A facile synthesis strategy to couple porous nanocubes of CeO2 with Ag nanoparticles: An excellent catalyst with enhanced reactivity for the 'click reaction' and carboxylation of terminal alkynes

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S. Ghosh, B. Satpati, S. Deka, S. Islam and T. Bala, New J. Chem., 2018, DOI: 10.1039/C8NJ00665B.

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ISSN 1144-0546

PAPER

Jason B. Benedict et al.

The role of atropisomers on the photo-reactivity and fatigue of

diarylethene-based metal–organic frameworks

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A facile synthesis strategy to couple porous nanocube of CeO₂

with Ag nanoparticles: An excellent catalyst with enhanced

reactivity for ‘click reaction’ and carboxylation of terminal alkynes

Received 00th January 20xx,

Accepted 00th January 20xx

Subhasis Das,^aParamita Mondal,^bSwarbhanu Ghosh,^bBiswarup Satpati,^cSasanka Deka,^dSk.

DOI: 10.1039/x0xx00000x

Manirul Islam*^band Tanushree Bala*^a

www.rsc.org/

Abstract: Oleic acid and oleylamine capped 3-D porous CeO₂nanocubes were synthesized by hot injection method. The

surface of the nanocube was modified with 2, 4-dimethylphenol (DMP). Reducing and capping abilities of DMP to form Ag

nanoparticles were explored to form these noble metal nanoparticles over porous CeO₂nanocube support at room

temperature. Surface modification and formation of Ag nanoparticles over CeO₂support were thoroughly characterized

with FTIR, UV-Vis spectroscopy, XRD, XPS, TEM, HRTEM, STEM, EDX and chemical mapping. This CeO₂-Ag nanocomposite

was found to have enhanced catalytic activities in click reaction as compared to unsupported Ag nanoparticles and porous

CeO₂nanocube. It was also found to have optimized catalytic activity in the carboxylation of terminal alkyne when Cs₂CO₃

0

was used as the base in DMF solvent at 80 C. The reaction could yield the desired product as high as 98% under several

experimental conditions via a green pathway. Recycling data showed that the catalyst could be reused five times without

considerable loss of its activity and without any deterioration of physical conditions as observed by various

characterizations like TEM, EDX, XRD and XPS.

has evolved as one of the very promising routes owing to its ability

to catalyze different types of reactions, easy accessibility and cost.

CeO₂is the most abundant rare earth metal oxide. Defects in their

1. Introduction:

With the advancement of technology, various types of metal oxide

nanoparticles have dragged the attention of scientific research

community owing to their diverse applications. Among the various

applications, catalysis can be considered to be in focus due to its

importance in industries. In this respect, CeO₂mediated catalysis

crystal structure due to oxygen vacancies determine the properties

which in turn dictate the applications in many cases. Moreover,

easy reversible conversion between Ce⁴⁺/Ce³⁺redox couple by

releasing (deoxygenation) / accepting (oxygenation) oxygen, which

is formally named as oxygen storage capacity (OSC) of ceria, makes

it precious for various catalytic reactions.^1-7Thus there is a healthy

demand for CeO₂which is reported to be synthesized following

number of experimental routes, e.g. co-precipitation process,⁸

hydrothermal or solvothermal techniques,⁹microemulsion based

synthesis,¹⁰sol-gel¹¹and solution combustion synthesis (SCS)

procedures¹²etc. CeO₂nanoparticles are already reported to have

successful use in the fields of colorimetric bioassays,¹³gas

sensors,¹⁴adsorbents,¹⁵low temperature water gas shift reaction,¹⁶

oxygen permeation membrane systems,¹⁷fuel cells,^18,19solar cells,²⁰

luminescence,²¹remediation of environmental pollutants via

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photocatalysis and several catalytic reactions.²²This wide range of catalysts can be developed for the synthesis of 1, 2, 3-triazole,

applications of nanosized CeO₂is found to depend on the shape and besides the reports available in the literature.

size of the particles. This has driven the contemporary researchers

CeO₂-Ag nanocomposite is also found to exhibit good catalytic

towards the synthesis of CeO₂particles with various shapes and activity in the carboxylation of terminal alkyne when Cs₂CO₃is used

0

dimensions, such as nanorods,²³nanowires,²⁴nanotubes,²⁵as a base in DMF solvent at 80 C. Alkynyl carboxylic acids are one

nanopolyhedrons,²⁶three-dimensional flower-like structures²⁷and of the very important classes of compounds due to its wide

hollow structures²⁸etc. Enhanced activity of CeO₂nanoparticles can applications in academic and pharmaceutical laboratories. It is also

also be achieved by doping different rare earth metals (like Gd, rigorously used as the starting materials for the synthesis of other

Zr)^29,30due to extraordinary synergetic effect between CeO₂and organic compounds. Carboxylation of terminal alkyne with CO₂as

metal. This synergetic phenomenon is known as strong metal- C1 building blocks has gained considerable momentum due to its

support (ceria) interaction effect (SMSI). Apart from rare earth abundance, nontoxicity and cost effectiveness. Chemically inert CO₂

metals, noble metal/CeO₂-supported catalyst is also well known for fixation reaction requires activation of CO₂before using it in

SMSI.^31,32Though several synthetic routes are available for the carboxylation reactions. The choice of catalysts is quite huge in

synthesis of pure CeO₂, only a few reports are available till date for number as per the current literature e.g. transition metals, amines,

formation of noble metal-supported over CeO₂.^33-35Further, most of N-heterocyclic carbenes^43,44and frustrated Lewis pair,⁴⁵noble

these reports require high temperature, hazardous materials or metals combined with various types of matrices,^46-48alkali metal

specialized technique like laser ablation,³⁶which makes these halides⁴⁹etc. We report such reactions with the very high yield of

syntheses difficult to practice in industries or by others.

the desired product (as high as 98%) under various combinations of

In this report, Ag nanoparticles are synthesized over 3-D experimental parameters with CeO₂-Ag nanocomposites which

porous CeO₂nanocubes whose surface is deliberately modified with seems to be very promising and quite different from the reports

2, 4-dimethylphenol (DMP), a known reducing agent of Ag⁺ion to available till date.

metallic Ag.³⁷Successful surface modification with DMP plays the

Recycling data for both types of reactions (Click reaction and

key role of dragging Ag⁺ions from aqueous AgNO₃solution to carboxylation reaction) were also encouraging to show that the

organic phase containing CeO₂nanocubes and then helps to reduce catalyst could be reused five times without considerable loss of its

them to form Ag nanoparticles site selectively on the surface of activity and without any deterioration of physical conditions as

CeO₂nanocubes at room temperature.

proved from various characterizations like TEM, EDX, XRD and XPS.

This CeO₂-Ag nanocomposite is found to have better catalytic

activity in click reaction as compared to unsupported Ag

nanoparticles and porous CeO₂nanocubes. Actually, 1,4-

disubstituted 1,2,3-triazoles are an important class of heterocyclic

compounds which are found to have the wide range of industrial

applications such as corrosion inhibitors, agrochemicals, optical

brighteners, photographic materials³⁸as well as in the field of

biology.³⁹Azide-alkyne [3+2] cycloaddition (AAC) reaction to form

1,2,3-triazole is typically called as “click reaction” which is mainly

catalysed by Cu(I) and is believed to proceed via Cu(I)-acetylide

intermediate produced from Cu(I) and terminal alkyne.⁴⁰High yield,

increase in reactivity even at low concentration and regioselectivity

are the main advantages of catalysed AAC reaction over thermally

induced reaction. Recently Cu(I)-modified zeolites⁴¹and Cu-Fe

bimetallic nanoparticles⁴²were also set up as the catalyst for this

kind of reaction. Thus it is always appreciated if a new class of

2. Experimental section:

Chemicals used:

Selenium powder (Se, 99.99%), sulphur powder (S, 99.99%) and

trioctylphosphine (TOP, 99%) were purchased from Strem

chemicals, USA. Cadmium oxide (CdO, 99.5%), oleyl amine (OLAM

70%), AgNO₃, 1-octadecene (ODE, 90%), oleic acid (OLAC, 90%), 2,

4-dimethylphenol (DMP) and trioctylphosphine oxide (TOPO, 99%)

were purchased from Sigma Aldrich, USA. n-hexylphosphonic acid

(HPA, >97%) and n-Octadecylphosphonic acid (ODPA, >97%) were

purchased from Plasma Chem, Germany. Anhydrous methanol,

toluene and other solvents as well as bases were purchased from

Thomas baker, India. All the chemicals were used as received

without any further purification.

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Synthesis of porous ceria nanocube:

water and poured drop-wise to the solution. After mixing it, NaN₃

3-Dimensionally self-assembled porous CeO₂nanocubes were (1.2 mmol) was added into the solution and kept under magnetic

prepared initially following a reported method.⁵In the synthesis stirring for 10 min. Then alkyne (1.2 mmol) and CeO₂-Ag

procedure, 1 mmol of Ce(NO₃)₃·6H₂O (0.434 g), 2 ml of oleylamine nanocomposites (20 mg) were added in the reaction mixture with

(OLAM), 2 ml of oleic acid (OA), 4 ml of octadecene, and 2.5 mmol nonstop stirring for 3 h at room temperature. Then, the CeO₂-Ag

of 1,12-dodecanediol (DDOL) (OA/OLAM/DDOL ratio = 1:1:2.5) were nanocomposites was separated by filtration and cleaned with H₂O,

added in a three-necked round-bottom flask (50 ml). The flask was EtOH and acetone and extraction of other parts of the reaction

heated to 100 °C under vigorous magnetic stirring. The reaction mixture were performed with ethyl acetate. The aqueous part

mixture was kept at this condition for 30 min under vacuum to present in the mixture was separated by Na₂SO₄and the reaction

remove water and oxygen. Then, the solution was heated to 300 °C mixture was added to a small amount of EtOH. After that, the

at a heating rate of approximately 15 °C min⁻¹under nitrogen separation of pure product was performed by crystallization to

atmosphere and kept at this temperature for another 60 min. As obtain the resultant 1,4-disubstituted 1,2,3-triazoles.

soon as the reaction was complete, the heating mantle was

removed and the reaction mixture was cooled to room temperature General procedure of carboxylation reaction:

naturally. The product was precipitated by adding acetone and A 50 ml high-pressure reactor was charged with DMF (5.0 ml), 1.0

purified by repeated centrifugation.

mmol of terminal alkynes, CeO₂-Ag nanocomposites (30 mg), and

Cs₂CO₃(1.5 mmol). After that CO₂(1 atm) was introduced into the

reaction mixture under stirring at 80 ⁰C for 14 h. After completion

Synthesis of CeO₂-Ag nanocomposite:

For this purpose, the surface of the as-synthesized CeO₂nanocube of the reaction, the reaction mixture was cooled to room

was modified first with 2, 4-dimethyl phenol (DMP). Typically, 10 ml temperature and transferred to the 2(N) potassium carbonate

of 10^-1(M) DMP in toluene was added to 15 ml of porous ceria solution (5 ml) under stirring for 30 min. The mixture was washed

nanocube solution and was stirred overnight. The solution then was with CH₂Cl₂and the aqueous layer was acidified with concentrated

centrifuged to get the solid after decanting off the colorless HCl to pH=1 at low temperature, then extracted with ethyl acetate.

supernatant. The precipitate was re-dispersed in toluene The combined organic layers were washed with saturated NaCl

maintaining a concentration of 0.12 mg/ml. 10 ml of this solution solution, dried over Na₂SO₄and filtered. The solvent was removed

was stirred with 10 ml aqueous solution of 10^-3(M) AgNO₃in in vacuum to afford the isolated acid product. The products were

presence of 5×10^-5(M) KOH solution, expecting a complete phase analyzed by Varian 3400 gas chromatograph (GC data) by their

transfer for all Ag⁺ions. But it was found only 80% of the whole retention times in comparison with the authentic samples.

amount got phase transferred (estimated by measuring the

concentration of the residual AgNO₃after phase transfer, the data

3. Characterisation:

not shown in the paper). The top layer i.e. the organic phase of the

biphasic mixture was separated using separating funnel where the

Fourier Transform Infrared (FTIR) Spectroscopy measurements:

surface bound DMP molecules acted as reducing agent to deposit

FTIR spectra were recorded from the pellet of the samples prepared

Ag nanoparticles on CeO₂. Further calculation showed 0.74 gm of Ag

with dry KBr at every step of the reaction on a Perkin Elmer

was deposited over 1 gm of CeO₂.

Spectrum-One Spectrometer operated in the diffuse reflectance

mode at a resolution of 4 cm^-1. The spectra of pristine porous ceria

General procedure for the synthesis of 1,4-disubstituted 1,2,3-

nanocube were also recorded for comparison.

triazoles:

In a 25 ml round bottom flask aromatic amine (1 mmol) was poured

UV-Vis spectroscopy:

0

and kept in an ice bath of the temperature of 0–5 C. A solution of

The spectra were measured from porous ceria nanocubes and

conc. H₂O-HCl in 1:1 ratio (V/V) was poured slowly and stirred for 5

CeO₂-Ag nanocomposite in toluene using

a Jasco UV-Vis

min. Then sodium nitrite (1 mmol) was taken in 1 ml of chilled

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spectrophotometer (V570 UV-VIS-NIR) operated at a resolution of 2

nm.

4. Results and discussion:

CeO₂nanoparticles synthesized by hot injection technique were

already well characterized. It was established that each nanocube

could be considered to be loose assembly of several small CeO₂

nanocrystals, which gave rise to porous nature to the cubes.^{5, 50}

Successful reproduction of this structure was evidenced by TEM

images, Supporting Information SI-1. The size of the cube was

estimated to be 44-46 nm. The smaller building units of these cubes

were the CeO₂nanocrystals of irregular size and shape which could

be seen clearly at the higher resolution of TEM, Supporting

Information SI-1. The composition of the material was established

from EDX analysis (Supporting Information SI-1) which had the

signatures of Ce, O, C and Cu. C and O signals came from the

organic capping ligands whereas Cu signal was from the TEM grid.

The absence of any other elements confirmed the purity of the

material.

X-ray diffraction (XRD) measurements:

XRD measurements of porous CeO₂nanocubes and CeO₂-Ag

nanocomposite were recorded from the dry samples using Philips

PW 3071 diffractometer operating at 40 kV and at a current of 30

mA with Cu K_αradiation.

X-ray photoelectron spectroscopy (XPS):

XPS measurement was made using a custom-built ambient pressure

XPS system from Physical Electronics (Model Name – Phi 5000

VersaProbe II) and equipped with unique monochromator using Al

K_αanode (1486.6 eV). The spectra were recorded at the pass energy

of 50 eV.

Transmission Electron Microscopy (TEM):

Transmission electron microscopy (TEM) performed using an FEI,

Tecnai G²F30, S-Twin microscope operating at 300 kV. The

microscope was also equipped with a high-angle annular dark field

(HAADF) microscopy in scanning mode. The compositional analysis

was performed using energy dispersive X-ray (EDX, EDAX Inc.) in the

same microscope. Samples of both porous CeO₂nanocube and

CeO₂-Ag nanocomposites were prepared by placing one drop of the

dilute solution on carbon-coated copper grids and were dried

thoroughly in the air.

The growth of Ag nanoseeds from Ag⁺ions on CeO₂nanocubes

could be initiated site selectively, only if, the reducing agent was

present on the surface and/or inside the porous CeO₂nanocubes.

Here, CeO₂nanocubes were capped by oleic acid and oleylamine

and these capping ligands were unable to serve this purpose. Thus

surface modification was carried out judicially with DMP molecules

since phenolic OH group was reported to initiate reduction of Ag⁺to

Ag nanoparticles.³⁷Surface modification step did not have any

detrimental effect on the shape or size of the porous CeO₂

nanocubes as observed in TEM images of CeO₂nanocubes modified

with DMP, Supporting Information SI-2.

Nuclear Magnetic Spectroscopy (NMR):

NMR spectra were monitored on

a Bruker AMX-400 NMR

The success of the surface modification was established from

FTIR analyses, Fig. 1. To comprehend the change due to surface

capping by DMP, FTIR spectra of as- synthesized CeO₂(curve 1),

DMP modified CeO₂(curve 2) and after the addition of AgNO₃to

this DMP modified CeO₂(curve 3) were compared thoroughly. The

as synthesized CeO₂nanocubes were capped with oleic acid and

oleyl amine. Several characteristic bands corresponding to both

these capping agents were identified in its FTIR spectra, curve 1, Fig.

1. Two sharp peaks at 2857 cm^-1and 2924 cm^-1appeared due to

CH₂symmetric and asymmetric stretching vibrations of oleic acid

whereas a small shoulder peak at 3007 cm^-1was the =C-H

(methylene H) stretching frequency of oleic acid. A broad peak in

the range of 3434 cm^-1was due to N-H stretching vibration of the

spectrophotometer (400 MHz for ¹H NMR) using tetramethylsilane

as internal standard.

Gas Chromatography (GC):

The gas chromatography (GC) of the samples were recorded by

using a Varian 3400 gas chromatograph equipped with a 30 m CP-

SIL8CB capillary column and a ﬂame ionization detector. The

products for carboxylation reactions were quantified by Varian

3400 gas chromatograph (GC data) by comparing with the authentic

samples.

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amine group of oleylamine. The peaks below 1500 cm^-1mostly merged with the N-H stretching in this case. Thus a broad band was

appeared due to various modes of combinations of C-C stretching, observed centered at 3554 cm^-1. These observations concluded the

C-O stretching, CH₂deformation and so on. The peak for carboxylic successful surface modification of CeO₂by DMP. Curve 3 retained

acid group of pure oleic acid was reported at 1709 cm^-1and –NH₂almost same features as that of curve 2 with minute damping for

scisssoring mode at 1593 cm^-1for pure oleylamine. C-O symmetric the phenolic –OH stretching at 3554 cm^-1and a bifurfacted band at

stretching of –COO^-group of oleic acid was found at 1710 cm^-11105 and 1155 cm^-1. This pointed out towards the interaction of

whereas the peak at 1527 cm^-1could be the shifted –NH₂scisssoring phenolic-OH group with new species, here presumably Ag⁺.^57-59It

mode of oleylamine. Literature showed an association between established that DMP molecules being on the surface of CeO₂phase

oleic acid and oleylamine could not be overlooked when both are transferred Ag⁺from precursor solution and subsequently reduced

present together and in such cases peaks were reported to appear it to Ag⁰. Such interaction with Ag⁺and phenolic –OH group was

between 1400-1600 cm^-1which could be assigned to C-O symmetric also reported by other groups.^{37, 60}

and asymmetric stretching of –COO^-group. Thus, in this study, the

band at 1434 cm^-1could be identified as carboxylate asymmetric

stretching.^{51, 52}

Fig. 2 (A) UV-Vis and (B) XRD plots of CeO₂(curve 1) and CeO₂-Ag

nanocomposite (curve 2).

The successful reduction of Ag⁺to form Ag nanoparticles was

primarily confirmed from UV-Vis spectra and XRD, Fig. 2. CeO₂

nanocube (curve 1, Fig. 2A) showed absorption peak in the UV

Fig. 1 FTIR spectra of oleic acid and oleylamine capped CeO₂(curve

1), DMP-modified CeO₂(curve 2) and Ag nanoparticles supported

over CeO₂(curve 3) obtained from the pellet prepared with dry KBr.

transition from O^2-(2p) to Ce⁴⁺(4f).⁶¹The direct band gap of CeO₂

region centered at 312 nm which appeared due to the charge

nanocube was measured 3.22 eV from the absorption spectra

After modifying the surface of CeO₂with DMP, a distinct

which was the characteristic band gap of the semiconductors. In

change was observed in curve 2 as compared to curve 1. The new

peaks were identified at 730, 880, 1105 and 1230 cm^-1which could

comparison to the pristine CeO₂nanocube, there appeared a broad

absorption peak from 320 nm to 550 nm with the maximum

be assigned to out of plane C=C of the benzene ring, out of plane C-

absorption at 420 nm when Ag⁺was added to the surface modified

H, deformation vibration of O-H group and Ph-O stretching

respectively due to dimethyl phenol.^53-56The O-H stretching was

CeO₂nanocube (curve 2, Fig. 2A). This absorption peak at 420 nm

expected in the region around 3400 cm^-1which was probably

was already well-known as the characteristic peak of Ag

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nanoparticles due to surface plasmon resonance (SPR). The 881.9 eV and 900.5 eV corresponded to d_5/2and d_3/2components

formation of Ag nanoparticles could be explained due to the respectively for Ce⁴⁺oxidation state. Separation between these two

presence of DMP (the reducing agent of Ag⁺ions) on the surface of components was 18.4 eV. Other peaks could be assigned as the

CeO₂nanocube.

satellite peaks of CeO₂denoted by ‘S’ in Fig. 3A. O 1s curve (Fig. 3B)

XRD was performed for both the samples i.e. CeO₂nanocube was fitted with a major component at 531.9 eV and a minor

(curve 1, Fig. 2B) as well as CeO₂-Ag nanocomposites (curve 2, Fig. component at 529.08 eV. The major component of O 1s came from

2B) to support the formation and to confirm the crystalline nature. CeO₂nanocube while the minor component had probably appeared

XRD profile of pristine CeO₂could be indexed with fcc structure of from DMP and other capping agents. Presence of oleylamine even

bulk CeO₂and the peaks were marked for various (hkl) planes after the formation of CeO₂-Ag nanocomposites was confirmed

according to JCPDS card #34-0394. Size of the CeO₂nanocube was from the N 1s curve (Fig. 3C), which was fitted with single Gaussian

measured 39.04 nm from the XRD peak of (200) planes using and had the peak at 401.01 eV. Ag 3d curve (Fig. 3D) had been

Scherrer formulae. The size matched very closely to the average fitted with two components. The peaks at 367.5 eV and 373.5 eV

size of the nanocube as obtained from TEM images. After the with a spin-orbit coupling factor of 6 eV corresponded to d_5/2and

formation of CeO₂-Ag nanocomposites, there appeared a sharp d_3/2of metallic Ag. A set of minor components at 368.6 eV and

peak at 2θ = 39.1⁰which was the fcc (111) plane of Ag (curve 2, Fig. 374.7 eV BE could be allocated to d_5/2and d_3/2components of Ag⁺

2B). Size of the Ag nanoparticles was measured 6.01 nm using respectively⁶²which might reflect some unreduced Ag⁺ions and/or

Scherrer formulae for the (111) peak at 2θ = 39.1⁰. Other two small Ag bound to DMP where interaction with phenolic oxygen might

peaks of Ag at 44.8⁰and 64.8⁰were corresponded to presence (200) shift the peak to higher BE.^{63, 64}

and (220) planes of fcc Ag respectively. The peaks for CeO₂

The success of the synthesis should vastly depend on the

remained undisturbed in curve 2. All the observations suggested proper surface modification by DMP. Ag⁺was expected to get

the formation of small Ag nanoparticles along with CeO₂nanocube reduced site selectively by surface bound DMP only to generate

without any clue about the real position of Ag nanoparticles.

CeO₂-Ag nanocomposites. The site selective growth of Ag

nanoparticles could only be proved by TEM analysis in combination

with EDX, Fig. 4. Fig. 4A-C represented the CeO₂-Ag nanocomposites

at different magnifications. All the micrographs clearly showed

formation of Ag nanoparticles on the surface of CeO₂nanocubes as

darker dots. The porous cubical nature was not disturbed due to

the formation of Ag nanoparticles. Size of the Ag nanoparticles was

found to vary from 3.26 nm to 5.95 nm which was found to be in

good agreement with the XRD analysis. HRTEM analysis (Fig. 4D)

showed two types of fringes. The lattice spacings were calculated to

be 2.7 Å and 2.2 Å. The first one was for CeO₂(200) planes whereas

the second one can be corroborated to be (111) planes of fcc Ag

nanoparticles. EDX analysis (Fig. 4E) was done from the same area

of Fig. 4A. Sharp peaks of Ag confirmed its formation. The peaks for

Ce, O and C came from ceria and the organic capping agents. Cu

peak was due to the grid material. For a detailed distribution of

atomic content inside the porous CeO₂nanocubes, elemental

mapping of Ce and Ag was performed using drift corrected EDX

imaging using STEM-HAADF mode, Fig. 5. The STEM-HAADF image

in Fig. 5A and the corresponding chemical maps for Ce and Ag

acquired using Ce-L and Ag-L energy, were presented in Fig. 5B and

Fig. 3 XPS analysis from CeO₂-Ag nanocomposite for (A) Ce 3d, (B) O

1s and (C) N 1s and (D) Ag 3d.

XPS analysis confirmed the presence of Ag in its metallic state

along with CeO₂, Fig. 3. Ce 3d spectra (Fig. 3A) was best fitted with

six components among which the peaks at binding energy (BE)

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5C, respectively. It was observed that the position of Ce and Ag

overlapped when Fig. 5B and 5C were considered together. This Study of Catalytic Activity:

undoubtedly established the formation of Ag nanoparticles on the Click reaction between phenyl azide and phenyl acetylene

surface of the CeO₂nanocubes.

1. Conc. HCl:H₂O (1:1)

NaNO₂(0^o- 5^oC)

R

NH₂

R₁

N₃

N

Ag-Ceria

Catalyst

3 h, RT

N

2. NaN₃

R

Scheme 1. Synthesis of 1, 4-disubstituted 1,2,3-triazole.

^aReaction conditions: phenyl acetylene (1.2 mmol); aromatic amine

(1equiv); sodium nitrite (1mmol), NaN₃(1.2 mmol); solvent (10 ml);

20 mg of CeO₂-Ag nanocomposites catalyst, room temperature.

^bIsolated yields.

Click reaction between phenyl azide generated in situ from aniline

and phenylacetylene in water was chosen as the model reaction to

check the catalytic ability of CeO₂-Ag nanocomposites. The reaction

was carried out at room temperature for 3 h in presence of 20 mg

of the catalyst (Scheme 1). A promising result with 98% yield of 1, 4-

disubstituted-1,2,3-triazole as product prompted to execute further

catalytic activity of this catalyst in the click reaction. It was

important to mention that no product was detected in absence of

catalyst. The reaction was also carried out in the presence of native

CeO₂and Ag nanoparticles under similar experimental conditions

but the yields were quite poor to report. Thus, CeO₂-Ag

nanocomposites were considered to to form triazole product

efficiently. Results were summarized in Supporting Information SI-3.

To ensure the role of CeO₂support, Ag nanoparticles were

embeded over two different supports, hyper-crosslinked polymer

(HCP) and mesoporous (MP) TiO₂. These two catalysts were

screened for the click reaction of phenyl azide and phenylacetylene.

From the result, presented in Supporting Information SI-3, it could

be easily concluded that CeO₂-Ag nanocomposites had better

catalytic ability than the rest. The same test reaction was also

performed with some unsupported silver salts to compare the

efficacy of supported catalyst. These silver salts were capable to

catalyse the reaction, but yield was found to be very low and the

reaction consumed more time. Due to large surface-to-volume ratio

of Ag metal nanoparticle than corresponding bulk metal salts, it

might improve the catalytic activity.

Fig.

4 (A-C) Transmission electron microscopic image of Ag

nanoparticles supported over CeO₂at different magnification. (D)

HRTEM image of the same clearly showing the lattice plane of Ag

and CeO₂. (E) EDX as obtained from the area of (A).

Fig.

5 (A) Scanning TEM-HAADF image of Ag nanoparticles

supported over CeO₂. (B-C) EDX maps obtained from the same area

in Fig. 5A using Ce-L and Ag-L energy respectively.

After obtaining some crucial insight into the effect of different

catalyst, the study was extended to check the effect of solvent,

reaction temperature, reaction time and the amount of catalyst on

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the reaction. Among several solvents chosen as the reaction observed with 20 mg catalyst. Increasing the catalyst amount from

medium, lowest amount of product was detected in toluene 20 mg to 30 mg did not alter the reaction yield. Temperature

medium with some unwanted side product (Supporting Information showed no such effect on the activity of the catalyst. A reaction at

SI-4, Entry 1). Using polar solvents such as DMF, DMSO, THF and higher temperature did not significantly increase the yield. The

ACN, the yield of the product increased (Supporting Information SI- dependence of the conversion to the product on reaction time was

4, Entry 2-5). But it is interesting that highest yield was obtained presented in Fig. 6B. Decreasing the reaction time from 3 h to 2 h

when the reaction was conducted in water medium (Supporting resulted in significantly diminished yields while increasing the

Information SI-4, Entry 6) rather than in organic solvents. Water as reaction time from 3 h to 4 h led no further improvement of yield of

a reaction medium could be considered as clean, non- hazardous the product.

and safe. So we performed all the reactions in the water medium.

A series of reactions with various substituted aniline and

alkynes under optimized reaction conditions were tested to prove

the versatility of the protocols with CeO₂-Ag nanocomposites as the

catalyst. The results were presented in Table 1. At first, the reaction

of substituted azides (generate in situ from anilines) and

phenylacetylene was carried out. A number of the functional group

on the aromatic ring of anilines were well tolerated and afforded

the desired product in good to excellent yields. The presence of

electron donating or electron withdrawing group on the azide could

not significantly affect the yield of the reaction (Table 1, Entry 6).

Ortho-substituted azide took slightly longer reaction time to reach

the goal (Table 1, Entry 2 and 3). Substituted phenyl acetylene was

also treated with the phenyl azide in standard reaction condition

resulting in the formation of 1, 2, 3-triazole derivatives (Table 1,

Entry 7-8). It was noteworthy that different combination of

substituted azides and substituted phenyl acetylene were applied

and they reacted with similar efficiencies with each other forming

the desired product in presence of CeO₂-Ag nanocomposites as

catalyst.

Fig. 6 Effect of catalyst amount^a(A) and time^b(B) on Click reaction.

^aReaction conditions: phenyl acetylene (1.2 equiv); aromatic amine

(1equiv); Water (10 ml); CeO₂-Ag nanocomposite catalyst, 3 h at

room temperature.

^bReaction conditions: phenyl acetylene (1.2 equiv); aromatic amine

(1equiv); Water (10 ml); CeO₂-Ag nanocomposite catalyst (20 mg) at

room temperature.

^cBoth Isolated yields.

Next, the effect of the amount of catalyst was also evaluated

for the model reaction. The quantity of the active metal had a

significant effect on this reaction (Fig. 6A). Different amount of

catalyst, 10 mg to 30 mg, were tested and the best result was

Table 1 Click reaction between different kinds of aromatic amine derivatives and phenyl acetylene catalyzed by CeO₂-Ag nanocomposite.^a

1. Conc. HCl:H₂O (1:1)

NaNO₂(0^o- 5^oC)

R₁

NH₂

R₁

N₃

N

Ag-Ceria

Catalyst

3 h, RT

2. NaN₃

N

R

Entry

R

R₁

Products

Time (h)

Yield^b(%)

1

H

3

98

N

8 | J. Name., 2012, 00, 1-3

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2

2-NO₂

H

4

95

N

NO₂

3

4

5

2-I

H

4

3

89

97

95

N

I

3-OH

3-Cl

N

HO

N

Cl

6

7

4-OMe

2-NO₂

H

3

4

98

89

MeO

N

OMe

4-OMe

N

NO₂

OMe

8

3-OH

4-OMe

3

94

N

HO

^aReaction conditions: phenyl acetylene (1.2 equiv); aromatic amine (1equiv); Water (10 ml); 20 mg CeO₂-Ag nanocomposite catalyst at

room temperature. Products were characterized by NMR spectroscopy (Supporting Information SI-5). ^bIsolated yields.

Comparison with other reported system

Table 2 Comparison of catalytic activity of the present catalyst in the ‘click’ reactions with other reported catalyst systems.

Entry

Catalyst

Reaction conditions

Phenyl acetylene, benzyl azide, caprylic

acid, PhMe, 90⁰C

Yield (%)

Ref.

1

Silver acetate complex

79

65

2

3

Cu(MeCN)₄PF₄and Silver acetylide

Silver(I)acetate complex (ligand: 2-

diphenylphosphino-N,N,-diisopropylcarboxamide)

Ag₂CO₃

Pyridine, azide, 24h, RT.

Phenyl acetylene, benzyl azide), caprylic

acid, PhMe, 48 h, RT.

75

95

66

67

4

5

Phenyl acetylene, NMP, ethyl 2-

isocyanoacetate, 80 ⁰C.

89

98

68

CeO₂-Ag nanocomposites

Aniline, phenyl acetylene, water, 20 mg of

CeO₂-Ag, 3 h, RT.

This

study

exhibited higher yields compared to those in the literature.^65-68

Moreover in the present study, reactions were conducted at room

temperature with shorter reaction time. Most importantly, here the

One-pot click reaction of aniline with phenylacetylene under

heterogeneous conditions over a variety of catalysts had already

been reported. Table 2 provides a comparison of the results

obtained for this present catalytic system with those reported in

the literature.^65-68From Table 2, it was seen that present catalyst

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coupling reactions were carried out in water using CeO₂-Ag Entry 8-11). Among the chosen solvents, DMF had the best yield of

nanocomposites as catalyst.

propiolic acid, as high as 98% (Supporting Information SI-6, Entry 3).

As DMF could act as a weak base, it also increased the solubility of

CO₂and hence reaction rates.⁶⁹Other solvents gave moderate to

low conversions. The reaction did not take place at all in toluene

medium (Supporting Information SI-6, Entry 11). After optimizing

solvent and base, the effect of temperature was estimated

(Supporting Information SI-6, Entry 12-15). Increasing the

Carboxylation reaction of terminal alkyne:

Ag Ceria catalyst

OH

O

HCl

Base

Solvent

80 ⁰

R

H

+

CO₂

R

C

Scheme 2. CeO₂-Ag nanocomposites catalyzed carboxylation of

terminal alkynes.

^aReaction conditions: alkyne (1.0 mmol), 30 mg of CeO₂-Ag

nanocomposite, Cs₂CO₃(1.5 mmol), CO₂(1.0 atm), 80 ⁰C, DMF (5

ml), 12 h, ^bIsolated Yield.

0

temperature from room temperature to 60 C, the yield of product

was just low to moderate. The most favorable reaction temperature

0

was thus concluded to be 80 C (Supporting Information SI-6, Entry

Several successful methodologies for the carbonylation reaction

had been reported by Islam and his group in recent years.

Generally, toxic carbon monoxide was used as the C1 source in

carbonylation reaction. In recent years, the attention had been

shifted to CO₂as the C1 source in different organic reactions for its

non-toxic nature and low cost for its resource. Here CeO₂-Ag

nanocomposites were used to investigate its catalytic activity for

the carboxylation of terminal alkynes using CO₂as the C1 source via

a green pathway (Scheme 2). To optimize reaction parameters,

carboxylation of 1-phenylethyne with CO₂was considered as a

model reaction. The reaction was chemoselective and highly

dependent on the reaction conditions, i.e. catalyst, solvent, base,

nature of the nucleophile and also the pressure of CO₂. At the first

step, 1-ethynylbenzene was taken as the substrate and was

converted to 3-phenylpropiolic acid using K₂CO₃as a base in DMF

solvent medium under 1 atm CO₂pressure. The reaction was

conducted in a 50 ml autoclave at 80 ⁰C for 12 h and the yield of the

product (49%) was quite reasonable. To increase the yield of the

3). It was interesting to note that above 80 ⁰C, yield decreased

considerably. This might be due to decomposition of silver

propynoate intermediate through decarboxylation at the higher

temperature. Also, the reaction was conceded under different time

ranging from 8 h to 14 h and complete conversion (98%) was

obtained at 12

h of reaction time and beyond (Supporting

Information SI-6, Entry 3, 15 and 19).

Fig.

7 Effect of amount of catalyst on carboxylation of 1-

phenylethyne.

^aReaction conditions: alkyne (1.0 mmol), CeO₂-Ag nanocomposites,

Cs₂CO₃(1.5 mmol), CO₂(1.0 atm), 80 ⁰C, DMF (5 ml), 12 h. ^bIsolated

yield.

product

a

number of reaction conditions were varied

systematically. It was demonstrated that base had a marked impact

on the reaction (Supporting Information SI-6, Entry 1-7). A blank

experiment revealed that no reaction occurred in absence of the

base. Several inorganic and organic bases were examined to

optimize the influence of the base on the catalytic activity. E.g.

Na₂CO_3,K₂CO₃, Cs₂CO₃, DBU and DBN were used and the best result

was obtained with Cs₂CO₃. Et₃N and KO^tBu were least efficient for

this reaction. It was found that Cs₂CO₃as a base furnished the

Amount of catalyst was also varied to investigate the effect of it

on product yield (Fig. 7). A catalyst (CeO₂-Ag nanocomposite)

amount of 30 mg afforded the production of propiolic acid with

98% yield. Yield was decreased sharply when catalyst amount was

reduced from 30 mg to 20 mg. The additional increase in catalyst

amount from 30 mg to 40 mg had no appreciable effect on the

yield. The optimized catalytic system was next successfully applied

to a range of terminal alkynes. The results were summarized in

Table 3. Different terminal alkynes were explored in CO₂medium

and converted into the corresponding analogous caboxylative

0

product with maximum yields (98%) in DMF at 80 C. The reaction

was carried out in several polar solvents like, DMF, DMSO, THF and

dioxane and also in the non-polar solvent like toluene to examine

the effect of solvent on the reaction (Supporting Information SI-6,

10 | J. Name., 2012, 00, 1-3

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products with high yields. Different electronic and steric silver propiolate intermediate was formed by the insertion of CO₂

substituents of the terminal alkynes were well tolerated under into the polar Ag–C bond of silver acetylide. In the last step, there

present reaction conditions. The phenyl ring of 1-phenylethyne was a nucleophilic attack by another terminal alkyne molecule at

substituted with electron withdrawing and electron donating silver propiolate intermediate, silver acetylide was regenerated and

groups were smoothly converted to the analogous product. the desired product was obtained (after acidification) (Scheme 3).

However, when strong electron donating or strong electron The 3^rdstep was slowed down when strong electron withdrawing

withdrawing group were present in phenyl ring, the yield of the group was present at aryl ring. From the reaction mechanism, it was

corresponding product was somehow lower than 1-phenylethyne. found that there was opposite electronic effect in the first and third

Methoxy (-OMe) as the strong electron-donating groups or nitro (- step and from overall assessment, it might be concluded that

NO₂) as the strong electron-withdrawing group on 1- moderately donating group performed better compared to strong

ethynylbenzene resulted in slightly low yields than 1- donating or withdrawing group.

ethynylbenzene (Table 3, Entry 3 and 4).

CO₂

Table

3 CeO₂-Ag nanocomposites catalyzed carboxylation of

a

terminal alkynes with CO₂

.

O

R

H

R

Ag

Ag-Ceria

R

C

Entry

Alkynes

1-phenyl

ethyne

Product

3-phenyl propiolic

acid

Yield^b(%)

OAg

Cs₂CO₃

CsHCO₃

H₃O⁺

1

98

O

R

H

R

C

OH

2

3

4

1-ethynyl-4-

methyl

3-

p

-tolyl propiolic

acid

96

92

90

Scheme

3 Proposed mechanism of CeO₂-Ag nanocomposite

benzene

catalyzed carboxylation of alkyne.

1-ethynyl-4-

methoxy

benzene

3-(4-methoxy

Comparison with other reported system

phenyl) propiolic

acid

Table 4 Comparative catalytic activity of the present catalyst system

with other reported system for carboxylation reactions.

1-ethynyl-4-

3-(4-nitro phenyl)

propiolic acid

nitro benzene

Entry

Catalyst

Reaction conditions

Yield Ref.

(%)

^aReaction conditions: alkyne (1.0 mmol), 30 mg of CeO₂-Ag

nanocomposite, Cs₂CO₃(1.5 mmol), CO₂(1.0 atm), 80 ⁰C, DMF (5

ml), 12 h, ^bGC Yield. Products were characterized by GC by

comparing with authentic samples.

1

Ag@MIL-

101

1-ethynylbenzene (1.0

mmol), catalyst (70 mg),

Cs₂CO₃(1.5 mmol), CO₂(1.0

atm), 50 ⁰C, DMF (5 ml), 15

h.

96

70

It was seen that, in present catalytic system moderately

donating group (methyl, -CH₃) gave the higher product yield (Table

3, Entry 2) compared to strong donating or withdrawing group. This

fact could be explained by the reaction mechanism. The present

carboxylative coupling reaction occurred in three major steps. In

the first step, silver acetylide intermediate was generated in

presence of the base. It was the key step of this reaction. Terminal

alkyne was deprotonated by the strong base and silver acetylide

was produced by the attachment of silver metal from leading

catalyst. This step was facilitated by the strong electron

withdrawing group present in the phenyl ring. In the next step,

2

Bridged

bis

(amidate)

rare-earth

metal

1-ethynylbenzene (1.0

mmol), Cs₂CO₃(2.0 mmol),

Catalyst (0.04 mmol), CO₂(1

atm), DMSO (5 ml), 24h.

94

71

amides

Copper-

NHC

3

4

1-ethynylbenzene (1.0

mmol), Cs₂CO₃(1.2 mmol),

CO₂(2.5 atm), DMF (5 ml),

120⁰C, 14 h.

95

82

72

73

Ag-NHC I

1-phenylethyne (2.0 mmol),

Ag-NHC I (0.02 mmol, 1

mol% Ag), Cs₂CO₃(3.0

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Heterogeneity Test

mmol), DMF (10 ml), rt, 16 h

alkyne (1.0 mmol), 30 mg

A typical hot filtration test was performed in the carboxylation

5

CeO₂-Ag

nanocom-

posites

98

This

work reaction of 1-phenylethyne to investigate whether the reaction

proceeded in a heterogeneous or a homogeneous fashion. The

reaction was carried out for 5 hr when 28% yield was obtained.

After that the catalyst was separated from the reaction mixture by

filtration and then without catalyst, the reaction was conducted for

CeO₂-Ag nanocomposite

,

Cs₂CO₃(1.5 mmol), CO₂(1.0

atm), 80 ⁰C, DMF (5 ml), 12

h.

Carboxylation of terminal alkynes with CO₂under heterogeneous

conditions over a variety of catalysts had been studied earlier. Table

4 provided a comparison of the results obtained for our present

catalytic system with those reported in the literature.^70-73

another 5 hr. It was observed that no reaction occurred without

catalyst and the yield remained unaltered indicating no leaching of

active metal from the support. This proved the heterogeneous

nature of the catalyst. For further confirmation, ICP-AES analysis

was carried out on filtrate of the reaction mixture to detect leached

metal in the solution. No silver metal was detected in the filtrate

which supported the result of the hot-filtration and confirmed the

same conclusion about the heterogeneity of the catalyst.

Catalyst reusability

It was also important to check the physical conditions of the

catalyst after the reaction. Thus TEM, EDX, XRD and XPS were

performed with the recovered catalyst (Supporting Information SI-

7-9). It was found that the structure of the catalyst remained almost

unaltered, the presence of CeO₂nanocubes was distinct along with

the surface-bound Ag nanoparticles (Supporting Information SI-7).

EDX in Supporting Information SI-4 had the signals from Ce, Ag, O, C

as expected. Cu came from the TEM grid. XRD demonstrated very

sharp and well-defined peaks for fcc CeO₂and fcc Ag (Supporting

Information SI-8). Thus the crystalline nature of the matrix i.e. CeO₂

nanocubes, as well as Ag, remained unchanged under the reaction

conditions. A detailed XPS (Supporting Information SI-9) analysis

showed signal for Ce⁴⁺(Ce 3d) from CeO₂same as Fig. 3A, indicating

no alteration in the matrix after catalysis. O 1s showed two peaks,

one from CeO₂and the other from the capping agents. N 1s signal

was also found which confirmed the presence of the capping agent

oleylamine even after 5 cycles of catalysis. Most importantly Ag 3d

signals could be fitted with the peaks at 367.5 eV and 373.5 eV with

a spin-orbit coupling factor of 6 eV corresponded to d_5/2and d_3/2of

metallic Ag. There was no sign of Ag⁺in the recycled catalyst.

Fig. 8 Recycling of CeO₂-Ag nanocomposite catalyst.

Recycling of heterogeneous catalysts could be considered as a

key issue to determine the economic and environmental benefit in

chemical and pharmaceutical industries. The reusability of CeO₂-Ag

nanocomposites as the catalyst in the click reaction and

carboxylation reaction of 1-phenylethyne were checked (Fig. 8). As

the reaction was completed, the catalyst was removed by plain

filtration and washed with methanol followed by acetone then

dried under low pressure at 50 ⁰C. Under optimum reaction

conditions, the next run was tested using the recovered catalyst.

The performance of the recycled catalyst over five successive runs

was shown in Fig. 8. The catalytic efficacy of the recycled catalyst

remained almost same even after five cycles.

5. Conclusion:

In this report, synthesis of Ag nanoparticles supported over 3-D

porous CeO₂nanocubes was shown at room temperature by

modifying the surface of CeO₂with DMP. Reducing and capping

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ability of DMP towards Ag nanoparticles played the key role in the

successful synthesis of the CeO₂-Ag nanocomposites. This

nanocomposite was found to show extremely promising catalytic

activity in click reaction as well as in carboxylation of terminal

alkyne via a green pathway. All probable reactions parameters were

varied to establish the optimized condition of the reaction to have

3169.

6 E. C. Su and W. G. Rothschild, J. Catal., 1986, 99, 506.

7 E. Mamontov, T. Egami, R. Brezny, M. Koranne and S. Tyagi, J.

Phys. Chem. B., 2000, 104, 1110.

8 F. Zhang, Q. Jin and S. W. Chan, J. Appl. Phys., 2004, 95, 4319.

9 C. Sun and L. Chen, Eur. J. Inorg. Chem., 2009, 3883.

the maximum yield of the product. It was vividly shown that several 10 C. Tiseanu, V. I. Parvulescu, M. Boutonet, B. Cojocaru, P. A.

combinations of reaction parameters had the yield as high as 98%.

The catalyst was very effectively reused for several cycles plausibly

Primus, C. M. Teodorescu, C. Solans and M. S. Dominguez, Phys.

Chem. Chem. Phys., 2011, 13, 17135.

owing to its unaltered physical conditions. It was established from 11 T. Yu, J. Joo, Y. Park and T. Hyeon, Angew. Chem. Int. Ed., 2005,

several characterizations with the reused samples. The study 44, 7411.

showed the high potential of this nanocomposite as the catalyst 12 L. Madler, W. J. Stark and S. E. Pratsinis, J. Mater. Res., 2002, 17

which was synthesized by an effective, easy and reproducible route 1356.

at an ambient temperature without using any toxic chemicals or 13 M. Ornatska, E. Sharpe, D. Andreescu and S. Andreescu, Anal.

,

solvents.

Chem., 2011, 83, 4273.

14 D. Barreca, A. Gasparotto, C. Maccato, C. Maragno, E. Tondello,

Conflicts of interest

E. Comini and G. Sberveglieri, Nanotechnology, 2007, 18

,

There are no conflicts to declare.

125502.

15 C. Binet, M. Daturi and J.-C. Lavalley, Catal. Today., 1999, 50

,

Acknowledgements

207.

SD thanks University Grant Commission (UGC) for a research

fellowship. SD and TB thank Department of Science and Technology

(DST, India) for funding through Fast Track Scheme (SR/FT/CS-

106/2011) and Centre for Research in Nanoscience and

Nanotechnology (CRNN), University of Calcutta for instrumental

support. PM is thankful to the University Grant Commission (UGC)

for funding under Dr. D.S. Kothari post-doctoral research fellowship.

SMI gratefully acknowledges the Department of Science and

Technology, DST-SERB, (Project sanction No. EMR/2016/004956),

New Delhi, India, and the Council of Scientific and Industrial

Research, CSIR, [Project sanction No. 02(0284)/16/EMR-II), Date:

06-12-2016] for financial support.

16 Q. Fu, A. Weber and M. Flytzani-Stephanopoulo, Catal. Lett.,

2001, 77, 87.

17 X. Yin, L. Hong and Z. L. Liu, J. Membr. Sci., 2006, 268, 2.

18 C. Sun, R. Hui and J. Roller, J. Solid State Electrochem., 2010, 14

1125.

,

19 C. Sun and U. Stimming, J. Power Sources, 2007, 171, 247.

20 A. Corma, P. Atienzar, H. García and J.-Y. Chane-Ching, Nat.

Mater., 2004, 3, 394.

21 E. L. Brosha, R. Mukundan, D. R. Brown, F. H. Garzon and J. H.

Visser, Solid State Ionics., 2002, 148, 61.

22 M. I. Litter, Appl. Catal. B, 1999, 23, 89.

23 C. Sun, H. Li, H. R. Zhang, Z. X. Wang and L. Chen,

N

anotechnology, 2005, 16, 1454.

24 Y. Ma, X. Wang, S. Li, M. S. Toprak, B. Zhu and M. Muhammd,

Reference:

Adv. Mater., 2010, 22, 1640.

1 F. A. Kroger and H. J. Vink, Solid State Phys., 1956, 3, 307.

25 C. C. Tang, Y. Bando and T. Sato, J. Phys. Chem. B., 2002, 106

,

2 S. R. Bishop, T. S. Stefanik and H. L. Tuller, Phys. Chem. Chem.

Phys., 2011, 13, 10165.

7449.

26 R. Si, Y. W. Zhang, L. P. You and C. H. Yan, Angew. Chem. Int. Ed.,

2005, 44, 3256.

3 H. C. Yao and Y. F. Y. Yao, J. Catal., 1984, 86, 254.

4 E. C. Su, C. N. Montreuil and W. G. Rothschild, Appl. Catal., 1985,

17, 75.

27 L. S. Zhong, J. S. Hu, A. M. Cao, Q. Liu, W. G. Song and L. J. Wan,

Chem.Mater., 2007, 19, 1648.

5 K. Deori, D. Gupta, B. Saha and S. Deka, ACS Catal., 2014, 4,

28 N. C. Strandwitz and G. D. Stucky, Chem. Mater., 2009, 21, 4577.

J. Name., 2013, 00, 1-3 | 13

Please do not adjust margins

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Page 14 of 15

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DOI: 10.1039/C8NJ00665B

ARTICLE

Journal Name

29 G. Li, D. Qu, L. Arurault and Y. Tong, J. Phys. Chem. C., 2009

,

113

,

54 Bellamy, Lionell John, 1954, The Infrared spectra of complex

1235.

molecules, John Wiley and Sons, Inc., New York, N. Y.

55 S. W. Dietrich, E. C. Jorgensen, P. A. Kollman and S. Rothenberg,

J. Am. Chem. Soc., 1976, 98 (26), 8310.

30 Q. Yuan, Q. Liu, W. G. Song, W. Feng, W. L. Pu, L. D. Sun, Y. W.

Zhang and C. H. Yan, J. Am. Chem. Soc., 2007, 129, 6698.

31 G. M. Schwab and K. Koller, J. Am. Chem. Soc., 1968, 90, 3078.

32 G. M. Schwab, Surf.Sci., 1969, 13, 198.

56 T. N. Pilev, J. Appl. Spectrosc., 1987, 47(6), 1259

.

57 K. E. Otto, S. Hesse, T. N. Wassermann, C. A. Rice, M. A. Suhm, T.

Stafforst and U. Diederichsen, Phys. Chem. Chem. Phys., 2011,

13, 14119.

33 M. Haruta, J. New Mater. Electrochem. Syst., 2004, 7, 163.

34 R. Si and M. Flytzani-Stephanopoulos, Angew. Chem., Int. Ed.,

2008, 47, 2884.

58 S. Jarmelo, I. Reva, P. R. Carey and R. Fausto, Vib. Spectrosc.,

2007, 43, 395.

35 M. B. Boucher, S. Goergen, N. Yi and M. Flytzani-

Stephanopoulos, Phys. Chem. Chem.Phys., 2011, 13, 2517.

36 J. Zhou, A. P. Baddorf, D. R. Mullins and S. H. Overbury, J. Phys.

Chem. C., 2008, 112, 9336.

59 G. Litwinienko, G. A. Dilabio, P. Mulder, H-G. Korth and K. U.

Ingold, J. Phys. Chem. A., 2009, 113, 6275.

60 P. R. Selvakannan, A. Swami, D. Srisathiyanarayanan, P. S.

37 T. Bala, A. Singh, A. Sanyal, C. O’Sullivan, F. Laffir, C. Coughlan

and K. M. Ryan, Nano Research., 2013, 6(2), 121.

38 R. Bohm and C. Karow, Die Pharmazie. 1981, 36, 243.

Shirude, R. Pasricha, A. B. Mandale and M. Sastry, Langmuir

,

2004, 20, 7825.

61 L. Yin, Y. Wang, G. Pang, Y. Koltypin and A. Gedanke, J. Colloid

Interface Sci., 2002, 246, 78.

39 P. M. E. Gramlich, C. T. Wirges, A. Manetto and T. Carell, Angew.

Chem., Int. Ed., 2008, 47, 8350.

62 NIST X-ray Photoelectron Spectroscopy Database, Version3.5,

http://srdata.nist.gov/xps/.

40 V. O. Rodionov, S. I. Presolski, D. D. Díaz, V. V. Fokin and M. G.

Finn, J. Am. Chem. Soc., 2007, 129, 12705.

63 G. G. Couto, J. J. Kleinb, W. H. Schreiner, D. H. Mosca, A. J. A. de

Oliveira and A. J. G. Zarbin, J. Colloid Interface Sci., 2007, 311,

461.

41 S. Chassaing, M. Kumarraja, A. S. S. Sido, P. Pale and J. Sommer,

Org. Lett., 2007, 9, 883.

42 R. Hudson, C-J. Li and A. Moores, Green Chem., 2012, 14, 622.

43 L. Yang and H. Wang, Chem Sus Chem., 2014, 7, 962.

64 H. Winnischofer, T. C. R. Rocha, W. C. Nunes, L. M. Socolovsky,

M. Knobel and D. Zanchet, Acs Nano, 2008, 2(6), 1313.

65 J. McNulty and K. Keskar, Eur. J. Org. Chem., 2012, 5462.

66 I. P. Silvestri, F. Andemarian, G. N. Khairallah, S. W. Yap, T.

Quach, S. Tsegay, C. M. Williams, R. A. J. O’Hair, P. S. Donnelly

44 D. Yu, M. X. Tan and Y. Zhang, Adv. Synth. Catal., 2012, 354, 969.

45 D. W.Stephan and G. Erker, Chem Sci., 2014, 5, 2625.

46 R. A. Molla, K. Ghosh, B. Banerjee, M. A. Iqubal, S. K. Kundu, S.

M. Islam and A. Bhaumik, J. Colloid Interface Sci., 2016, 477, 220.

47 X-H. Liu, J-G. Ma, Z. Niu, G-M. Yang and P. Cheng, Angew. Chem.

Int. Ed., 2015, 54, 988.

and S. J. Williams, Org. Biomol. Chem., 2011, 9, 6082.

67 J. McNulty, K. Keskar and R. Vemula, Chem. Eur. J., 2011, 17

14727.

,

48 B. Yu, J-N. Xia, C-L. Zhong, W. Li and L-N. He, ACS Catal., 2015,

5(7), 3940.

68 M. Gao, C. He, H. Chen, R. Bai, B. Cheng and A. Lei, Angew.

Chem., Int. Ed., 2013, 125, 7096.

49 B. Yu, P. Yang, X. Gao, Z. Z. Yang, Y. F. Zhao, H. Y. Zhang and Z.

M. Liu, New J. Chem., 2017, 41, 9250

69 S. N. Riduan, Y. Zhang and J. Y. Ying, Angew. Chem., Int. Ed.,

2009, 48, 3322.

50 S Das, G. Bhattacharjee, B. Satpati, M. Kumar, S. Deka, M. K.

70 X. H. Liu, , J. G. Ma, Z. Niu, G. M. Yang and P. Cheng, Angew.

Chem., Int. Ed., 2015, 54, 988.

Ghosalaya, C. S. Gopinath and T. Bala, New. J. Chem, 2018, 42

,

1379.

71 H. Cheng, B. Zhao, Y. Yao and C. Lu, Green Chem., 2015, 17,

1675.

51 N. Shukla, C. Liu,P. M. Jones and D. Weller, J. Magn. Magn.

Mater., 2003, 266, 178.

72 Y. Dingyi and Z. Yugen, Green Chem., 2011, 13, 1275.

73 S. Li, J. Sun, Z. Zhang, R. Xie, X. Fang and M. Zhou, Dalton Trans.

2016, 45, 10577.

52 M. Gasgnier, J. Mater. Sci., 2001, 20, 1259.

53 Randall, Harrison McAllister. 1952. Infrared Determination of

Organic Structure. D. Van Nostrand Company, Princeton, N.J.

,

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New Journal of Chemistry

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DOI: 10.1039/C8NJ00665B

A facile synthesis strategy to couple porous nanocube of CeO₂with Ag

nanoparticles: An excellent catalyst with enhanced reactivity for ‘click

reaction’ and carboxylation of terminal alkynes

Subhasis Das, Paramita Mondal, Swarbhanu Ghosh, Biswarup Satpati, Sasanka Deka, Sk. Manirul Islam and

Tanushree Bala

Surface of the CeO₂nanocube was modified with DMP which helped to drag Ag⁺ions to the

organic medium and also to reduce to Ag nanoparticles over the nanocubes. This CeO₂-Ag

nanocomposites was found to have excellent catalytic properties towards the synthesis of 1,4-

disubstituted 1,2,3 triazole from phenyl azide and phenyl acetylene. It also efficiently catalyzed

the carboxylation of terminal alkyne.

Article Doi

A facile synthesis strategy to couple porous nanocubes of CeO2 with Ag nanoparticles: An excellent catalyst with enhanced reactivity for the 'click reaction' and carboxylation of terminal alkynes

DOI: 10.1039/c8nj00665b

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Article abstract of DOI:10.1039/c8nj00665b

Full text of DOI:10.1039/c8nj00665b

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