Nanosilica-anchored Pd(II)-Schiff base complex as efficient heterogeneous catalyst for activation of aryl halides in Suzuki–Miyaura cross-coupling reaction in water

Article abstract of DOI:10.1002/aoc.3686

A nanosilica (derived from rice husk)-anchored Pd(II)–Schiff base complex has been synthesized and characterized. This immobilized complex has been found to be a very effective and recyclable heterogeneous catalyst for the Suzuki–Miyaura cross-coupling reaction of various aryl halides with arylboronic acid in aqueous medium under mild conditions. The products were identified using ¹H NMR and mass spectral studies. This complex can be easily filtered out from the reaction medium and reused up to six times without significant loss of catalytic activity. Since the reaction proceeds under mild conditions in aqueous medium as well as the catalyst being recyclable, it provides an environmentally benign alternative route to the existing protocols for the Suzuki–Miyaura reaction.

Full text of DOI:10.1002/aoc.3686

Received: 15 September 2016
DOI 10.1002/aoc.3686
Revised: 6 October 2016
Accepted: 18 October 2016
F U L L PA P E R
Nanosilica‐anchored Pd(II)‐Schiff base complex as efficient
heterogeneous catalyst for activation of aryl halides in Suzuki–
Miyaura cross‐coupling reaction in water
Nibedita Gogoi1 | Utpal Bora2 | Geetika Borah1 | Pradip K. Gogoi1
1 Department of Chemistry, Dibrugarh University,
A nanosilica (derived from rice husk)‐anchored Pd(II)–Schiff base complex has been
Dibrugarh 786004, Assam, India
2 Department of Chemical Sciences, Tezpur
University, Tezpur 784028, Assam, India
synthesized and characterized. This immobilized complex has been found to be a
very effective and recyclable heterogeneous catalyst for the Suzuki–Miyaura cross‐
coupling reaction of various aryl halides with arylboronic acid in aqueous medium
Correspondence
1
Geetika Borah or Pradip K. Gogoi, Department of
Chemistry, Dibrugarh University, Dibrugarh –
786004, Assam, India.
under mild conditions. The products were identified using H NMR and mass
spectral studies. This complex can be easily filtered out from the reaction medium
and reused up to six times without significant loss of catalytic activity. Since the
reaction proceeds under mild conditions in aqueous medium as well as the catalyst
being recyclable, it provides an environmentally benign alternative route to the
existing protocols for the Suzuki–Miyaura reaction.
Email: geetikachem@yahoo.co.in;
dr.pradip54@gmail.com
Funding information
UGC, New Delhi, India, SAD‐DRS‐I programme
(2016–2021); UGC‐BSR (RFSMS) Fellowship.
KEYWORDS
aryl halides, arylboronic acid, rice husk, Schiff base, Suzuki–Miyaura
1
|
INTRODUCTION
contains 90–97%[13] silica and can be extracted using a very
easy procedure.
Schiff bases are some of the most widely explored ligands as
they play a significant role not only in coordination but also
in catalysis and synthetic organic chemistry. There are many
Schiff base‐containing Pd(II) complexes acting either as
homogeneous or heterogeneous catalysts for cross‐coupling
reactions with excellent yields of products.[1,2] Though
homogeneous catalysts show very good activity, they are
difficult to separate and rarely reusable, hence heterogeneous
catalysts score better because of their easy separation from
products, reusability and high stability if immobilized on a
robust support like silica or alumina. In recent years, various
reports have been published dealing with immobilization of
palladium‐based compounds on a variety of solid supports
like silica,[3–5] MCM‐41,[6,7] SBA‐15,[8,9] FSM‐16,[10]
alumina,[11,12] etc. However, because of some specific
characteristics like wide accessibility, ease of processing,
low cost, high thermal stability and better surface reactivity,
silica is one of the best and widely used supports for immobi-
lization of transition metal compounds. One of the cheapest
and most eco‐friendly sources of silica is rice husk that
The Suzuki–Miyaura reaction is one of the most widely
studied, involving cross‐coupling between aryl halides and
arylboronic acid to give homoaryl and biaryl derivatives.
Most of the available reports indicate the use of palladium‐
based catalysts for such C─C coupling reactions with aryl
bromides/iodides as substrates;[3,14–18] however, there are
only a few reports of aryl chlorides as substrates. Since aryl
chlorides are easily available and economically more
favourable than bromides and iodides, they may act as more
suitable substrates in Suzuki–Miyaura reactions. Therefore,
there is a need to develop new silica‐supported palladium cat-
alysts for efficient activation of aryl chlorides, preferably with
low palladium loading but reusable for several reaction runs.
Here we report the synthesis of a reusable palladium
compound with tetradentate Schiff base complex
immobilized on rice husk‐derived nanosilica and its
evaluation as a heterogeneous catalyst in Suzuki–Miyaura
cross‐coupling reactions between aryl halides (including aryl
chlorides) and arylboronic acid in aqueous media under mild
reaction conditions.
Appl Organometal Chem 2016; e3686;
wileyonlinelibrary.com/journal/aoc
Copyright © 2016 John Wiley & Sons, Ltd.
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DOI 10.1002/aoc.3686

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GOGOI ET AL.
2
|
EXPERIMENTAL
namely Fourier transform infrared (FT‐IR) spectroscopy,
X‐ray diffraction (XRD), scanning electron microscopy
(SEM) coupled with energy‐dispersive X‐ray analysis
(EDX), Brunauer–Emmett–Teller (BET) surface area mea-
surement, elemental analysis and inductively coupled plasma
atomic emission spectrometry (ICP‐AES).
Nanosilica was derived from rice husk using a reported
method[19] and it was used for immobilization of the
Pd(II)–Schiff base complex. The overall process is shown
in Scheme 1.
To set up the reaction, a mixture of aryl halide (1 mmol),
arylboronic acid (1.2 mmol), K2CO3 (2 eq.), catalyst (appro-
priate quantity) and solvent (6 ml) was taken in a 50 ml
round‐bottom flask and allowed to stir at the appropriate
temperature. After completion of the reaction, the catalyst
was separated by filtration and the residue was extracted from
the filtrate using a water–ether mixture (1:3) followed by
washing with brine and drying over Na2SO4. The products
were isolated by column chromatography of the residue using
ethyl acetate–hexane (1:9) as eluent.
3.1.1
| FT‐IR study
In the FT‐IR spectra of nanosilica and (3‐aminopropyl)
triethoxysilane (APTES)‐functionalized nanosilica, the peaks
at 1629 and 3457.27 cm−1 are assigned to OH bending and
OH stretching, respectively. The FT‐IR spectrum of
APTES@nanoSiO2 exhibits a new band at 1543 cm−1
(γNH2) indicating grafting of APTES onto nanosilica (Fig.
1Sb). A new band observed at 1633.23 cm−1 is assigned
to νC═N which indicates the formation of Schiff base
anchored to nanosilica (Fig. 1Sc). In the FT‐IR spectrum
of the Pd(II)–Schiff base complex (Fig. 1Sd) new bands at
564 cm−1 (νP═N) and 557 cm−1 (νP‐d‐O) clearly indicate
that Pd is coordinated through nitrogen and oxygen. Interest-
ingly, it is observed that the νC═N band is shifted from
1633.23 to 1624.32 cm−1 on complexation. However, the
FT‐IR spectrum of Schiff base ligand L1 (Figure 1) displays
3
| RESULTS AND DISCUSSION
3.1 | Characterization
The synthesized nanosilica and nanosilica‐based materials
were characterized using various analytical techniques,
SCHEME 1 General procedure: (a) Schiff base of nanosilica; (b) Schiff base ligand; (c) nanosilica‐anchored Pd(II)–Schiff base complex

GOGOI ET AL.
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cubic system of the Pd complex consistent with results
reported previously.[15,20]
The morphological change that occurs on the surface of
nanosilica after loading of the Pd complex can be confirmed
from the SEM images of the free nanosilica and supported Pd
complex. It is observed that there is a significant decrease in
the silica particle size in the presence of Pd which could be
due to modification of surface morphology of silica due
to immobilization of the Pd complex (Figure 3). The
SEM–EDX results indicate the metal content along with
the O, N and Si proportions and suggest the formation of
metal complex with the anchored ligand in successive steps
as shown in Figure 2S.
The ICP‐AES analysis indicates that there is 0.068 mmol
Pd content per 10 mg of the catalyst.
FIGURE 1 FT‐IR spectrum of Schiff base ligand (L1)
bands at 1636, 3446 (broad) and 1265 cm−1, attributable to
νC═N, νOH and νC─O, respectively, confirming the forma-
tion of the Schiff base ligand.
3.1.2
| Elemental analysis
The elemental analysis data of free nanosilica, Schiff base of
nanosilica, Schiff base ligand and the complex are presented
in Table 1S.
3.1.3
| XRD, SEM–EDX and ICP‐AES analyses
In the XRD pattern of amorphous nanosilica, a strong diffrac-
tion peak at 2θ ≈ 21.1° indicates SiO2 (Figure 2) and the
diffraction pattern of nanosilica‐immobilized Pd complex
exhibits two new peaks at 2θ = 38.09° and 47.25° corre-
sponding to the (111) and (200) lattice planes of face‐centred
FIGURE 2 XRD patterns of (a) nanosilica and (b) Pd(II)–Schiff base
complex
FIGURE 3 SEM images of (a) nanosilica, (b) Schiff base of nanosilica and
(c) Pd(II)–Schiff base complex

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GOGOI ET AL.
TABLE 1 BET surface area measurement of nanosilica‐based materials
(Table 2, entry 2); however, no product is isolated in the
absence of catalyst (Table 2, entry 9). The reaction was also
performed in the absence of Pd metal (Table 2, entries 7
and 8), when no product can be isolated from the reaction
mixture, clearly indicating the crucial role of Pd metal in
the reaction.
Entry
Material
SBET (m2 g−1
)
1
2
3
4
Nanosilica
189.97a
175.45a
169.21
160
APTES@nanoSiO2
Schiff base anchored to nanosilica (L)
Pd(II)–Schiff base complex (C)
The catalyst is less active at room temperature (ca 30 °C)
producing only 55% yield after 5 h (Table 2, entry 5). Various
aReported in Gogoi et al.[19]
i
solvents like C2H5OH, H2O, PrOH, MeOH, CH3CN and
3.1.4
|
Surface area measurement
dimethylsulfoxide (DMSO) as well as various bases like
K2CO3, Na2CO3, NaHCO3 and Cs2CO3 were also tested in
order to determine the optimum reaction conditions. Since
water has high polarity index (9.0), bases are easily soluble
in it, which activates the boronic acid. Thus, this may be
the reason for obtaining the highest yield in water for the
Suzuki coupling reaction (Table 2, entry 2). Furthermore,
the best result is obtained in the case of 2 eq. of K2CO3 (entry
2). No product is obtained in the absence of base (entry 16).
The reaction was also carried out with 1.5 and 2.5 eq. of
K2CO3, which afford 78 and 98% yields, respectively (entries
17 and 18). Therefore, we carried out further reactions taking
2 eq. of K2CO3 as the optimum amount.
The specific surface areas of the produced silica‐based mate-
rials were calculated using the BET method. The gradual
decrease in surface area (Table 1) from nanosilica to
anchored Pd(II)–Schiff base complex is indicative of immo-
bilization of the complex onto the nanosilica surface.
3.2 | Catalytic activity
We employed an aryl bromide (p‐bromoanisole) and
phenylboronic acid as model substrates in order to investigate
the reaction conditions. At first, we conducted the reaction
with various amounts of the catalyst, 5, 10, 15, 20 mg, and
even in the absence of the catalyst. It is observed that
10 mg of catalyst is very efficient for the required conversion
Next, we applied the optimized reaction conditions to var-
ious aryl bromides and arylboronic acid having either
TABLE 2 Optimization of Suzuki–Miyaura reaction of aryl bromide (p‐bromoanisole) and phenylboronic acid at 50°Ca
Entry
Catalyst (amount in mg)
Solvent
Base (eq.)
Time (h)
Yield (%)b
1
Pd(II)–Schiff base complex (5)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (15)
Pd(II)–Schiff base complex (20)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Schiff base of nanosilica (20)
Nanosilica (20)
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
K2CO3(2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3
1
70
98
98
99
55c
98d
—
—
—
67
71
85
80
74
65
—
78
98
67
65
67
2
0.5
0.5
0.5
5
3
4
5
6
0.5
6
7
8
6
9
—
6
10
11
12
13
14
15
16
17
18
19
20
21
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
C2H5OH
iPrOH
H2O–iPrOH (1:1)
CH3CN
MeOH
DMSO
H2O
3
2
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
—
1
2
4
5
6
H2O
K2CO3 (1.5)
K2CO3 (2.5)
Cs2CO3 (2)
NaHCO3 (2)
Na2CO3 (2)
1
H2O
0.5
2.5
2
H2O
H2O
H2O
2
aReaction conditions: aryl bromide (1 mmol), arylboronic acid (1.2 mmol), Pd catalyst (10 mg), K2CO3 (2 eq.), H2O (3 ml), ca 50 °C in air unless otherwise noted.
bIsolated yield.
cRoom temperature.
dAt 60 °C.

GOGOI ET AL.
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electron‐withdrawing group or electron‐donating group as
coupling partner. The results are given in Table 3. It is found
that aryl bromides with both electron‐withdrawing and
electron‐donating groups underdo coupling reaction with
arylboronic acid effectively to give products in high yields
in water. In addition, the present protocol is also effective
in the case of heteroaryl halide with 4‐fluoroboronic acid
(Table 3, entry 16). This procedure is found to be very useful
and green resulting in excellent yields under mild reaction
conditions.
To investigate the scope and limitations of the present cat-
alytic system, we also conducted cross‐coupling reactions
using an aryl chloride under a similar set of conditions as
with aryl bromides, when 25% yield is obtained even after
6 h of reaction time clearly indicating the low efficiency of
the catalyst for aryl chlorides. However, when we used
dimethylformamide (DMF)–H2O (1:1) as solvent with
20 mg of catalyst loading at 65 °C, comparatively higher
yield of product is obtained (Table 4, entry 7). Increasing
the amount of base to 2.5 eq. does not affect the product yield
(Table 4, entry 9). We also carried out the reaction by replac-
ing the base with Cs2CO3 and Na2CO3, but this does not
improve the yield (Table 4, entries 9 and 10).
In our next move, we carried out the reaction using aryl
chlorides containing an electron‐withdrawing group, such as
p‐chloroacetophenone (Table 5, entry 2), an electron‐donat-
ing group, such as p‐chloroanisole (entry 6), and an elec-
tron‐neutral group, such as chlorobenzene (entry 3), with
phenylbronic acid. Excellent yields of the desired biphenyl
are achieved. However, on replacement of phenylboronic acid
by p‐methoxyboronic acid (entries 1 and 7) and p‐
fluoroboronic acid (entry 5) no significant effect on the yield
TABLE 3 Suzuki–Miyaura reaction of aryl bromides with various arylboronic acidsa
Entry
R1
R2
Product
Time (h)
Yield (%)b
1
4‐MeO
H
1
98
2
3
4‐MeO
4‐MeO
4‐MeO
3‐Me
1
2
100
97
4
4‐NO2
4‐NO2
4‐CHO
4‐CHO
4‐CH3CO
4‐Me
4‐MeO
H
3
3
2
3
3
2
2
4
95
92
92
95
93
96
94
97
5
6
H
7
4‐MeO
4‐MeO
4‐MeO
4‐F
8
9
10
11
4‐NO2
4‐Me
3‐Me
12
13
H
H
0.5
2
100
96
4‐MeO
2‐Me
14
15
16
4‐MeO
4‐MeO
4‐CHO
4‐F
3
3
6
97
95
94
4‐F
aReaction conditions: aryl bromide (1 mmol), arylboronic acid (1.2 mmol), Pd catalyst (10 mg), K2CO3 (2 eq.), H2O (3 ml), ca 50 °C in air.
bIsolated yield.

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GOGOI ET AL.
TABLE 4 Optimization of Suzuki–Miyaura reaction of aryl chloride (p‐chloroanisole) and phenylboronic acid at 50°Ca
Entry
Catalyst (amount in mg)
Solvent
Base (eq.)
Time (h)
Yield (%)b
1
2
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (10)
Pd(II)–Schiff base complex (15)
Pd(II)–Schiff base complex (20)
Pd(II)–Schiff base complex (20)
Pd(II)–Schiff base complex (20)
Pd(II)–Schiff base complex (20)
H2O
iPrOH
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2)
K2CO3 (2.5)
Cs2CO3 (2)
Na2CO3 (2)
6
6
6
6
5
5
5
5
6
6
25
56
3
H2O–iPrOH (1:1)
DMF–H2O (1:1)
DMF–H2O (1:1)
DMF–H2O (1:1)
DMF–H2O (1:1)
DMF–H2O (1:1)
DMF–H2O (1:1)
DMF–H2O (1:1)
54
4
64
5
70c
70c
74c
74c
65c
59c
6
7
8
9
10
aReaction conditions: aryl chloride (1 mmol), arylboronic acid (1.2 mmol), K2CO3 (2 eq.), H2O (3 ml).
bIsolated yield.
cAt 65 °C.
is observed. These results are quite significant for cross‐cou-
pling reactions of aryl chlorides with various arylboronic
acids.
bromoanisole and phenylboronic acid as substrates. After
10 min, the reaction was stopped and the catalyst filtered
off (20% yield determined using GC–MS), and the reaction
was allowed to continue for a further 3 h without the solid
catalyst (Figure 4). No catalytic activity could be seen in
the filtrate (using GC analysis) which rules out the possibility
of homogeneous/semi‐heterogeneous catalysis. No Pd is
leached into the solution, indicating the heterogeneous nature
of our catalyst. To further establish this result, we performed
ICP‐AES analysis of the filtrate and no trace of Pd was found
3.3 | Catalyst leaching and reusability
3.3.1
| Hot filtration test
The hot filtration test is an important method for checking
whether a catalysed reaction is truly heterogeneous or
not.[21] We carried out a hot filtration test by taking p‐
TABLE 5 Suzuki–Miyaura reaction of aryl chlorides with various arylboronic acidsa
Entry
R1
4‐Me
R2
Product
Time (h)
Yield (%)b
1
4‐MeO
5
62
2
3
4
5
6
7
4‐CH3CO
H
H
5
4
5
5
5
3
65
85
68
67
74
76
H
4‐CHO
4‐MeO
4‐MeO
4‐MeO
H
4‐F
H
4‐MeO
aReaction conditions: aryl chloride (1 mmol), arylboronic acid (1.2 mmol), Pd catalyst (20 mg), K2CO3 (2 eq.), DMF–H2O (4 ml), ca. 65 °C in air.
bIsolated yield.

GOGOI ET AL.
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FIGURE 6 SEM image of Pd complex (after sixth use)
recovered after completion of reaction (Figure 7). Results
show that the valance of the nanosilica‐anchored Pd(II)–Schiff
base complex remains same after completion of the reaction
under the same conditions. The appearance of peaks at 251
and 395 nm for fresh and used catalyst confirms that the Pd
metal in the catalyst is in the +2 oxidation state.[22]
FIGURE 4 Activity of the catalyst for the reaction between phenylboronic
acid and 4‐bromoanisole with hot filtration and without filtration
in the filtrate, supporting the absence of leaching of Pd and
establishing the heterogeneous nature of the catalyst.
We have also compared the catalytic activity of our cata-
lyst with that of some previously reported catalysts,[15,23,24]
indicating the superior activity of our catalyst (Table 6).
3.3.2
| Recyclability
The recyclability of the catalyst was investigated by choosing
phenylboronic acid and 4‐bromoanisole as coupling partner.
Figure 5 shows that the nanosilica‐anchored Pd(II)–Schiff
base complex can be used for up to six consecutive cycles
without any significant loss of its efficiency. Because of the
solid nature of the catalyst, it is easily recoverable by
centrifuging the reaction mixture after completion. The cata-
lyst is reusable in a subsequent coupling reaction after
thoroughly washing with water and ethyl acetate and drying.
However, the reaction time increases slightly in successive
cycles. Since there is no significant leaching of palladium
during the catalysis and recovery, the slight gradual decrease
in product yield after successive reuse may be due to physical
loss of the amount of the catalyst. Moreover, the SEM–EDX
analysis of the used catalyst (after the sixth cycle) shows the
presence of Pd metal and the SEM image (Figure 6) is similar
to that of the fresh catalyst.
4
| CONCLUSIONS
The novelty of the present work is that the catalyst is reusable
up to six times and also it is active for both aryl chlorides and
aryl bromides as one of the coupling partners with low cata-
lyst loading. The catalyst exhibited a high activity in aqueous
media under mild reaction conditions. Overall, the present
protocol offers a mild, efficient and attractive alternative to
the existing methods because of the use of green solvent
and inorganic base and the broad substrate scope.
To know the valance state of the catalyst after completion
of a catalytic cycle, we performed solid‐state UV–visible
spectral analysis of the fresh catalyst and also of the catalyst
FIGURE 5 Recyclability of the catalyst
FIGURE 7 UV–visible spectra of (a) fresh catalyst and (b) used catalyst

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GOGOI ET AL.
TABLE 6 Comparison of catalytic activity of present catalyst with that of other previously reported supported Pd catalysts
Aryl
halide
Yield (%), reaction
time
Temperature (°C),
base
Entry
Catalyst
Pd@imineSiO2
Solvent
Ref.
iPrOH–H2O (1:1)
iPrOH–H2O (1:1)
27, Na2CO3
27, Na2CO3
[15]
1
PhBr
PhCl
100, 1 h
No reaction
Pd0/SBA‐15
PhBr
PhCl
80.2, 4 h
60.0, 4 h
DMF
DMF
iPrOH–H2O (1:1)
DMF
110, NEt3
110, NEt3
[21]
[24]
[23]
2
3
4
5
PdNP@SiO2‐PPh2
Poly‐NHC‐2‐Pd2+
PhBr
PhCl
94, 3 h
95, 5 h
60, K2CO3
100, K2CO3
PhBr
PhCl
99, 5 min
100, 3 h
EtOH–H2O
EtOH–H2O
80, K3PO4⋅3H2O (3 eq.)
80, K3PO4⋅3H2O (3 eq.)
Pd(II)–Schiff base complex on rice
husk‐derived nanosilica support
PhBr
PhCl
100, 0.5 h
85, 4 h
H2O
DMF–H2O (1:1)
50, K2CO3 (2 eq.)
65, K2CO3 (2 eq.)
Present work
ACKNOWLEDGMENTS
[15] T. Begum, M. Mondal, U. Bora, P. K. Gogoi, RSC Adv. 2015, 5, 38085.
[16] D. X. Liu, W. J. Gong, H. X. Li, J. Gao, F. L. Li, J. P. Lang, Tetrahedron
2014, 70, 3385.
The authors acknowledge SAIC‐Tezpur University for carry-
ing out SEM–EDX and CHN elemental analysis. The authors
are also grateful to SAIF‐Kochi for carrying out ICP‐AES
and 1H NMR analyses of the products. The authors are grate-
ful to UGC, New Delhi, India for financial support under the
SAD‐DRS‐I programme (2016–2021). N.G. also thanks
UGC, New Delhi for financial assistance in the form of
UGC‐BSR (RFSMS) Fellowship.
[17] Q. Li, L. M. Zhang, J. J. Bao, H. X. Li, J. B. Xie, J. P. Lang, Appl.
Organometal. Chem. 2014, 28, 861.
[18] J. J. Ning, J. F. Wang, Z. G. Ren, D. J. Young, J. P. Lang, Tetrahedron 2015,
71, 4000.
[19] N. Gogoi, T. Begum, U. Bora, P. K. Gogoi, RSC Adv. 2015, 5, 95344.
[20] C. Sarmah, D. Sahu, P. Das, Catal. Today 2012, 198, 197.
[21] S. Xu, K. Song, T. Li, B. Tan, J. Mater. Chem. A 2015, 3, 1272.
[22] E. N. Daley, K. A. Moffat, M. N. Wilson, M. M. Brown, E. S. A. Williams,
M. I. Farren‐Dai, C. M. Vogels, A. A. Letourneau, T. M. Brooks, A. Decken,
F. J. Baerlocher, S. A. Westcott, Transition Met. Chem. 2015, 40, 605.
REFERENCES
[1] P. G. Cozy, Chem. Soc. Rev. 2004, 33, 410.
[2] P. Das, W. Linert, Coord. Chem. Rev. 2016, 311, 1.
[3] W. Chen, P. Li, L. Wang, Tetrahedron 2011, 67, 318.
[23] A. Martínez, J. L. Krinsky, I. Peñafiel, S. Castillon, K. Loponov, A. Lapkin,
C. Godard, C. Claver, Catal. Sci. Technol. 2015, 5, 310.
[24] D. Sahu, P. Das, RSC Adv. 2015, 5, 3512.
[4] N. Fukaya, M. Ueda, S. Onozawa, K. K. Bando, T. Miyaji, Y. Takagi, T.
Sakakura, H. Yasuda, J. Mol. Catal. A 2011, 58, 342.
[5] S. Paul, J. H. Clark, Green Chem. 2003, 5, 635.
SUPPORTING INFORMATION
[6] H. Zhao, J. Peng, R. Xiao, M. Cai, J. Mol. Catal. A 2011, 337, 56.
[7] S. Jana, S. Haldar, S. Koner, Tetrahedron Lett. 2009, 50, 4820.
[8] C. M. Crudden, M. Sateesh, R. Lewis, J. Am. Chem. Soc. 2005, 127, 10045.
Additional Supporting Information may be found online in
the supporting information tab for this article.
[9] S. E. Hankari, A. E. Kadib, A. Finiels, A. Bouhaouss, J. J. E. Moreau, C. M.
Crudden, D. Brunel, P. Hesemann, Chem. – Eur. J. 2011, 17, 8984.
How to cite this article: Gogoi N, Bora U, Borah G,
Gogoi PK. Nanosilica‐anchored Pd(II)‐Schiff base
complex as efficient heterogeneous catalyst for activa-
tion of aryl halides in Suzuki–Miyaura cross‐coupling
reaction in water. Appl Organometal Chem. 2016;
e3686. doi: 10.1002/aoc.3686
[10] P. Das, U. Bora, A. Tairai, C. Sharma, Tetrahedron Lett. 2010, 51, 1479.
[11] P.Das,C.Sarmah,A.Tairai,U.Bora,Appl.Organometal.Chem.2011,25,283.
[12] K. G. Mansaray, A. E. Ghaly, Energy Sources 1997, 19, 989.
[13] T. W. Dijkstra, R. Duchateau, A. Rutger, V. Santen, A. Meetsma, G. P. A.
Yap, J. Am. Chem. Soc. 2002, 124, 9856.
[14] N. J. S. Costa, P. K. Kiyohara, A. L. Monterio, Y. Coppel, K. Philippot,
L. M. Rossi, J. Catal. 2010, 276, 382.