A novel protocol for selective synthesis of monoclinic zirconia nanoparticles as a heterogeneous catalyst for condensation of 1,2-diamines with 1,2-dicarbonyl compounds

Article abstract of DOI:10.1039/c3nj00655g

ZrO₂ nanocatalyst has been obtained successfully using novel and safe agents through a simple and safe sol-gel method (polymerizing-complexing) and characterized by XRD, FT-IR, Raman spectroscopies and transmission electron microscopy (TEM). Raman spectroscopies and XRD results indicated only formation of monoclinic zirconia. TEM images revealed spherical nanoparticles with 20-40 nm diameter range. The spectral and analysis data confirmed the effectiveness of the method for preparation of monoclinic zirconia by preventing grain growth or agglomeration of particles. The nanostructured ZrO₂ exhibited high efficiency in catalyzing condensation of various 1,2-diamine and 1,2-dicarbonyl compounds for the synthesis of heterocyclic compounds. The recovery of the title heterogeneous nanocatalyst was easy and efficient and its catalytic activity was strikingly different from the bulk one.

Full text of DOI:10.1039/c3nj00655g

NJC
View Article Online
View Journal
PAPER
A novel protocol for selective synthesis
of monoclinic zirconia nanoparticles as a
heterogeneous catalyst for condensation
of 1,2-diamines with 1,2-dicarbonyl compounds
Cite this:DOI: 10.1039/c3nj00655g
Maasoumeh Jafarpour,* Elham Rezapour, Mahboobe Ghahramaninezhad and
Abdolreza Rezaeifard*
ZrO2 nanocatalyst has been obtained successfully using novel and safe agents through a simple and safe
sol–gel method (polymerizing–complexing) and characterized by XRD, FT-IR, Raman spectroscopies
and transmission electron microscopy (TEM). Raman spectroscopies and XRD results indicated only
formation of monoclinic zirconia. TEM images revealed spherical nanoparticles with 20–40 nm diameter
range. The spectral and analysis data confirmed the effectiveness of the method for preparation of
monoclinic zirconia by preventing grain growth or agglomeration of particles. The nanostructured ZrO2
exhibited high efficiency in catalyzing condensation of various 1,2-diamine and 1,2-dicarbonyl compounds
for the synthesis of heterocyclic compounds. The recovery of the title heterogeneous nanocatalyst was
easy and efficient and its catalytic activity was strikingly different from the bulk one.
Received (in Porto Alegre, Brazil)
19th June 2013,
Accepted 9th November 2013
DOI: 10.1039/c3nj00655g
www.rsc.org/njc
process. Therefore, the study of influence of various parameters
such as initial solution combination, time and temperature of
1. Introduction
Inorganic nanopowders are among the most important factors in heat treatments, and also type of complexing and polymerizing
many fields of materials such as ceramics, catalysis, medicines and agents is very important for nanopowder production. Indeed, the
food.1
PC (polymerizing–complexing) sol–gel method provides a more
ZrO2 nanoparticles have attracted much attention due to homogeneous fine powder than any other techniques with
their specific optical and electrical properties and potential immobilization of metal–chelate complexes and forming stable
applications in transparent and optical devices, sensors, fuel metal complexes via increasing the polymerization agent.
cells, advanced ceramics and catalysis.2–7
Recently we presented a novel procedure for the preparation of
Ceramics containing nanozirconia are of great interest for their a-MoO3 nanobelts using a PC (polymerizing–complexing) sol–gel
obvious improvement in strength and toughness,8 which change method.19,20 We found that this procedure is applicable for the
the mechanical properties, electrical performance, thermal perfor- synthesis of monoclinic nanoZrO2. In general, the synthesis of ZrO2
mance, magnetic performance and optical performance of ceramic usually results in amorphous structures or the formation of a
components.9 Furthermore, nanozirconia has attractive catalytic mixture of phases,21 while, the PC sol–gel method has the advan-
actions for the isomerization of olefins and epoxides,10 dehydration tage in this regard as it produces single phase nanoparticles. The
of alcohols,11 selective synthesis of dimethyl carbonate,12 methanol- structure of monoclinic zirconia nanoparticles was investigated by
selective oxidation13 and redox activity.14
XRD, FT-IR and Raman spectroscopies. Also, the simplicity of this
Several methods including hydrothermal,15 sol–gel,16 method allows scaling up for mass production.
chemical vapor deposition (CVD)17 and sputtering18 have been
used to prepare ZrO2 nanoparticles.
Then, we have explored the possibility of synthesizing
quinoxaline derivatives and pyrido pyrazines using ZrO2 nano-
However, preparation of nanoparticles of metal oxides at low particles as a practical, environmentally benign and reusable
cost in industrial scale is a challenge in material production. So, heterogeneous catalyst in ethanol (Scheme 1).
the use of cheap materials, simple fabrication processes and
suitable synthesis conditions are the main requirements for this
2. Experimental
2.1. General remarks
Catalysis Research Laboratory, Department of Chemistry, Faculty of Science,
University of Birjand, Birjand, 97179-414 Iran. E-mail: mjafarpour@birjand.ac.ir,
All chemicals were purchased from Merck or Fluka Chemical
Companies and used as received. Powder X-ray diffraction
rrezaeifard@birjand.ac.ir, rrezaeifard@gmail.com; Fax: +98 561 2502515;
Tel: +98 561 2502516
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014
New J. Chem.

View Article Online
Paper
NJC
Scheme 1 Synthesis of quinoxaline derivatives and pyrido pyrazines in the
presence of 3.2 mol% of m-ZrO2 nanoparticles in ethanol.
(XRD) was performed on a Bruker D8-advance X-ray diffractometer
with Cu Ka (l = 1.54178 Å) radiation. The FT-IR spectra of it were
recorded on a NICOLET system 800 beam splitter KBr SCAL =
800 with resolution in the range 400–4000 cm. Raman spectra were
recorded on a Brucker’s senterra (2009) model with spectral range
200–3500 cmꢀ1 and laser wavenumber 785 nm. Thermogravimetric
analysis (TGA) of powders was performed in air by a Shimadzu 50.
TEM images were obtained by TEM instrumentation (Philips
CM 10).
Progresses of the reactions were monitored by TLC using
silica-gel SIL G/UV 254 plates. NMR spectra were recorded on a
Brucker Avance DPX 250 MHz and 400 MHz instrument. Mass
spectra were recorded on a Shimadzu GC-MS-QP 5050A.
2.2. Catalyst preparation
Initially, a solution of ZrOCl2ꢁ8H2O (0.003 mol) in distilled water
was prepared. Then, citric acid (0.126 mol) and ethylene glycol
(0.126 mol) were subsequently added to this solution. The resulting
mixture was stirred at 80 1C for 30 min to give rise to a clear solution.
The solution was refluxed at 95 1C for 12 h which turned it white,
resulting from a metal–citrate homogeneous complex. After cooling
down, in order to bring about the required chemical reactions for
the development of polymerization and evaporation of the solvent,
the sol was further slowly heated at 80 1C for 5 h in an open bath.
During continuous heating at this temperature, the polymerization
between citric acid, ethylene glycol and the complexes is developed,
and ultimately the sol became more viscous as a wet gel. In the final
step of the sol–gel process, the wet gel was fully dried by direct
heating on the hot plate at 120 1C for 3 h. The resultant production
was a light brown powder. Then it was calcined in a furnace at
750 1C for 4 h at a rate of 4 1C minꢀ. Finally, ZrO2 nanoparticles
with white color were obtained (Fig. 1).
Fig. 1 The flow chart of preparation of m-ZrO2 nanoparticles by a sol–gel
process.
(3 ꢂ 5 ml ethanol). Most of the product was precipitated purely by
concentrating and cooling of the ethanolic solution. The remaining
product was then isolated from an excess of 1,2-diamine by plate
chromatography eluted with n-hexane–EtOAc (10/2). Structural
1
assignment of the product was based on its H NMR, 13C NMR
and MS spectra.
2.4. Reusability of catalyst
A mixture of benzil (1 mmol) and nanoZrO2 (3.2 mol%, 0.004 g) in
ethanol (0.5 ml) was stirred at 25 1C for 2 min. Then, o-phenyl-
enediamine (1.5 mmol) was added to the reaction mixture and
stirred at 60 1C for the appropriate reaction time. The progress of the
reaction was monitored by TLC or GC. After the completion of the
reaction, the precipitated product was dissolved by adding ethanol
and nanoZrO2 was separated by centrifuging followed by decanta-
tion (3 ꢂ 5 ml ethanol). The isolated solid phase (nanoZrO2) was
dried under reduced pressure and reused for five runs without any
noticeable drop in the product yield and its catalytic activity.
2.3. General procedure for the synthesis of quinoxaline
derivatives and pyrido pyrazines in the presence of ZrO2
nanoparticles in ethanol
A mixture of 1,2-dicarbonyl (1 mmol) and nanoZrO2 (3.2 mol%,
0.004 g) in ethanol (0.5 ml) was stirred at 25 1C for 2 min. Then,
1,2-diamine (1.5 mmol) was added to the reaction mixture and
stirred at 60 1C for the appropriate reaction time. The progress of the
reaction was monitored by TLC or GC. After the completion of the
3. Results and discussions
3.1. Characterization of catalyst
reaction, the precipitated products were dissolved by adding ethanol, A monoclinic structure of the ZrO2 with lattice parameters of
and nanoZrO2 was separated by centrifuging followed by decantation a = 5.147 Å, b = 5.203 Å and c = 5.315 Å was identified with XRD
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014

View Article Online
NJC
Paper
Fig. 4 FT-IR patterns of m-ZrO2 nanoparticles.
Fig. 2 XRD pattern of m-ZrO2 nanoparticles.
(Fig. 2). The peaks observed at 2y = 28.2, 31.5, 33.8, 35.1, 38.5,
40.5, 44.5, 45.3, 50.3, 50.9, 53.8, 55.3, 57.0, 57.7 and 60.1 were
assigned to the (11-1), (111), (002), (200), (021), (21-1), (112), (20-2),
(122), (221), (300), (013), (212), (22-2) and (302) reflection planes
of monoclinic ZrO2, respectively, which is in agreement with the
37–1484 standard card from the JCPDS.22
No characteristic peak of cubic or tetragonal phase and any
other impurities are found in the XRD pattern. This observation
suggests that the high purity of monoclinic phase ZrO2 was
obtained. The size of particles were estimated to be 20–30 nm
according to the Debye scherrer formula (D500 = Kl/b cos y).
Fig. 3 shows the Raman spectra of ZrO2 nanopowders
obtained by the PC sol–gel method.
Fig. 5 TEM images of m-ZrO2 nanoparticles.
Transmission electron microscopy (TEM) observations
Active Raman modes at 179, 330, 380, 474, 559 and 637 cmꢀ1 clearly revealed spherical nanoparticles with size ranging
can be identified in Fig. 3. According to the literature,23,24 these between 20–40 nm (Fig. 5).
bands are related to the monoclinic structure and are in
agreement with the XRD results of m-ZrO2.
The thermal behavior of ZrO2 powders showed three
decreases in the weight percentage at about 331, 450, and
Further, the bonding nature and purity of nanoparticles are 738 1C (Fig. 6). The organic additives were removed completely
studied by the FT-IR. Fig. 4 showed the FT-IR spectra of from the powders at high annealing temperatures, especially
nanoZrO2. It revealed the presence of major bands at 736 and above 750 1C, and monoclinic ZrO2 was formed.
583 cmꢀ1 which are attributed to the strong stretching vibrations
The measurement of BET surface area of the prepared
of the Zr–O group. These bands are the characteristic monoclinic nanoZrO2 (3.6 m2 gꢀ1) showed well increased surface area as
phase of ZrO2.25 The FT-IR studies are in agreement with the compared to its bulk one (2.15 m2 gꢀ1).
XRD patterns of the ZrO2 that both confirm the presence of a
monoclinic ZrO2 phase.
A literature survey regarding the synthesis and characteriza-
tion of nanoZrO2 highlights the strong points of the title work
Fig. 3 Raman spectra of m-ZrO2 nanoparticles.
Fig. 6 The TGA and DTA of ZrO2 powders.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014
New J. Chem.

View Article Online
Paper
NJC
Table 1 The comparison of the synthesis conditions and structural properties of m-ZrO2 nanoparticles with other procedures
Entry Method
Condition
Size (nm) Shape
m-ZrO2 spherical
Ref.
a
1
2
3
4
5
6
Sol–gel
ZrOCl2ꢁ8H2O/citric acid, ethylene glycol 20–30
—
26
27
28
29
Thermal decomposition method
Aqueous combustion method
Spray reaction method
Hydrothermal method
ZrOCl2ꢁ8H2O/Na2CO3
20–60
25
m-ZrO2 nano rods
t-ZrO2 nano crystals
ZrO(NO3)2ꢁH2O/glycine
Zirconium salt/NH3(g)
Commercial zirconia/NaOH
17.7–20.8 c-ZrO2 spherical
15–30
o8
Nano particles
m and t-ZrO2 spherical 30
Thermal decomposition of Zr(ox)2 in an autoclave Zr(C2O4)2ꢁ4H2O
a
The present work.
which develops an operationally simple and safe protocol was not satisfactory from methodological point of view and the
(Table 1).
desired product was formed only in 58% yield after 3 h.
Then, the optimized reaction conditions were investigated
on the same condensation reaction in the presence of nanoZrO2
3.2. Catalytic activity of nanoZrO2
The catalytic potential of nanoZrO2, was evaluated in the with respect to temperature, time, and the molar ratio of catalyst
condensation reactions. The condensation of various 1,2-diamine to the substrate in ethanol (0.5 ml). We found that 3.2 mol% of
and 1,2-dicarbonyl compounds for the synthesis of quinoxaline nanocatalyst was sufficient to obtain the desired quinoxaline in
derivatives and pyrido pyrazines in the presence of the title hetero- 96% yield within 10 min at 60 1C.
geneous catalyst have been investigated.
It should be mentioned that, when the nanoZrO2 was
In the family of biologically active heterocyclic templates, replaced by a bulk counterpart, the reaction yield was reduced
quinoxalines and pyrido pyrazines have their own identity. almost close to that observed in ethanol under catalyst-free
These compounds play a key role and have great synthetic conditions. Enhanced BET surface area of nanostructured ZrO2
potential for applications in academia and in many aspects of may be a good reason for the improvement in its catalytic
pharmaceutical and medicinal chemistry.31–42
activity compared to that of the bulk one.
Blank experiments were addressed to the condensation of
The optimized reaction conditions were applied for various
o-phenylenediamine (1.5 mmol) and 4,40-dimethoxybenzil aryl 1,2-diamines and 1,2-dicarbonyl compounds. The yields of
(1 mmol) as a model reaction under neat conditions which products were highly dependent on the electronic demands of
gave 45% yield (NMR) after 7 hours. After that, the influence of the substrate used. For instance, the condensation reaction of a
the solvent nature on this reaction at room temperature was diamine bearing a strong electron-withdrawing group (Table 2,
investigated. From the evaluation of different solvents, EtOH, entries 3, 5, 7, 9 and 11) or a dicarbonyl compound substituted
which is a standard ‘‘green’’ medium, was found to be the best with
a strong electron-donating group proceeded slowly
solvent in terms of yield and selectivity, nevertheless, the result (Table 2, entries 4, 5 and 13).
Table 2 Synthesis of quinoxaline derivatives and pyrido pyrazines in the presence of m-ZrO2 nanoparticlesa
Entry
Diamine R1
1,2-Diketone R2
Product R1, R2
Time (min)
Isolated yieldb (%)
1
2
3
4
5
H
H
H
H
OCH3
OCH3
H, H
2
6
4 h
10
4 h
95
96
78
96
o10
CH3
NO2
H
CH3, H
NO2, H
H, OCH3
NO2, OCH3
NO2
6
7
H
3
92
95
NO2
30
8
H
12
94
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014

View Article Online
NJC
Paper
Table 2 (continued)
Entry
9
Diamine R1
1,2-Diketone R2
Product R1, R2
Time (min)
4 h
Isolated yieldb (%)
NO2
76
10
11
12
H
7
85
75
90
NO2
5.30 h
H
25
13
14
15
OCH3
7 h
70
95
95
8
35
16
20
84
a
b
The reactions were run at 60 1C and the molar ratio of 1,2-dicarbonyl–1,2 diamine–ZrO2 was 100 : 150 : 3.2 in 0.5 ml ethanol. All products were
identified by their spectroscopic data.19
Also, when we applied similar reaction conditions for the high stability and catalytic activity of prepared nanoZrO2. This
condensation of 5-bromo-2,3-diaminopyridine and a variety of was further supported by evaluation of the recovery potential
1,2-diketones for the synthesis of pyrido[2,3-b] pyrazines, the desired of the catalyst in the condensation of various 1,2-diamine and
products were isolated in high yields (Table 2, entries 12–16). 1,2-dicarbonyl compounds for the synthesis of heterocyclic
As expected, the condensation reaction of 5-bromo-2,3- compounds under the conditions mentioned in Table 1.
diaminopyridine with dicarbonyl compounds showed a longer
reaction time than that of aryl 1,2-diamines.
Recovery of nanoZrO2 catalyst was easy and efficient. For
this reason, the condensation reaction of o-phenylenediamine
and benzil in ethanol at 60 1C in the presence of nanoZrO2
(3.2 mol%) was studied. When the reaction was completed, the
3.3. Recovery of catalyst
The excellent yields of quinoxaline derivatives and pyrido pyrazines precipitated products were dissolved by adding ethanol, and
obtained using this new catalytic method demonstrated the nanoZrO2 was separated by centrifuging followed by decantation
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014
New J. Chem.

View Article Online
Paper
NJC
4. Conclusions
Nano monoclinic ZrO2 has been obtained successfully using
novel and safe agents through a simple and safe sol–gel method
(polymerizing–complexing) and characterized by XRD, FT-IR,
Raman spectroscopies and transmission electron microscopy
(TEM). The results revealed a monoclinic space group for ZrO2
nanoparticles. The TEM images show spherical ZrO2 nano-
particles with size ranging between 20–40 nm. The spectral
and analysis data confirmed the effectiveness of the method for
the preparation of monoclinic ZrO2 by preventing grain growth
or agglomeration of particles.
NanoZrO2 as an effective and reusable heterogeneous
catalyst can provide environmentally friendly alternatives for
the heterogeneous synthesis of quinoxaline derivatives and
pyrido pyrazines under mild conditions.
Acknowledgements
Fig. 7 Raman spectra of fresh m-ZrO2 nanoparticles (A) and after 5 times
reuse (B) in the condensation reaction of o-phenylenediamine and benzil
in ethanol at 60 1C using 3.2 mol% catalyst.
Support for this work by the Research Council of the University
of Birjand is highly appreciated. We kindly acknowledge Prof.
Helen Stoeckli-Evans for her assistance in XRD analysis.
(3 ꢂ 5 ml ethanol). The isolated solid phase (nanoZrO2) was
dried under reduced pressure and reused for five runs without
any noticeable drop in the product yield and its catalytic activity.
The comparison of Raman spectra (Fig. 7) of used and fresh
nanoZrO2 showed the fact that the structure of the catalyst
remained almost intact after five times recovering.
References
1 (a) R. J. White, R. Luque, V. L. Budarin, J. H. Clark and
D. J. Macquarrie, Chem. Soc. Rev., 2009, 38, 481–494;
(b) C. Sanchez, B. Julian, Ph. Belleville and M. Popall,
´
Therefore, the title methodology is environmentally friendly,
cost effective and industrially important because of reuse of the
catalyst and using safe reaction media.
These advantages for this high yielding condensation
method offered ready scalability. For example, the condensation
of o-phenylenediamine and benzil in a 20 mmol scale in the
presence of the nanocatalyst was investigated. As expected, the
reaction proceeded similarly to the smaller scale, and the desired
corresponding product was obtained at the same isolated yield
and reaction time.
J. Mater. Chem., 2005, 15, 3559–3592.
2 G. Liu and Y. Lin, Anal. Chem., 2005, 77, 5894–5901.
3 Sh. Liu and M. Y. Han, Chem.–Asian J., 2010, 5, 36–45.
4 J. Lu, J. B. Zang, S. X. Shan, H. Huang and Y. H. Wang, Nano
Lett., 2008, 8, 4070–4074.
5 T. Z. Sholklapper, V. Radmilovic, C. P. Jacobson, S. J. Isco
and L. C. De Jonghe, Electrochem. Solid-State Lett., 2007, 10,
B74–B76.
6 X. Luo, A. Morrin, A. J. Killard and M. R. Smyth, Electro-
analysis, 2006, 18, 319–326.
In Table 3, we have also shown the merit of this operationally
simple catalytic protocol for condensation of o-phenylenediamine
and benzil in comparison with the other catalysts in terms of
conversion rate, catalyst loading and media used for this purpose.
7 S. A. Steiner, Th. F. Baumann, B. C. Bayer, R. Blume,
¨
M. A. Worsley, W. J. MoberlyChan, E. L. Shaw, R. Schlogl,
A. John Hart, S. Hofmann and B. L. Wardle, J. Am. Chem.
Soc., 2009, 131, 12144–12154.
8 A. Hirvonen, R. Nowak, Y. Yamamoto, T. Sekino and
K. Niihara, J. Eur. Ceram. Soc., 2006, 26, 1497–1505.
9 F. Gaog, B. Zhao, D. H. Xiang and Q. H. Kong, J. Mater.
Process. Technol., 2009, 209, 32–37.
Table 3 Catalytic activity of m-ZrO2 nanoparticles in comparison with
other catalysts used for condensation of o-phenylenediamine and benzil
10 X. Xu and X. Wang, Nano Res., 2009, 2, 891–902.
11 L. Nakka, J. E. Molinari and I. E. Wachs, J. Am. Chem. Soc.,
2009, 131, 15544–15554.
12 K. Tomishig, Y. Ikeda, T. Sakaihori and K. Fujimoto,
J. Catal., 2000, 192, 355–362.
13 W. Li, H. Huang, H. Li, W. Zhang and H. Liu, Langmuir,
2008, 24, 8358–8366.
14 R. Wang, P. A. Crozier, R. Sharma and J. B. Adams, Nano
Lett., 2008, 8, 962–967.
Entry Catalyst
Catalyst (mol%) Time (min) Yield (%) Ref.
a
1
2
3
4
5
6
7
8
m-ZrO2/ethanol
ZrCl4/methanol
Zr(DS)4/H2O
3.2
5
2.5
2
5
95
100
94
—
43
44
45
46
47
48
49
30
90
15
10
150
20
Zr-CAP-SG/ethanol 10 wt%
92
96
95
CuSO4ꢁ5H2O/H2O
Zn[(L)proline], HOAc
Mont K-10, H2O
[Hbim]BF4
10
10
10
2 ml
100
96
a
The present work.
New J. Chem.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014

View Article Online
NJC
Paper
15 M. N. Tahir, L. Gorgishvili, J. Li, T. Gorelik, U. Kolb, 31 A. Jaso, B. Zarranz, I. Aldana and A. Monge, J. Med. Chem.,
L. Nasdala and W. Tremel, Solid State Sci., 2007, 9, 1105. 2005, 48, 2019–2025.
16 G. Ehrhart, B. Capoen, O. Robbe, P. Boy, S. Turrell and 32 H. U. Gali-Muhtasib, M. Diab-Assaf and M. Haddadin,
M. Bouazaoui, Thin Solid Films, 2006, 496, 227. Cancer Chemother. Pharmacol., 2005, 55, 369–378.
17 A. M. Torres-Huerta, M. A. Dominguez-Crespo, E. Ramirez- 33 G. Aguirre, H. Cerecetto, R. Di Maio, M. Gonzales, M. E. M. A.
Meneses and J. R. Vargas-Garcia, Appl. Surf. Sci., 2009,
255, 4792.
Alfaro, A. Jaso, B. Zarranz, M. A. Ortega, I. Aldana and A. Monge-
Vega, Bioorg. Med. Chem. Lett., 2004, 14, 3835–3839.
18 C. Rozo, D. Jaque, L. F. Fonseca and J. G. Sole, J. Lumin., 34 K. Toshima, T. Ozawa, T. Kimura and S. Matsumara, Bioorg.
2008, 128, 1197. Med. Chem. Lett., 2004, 14, 2777–2779.
19 M. Jafarpour, A. Rezaeifard, M. Ghahramaninezhad and 35 B. K. Santra, P. A. N. Reddy, G. Neelakanta, S. Mahadevan,
T. Tabibi, New J. Chem., 2013, 37, 2087.
20 M. Jafarpour, M. Ghahramaninezhad and A. Rezaeifard,
RSC Adv., 2014, 4, 1601.
M. Nethaji and A. R. Chakravarty, J. Inorg. Biochem., 2002,
89, 191–196.
36 A. M. Thomas, M. Nethaji, S. Mahadevan and
A. R. Chakravarty, J. Inorg. Biochem., 2003, 94, 171–178.
21 (a) A. S. Barnard and R. R. Yeredla, Nanotechnology, 2006,
17, 3039; (b) C. Klett, Y. Cui, S. Devineau, E. Foy, R. Dagnelie 37 J.-Z. Wu, Z.-G. Xu, Y. Li, W.-G. Zhang, H.-P. Zeng, X. Xu and
and J. P. Renault, Int. J. Hydrogen Energy, 2013, 38, 3889; Z.-Z. Zhou, J. Chem. Crystallogr., 2002, 32, 75–80.
(c) N. Chandra, D. K. Singh, M. Sharma, R. K. Upadhyay, 38 C. Temple, G. A. Rener, W. R. Waud and P. E. Noker, J. Med.
S. S. Amirtphale and S. K. Sanghi, J. Colloid Interface Sci., Chem., 1992, 35, 3686.
2010, 342, 327; (d) K. M. Rahulan, G. Vinitha, L. D. Stephan 39 A. Cugola, D. Donati, M. Guarneri, F. Micheli, A. Missio,
and C. C. Kanakam, Ceram. Int., 2013, 39, 5281;
(e) S. Jayakumar, P. V. Ananthapadmanabhan, K. Perumal,
A. Pecunioso, A. Reggiani, G. Tarzia and V. Zanirato, Bioorg.
Med. Chem. Lett., 1996, 6, 2749.
T. K. Thiyagarajan, S. C. Mishra, L. T. Su, A. I. Y. Tok and 40 C. Temple, J. D. Rose, R. D. Elliott and j. A. Montgomery,
J. Guo, Mater. Sci. Eng., B, 2011, 176, 894. J. Med. Chem., 1968, 11, 1216.
22 Joint Committee on Powder Diffraction Standards. Diffrac- 41 I. Y. Postovskii, V. N. Carushin, G. A. Mokrushina,
tion Data File, no. 37-1484, International Centre for Diffrac-
tion Data (ICDD, formerly JCPDS), Newtown Square, PA,
2001.
S. K. Kotovskaya, A. S. Barybin, O. N. Chupakhin and
A. I. Chernyshev, Pharm. Chem. J., 1982, 16, 824.
42 J. Valdez, R. Cedillo, A. Hernandez-Campos, L. Yepez,
F. Hernandez-Luis, G. Navarrete-Vazquez, A. Tapia,
R. Cortes, M. Hernandezc and R. Castilloa, Bioorg. Med.
Chem. Lett., 2002, 12, 2221.
23 B. M. Reddy, P. M. Sreekanth and R. V. R. Eddy, J. Mol.
Catal. A: Chem., 2005, 225, 71.
24 C. Li and M. Li, J. Raman Spectrosc., 2002, 33, 301.
25 M. M. Rashad and H. M. Baioumy, J. Mater. Process. Tech- 43 K. Aghapoor, H. R. Darabi, F. Mohsenzadeh, Y. Balavar and
nol., 2008, 195, 178–185. H. Daneshyar, Transition Met. Chem., 2010, 35, 49–53.
26 L. Liangrong and W. Wenzhong, Solid State Commun., 2003, 44 A. Hasaninejada, A. Zare, M. A. Zolfigol and M. Shekouhy,
127, 639–643. Synth. Commun., 2009, 39, 569–579.
27 B. S. B. Reddy, I. Mal, Sh. Tewari, K. Das and S. Das, Metall. 45 R. K. Sharma and Ch. Sharma, Catal. Commun., 2011, 12,
Mater. Trans. A, 2007, 38A, 1787. 327–331.
28 H. Zhanga, D. D. Wanga, L.-E. Denga, Zh.-T. Anb, Q. Tangb, 46 M. M. Heravi, Sh. Taheri, Kh. Bakhtiari and H. A. Oskooie,
Y. S. Wanga and W.-Ch. Lic, Mater. Charact., 2008, 59,
493–497.
29 A. Behbahani, S. Rowshanzamir and A. Esmaeilifar, Procedia
Eng., 2012, 42, 908–917.
Catal. Commun., 2007, 8, 211–214.
47 M. M. Heravi, M. H. Tehrani, Kh. Bakhtiari and
H. A. Oskooie, Catal. Commun., 2007, 8, 1341–1344.
48 T. K. Huang, R. Wang, L. Shi and X. X. Lu, Catal. Commun.,
2008, 9, 1143–1147.
¨
¨
30 N. Zink, F. Emmerling, T. Hager, M. Panthofer, M. Nawaz
Tahir, U. Kolbd and W. Tremel, Dalton Trans., 2013, 42, 49 T. M. Potewar, S. A. Ingale and K. V. Srinvasan, Synth.
432–440. Commun., 2008, 38, 3601–3612.
This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014
New J. Chem.