Rapid gram-scale synthesis of Au/chitosan nanoparticles catalysts using solid mortar grinding

Article abstract of DOI:10.1039/d0nj04255b

Owing to the abundant functional groups present in the chitosan polymer, high density catalytic tiny gold particles with greater dispersion can be anchored on the chitosan powder using simple mortar and pestle. Chitosan-supported gold nanoparticles (NPs) with excellent control of size and shape were rapidly synthesized in gram-scale by solid-grinding without the need of any toxic solvents. The structure of catalysts and products was established by advanced instrumental and spectroscopic methods. The supported gold NPs functions as a heterogeneous catalyst for the homocoupling of phenylboronic acid and the aerobic oxidation of benzyl alcohol in water. The catalytic behaviour and activity of supported gold NPs was tuned/modulated by varying the ratio of chitosan polymer and gold precursor. Comparative studies showed that the solid chitosan supported gold catalyst exhibits superior catalytic activity and selectivity than the well known hydrophilic polymer-stabilized gold NPs catalysts prepared by the conventional solution-based methods.

Full text of DOI:10.1039/d0nj04255b

View Article Online
View Journal
NJC
New Journal of Chemistry
Accepted Manuscript
A journal for new directions in chemistry
This article can be cited before page numbers have been issued, to do this please use: M. Arumugam, K.
Paul Reddy, R. S. Meerakrishna, B. Satpati and P. Shanmugam, New J. Chem., 2020, DOI:
10.1039/D0NJ04255B.
Volume 42
This is an Accepted Manuscript, which has been through the
Number
6
21 March 2018
Pages 3963-4776
Royal Society of Chemistry peer review process and has been
accepted for publication.
NJC
New Journal of Chemistry
rsc.li/njc
A journal for new directions in chemistry
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 1144-2546
PAPER
Chechia Hu, Tzu-Jen Lin et al.
Yellowish and blue luminescent graphene oxide quantum dots
prepared via a microwave-assisted hydrothermal route using
H2O2 and KMnO4 as oxidizing agents
rsc.li/njc

Please do not adjust margins
Page 1 of 11
New Journal of Chemistry
1
2
3
4
5
6
7
View Article Online
DOI: 10.1039/D0NJ04255B
ARTICLE
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Rapid Gram-Scale Synthesis of Au/Chitosan Nanoparticles catalysts by
Using Solid Mortar Grinding
K. Paul Reddy a, R. S. Meerakrishnab, P. Shanmugamb, Biswarup Satpatic and A. Murugadoss*a
Received 00th January 20xx,
Accepted 00th January 20xx
Owing to the abundant functional groups present in the chitosan polymer, high density catalytic tiny gold particles
with greater dispersion can be anchored on chitosan powder by using simple mortar and pestle. Chitosan supported gold
nanoparticles (NPs) with excellent control of size and shape has been synthesized rapidly in gram-scale by solid-grinding
without the need of any toxic solvents. The structure of the catalysts and products was established by advanced
instrumental and spectroscopic methods. The supported gold NPs possesses as heterogeneous catalyst for the
homocoupling of phenylboronic acid and the aerobic oxidation of benzyl alcohol in water. The catalytic behaviour and
activity of the supported gold NPs was tuned/modulated by varying the ratio of chitosan polymer and gold precursor.
Comparative studies showed that the solid chitosan supported gold catalyst exhibits superior catalytic activity and
selectivity than the well known hydrophilic polymers stabilized gold NPs catalysts prepared by conventional solution based
methods.
DOI: 10.1039/x0xx00000x
These unique features make the colloidal nanogold as
promising model catalysts for fundamental studies of
heterogeneous catalysis.
Introduction
The gram scale synthesis of highly stable with excellent size
and shape controllability of gold nanoparticles (NPs) catalysts
is continuing as one of the attractive research areas in various
fields of science and technology, specifically in catalysis1-4. The
unique catalytic performance of polymer protected nanogold
catalysts has been demonstrated in a number of chemical
transformations such as alcohol oxidations5-7, carbon-carbon
bond formation reactions8-10, and hydrogenations11 etc. In the
last two decades, various hydrophilic functional polymers such
as poly vinyl alcohols, thiol linked polyethylene glycol, poly
vinyl 2-pyrrolidone, starch, and cellulose have been used as
stabilizers as well as capping agents for the synthesis of well-
defined size and shape tuneable colloidal nanogold catalysts12-
17. In contrast to solid metal oxide support, this hydrophilic
polymers act as a catalytically inert stabilizer by multiple
coordination sites, which weakly bound to gold NPs surface
without affecting the intrinsic chemical properties of gold.
Multifunctional groups present in the hydrophilic polymers
have also potential to control both catalytic activity by
donating the electronic charge and selectivity by activating the
Although significant progresses have been made for the
synthesis of such polymers stabilized colloidal nanogold
catalysts, these methodologies are mostly solution-based
synthetic procedures, which are complex, tedious, consume
large amounts of solvents20. In addition, these solution-based
methods are always slow in progress of nanogold catalysts
based technologies and difficult to scale-up for laboratory/
industrial synthetic procedures21-23
.
Another important
constraint in the solutions-based approaches using functional
polymers as a protective matrix is severely restricts in both
scaling-up process and catalysis24-27. Due to their inherent
viscous nature, it not only requires multiple purifications/
washing processes with excessive solvents, but also needed
sophisticated equipment for purifications and drying to obtain
the polymer protected colloidal nanogold catalysts24-25,28. In
addition, high loading of catalytically active gold NPs with good
dispersion is always crucial to achieve excellent catalytic
performance in the functional polymer stabilized nanogold
catalysts using solution-based methods. Therefore, it is highly
desirable to develop an alternative strategy that can overcome
these drawbacks for the gram-scale preparation of the
hydrophilic functional polymer supported gold NPs.
substrates during the catalytic reactions18-19
.
a. Department of Inorganic Chemistry, University of Madras, Guindy Campus,
Chennai – 600025, India. E-mail: murugadoss@unom.ac.in
Chitosan is β-1,4-linked poly(d-glucosamine) derived from
partial deacetylation of chitin29-30. In contrast to other
hydrophilic functional polymers, chitosan is an inexpensive,
highly stable solid polymer with rich multifunctional groups
b. Organic and Bioorganic Chemistry Division, Council of Scientific and Industrial
Research (CSIR) – Central Leather Research Institute (CLRI), Adyar, Chennai –
600020, India.
c.Surface Physics and Material Science Division, Saha Institute of Nuclear Physics,
Kolkata – 700064, India.
+ Electronic Supplementary Information (ESI) available: More TEM images, XPS,
XANES and Langmuir-Isotherm plots for supported gold catalysts. Experimental
procedure and reproduced spectra of products. See DOI: 10.1039/x0xx00000x
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 2 of 11
1
2
3
4
View Article Online
DOI: 10.1039/D0NJ04255B
5
6
7
8
ARTICLE
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Table 1. Content of gold before and after reduction (determined by ICP-OES), gold loading on chitosan supports (aglucosamine monomer
unit), and their effective surface area (bdetermined from Langmuir-adsorption isotherm) and particles sizes of gold NPs supported on solid
chitosan.
Sample
name
Initial amount
of gold
(mmol)
0.02
Amount of
chitosan
(mmol)a
0.84
0.84
4.2
0.84x5
Gold loading
(wt %)
Mole ratio of
gold
Particle
size (nm)
Effective surface
area (m2/g)b
Amount of Au
from ICP-OES
(mmol)
and chitosana
1:42
Chit-Au1
Chit-Au2
Chit-Au3
Chit-Au4
2.4
12.5
0.47
2.4
5.6±1.5
9.5±2.7
3.8±1.7
2.8±1.7
5.5 × 103
1.5 × 103
4.9 × 103
2.8 × 104
0.0198
0.0981
0.0195
0.0197
0.1
0.02
0.02x5
1:8
1:210
1:42
possesses great potential as an excellent support for metal report that catalytic activity of hydrophilic polymer supported
cluster catalysts31-34. For example, Ag NPs can be supported on metal NPs can be tuned/modulated by varying the ratio of the
solid chitosan which was subsequently used for the synthesis polymer and metal precursor using simple mortar and pestle
of bimetallic Au-Ag alloy NPs, where the chitosan powder used without the need of solvents.
as both reducing as well as stabilizer for Ag and Au-Ag alloy
NPs. Contrary to the solution-based processes, gram-scale
Results and Discussion
quantity of solid chitosan supported Au-Ag alloy NPs catalysts
Grinding of white solid chitosan with few microlitres of
can be synthesized by mortar grinding35. Because of the weak
highly concentrated HAuCl4 results in the formation of the
reducing nature of chitosan, it is incapable to synthesize other
yellow solid, which was subsequently changed into dark
noble metal NPs such as palladium and gold NPs by solid
greyish powder by addition of solid NaBH4, indicating the
grinding. On the other hand, the gram-scale syntheses PVP
formation of gold NPs in the solid mixtures. As shown in Table
stabilized Au NPs of achieved by using vibrating ball milling.
1, the mole ratio of gold and chitosan polymer (in glucosamine
However, this method produces inhomogeneous size
monomer unit) was to be 1:42. This solid mixture was then
distribution of Au NPs, which limits the practical applications36.
purified with water using filter paper. It should be mentioned
Since solid grinding requires a small amount of solvent or does
that neither unreduced gold ions nor gold NPs are leached out
not need any solvent, it would have been highly promising if
from the solid chitosan during washing and filtration (Figure
one could able to synthesize the solid chitosan supported gold
S1: ESI). This observation indicates that the reduction of gold
NPs in gram-scale through solid-grinding method. This
ions proceeded quantitatively and the gold NPs are effectively
achievement would surely advance their practical applications.
anchored on chitosan polymer. In this synthetic strategy, the
Thus, herein we report an efficient solid-grinding approach
process of supporting the gold NPs on the solid chitosan
for the synthesis of gram-scale quantity of solid chitosan
completed within 5-10 minutes, much shorter than 3 to 12 hrs
supported gold NPs using sodium borohydride (NaBH4)
or even a day often required by the solution-based process.
reducing agent. Hence, large amount of gold NPs (0.47-12.5 wt
More specifically, no solvents are needed; hence, the solubility
%) can be loaded onto the solid chitosan support with gold NPs
of hydrophilic polymers, molecular weight and their viscosity
sizes in the range of 2.8 to 9.5 nm. This solid chitosan
problem can in principle be ignored37. In order to verify this,
supported gold NPs used as heterogeneous catalysts for the
conventional solution approach was used to prepare the
oxidative homocoupling of arylboronic acids into biphenyls
chitosan stabilized gold NPs with maintaining the 1:42 mole
and the aerobic oxidation of benzyl alcohols into
ratio of gold and chitosan. For example, when the chitosan
corresponding aldehyde and acids in water under open air. In
was dissolved in an aqueous acidic solution and followed by
contrast to conventional solution-based synthesis, solid
addition of HAuCl4 and a NaBH4 a gel formation was occurred
chitosan supported gold NPs catalysts showed higher activity
(see Figure S2: ESI)33. Further, it was observed that gold NPs
and selectivity for homocoupling of arylboronic acid reactions.
are severally aggregated in the gel. This result clearly reveals
More importantly, the catalytic activity of chitosan-supported
that solid-grinding strategy is facile and effective for the direct
nanogold easily modulated by changing the mole ratio of
dispersion of gold NPs on the chitosan polymer support. More
chitosan polymer and gold precursor using the simple solid
loading of catalytically active metals in the form of tiny NPs
grinding method. The best of our knowledge, this is the first
with greater dispersion onto solid support materials is of
Please do not adjust margins

Please do not adjust margins
Page 3 of 11
New Journal of Chemistry
Journal Name
ARTICLE
1
2
3
4
paramount importance for the development high performance amount of chitosan support (Table 1), more amount of gold
View Article Online
metal catalyst38-39. Owing to the significant content of primary content in chit-Au2 may causes the aggregation of gold NPs on
DOI: 10.1039/D0NJ04255B
amines, hydroxyls and esters functional groups in the chitosan the support, which resulted the shifting of SPR band at longer
polymer, the solid chitosan might function as an excellent wavelength than chit-Au1. In contrast, as the amount of
platform for loading high density gold NPs without significant chitosan is increased in five times, the SPR peak significantly
aggregations. To investigate whether chitosan would be a reduced in Chit-Au3. This result indicating the more content of
superior support material for loading of large amounts of gold the chitosan support leads to the high dispersion of gold NPs.
NPs, we have prepared different solid chitosan supported gold when the content of both gold and chitosan increased in the
NPs by changing the mole ratio of chitosan and gold precursor chit-Au4 resulted in narrow SPR band at 525 nm. In order to
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
using solid-grinding.
understand the shifting of SPR band and to investigate the size
and morphology of chitosan supported nanogold, high-
resolution TEM analysis were performed. As shown in Figures
2a-2d and Figure S4: ESI, the morphology of gold NPs in all four
samples exhibits nearly spherical in shapes, and are distributed
homogeneously in the chitosan support. This particles exhibits
clear diffraction rings in SAED patterns (Figure S4d insert
image, ESI), and corresponding to d-spacing of 2.27, 1.96, 1.39
and 1.19 A˚ for (111), (200), (220) and (311) planes of the fcc
structure of metallic gold (JCPDS No. 04-0784)41-43. The size
distribution histogram plots were constructed for all four
samples by analyzing more than 250 particles from the HRTEM
images of corresponding samples and particles sizes were
determined to be 5.6±1.5, 9.5±2.7, 3.8±1.7 and 2.8±1.7 nm for
chit-Au1, chit-Au2, chit-Au3, and chit-Au4, respectively
(Figures 2e-2h and Table 1). Both HRTEM images and
histogram plots revealed increasing the chitosan support in
chit-Au3 and chit-Au4, not only reduce the size of gold NPs but
also the particles were greatly dispersed homogeneously
without bulk or lumps of aggregations on the solid chitosan
support (see Figure S4: ESI). It is reported elsewhere that more
amount of stabilizing polymer increases large number of
nucleation sites for growth of more number of tiny particles44-
45. Because of this high dispersion of smaller gold NPs on the
chitosan support, the SPR band was significantly blue shifted in
both chti-Au3 and chit-Au4. In contrast to chit-Au1, the bigger
sized gold NPs were obtained for chit-Au2. Obviously, the
loading of more amounts of gold NPs on less amount of solid
support tends to form bigger sized particles due to aggregation
that causes the red shifting of SPR band in chit-Au2. It is
noteworthy to mention that more loading of metals on solid
support materials like metal organic framework and other
mesoporous materials leads to formation of rods and wire like
structures by aggregation due to weak interaction between
metals and support functional groups46-48. In contrast, the
multifunctional groups present in the chitosan not only
strongly interacting with the gold atoms and also providing a
large number of adsorption site for high dispersion of gold
NPs. This observation further supports from the FTIR study of
chitosan supported gold NPs (Figure S5: ESI). The absorption
bands at 1659 cm-1, (amide I for C=O vibration), 1598 cm-1 (NH2
bending in primary amines), 1552 cm-1 (NH bending in amide II
vibration and 3422 cm-1 (OH and NH vibration) are slightly
shifted with reduced intensities. The shifting of absorption
bands with peak intensity reduction compared to free chitosan
Figure 1. (a) Photographic images of solid chitosan supported gold NPs
powder, b) corresponding powders dissolved in 1 % (V/V) aqueous acetic
acid solution and their (c). UV-Visible absorption spectra.
As summarized in Table 1; hereafter, the different content of
gold NPs supported on chitosan are denoted as Chit-Au1, Chit-
Au2, Chit-Au3, and Chit-Au4. The gold content in each solid
chitosan was determined using ICP-OES, indicating the gold
ions reduced quantitatively and successfully anchored onto
the solid chitosan support. Notably, the synthesis of gold NPs
supported on solid chitosan using simple mortar and pestle
was reproducible for several times (See Figure S3: ESI). Figure
1a shows the photographic images of chitosan supported
nanogold powder. Depending on the content of gold and
chitosan or vice versa, the color of the solution changes from
dark to pale red. The color in the aqueous acidic solutions
caused by the light scattering due to surface plasmon
resonance band (SPR) of gold NPs40. UV-Visible spectra of
Figure 1c demonstrate that the wavelength maxima and
intensity of the SPR band are highly sensitive to the content of
gold and chitosan polymers in the samples. As compared to
Chit-Au1, Chit-Au2 exhibit intense SPR band at longer
wavelength (550 nm). Though both samples contain same
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 4 of 11
ARTICLE
Journal Name
1
2
3
4
5
6
7
8
9
can be attributed to the interaction between chitosan and gold few milligram of solid chitosan supported gold NPs in aqueous
View Article Online
NPs49-50. In addition, the peak reduction was very significant in solutions. The mole of adsorbed PNTP on the gold NPs surface
DOI: 10.1039/D0NJ04255B
the case of chit-Au2, which is due to the more loading of gold was calculated from a calibration curve using the extinction
NPs on chitosan support.
coefficient of PNTP (refer ESI)55. It should be mentioned that
PNTP adsorb selectively only on gold NPs surface and not on
chitosan polymer. As shown in Figure 3, the adsorption
isotherm was plotted between the number of moles of
adsorbed PNTP per gram of gold NPs and the equilibrium
concentration of PNTP for four samples to determine the
surface area of supported gold NPs. Interestingly, all four
samples show the straight line in the adsorption isotherm.
Langmuir-isotherm plots were then used to determine the
available surface area of gold NPs on the chitosan support.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(a)
(b)
(c)
(d)
(f)
(e)
(g)
Figure 2. TEM images and corresponding particles size histogram plot (a) &
(e) chit-Au1, (b) & (f) chit-Au2, (c)&(g) chit-Au3, and (d) & (h) chit-Au4.
(h)
The electronic structure of chitosan supported gold NPs
were analyzed by using XPS and XANES. The two peaks are due
to spin-orbit coupling of Au4f at 83.7 and 87.9 eV in the XPS
spectra (Figure S6b; ESI) ensuring the complete reduction of
Au3+ to Au(0) occurred during solid-grinding. The reduction of
white line intensity at 11923 eV compared to Au foil in the
XANES spectra at Au-L3 edge (Figure S7: ESI) is implying the
significant reduction of d-holes51-53 in the chitosan supported
gold NPs confirming the formation gold NPs in chit-Au1. These
results clearly demonstrate that chitosan can be used as
superior support materials for both loading of high density of
gold NPs as well as the preparation of different sized gold
particles using simple solid-grinding.
Figure 3. (a), (c), (e), and (g) are adsorption isotherm of PNTP on Chit–
Au1, Chit–Au2, Chit–Au3, and Chit–Au4, (b), (d), (f), and (h) are
Langmuir isotherm of the adsorption of PNTP on the Chit–Au1, Chit–
Au2, Chit–Au3, and Chit–Au4, respectively.
Though all four samples have shown higher surface area, the
highest surface area ca. 2.8x104 m2
/g was observed only in
chit-Au4. This may be due to high dispersion of large number
of smaller sized gold NPs on the chitosan support. Compared
to chit-Au3, chit-Au1 has showed higher surface area, ca.
To determine the available surface area of gold NPs
supported on solid chitosan, the Langmuir-adsorption
isotherm was used with P-nitro thiophenol (PNTP) as a probe
ligand54-55. Various concentrations of PNTP were mixed with
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Page 5 of 11
New Journal of Chemistry
Journal Name
ARTICLE
1
2
3
4
5.5x103 m2/g, even though chit-Au3 has smaller sized gold NPs. even at higher gold content. This result implies thVaietwwAhrtieclne Ognolinlde
DOI: 10.1039/D0NJ04255B
Since chit-Au3 contains large amount of chitosan polymer than loading exceed more than 0.02 mmol on 0.84 mmol chitosan
chit-Au1, either some of the gold NPs may be buried inside the leads to aggregation of gold NPs, which reduces the total
chitosan polymer or the exposed surface atoms at gold NPs available surface areas and thus decreases the catalytic activity
may be covered by polymers. Both concomitantly affect the of gold NPs (chit-Au2 details in table 1). To study whether
thiol binding at gold NPs surfaces, which in turn reduces the more content of chitosan support have any impact on the
available surface area of gold NPs in chit-Au3. In contrast, the catalytic activity of gold NPs, the chitosan support was
Langmuir-isotherm plots of chit-Au2 have higher slope of 74 increased from 0.28 to 4.2 mmol and the amount of gold was
gmol-1 and the corresponding surface area was found to be kept constant (0.02 mmol Au) during the solid-grinding. As
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
much lower than other three samples.
depicted in Figure 4b, when chitosan polymer increased or
decreased from 0.84 mmol, the catalytic activity of gold NPs
decreases. This could be due to the aggregation of gold NPs
might occurs at lesser amount of chitosan or some of the
active sites at gold NPs may be partially blocked at higher
amount of chitosan polymer. These both concurrently affect
the catalytic activity of gold NPs. From these results, 0.02
mmol Au on 0.84 mmol chitosan (1:42 mole ratio of gold and
chitosan was chosen as an optimum catalysts for
homocoupling reactions. In order to demonstrate that the
solid grinding is facile and promising technique for gram-scale
synthesis of chitosan supported nanogold catalysts, both gold
and chitosan was increased up to five times with keeping 1:42
mole ratio of gold and chitosan. It is noteworthy to mention
that due to high viscous nature of chitosan polymer in aqueous
solutions, it is impossible to synthesize the catalytically active
chitosan stabilized gold NPs in gram scale using solution based
methods (see details in ESI, Table S1). As the amount of gold
and chitosan were increased gradually with maintaining 1:42
mole ratio, the catalytic activity of gold NPs was greatly
increased (Figure 4c). These results strongly demonstrating the
chitosan can be used as excellent support for high loading of
gold NPs. Thus, highly active and selective Au NPs catalysts
supported on chitosan could be achieved in gram-scale rapidly
by using simple mortar-solid grinding, which is not possible in
solution-based method.
Figure 4. The catalyst optimization in homocoupling of phenylboronic acid.
(a) Varying of mole of gold on fixed amount of chitosan support (0.84 mmol
in glucosamine monomer unit), (b) varying chitosan support with fixed gold
content (0.02 mmol Au) and (c) simultaneously increasing both the content
of gold and chitosan.
This result clearly implies that the available surface area of
gold NPs supported on solid chitosan not only strongly
dependent on the size of gold NPs, but also dependent on the
amount of chitosan polymer. Therefore, higher available
surface area of supported gold NPs could be easily synthesized
in gram scale by simple solid-grinding. Solid-grinding with
mortar and pestle using chitosan as a unique support allowed
for rapid preparation of supported catalysts with an improved
loading efficiency and greater uniformity of gold NPs, which
were then employed in the homocoupling of phenylboronic
acid in water at room temperature under air (see ESI for
reaction details). It is worthy to mention that these solid
chitosan supported gold NPs were functioning as
heterogeneous catalysts during the reactions. As shown in
Figure 4a, while the amount of gold loading increases from
0.0025 to 0.1 mmol on fixed amount of chitosan support (0.84
mmol), the time taken for the complete conversion of
phenylboronic acid into biphenyl was reduces sharply
indicating the gold NPs supported on solid chitosan actively
catalyzing the homocoupling reaction. After 0.02 mmol gold,
the reaction time has not reduced sharply and almost constant
Table 2. Homocoupling of various p-substituted phenylboronic acids
catalyzed by solid chitosan supported gold NPsa.
cat., Au NPs (8 atom %)
B(OH)2
R
R
R
+
R
OH
H2O, rt, air
1
2
3
Yield (%)b
Entry
R
Time (h)
2
3
1
2
3
4
5
6
H
Me
OMe
F
Cl
CN
1
2
2
2
3
5
98
99
95
97
97
94
Trace
0
Trace
0
Trace
Trace
aReaction conditions: substrate (0.25 mmol), water (15 mL),
chitosan 0.84 mmol, and Au (0.02 mmol). bIsolated yields
It is interesting to note that solid chitosan supported gold
catalysts possess excellent selectivity toward the formation of
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 6 of 11
ARTICLE
Journal Name
1
2
3
4
biphenyl regardless of the amount of gold and chitosan. As substituted benzyl alcohols into corresponding aldehyde and
View Article Online
DOI: 10.1039/D0NJ04255B
chitosan possesses an excellent matrix to activate the acids (Table 3). For example, the oxidation of benzyl alcohol in
phenylboronic acids into tetra coordinated phenylbornate the presence of the supported gold catalyst gave
ester at the gold surfaces, it completely eliminated the use of corresponding acids in 99 % yield after 90 min. Hydroxyl and
inorganic bases and increases the selectivity to biphenyl methoxy substituted benzyl alcohols were oxidized
formation20,56. Since all the reactions were carried out in water quantitatively into corresponding aldehydes in 25 and 5
at pH of 6.5-7.0, only a trace amount of phenol (> 2-3%) minutes (entry 2 and 3, table 3), respectively. In contrast,
formation was observed, which is inevitable due to the electron withdrawing substituent of p-nitro benzyl alcohol was
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
formation of superoxide species around gold NPs surfaces19,57- almost converted into the corresponding acids in 150 min
58
.
under the same reaction conditions (entry 4, table 3). This
experimental result showed that the strong electron donating
groups present in the benzyl alcohols not only increase the
rate of the oxidation reactions but also exclusively affording to
desired aldehyde products. Further, 1-indanol selectively
oxidized into 1-indanone in 99 % yield after 80 min (entry 5,
table 3).
Table 3. Oxidation of various p-substituted benzyl alcohols
catalyzed by solid chitosan supported gold NPsa
O
O
OH
cat., Au NPs (8 atom %)
H2O, rt, air
OH
H
+
R
R
R
In a typical solid materials supported metal nanoparticles
catalysts, the catalysts recovery and reusability is an important
property from economic and industrial point of view.
Therefore, the reusability of solid chitosan supported nanogold
catalysts was established in both homocoupling of 4-methyl
phenylboronic acid and aerobic oxidation of p-hydroxyl benzyl
alcohols under the optimized reaction conditions as listed in
entry 2 (table 2) and entry 2 (table 3). After completion of each
homocoupling and alcohol oxidation reaction, the solid
catalysts centrifuged, washed with water, dried and
successfully reused for five cycles without notable loss of
activity and selectivity. As shown in Figure S9: ESI, p-methyl
phenylboronic acids was exclusively converted into the
corresponding biphenyl in excellent yield was observed over
the five cycles. On the other hand, the oxidation of p-hydroxyl
benzyl alcohol gave more selectively into the corresponding
aldehydes and the yields over the five cycles were 99, 95, 98,
96 and 94%, respectively. Figure S10: ESI shows the TEM
micrograph of recovered catalysts obtained from the
homocoupling reaction of p-methyl phenylboronic acids after
fifth cycles. As can be seen in from these images, the gold NPs
were well distributed over the chitosan support without any
noticeable aggregations. Therefore, it can be realized that gold
NPs on the chitosan support was preserved after fifth cycles.
The ICP-OES analysis of the corresponding filtrate showed no
gold was leached from the catalyst indicating the gold NPs
were effectively anchored on the chitosan support. Next, to
study the preparation of solid chitosan supported gold NPs
catalysts by physical mixing of gold chloride and NaBH4 with
the chitosan in pestle and mortar exhibits comparable or
better catalytic activity as compared to other hydrophilic
polymer stabilized gold NPs catalysts synthesis. Hence, other
well-known polymers such as PVA and PVP stabilized gold NPs
catalysts were prepared using mortar and pestle (refer ESI)
and their catalytic activity was tested for homocoupling of
phenylboronic acid (entry 1, table 2). It should be mentioned
that the 1:42 ratio of gold and PVA / PVP in monomer was
maintained during solid grinding. As indicated in entries 2 and
5
6
4
Yield (%)b
Entry
R
Time (min)
5
0
6
99
0
Trace
98
1
2
3
4
5
H
OH
OMe
NO2
1-Indanol
90
25
5
150
80
99
97
0
99c
-
aReaction conditions: substrate (0.25 mmol), 300 mol%, K2CO3
(0.75 mmol), water (15 mL), chitosan (0.84 mmol), and Au
(0.02 mmol). bIsolated yields. c1-Indanone
To examine the versatility of this chitosan supported nanogold
catalysts under an optimized conditions (0.02 mmol Au on 0.84
mmol chitosan), homocoupling reactions involving other p-
substituted arylboronic acids was tested. Phenylboronic acid
possessing electron donating groups such as 4-methyl and 4-
methoxy arylboronic acids afforded excellent yields and
selectivity into corresponding biphenyl in 2 hrs (entries 2 and
3, Table 2), even though they have taken longer reaction times
than phenylboronic acids. Phenylboronic acids with electron-
withdrawing 4-flouro, 4-chloro and 4-cyano substituents
(entries 4, 5 and 6, Table 2) gave the corresponding biaryls in
97, 97 and 94% yields and the corresponding phenols in 0, 2
and 6% yields after 2, 3 and 5 hours, respectively. This result
demonstrates that this catalyst works very efficient in terms of
achieving higher activity and selectivity for both electron
donating and withdrawing substituents in the phenylboronic
acid.
Encouraged by these results, we are further interested to
investigate the potential of solid chitosan supported nanogold
catalysts in aerobic oxidation of benzyl alcohols into
corresponding aldehydes and acids. Thus, the catalyst was
tested for the oxidation of various p-substituted benzyl
alcohols in aqueous solutions in the presence of 300 mol%
K2CO3 using molecular oxygen as oxidant. However, solid
chitosan supported nanogold applied as heterogeneous
catalysts, it works very efficient for oxidation of various p-
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Page 7 of 11
New Journal of Chemistry
Journal Name
ARTICLE
1
2
3
4
5
3 in table 4, PVA and PVP-stabilized gold NPs show inferior Au NPs effectively in solid grinding using mortar and pestle
View Article Online
DOI: 10.1039/D0NJ04255B
catalytic activity toward the homocoupling of phenylboronic (Figure S10 and Table S2; ESI).
acid indicating both PVA and PVP are incapable to stabilize the
6
7
Table 4. Catalytic activity and selectivity comparison toward the homocoupling of phenylboronic acids using solid chitosan supported gold
8
catalyst and other reported gold catalysts synthesized from conventional solution based methods.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Entry
Method
Catalysts
Amount of gold
(mmol)
Time
(hr)
Yield (%)
ref
2
3
1
2
3
3
4
5
6
7
8
SG
SG
SG
SB
SB
SB
SB
SB
SB
Chit/ Au
PVA/Au
PVP/Au
0.005a
0.005a
0.005a
0.005a
0.005a
12-36b
6.8c
5
5
-
9
7
98
ND
ND
93
96
<95
99
Trace
This work
See ESI
See ESI
20
20
59-60
61
ND
ND
6
4
Chit/Au
Starch/Au
PNIPAM/Au
PS-co-PMAA/Au
PS-PAMAM/Au
PVP/Au
2-12
trace
8f
-
-
69
0.007d
24
15
99
31
62
20 and 63
0.005a
a, b, c, and d
SG and SB are solid-grinding and solution based, respectively.
are 0.25, 0.17, 0.24, and 0.5 mmol of phenylboronic
acids were used, respectively. f– 105 oC used for coupling reaction.
Indeed, the comparative studies between other hydrophilic pestle. The supported gold NPs works as efficient
polymer stabilized gold NPs using conventional solution based heterogeneous catalysts and possesses outstanding activity
methods reported in the literature and chitosan supported and selectivity in oxidative homocoupling of phenylboronic
gold catalysts obtained from solid-grinding clearly acids and aerobic oxidation alcohols in water as greener
demonstrating the chitosan supported gold NPs works very solvents. The catalytic activity of solid chitosan supported gold
efficient catalysts in homocoupling of phenylboronic acid. For NPs can be easily modulated by changing the mole ratio of
example, though starch can effectively stabilize the gold NPs, chitosan polymer and gold precursors. Further, the catalytic
however, it lost their catalytic activity at the end of the activity comparison studies between the other well known
coupling reaction due to aggregation. When the same reaction hydrophilic polymers stabilized colloidal nanogold catalysts
was carried out using PVP-stabilized gold NPs under quasi- prepared from conventional solution based methods and the
homogeneous conditions in aqueous acidic solution only 17% present supported gold catalysts indicates that solid chitosan
of biphenyl product was obtained after 9 hrs. Despite the supported gold NPs possess superior catalytic activity and
composite of the PNIPAM/Au system possess interesting selectivity. Therefore, rapid preparation of biopolymer of
thermosensitive property, the present catalytic system shows chitosan supported gold NPs in gram-scale by simple solid-
quite high catalytic activity. This comparative study clearly grinding can inspire more studies on the design and
indicates that chitosan possesses excellent matrix for synthesis application of the solid polymer supported metal catalysts.
of highly efficient and versatile supported gold catalysts in
gram-scale using simple mortar and pestle by solid grinding.
Further, the deposited gold on solid metal oxides such as TiO2
and MAO possesses interesting catalytic activities63-64
however their preparation is more complex and laborious
compared to the presents catalysts system. This result further
demonstrates that solid grinding with simple mortar and
pestle could be used as promising tool to achieve highly
efficient heterogeneous metal catalysts.
Conflicts of interest
,
There are no conflicts to declare.
Acknowledgements
AM acknowledges DST-SERB, New Delhi for the award of
financial support vide grant No: YSS/2015/001124. We also thank
UGC-DAE Consortium for Scientific Research (CSR-IC-ISUM-06/CRS-
289/2019-20/1341). Characterization studies acquired from
GNR Instrumental facility, University of Madras, Guindy
Campus is greatly acknowledged. Thanks to Dr. S. N. Jha, for
XANES analysis at Indus-2, RRCAT, India.
Conclusions
In conclusion, a facile and sustainable approach was
developed for gram-scale synthesis of chitosan supported gold
NPs by solid-grinding. Abundant hydroxyl and amine functional
groups present in the chitosan polymer allowed for rapid
preparation of supported catalysts with an improved loading
efficiency and greater uniformity of gold NPs using mortar and
Notes and references
1
T. Ishida, N. Kinoshita, H. Okatsu, T. Akita, T. Takei, M.
Haruta, Influence of the Support and the Size of Gold
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 8 of 11
ARTICLE
Journal Name
1
2
3
4
5
6
7
8
9
Clusters on Catalytic Activity for Glucose Oxidation, Angew.
Metal Nanoparticle Catalysts, Dalt. Trans., 2018, 47, 5889-
View Article Online
Chem. Int. Ed., 2008, 47, 25, 9265-9268.
DOI: 10.1039/D0NJ04255B
5915.
2
L. X. Dien, T. Ishida, A. Taketoshi, Q-D. Truong, H. D. Chinh, T.
Honma, T. Murayama, M. Haruta, Supported gold cluster
catalysts prepared by solid grinding using a non-volatile
organogold complex for low-temperature CO oxidation and
the effect of potassium on old particle size, Appl. Catal. B,
2019, 241, 539−547.
T. Ishida, M. Nagaoka, T. Akita and M. Haruta, Chem.–Eur. J.,
2008, 14, 8456–8460.
L. X. Dien, Q. D. Truong, T. Murayama, H. D. Chinh, A.
Taketoshi, I.Honma, M. Haruta, T. Ishida, Gold Nanoparticles
Supported on Nb2O5 for Low-Temperature CO Oxidation and
as Cathode Materials for Li-ion Batteries, Appl. Catal., A,
2020, 603, 117747.
17 J. Van Rie, and W. Thielemans, Cellulose–gold nanoparticle
hybrid materials, Nanoscale, 2017, 9, 8525-8554.
18 H. Tsunoyama, N. Ichikuni, H. Sakurai and T. Tsukuda, Effect
of Electronic Structures of Au Clusters Stabilized by Poly(N-
Vinyl-2-Pyrrolidone) on Aerobic Oxidation Catalysis, J. Am.
Chem. Soc., 2009, 131, 7086-7093.
19 R. N. Dhital, A. Murugadoss and H. Sakurai, Dual Roles of
Polyhydroxy Matrices in the Homocoupling of Arylboronic
Acids Catalyzed by Gold Nanoclusters under Acidic
Conditions, Chem. Asian J., 2012, 7, 55-59.
20 J. A. Dahl, B. L. S. Maddux, and J. E. Hutchison, Toward
greener nanosynthesis, Chem. Rev., 2007, 107, 6, 2228-2269.
21 T. Tsuzki, Commercial scale production of inorganic
nanoparticles, Int. J. Nanotechnol., 2009, 6, 5-6, 567-578.
22 P. F. M. de Oliveira, R. M. Torresi, F. Emmerling and P. H. C.
Camargo, Challenges and opportunities in the bottom-up
mechanochemical synthesis of noble metal nanoparticles, J.
Mater. Chem. A, 2020, 8, 16114-16141.
23 B. Donoeva and P. E. de Jongh, Colloidal Au catalyst
preparation: selective removal of polyvinylpyrrolidone from
active Au sites, ChemCatChem, 2018, 10, 989-997.
24 H. Li, J. V. John, S. J. Byeon, M. S. Heo, J. H. Sung, K. H. Kim
and I. Kim, Controlled accommodation of metal
nanostructures within the matrices of polymer architectures
through solution-based synthetic strategies, Prog. Polym.
Sci., 2014, 39, 1878-1907.
25 R. Narayanan, M. A. El-Sayed, Effect of Catalysis on the
Stability of Metallic Nanoparticles:ꢀ Suzuki Reaction
Catalyzed by PVP-Palladium Nanoparticles, J. Am. Chem.
Soc., 2003, 125, 27, 8340–8347.
26 S. Haesuwannakij, Y. Yakiyama, and H. Sakurai, Partially
Fluoride-Substituted Hydroxyapatite as a Suitable Support
for the Gold-Catalyzed Homocoupling of Phenylboronic Acid:
An Example of Interface Modification, ACS Catal., 2017, 7, 4,
2998−3003.
27 Y. Mikami, A. Dhakshinamoorthy, M. Alvaro and H. Garcia,
Catalytic Activity of Unsupported Gold Nanoparticles, Catal.
Sci. Technol., 2013, 3, 58-69.
28 L. M. Dias Ribeiro de Sousa Martins, S. A. C. Carabineiro, J.
Wang, B. G. M. Rocha, F. J. Maldonado-Hodar and A. J.
Latourrette de Oliveira Pombeiro, Supported Gold
Nanoparticles as Reusable Catalysts for Oxidation Reactions
of Industrial Significance, ChemCatChem, 2017, 9, 1211-
1221.
29 Li. Q. Wu, A. P. Gadre, H. Yi, M. J. Kastantin, G. W. Rubloff,
W. E. Bentley, G. F. Payne, and R. Ghodssi, Voltage-
dependent assembly of the polysaccharide chitosan onto an
electrode surface, Langmuir, 2002, 18, 8620-8625.
30 E. I. Rabea, M. E. T. Badawy, C. V. Stevens, G. Smagghe, and
W. Steurbaut, Chitosan as antimicrobial agent: applications
and mode of action, Biomacromolecules, 2003, 4, 6, 1457-
1465.
3
4
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
5
6
M. Stratakis and H. Garcia, Catalysis by supported gold
nanoparticles: beyond aerobic oxidative processes, Chem.
Rev., 2012, 112, 4469-4506.
T. Tsukuda, H. Tsunoyama and H. Sakurai, Aerobic Oxidations
Catalyzed by Colloidal Nanogold, Chem. Asian J., 2011, 6,
736-748.
Y. Zhang, X. Cui, F. Shi, and Y. Deng, Nano-gold catalysis in
fine chemical synthesis, Chem. Rev., 2012, 112, 2467-2505.
J. Garcia-Calvo, V. Garcia-Calvo, S. Vallejos, F. C. Garcia, M.
Avella, J. M. Garcia, and T. Torroba, Surface coating by gold
nanoparticles on functional polymers: on-demand portable
catalysts for Suzuki reactions, ACS Appl. Mater. Interfaces,
2016, 8, 24999-25004.
H. Tsunoyama, H. Sakurai, N. Ichikuni, Y. Negishi and T.
Tsukuda, Colloidal Gold Nanoparticles as Catalyst for Carbon-
Carbon Bond Formation: Application to Aerobic
Homocoupling of Phenylboronic Acid in Water Langmuir,
2004, 20, 11293-11296.
7
8
9
10 W. Jang, H. Byun, and J. H. Kim, Encapsulated gold
nanoparticles as a reactive quasi-homogeneous catalyst in
base-free aerobic homocoupling reactions, ChemCatChem,
2020, 12, 3, 705-709.
11 M. Haruta, Gold rush, Nature, 2005, 437, 7062, 1098-1099.
12 E. Oh, K. Susumu, A. J. Makinen, J. R. Deschamps, A. L.
Huston, and I. L. Medintz, Colloidal stability of gold
nanoparticles coated with multithiol-poly (ethylene glycol)
ligands: importance of structural constraints of the sulfur
anchoring groups, J. Phy. Chem. C, 2013, 117, 37, 18947-
18956.
13 K. M. Koczkur, S. Mourdikoudis, L. Polavarapu and S. E.
Skrabalak, Polyvinylpyrrolidone (PVP) in nanoparticle
synthesis, Dalt. Trans., 2015, 44, 17883-17905.
14 A. Villa, D. Wang, D. S. Su, and L. Prati, Gold sols as catalysts
for glycerol oxidation: The role of stabilizer, ChemCatChem,
2009, 1, 4, 510-514.
15 K. Wongmanee, S. Khuanamkam, and S. Chairam, Gold
nanoparticles stabilized by starch polymer and their use as
catalyst in homocoupling of phenylboronic acid, Journal of
King Saud University - Science, 2017, 29, 5, 547-552.
16 L. M. Rossi, J. L. Fiorio, M. A. S. Garcia and C. P. Ferraz, The
Role and Fate of Capping Ligands in Colloidally Prepared
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Page 9 of 11
New Journal of Chemistry
Journal Name
ARTICLE
1
2
3
4
5
6
7
31 A. Murugadoss, and A. Chattopadhyay, A ‘green’chitosan– 46 J. Han, J. Cho, J. C. Kim, and R. Ryoo, Confinement of
View Article Online
DOI: 10.1039/D0NJ04255B
silver nanoparticle composite as a heterogeneous as well as
micro-heterogeneous catalyst, Nanotechnology, 2018, 19, 1,
015603.
supported metal catalysts at high loading in the mesopore
network of hierarchical zeolites, with access via the
microporous windows, ACS Catal., 2018, 8, 2, 876-879.
32 M. Lee, B. Y. Chen, and W. Den, Chitosan as a Natural 47 D. Kunwar, S. Zhou, A. DeLaRiva, E. J. Peterson, H. Xiong, X. I.
Polymer for Heterogeneous Catalysts Support: A Short
Review on Its Applications, Appl. Sci., 2015, 5, 4, 1272-1283.
33 A. Murugadoss and H. Sakurai, Chitosan-Stabilized Gold,
Gold-Palladium, and Gold-Platinum Nanoclusters as Efficient
Catalysts for Aerobic Oxidation of Alcohols, J. Mol. Catal. A
Chem., 2011, 341, 1-6.
34 W. Wang, and H. Cui, Chitosan-luminol reduced gold
nanoflowers: from one-pot synthesis to morphology-
dependent SPR and chemiluminescence sensing, J. Phys.
Chem. C, 2008, 112, 10759-10766.
Pereira-Hernandez, S. C. Purdy, R. ter Veen, H. H.
Brongersma, J. T. Miller, and H. Hashiguchi, Stabilizing high
metal loadings of thermally stable platinum single atoms on
an industrial catalyst support, ACS Catal., 2019, 9, 5, 3978-
3990.
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
48 X. Y. Hao, Y. Q. Zhang, J. W. Wang, W. Zhou, C. Zhang, and S.
Liu, A novel approach to prepare MCM-41 supported CuO
catalyst with high metal loading and dispersion, Microporous
and Mesoporous Materials, 2006, 88, 1-3, 38-47.
49 A. Regiel-Futyra, M. Kus-Liskiewicz, V. Sebastian, S. Irusta, M.
Arruebo, G. Stochel, and A. Kyziol, Development of
noncytotoxic chitosan–gold nanocomposites as efficient
antibacterial materials, ACS Appl. Mater. Interfaces, 2015, 7,
2, 1087−1099.
35 A. Murugadoss, N. Kai and H. Sakurai, Synthesis of Bimetallic
Gold-Silver Alloy Nanoclusters by Simple Mortar Grinding,
Nanoscale, 2012, 4, 1280-1282.
36 D. Debnath, S. H. Kim, K. E. Geckeler, The first solid-phase
route to fabricate and size-tune gold nanoparticles at room 50 Q. Li, F. Lu, G. Zhou, K. Yu, B. Lu, Y. Xiao, F. Dai, D. Wu, and G.
temperature, J. Mater.Chem., 2009, 19, 8810-8816.
37 P. F. M. de Oliveira, J. Quiroz, D. C. de Oliveira and P. H. C.
Camargo, A mechano-colloidal approach for the controlled
synthesis of metal nanoparticles, Chem. Commun., 2019, 55,
14267-14270.
38 H. Schreyer, R. Eckert, S. Immohr, J. de Bellis, M. Felderhoff,
and F. Schuth, . A general process for the direct dry synthesis
of supported metal catalysts, Angew. Chem. Int. Ed., 2019,
58, 11262-11265.
39 B. Gole, U. Sanyal and P. Sarathi Mukherjee, A smart
approach to achieve an exceptionally high loading of metal
nanoparticles supported by functionalized extended
frameworks for efficient catalysis, Chem. Commun., 2015, 51,
4872-4875.
40 L. M. Liz-Marzan, M. Giersig, and P. Mulvaney, Synthesis of
Nanosized Gold−Silica Core−Shell Particles, Langmuir, 1996,
12, 18, 4329-4335.
Lan, Silver inlaid with gold nanoparticle/chitosan wound
dressing enhances antibacterial activity and porosity, and
promotes wound healing, Biomacromolecules, 2017, 18,
3766-3775.
51 A. Murugadoss, K. Okumura and H. Sakurai, Bimetallic AuPd
Nanocluster Catalysts with Controlled Atomic Gold
Distribution for Oxidative Dehydrogenation of Tetralin, J.
Phys. Chem. C, 2012, 116, 26776-26783.
52 E. K. Gibson, A. M. Beale, C. R. A. Catlow, A. Chutia, D.
Gianolio, A. Gould, A. Kroner, K. M. Mohammed, M. Perdjon,
S. M. Rogers, and P. P. Wells, Restructuring of AuPd
nanoparticles studied by a combined XAFS/DRIFTS approach,
Chem. Mater., 2015, 27, 3714-3720.
53 P. Dash, T. Bond, C. Fowler, W. Hou, N. Coombs, and R. W.
Scott, Rational design of supported PdAu nanoparticle
catalysts from structured nanoparticle precursors, J. Phys.
Chem. C, 2009, 113, 12719-12730.
41 X. B. Qian, W. Peng, Y. B. Shao, and J. H. Huang, Synthesis 54 M. A. Mahmoud, B. Garlyyev, and M. A. El-Sayed,
and visible light-driven photocatalytic hydrogen production,
Int. J. Hydrog. Energy, 2018, 43, 4, 2160-2170.
42 D. Su, S. Dou, and G. Wang, Gold nanocrystals with variable
index facets as highly effective cathode catalysts for lithium–
oxygen batteries, NPG Asia Mater., 2015, 7, 1, e155.
43 R. Torres-Mendieta, D. Ventura-Espinosa, S. Sabater, J.
Lancis, G. Minguez-Vega, and J. A. Mata, situ decoration of
graphene sheets with gold nanoparticles synthetized by
pulsed laser ablation in liquids, Sci. Rep., 2016, 6, 30478.
44 A. Q. Zhang, L. J. Cai, L. Sui, D. J. Qian, and M. Chen, Reducing
properties of polymers in the synthesis of noble metal
nanoparticles, Polym. Rev., 2013, 53, 2, 240-276.
Determining the mechanism of solution metallic
nanocatalysis with solid and hollow nanoparticles:
homogeneous or heterogeneous, J. Phys. Chem. C, 2013,
117, 21886-21893.
55 K. Paul Reddy, K. Jaiswal, B. Satpati, C. Selvaraju and A.
Murugadoss, High yield synthesis of branched gold
nanoparticles as excellent catalysts for the reduction of
nitroarenes, New J. Chem., 2017, 41, 11250-11257.
56 R. N. Dhital, and H. Sakurai, Oxidative Coupling of
Organoboron Compounds, Asian J. Org. Chem, 2014, 3, 6,
668.
57 S. Karanjit, M. Ehara, and H. Sakurai, Mechanism of the
aerobic homocoupling of phenylboronic acid on Au20−: A
DFT study, Chem. Asian J., 2015, 10, 2397-2403.
45 X. Xia, Z. Qiang, G. Bass, M. L. Becker and B. D. Vogt,
Morphological control of hydrothermally synthesized cobalt
oxide particles using poly (vinyl pyrrolidone), Colloid and 58 S. Carrettin, J. Guzman, and A. Corma, Supported gold
Polymer Science, 2019, 297, 59-67.
catalyzes the homocoupling of phenylboronic acid with high
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 9
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 10 of 11
ARTICLE
conversion and selectivity, Angew. Chem. Int. Ed., 2005, 44,
Journal Name
1
2
3
4
5
6
View Article Online
DOI: 10.1039/D0NJ04255B
2242-2245.
59 P. N. Eyimegwu, J. A. Lartey, and J. H. Kim, Gold-
Nanoparticle-Embedded
Poly
(N-isopropylacrylamide)
Microparticles for Selective Quasi-Homogeneous Catalytic
Homocoupling Reactions, ACS Appl. Nano Mater., 2019, 2, 9,
6057-6066.
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
60 W. Jang, H. Byun, and J. H. Kim, Encapsulated gold
nanoparticles as a reactive quasi-homogeneous catalyst in
base-free aerobic homocoupling reactions, ChemCatChem,
2020, 12, 3, 705-709.
61 X. Zhang, H. Zhao, and J. Wang, Recyclable Au (I) Catalyst for
Selective Homocoupling of Arylboronic Acids: Significant
Enhancement of Nano-Surface Binding for Stability and
Catalytic Activity, J. Nanosci. Nanotechnol., 2010, 10, 5153-
5160.
62 J. Zheng, S. Lin, X. Zhu, B. Jiang, Z. Yang and Z. Pan,
Reductant-directed formation of PS–PAMAM-supported gold
nanoparticles for use as highly active and recyclable catalysts
for the aerobic oxidation of alcohols and the homocoupling
of phenylboronic acids, Chem. Commun., 2012, 48, 6235–
6237.
63 Vinsen, Y. Uetake, and H. Sakurai, Selective Oxidative
Hydroxylation of Arylboronic Acids by Colloidal Nanogold
Catalyzed in Situ Generation of H2O2 from Alcohols Under
Aerobic Conditions, Bull. Chem. Soc. Jpn., 2020, 93, 299-301.
64 L. Wang, W. Zhang, D. S. Su, X. Meng. F.-S. Xiao, Supported
Au nanoparticles as efficient catalysts for aerobic
homocoupling of phenylboronic acid, Chem.
2012,48, 5476-5478.
Commun.,
65 W. Jang, J. Yun, L. Ludwig, S. G. Jang, J. Y. Bae, H. Byun, J.-H.
Kim, Comparative Catalytic Properties of Supported and
Encapsulated Gold Nanoparticles in Homocoupling
Reactions, Front. Chem. 2020, 8, 834-842.
10 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 11 of 11
New Journal of Chemistry
View Article Online
DOI: 10.1039/D0NJ04255B
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60