mater. Sci. Eng., C, 2019, 96, 310–316; (c)
H. Veisi, M. Ghorbani and S. Hemmati, Mater. Sci. Eng., C,
2019, 98, 584–593; (d) H. Veisi, M. Pirhayati,
A. Kakanejadifard, P. Mohammadi, M. R. Abdi, J. Gholami
and S. Hemmati, ChemistrySelect, 2018, 3, 1820–1826; (e)
H. Veisi, M. Pirhayati and A. Kakanejadifard, Tetrahedron
Lett., 2017, 58, 4269–4276; (f) H. Veisi, S. A. Mirshokraie
and H. Ahmadian, Int. J. Biol. Macromol., 2018, 108, 419–
425; (g) H. Veisi, S. Hemmati and P. J. Safarimehr,
Catalysis, 2019, 365, 204–212; (h) H. Veisi, M. Ghorbani
and S. Hemmati, Mater. Sci. Eng., C, 2019, 98, 584–593; (i)
H. Veisi, S. Razeghi, P. Mohammadi and S. Hemmati,
Mater. Sci. Eng., C, 2019, 97, 624–631; (j) H. Veisi,
S. B. Moradi, A. Saljooqi and P. Safarimehr, Mater. Sci.
Eng., C, 2019, 100, 445–452; (k) H. Veisi, L. Mohammadi,
S. Hemmati, T. Tamoradi and P. Mohammadi, ACS Omega,
2019, 4, 13991.
References
1
2
3
4
5
6
7
G. Fan, B. Zou, S. Cheng and L. Zheng, J. Ind. Eng. Chem.,
010, 16, 220–223.
M. Zheng, L. Wang, F. Huang, P. Guo, F. Wei and Q. Deng, J.
Mol. Catal. B: Enzym., 2013, 95, 82–88.
S. M. Islam, P. Mondal, A. S. Roy, S. Mondal and D. Hossain,
Tetrahedron Lett., 2010, 51, 2067–2070.
F. Amoroso, S. Colussi, A. Del, J. Llorca and A. Trovarelli,
Catal. Commun., 2011, 12, 563–567.
2
K. Shimizu, R. Maruyama, S. Komai, T. Kodama and
Y. Kitayama, J. Catal., 2004, 227, 202–209.
M. I. Burrueco, M. Mora and J. R. Ruiz, Appl. Catal., A, 2014,
485, 196–201.
H. A. Elazab, A. R. Siamaki, S. Moussa, B. F. Gupton and
M. S. El-shall, Appl. Catal., A, 2015, 491, 58–69.
D. Astruc, Inorg. Chem., 2007, 46, 1884.
8
9
Z. Q. Xue, P. P. Huang, T. S. Li, P. X. Qin, D. Xiao, M. H. Liu,
P. L. Chen and Y. J. Wu, Nanoscale, 2017, 9, 781.
1
1
0 D. Z. Yuan, L. Chen, L. G. Yuan, S. J. Liao, M. M. Yang and 28 (a) H. Veisi, A. Sedrpoushan, A. R. Faraji, M. Heydari,
Q. H. Zhang, Chem. Eng. J., 2016, 287, 241.
1 F. Giacalone, V. Campisciano, C. Calabrese, V. L. Parola,
Z. Syrgiannis, M. Prato and M. Gruttadauria, ACS Nano,
S. Hemmati and B. Fatahi, RSC Adv., 2015, 5(84), 68523–
68530; (b) M. Pirhayati, H. Veisi and A. Kakanejadifard,
RSC Adv., 2016, 6(32), 27252–27259.
2
016, 10, 4627.
29 K. Said and R. B. Salem, Ultrasonic Activation of Suzuki and
Hiyama Cross-Coupling Reactions Catalyzed by Palladium,
Adv. Chem. Eng. Sci., 2016, 6(02), 111.
1
2 D. V. Jawale, E. Gravel, C. Boudet, N. Shah, V. Geertsen,
H. Y. Li, I. N. N. Namboothiri and E. Doris, Catal. Sci.
Technol., 2015, 5, 2388.
This journal is © The Royal Society of Chemistry 2019
RSC Adv., 2019, 9, 41581–41590 | 41589

View Article Online
RSC Advances
Paper
3
3
3
3
0 M.
Ghiaci,
M.
Zargani,
F.
Moeinpour
and 34 Q. X. Liu, W. Zhang, X. J. Zhao, Z. X. Zhao, M. C. Shi and
A. khojastehnezhad, Appl. Organomet. Chem., 2014, 28, 589.
1 S. M. Shakil Hussain, M. B. Ibrahim, A. Fazal, R. Suleiman, 35 S. Sobhani, M. S. Ghasemzadeh, M. Honarmand and F. Zari,
M. Fettouhi and B. El Ali, Polyhedron, 2014, 70, 39. RSC Adv., 2014, 4, 44166.
2 F. R. Fortea-P ´e rez, I. Schlegel, M. Julve, D. Armentano, G. De 36 V. I. de Paula, C. A. Sato and R. Buffon, J. Braz. Chem. Soc.,
Munno and S. E. Stiriba, J. Organomet. Chem., 2013, 743, 102.
3 S. Sobhani and F. Zari, Chin. J. Catal., 2015, 555.
X. G. Wang, Eur. J. Org. Chem., 2013, 1253.
2012, 23, 258.
41590 | RSC Adv., 2019, 9, 41581–41590
This journal is © The Royal Society of Chemistry 2019