A novel Schiff base of Mn(III) complex supported on magnetic cobalt nanoparticles as a highly efficient retrievable heterogeneous catalyst in oxidation of alcohols and sulfides compounds

Article abstract of DOI:10.1016/j.materresbull.2015.05.016

Abstract A novel Schiff base Mn(III) complex was successfully synthesized and covalently immobilized on silica-coated magnetic cobalt nanoparticles as a support. The prepared heterogeneous catalyst showed a high catalytic activity in the oxidation of alcohols with high yield and in a milder conditions. The synthesized hybrid nanomaterials were fully characterized by FT-IR spectra, XRD and EDAX analysis. Morphology of the nanomaterials was determined by SEM and TEM. Also, the metallic magnetic cobalt and silica in the core-shell structure were determined by XPS analyses. The synthesized catalyst shows a high catalytic activity in the oxidation of alcohols and sulfides to the corresponding aldehydes and sulfoxides. Also the magnetic properties of the magnetic support and hybrid nanomaterials were measured by AGFM analysis.

Full text of DOI:10.1016/j.materresbull.2015.05.016

Accepted Manuscript
Title: A novel Schiff base of Mn(III) complex supported on
magnetic cobalt nanoparticles as a highly efficient retrievable
heterogeneous catalyst in oxidation of alcohols and sulfides
compounds
Author: Amir Reza Judy Azar Elham Safaei Sajjad Mohebbi
PII:
S0025-5408(15)00340-2
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.materresbull.2015.05.016
MRB 8227
To appear in:
MRB
Received date:
Revised date:
Accepted date:
26-12-2014
16-4-2015
10-5-2015
Please cite this article as: Amir Reza Judy Azar, Elham Safaei, Sajjad
Mohebbi, A novel Schiff base of Mn(III) complex supported on magnetic
cobalt nanoparticles as a highly efficient retrievable heterogeneous catalyst in
oxidation of alcohols and sulfides compounds, Materials Research Bulletin
http://dx.doi.org/10.1016/j.materresbull.2015.05.016
This is a PDF file of an unedited manuscript that has been accepted for publication.
As a service to our customers we are providing this early version of the manuscript.
The manuscript will undergo copyediting, typesetting, and review of the resulting proof
before it is published in its final form. Please note that during the production process
errors may be discovered which could affect the content, and all legal disclaimers that
apply to the journal pertain.

A novel Schiff base of Mn(III) complex supported on magnetic cobalt nanoparticles as a highly
efficient retrievable heterogeneous catalyst in oxidation of alcohols and sulfides compounds
Amir Reza Judy Azar, Elham Safaei, Sajjad Mohebbi*
*Department of Chemistry, University of Kurdistan, P.O. Box 66175-416, Sanandaj, Iran
Corresponding author email address: smohebbi@uok.ac.ir, Tel: +98 (871) 6624133
Graphical abstract
1

Highlights





A novel magnetic hybrid catalyst was synthesized.
Oxidation reactions were run with an environmentally friendly oxidant.
The catalyst was capable of running different oxidation reactions.
The heterogeneous catalyst could be easily recoverable from the system.
The heterogeneous catalyst was capable of running oxidation reaction several times without
significant loss in its activity.
Abstract
A novel Schiff base Mn(III) complex was successfully synthesized and covalently immobilized on
silica-coated magnetic cobalt nanoparticles as a support. The prepared heterogeneous catalyst
showed a high catalytic activity in the oxidation of alcohols with high yield and in a milder
conditions. The synthesized hybrid nanomaterials were fully characterized by FT-IR spectra, XRD
and EDAX analysis. Morphology of the nanomaterials was determined by SEM and TEM. Also,
the metallic magnetic cobalt and silica in the core-shell structure were determined by XPS
analyses. The synthesized catalyst shows a high catalytic activity in the oxidation of alcohols and
sulfides to the corresponding aldehydes and sulfoxides. Also the magnetic properties of the
magnetic support and hybrid nanomaterials were measured by AGFM analysis.
Keywords: Schiff base, manganese, magnetic cobalt, nanoparticles, sulfide oxidation, alcohol
oxidation.
2

1
. Introduction
Generally, hybrid organic-inorganic materials are a linkage between two classes of chemistry. In
hybrid materials, each part has considerably significant contributions to the field of materials
science, and each has specific properties that all together manifest distinct advantages [1].
The separation of the catalyst-product mixture is a huge problem in catalytic system. Thus, to
overcome this problem heterogenization of homogeneous catalyst has been recommended. To
date, several methods have been proposed for this issue which involves anchoring the metal
complexes on inorganic and organic supports through the formation of a covalent bond
between a linkage and the complex [2,3] or immobilizing metal complexes into or onto
inorganic supports [4-6].
More recently, salen and salophen ligands have attracted considerable attention due to their
widespread applications in the fields of catalysis and synthesis [7]. Besides, metal complexes of
salen and salophen ligands have been used as catalysts in organic reactions such as nucleic acid
modification, electrochemical reduction, olefin epoxidation, Diels-Alder transformations,
hydroxylation of alkane, carboxylic acid decarboxylation and amine oxidation [8-10].
However, these reactions generally proceed in homogeneous systems and the major
disadvantages of homogeneous catalysis systems is the problem of separation and recovery of
the catalysts from the reaction mixture at the end of the process [11-17]. From the
environmental and economic point of view, the development of suitable processes running by a
heterogeneous catalyst is of great interest.
It has been proved that the immobilization of homogeneous metal complexes onto/in solid
supports is one of the most efficient methods for preparation of heterogeneous metal
3

complexes. Various solid supports include organosilica materials [18,19], carbon materials
20,21], silica materials [22-24], zeolites [25] and layered compounds [26,27]. The
[
immobilization occurs through covalent, dative, electrostatic, encapsulation or adsorption
binding onto/in the solid supports [28-33].
In recent years, immobilization of Mn(III) complexes on solid supports has attracted
considerable attention due to the some of the advantages such as easy separation from the
reaction mixture and simple recycling of heterogeneous catalysts in the reaction system [34-
3
7].
The best point about Mn(III) complexes is that these complexes are easily synthesized, need
milder reaction condition and shorter reaction time [38].
Until now various supports have been synthesized and reported for the immobilization of
Mn(III) complexes. These supports include activated carbon [39,40], polymers [41,42] and
mesoporous silica [43-47]. Generally, organosiliconic materials are necessary for the fabrication
of heterogeneous Mn(III) catalysts immobilized on inorganic materials as support. The efficient
alcohol oxidations with O using the magnetically-recoverable heterogeneous catalyst have
2
been already investigated by researchers [48,49].
Very recently some publication have been reported for sulfides oxidation using phthalazine-
based diiron complexes [50], β-brominated meso-tetraphenylporphyrinatomanganese(III)
acetate [51], Copper-Schiff base complex [52], immobilized metalloporphyrins [53], TsOH by
phenyliodine diacetate as an oxidant [54], dendritic bis(acylamino)pyridines [55],
PyHBr
3
/TBN/H O [56], MWW-type titanosilicate zeolite [57] and ruthenium porphyrins with
2
iodobenzene diacetate [58].
4

Herein, we report the synthesis of novel magnetic hybrid organic-inorganic nanomaterials as an
efficient catalyst for alcohols and sulfides oxidation. To the best of our knowledge this is the
first report of the synthesis of Mn(III) Schiff base complex immobilized on Co@SiO
magnetic support.
2
as a
2
2
. Experimental
.1. Synthesis of magnetic cobalt nanoparticles
Cobalt nanoparticles were synthesized by a modified method [59]. In a typical procedure, 1 g
CoCl 6H O was dissolved in 60 ml doubly distilled water. Then 0.07 g citric acid was added to
2
2
the solution followed by argon bubbling into the solution for 2 minutes. In a beaker, 3 g NaBH
was dissolved in 100 ml water and drop wise added to the stock solution under argon
4
atmosphere. With the first drop of NaBH
black indicating the formation of cobalt nanoparticles.
.2. Synthesis of magnetic Co@SiO core-shell nanoparticles,
The solution containing magnetic Co nanoparticles was left to be stirred for 30 minutes. Then
00 ml ethanolic solution of 200 µl 3APTES and 800 µl TEOS was added to the stock solution
4
, the color of the solution was rapidly changed to
2
2
2
under argon atmosphere. The argon atmosphere was cut off and the solution was left to be
strongly stirred for 24 h. After this period, a puffy black precipitate with strong magnetic
property was obtained, separated by magnet, washed with ethanol and water several times.
Then the precipitate was left to be dried at 50 °C in the oven.
2
.3. Synthesis of Schiff base ligand
Typically, an equimolar amount of 3-aminopropyl triethoxysilane (3APTES) and 2-hydroxy
benzaldehyde was mixed as follows: 1 mmol of 3-aminopropyl triethoxysilane along with 1
5

mmol of 2-hydroxy benzaldehyde was added to 10 mmol methanol. The obtained mixture
stirred for 30 minutes. A yellow solution was obtained which is indicative of the formation of an
immine bond in Schiff base ligand.
2
.4. Synthesis of Schiff base Mn(III) complex
A methanolic solution (10 ml) of Mn (acac) (1mmol) was added to 5 ml methanolic solution of
3
Schiff base ligand and the total volume was reached to 40 mL by adding the same solvent. The
mixture was refluxed for an hour to complete the reaction. A darkish green precipitate was
obtained and washed with water and ethanol and filtered by Whatman paper and dried at 60
°
C.
.5. Synthesis of magnetic hybrid nanomaterial
The magnetic hybrid nanomaterials were synthesized as following procedures: 0.3g of magnetic
Co@SiO nanoparticles were ultrasonically dispersed in 10ml ethanol. Then 0.4g of the Schiff
2
2
base complex of Mn (III) was added to the solution and total volume was reached to 30 ml of
solvent. The mixture was refluxed for 10 hours. The obtained light green magnetic precipitate
was collected by a magnet and washed with water and dried in an oven at 60 °C for 12h.
2
.6. Typical procedure for oxidation of alcohols
All the reactions were carefully carried out at 40 °C in a 25 ml flask. In a typical procedure an
amount of catalyst along with H was used for the oxidation process under mild conditions.
The oxidation process was monitored by thin layer chromatography technique.
O
2 2
6

3
. Results and discussion
Fig. 1 Shows the XRD pattern of magnetic Co@SiO
support. the diffraction peaks at 2Ɵ= 44.2, 51.5 and 75.9 are attributed to the (111), (200) and
220) reflections of fcc metallic cobalt (15-0806). As it is observed, XRD pattern of the
2
support and immobilized Schiff base on the
(
immobilized Schiff base on the support also shows three peaks related to metallic cobalt. This
shows that the magnetic support does not change during immobilization of the Schiff base
complex.
Further confirmation was carried out by EDAX analysis. As shown, characteristic peaks
containing Si, O and Co are indicative of the formation of silica coated magnetic support. Also,
the EDAX analysis of magnetic catalyst shows the elements Si, O, Co, Mn, C and nitrogen, which
confirm the fabrication of Co@SiO
taken from the EDAX analyses is that there are no any extra peaks related to any impurity such
as Co , CoO or Co were observed.
2
@Mn (III) Schiff base catalyst (Fig. 2). Also, another point
O
3 4
B
3 2
To further confirm the formation of the catalyst and surface modification of the support, FT-IR
-
1
spectra were provided (Fig. 3). The synthesized Co@SiO
2
possesses the main peak at 1090 cm
-1
which indicates the formation of silica layer on magnetic cobalt NPs. The peak at 3471 cm is
assigned to the OH groups on the surface of cobalt nanoparticles. Obvious different bands can
be seen among the FT-IR spectra of the free Schiff base ligand and Schiff base complexes of
-
1
metal ion. The free Schiff base ligand shows υ(C-N) stretch at 1630-1635 cm while this band
-
1
shifts to lower frequency in the complex and manifests at 1623 cm which is due to the
-
1
coordination of the nitrogen with the metal. Vibrations in the range of 1475-1608 cm are
7

-
1
attributed to aromatic rings. Also the bands in the range of 2770-2900 cm are related to the C-
H stretching vibration of methylene groups.
3
.1. Morphological study
To investigate the morphology of the hybrid nanomaterials SEM and TEM images were
provided (Fig. 4). TEM images confirm the formation of cobalt nanoparticles coated with silica
layer. It is seen that the thickness of the silica layer is about 12 nm. As it is clear the
nanoparticles are spherical and the size of the nanoparticles is in the range of 25-50 nm.
The magnetic properties of the synthesized hybrid nanomaterials were also investigated by
alternative gradient force magnetometer (AGFM) at room temperature. Fig. 5 shows the
magnetization curves of prepared materials. The magnetization curve of magnetic Co@SiO
2
nanoparticles shows no remanence which indicates their superparamagnetic properties. Also,
magnetization curve of the hybrid nanomaterials shows superparamagnetic behavior. The
decreased saturation magnetization further confirms the immobilization of the Schiff base
complex of Mn(III) ion on the silica-coated cobalt nanoparticles. Thus, the synthesized catalyst
can still be separated from the product by applying an external magnetic field.
3
.2 X-ray photoelectron spectroscopy (XPS)
XPS analysis is a technique that is sensitive to the surface of the materials. In order to
investigate the chemical states of the elements XPS analyses were perfomed. To investigate the
stability of the magnetic support it was placed in an oven and heated an hour at 100 °C. Fig 6a
depicts the Si 2p XPS spectra of the magnetic Co@SiO nanoparticles at two temperatures (50
2
and 100 °C). As seen, in the XPS spectra of the Si 2p there is no change by rising temperature. In
the XPS spectra of the Co 2p (Fig 6b) at 50 °C the peak at 778.2 eV can be assign to the metallic
8

cobalt. By rising the temperature to 100 °C a sholder is appeared which is attributed to cobalt
oxide (779.0 eV). Thus, the XPS measurments show that the magnetic support has been made
of metallic cobalt and there is no any trace of cobalt oxide.
3
.2. Effect of reflux time on loading of metal content over magnetic support
To synthesize the hybrid material, the Schiff base complex of Mn(III) ion and silica-coated
magnetic support were refluxed in ethanolic solution. To find the effect of reflux time on the
metal content immobilized on magnetic support the mixture was refluxed for different period
of time. The results have been summed up in table 1. As it is shown by increasing the reflux
time the amount of loaded metal on the support has been increased. The maximum metal
content is 7.19 wt% after 360 minutes of reflux. Thus, this amount was chosen as a catalyst for
the oxidation reactions.
4
4
. Catalytic activities of the synthesized catalyst
.1. Oxidation of alcohols
The catalytic activity of the Co@SiO @[Mn(III)SB] was investigated in the reaction of alcohol
2
oxidation. Benzyl alcohol was used as a sample. The reaction was run in different solvents and
in solvent free conditions. As an initial test, different amounts of the catalyst and ethyl acetate
as a solvent was mixed in a glass tube and stirred with a magnet. Then, hydrogen peroxide
(
30%) was added to the solution. The reaction progress was monitored by thin layer
chromatography in a regular alternative time. The results have been summed up in table 2. The
obtained results show that the magnetic catalyst is considerably selective and transforms
alcohols to the corresponding aldehydes. To improve the yield of the reaction and find the
optimized conditions, several reactions were carried out in the same conditions with changing
9

parameters (table 2, entry 2-9). Also, the oxidation reaction was run in the absence of the
catalyst and it was found that the reaction proceeds only 4%, which confirms the importance of
the catalyst for the reaction completion (table 2, entry 10).
The yield of the reactions was determined by extraction method as follows: The heterogeneous
catalyst was separated from the reaction mixture. Then the organic phase was separated by
water/ethyl acetate extraction method and the solvent was dried. Next, in order to isolate the
aldehyde from the remaining alcohol the mixture was stirred in warm n-hexane several times.
Thus, the aldehyde was dissolved in warm n-hexane and isolated from remaining alcohol. The
aldehyde was weighted and the yield of the reaction was calculated.
According to the metal content turn over number (TON) and turn over frequency (TOF) of the
catalyst were calculated (table 2, entry 11). The amount of metals loaded on magnetic support
determined by flame atomic absorption spectrophotometer (FAAS).
To investigate the performance capability of the magnetic catalyst in solution the oxidation
reaction was carried out in various solvents. The results show that the catalyst is highly active in
different solvents and convert alcohols to the corresponding aldehyde with high yield (Table 3).
Also the highest yield was obtained in acetonitrile and ethyl acetate. An important point is that
the catalyst acts selectively in various solvent which is of great importance.
4
.2. Effect of temperature on the reaction of alcohol oxidation
To investigate the effect of temperature on the oxidation process the reaction was run at
different temperature in the range of 20 to 60 °C (Fig. 7a). By raising the temperature from 20
to 60 °C the yield of the reaction is increased from 35 to 92%. Upper than 45 °C no considerable
10

change in the yield of the reaction occurs. So, the optimized temperature was chosen 45 °C for
further reactions.
Table 4 shows the results of the oxidation of the variety of aromatic and aliphatic alcohols in
the presence of the catalyst Co@SiO @[Mn(III)SBC]. As it is seen the selectivity is 100% in any
2
case of alcohol. A slight difference in the time of the reactions is probably due to the presence
of electron-donating and electron-withdrawing groups on the benzene ring which cause the
alcohols to be slightly active or inactive.
4
.3. Separation and recyclability
The supported catalyst was applied in the oxidation reaction. Totally, to evaluate the
performance of the catalyst, after recycling the reaction was carried out for several times. After
each run the magnetic catalyst was separated by external magnetic field and applied in another
run. As it is seen (Fig. 7b) the synthesized catalyst is capable to run the oxidation reaction after
8
runs without any considerable loss in its catalytic activity.
5
. Oxidation of sulfides
To further evaluate the performance of the synthesized catalyst, oxidation of sulfides was also
investigated. Methyl (phenyl) sulfide was used as a sample and hydrogen peroxide was used as
an oxidant. The reaction was carried out in different solvents and in solvent free conditions.
Firstly, different amounts of the magnetic Schiff base complex along with methyl phenyl sulfide
were stirred in a glass tube. Then ethyl acetate as a solvent was added and the mixture was
11

stirred with a magnet. After some minutes hydrogen peroxide (30%) was added to the solution.
Thin layer chromatography was used for monitoring the reaction progress in a regular
alternative time. The results summed up in table 5. As the results show the magnetic catalyst is
considerably selective and transforms methyl phenyl sulfide to the corresponding sulfoxide and
there is not any trace of second order oxidation product like sulfone which is a great advantage
of this catalyst.
To confirm the necessity of the catalyst presence for completion of the reaction (table 5, entry
8
) the oxidation reaction was carried out in the absence of the catalyst. The result showed that
reaction is not completed and only 7% of the reaction proceeds which shows the importance of
the catalyst in oxidation reaction.
In continue, the effect of solvents on the oxidation reaction was investigated. To do this,
oxidation of methyl phenyl sulfide was carried out in different solvent. It was found that the
synthesized catalyst is capable to act selectively in different solvents and produce the desired
product with high yield. As observed, the maximum conversion with 100% selectivity is
obtained in acetonitrile and dimethylformamide solvent.
To evaluate the performance capability of the magnetic Mn(III) Schiff base complex, different
sulfides compounds were subjected to the catalyst. The results show that the catalyst is capable
of oxidizing all sulfide compounds and convert them to the corresponding sulfoxides with high
yield and 100 % selectivity (Table 7).
12

5
.1. Sheldon’s test for heterogeneous catalyst
To determine whether the reaction is truly carried out in a heterogeneous way or not, hot
filtration test was investigated [60]. The result is as follows. In the half way of the reaction
process the reaction media were filtered in hot condition. The magnetic catalyst remained on
the filter paper and the filtrate came through. In the next step the reaction was continued. It
was found that the conversion remained the same of the filtrate. This showed that there was
no leaching of the immobilized Schiff base complex. Thus, this confirms that the synthesized
catalyst acts heterogeneously.
5
.2 Utilization efficiency of hydrogen peroxide
Table 8 shows the results of the hydrogen peroxide utilization efficiency in oxidation reactions
of alcohol and sulfide. As indicated above, in the oxidation of alcohols and sulfides the amount
of substrates were 0.5 mmol and 1 mmol respectively, and the amount of consumed hydrogen
peroxide was 90 µl and 130 µl for alcohols and sulfides.
Table 8.
The utilization efficiency of the hydrogen peroxide in alcohol oxidation is 69% and in sulfide
oxidation is 78%.
Conclusion
Synthetic processes for magnetic nanomaterials are currently undergoing quick improvement
and open tremendous possibilities for the fabrication of magnetically-recoverable catalysts.
Separation and recovery of catalysts by external magnetic field is an environmentally friendly
alternative because not only it minimizes the use of auxiliary materials, but also prevents mass
loss and reduces the operation time. We have synthesized a highly active catalyst based on
13

Schiff base complexes of Mn(III) ion supported on magnetic cobalt nanoparticles for the first
time. This synthesized catalyst was capable to run the oxidation reactions of alcohols and
sulfides with high yield. Also investigation of other catalytic reactions with this synthesized
nanocatalyst is in progress.
Acknowledgment
The financial support rendered by the University of Kurdistan is gratefully acknowledged.
References
[
[
[
[
[
1] P. Gomez-Romero, Adv. Mater. (2001) 163-174.
2] A.R. Silva, J.L. Figueiredo, C. Fieire, B.D. Castro, Micropor. Mesopor. Mater. 68 (2004) 83-89.
3] C. Venkatesan, A.P. Singh, , J. Catal. 227 (2004) 148-163.
4] A´. Zsigmond, K. Boga´ r, F. Notheisz, J. Catal. 213 (2003) 103-108.
5] D. Gournis, M. Louloudi, M.A. Karakassides, C. Kolokytha, K. Mitopoulou, N. Hadjiliadis, ,
Mater. Sci. Eng. C 22 (2002) 113-116.
6] T. Joseph, S.B. Halligudi, C. Satyanarayan, D.P. Sawant, S. Gopinathan, J. Mol. Catal. A: Chem.
68 (2001) 87-97.
[
1
[
[
[
[
(
(
7] L. Canalai, D.C. Sherrington, Chem. Soc. Rev. 72 (1999) 603.
8] W. Zhang, J.L. Loebach, S.R. Wilson, E.N. Jacobsen, J. Am. Chem. Soc. 112 (1990) 2801-2803.
9] S.B. Routier, J.L. Bernier, M.P. Catteau, C. Bailly, Bioorg. Med. Chem. Lett. 7 (1997) 63-66.
10] (a) V. Mirkhani, S. Tangestaninejad, M. Moghadam, M. Moghbel Bioorg. Med. Chem. 12
2004) 903-906.
b) V. Mirkhani, S. Tangestaninejad, M. Moghadam, M. Moghbel, Bioorg. Med. Chem. 12 (2004)
4
673-4677.
14

[
11] M. Moghadama, S. Tangestani nejada, V. Mirkhani, I. Mohammadpoor-Baltork, A. Mirjafari,
N.S. Mirbagheri, J. Mol. Catal. A: Chem. 329 (2010) 44-49.
12] S.L. Weia, Y.H. Tang, X.Q. Xu, G.J. Xu, Y. Yu, Y. Sun, Y.S. Zheng, Appl. Organometal. Chem.
5 (2011) 146-153.
13] M.E. Amato, F.P. Ballistreri, A. Pappalardo, G.A. Tomaselli, R.M. Toscano, D.J. Williams, Eur.
J. Org. Chem. (2005) 3562-3570.
[
2
[
[
(
[
[
14] J.Y. Yang, S.Y. Liu, I.V. Korendovych, E.V. Rybak-Akimova, D.G. Nocera, Chem Sus Chem. 1
2008) 941-949.
15] K. Yu, L.L. Lou, F. Ding, S.J. Wang, Z.L. Wang, S.X. Liu, Catal. Commun. 7 (2006) 170-172.
16] P.A. Ulmann, A.B. Braunschweig, O. Lee, M.J. Wiester, G.C. Schatz, C.A. Mirkin, Chem.
Commun. (2009) 5121-5123.
[
[
17] J. Huang, X.K. Fu, G. Wang, Y.Q. Ge, Q. Miao, Sci. Technol. 2 (2012) 1040-1050.
18] J.L. Hu, Q.Y. Wu, K.X. Li, W. Li, F.Y. Ma, S.Q. Zhang, F. Su, Y.H. Guo, Y.H. Wang, Catal.
Commun. 12 (2010) 238-242.
19] J.L. Hu, Q.Y. Wu, W. Li, L. Ma, F. Su, Y.H. Guo, Y.Q. Qiu, Chem Sus Chem. 4 (2011) 1813-
822.
[
1
[
[
[
[
20] A.R. Silva, V. Budarin, J.H. Clark, C. Freire, Carbon 45 (2007) 1951-1964.
21] A.R. Silva, V. Budarin, J.H. Clark, Carbon 43 (2005) 2096-2105.
22] H. Zhang, Y. Zhang, C. Li, J. Catal. 238 (2006) 369-381.
23] R.I. Kureshy, I. Ahmad, N.H. Khan, S.H.R. Abdi, K. Pathak, R.V. Jasra, J. Catal. 238 (2006)
1
34-141.
[
24] H. Zhang, S. Xiang, C. Li, Chem. Commun. (2005) 1209-1211.
15

[
[
25] M. Salavati-Niasari, M.R. Ganjali, P. Norouzi, J. Porous Mater. 14 (2007) 423-432.
26] B.M. Choudary, T. Ramani, H. Maheswaran, L. Prashant, K.V.S. Ranganath, K.V. Kumar, Adv.
Synth. Catal. 348 (2006) 493-498.
[
[
[
[
[
27] S. Bhattacharjee, T.J. Dines, J.A. Anderson, J. Phys. Chem. C 112 (2008) 14124-14130.
28] M. Beigi, R. Haag, A. Liesec, Adv. Synth. Catal. 350 (2008) 919-925.
29] A. Zulauf, M. Mellah, X. Hong, E. Schulz, Dalton Trans. 39 (2010) 6911-6935.
30] L. Saikia, D. Srinivas, P. Ratnasamy, Micropor. Mesopor. Mater. 104 (2007) 225-235.
31] I. Kuz´niarska-Biernacka, O. Rodrigues, M.A. Carvalho, I.C. Neves, A.M. Fonseca, Appl.
Organometal. Chem. 26 (2012) 44-49.
32] A.R. Silva, J.L. Figueiredo, C. Freire, B.D. Castro, Micropor. Mesopor. Mater. 68 (2004) 83-
9.
33] R.I. Kureshy, N.H. Khan, S.H.R. Abdi, I. Ahmad, S. Singh, R.V. Jasra, J. Catal. 221 (2004) 234-
40.
[
8
[
2
[
[
34] A.F. Trindade, P.M.P. Gois, C.A.M. Afonso, Chem. Rev. 109 (2009) 418-514.
35] J.M. Fraile, J.I. García, C.I. Herrerías, J.A. Mayoral, E. Pires, Chem. Soc. Rev. 38 (2009) 695-
7
06.
36] N.C. Maity, S.H.R. Abdi, R.I. Kureshy, N.H. Khan, E. Suresh, G.P. Dangi,H.C. Bajaj, J. Catal.
77 (2011) 123-127.
[
2
[
[
[
[
37] R. Tan, D. Yin, N. Yu, Y. Jin, H. Zhao, D. Yin, J. Catal. 255 (2008) 287-295.
38] W. Sun, H. Wang, C. Xia, J. Li, P. Zhao, Angew. Chem. Int. Ed. 115 (2003) 1072-1074;
39] A.R. Silva, C. Freire, B. De Castro, Carbon 42 (2004) 3027-3030.
40] A.R. Silva, V. Budarin, J.H. Clark, C. Freire, B. de Castro, Carbon 45 (2007) 1951-1964.
16

[
[
[
41] B. Gong, X. Fu, J. Chen, Y. Li, X. Zou, X. Tu, P. Ding, L. Ma, J. Catal. 262 (2009) 9-17.
42] X. Tu, X. Fu, X. Hu, Y. Li, Inorg. Chem. Commun. 13 (2010) 404-407.
43] H. Zhang, Y.M. Wang, L. Zhang, G. Gerrtsen, H.C.L. Abbenhuis, R.A. van Santen, C. Li, J.
Catal. 256 (2008) 226-236.
[
[
44] H. Zhang, Y. Zhang, C. Li, J. Catal. 238 (2006) 369-381.
45] R.I. Kureshy, I. Ahmad, N.H. Khan, S.H.R. Abdi, K. Pathak, R.V. Jasra, J. Catal. 238 (2006)
1
34-141.
46] R.I. Kureshy, I. Ahmad, N.H. Khan, S.H.R. Abdi, K. Pathak, R.V. Jasra, Tetrahedron:
Asymmetry. 16 (2005) 3562-3569.
[
[
[
(
[
[
47] X. Tang, Y. Tang, G. Xu, S. Wei, Y. Sun, Catal. Comm. 10 (2008) 317-320.
48] K. Mori, S. Kanai, T. Hara, T. Mizugaki, K. Ebitani, K. Jitsukawa, K. Kaneda, Chem. Mater. 19
2007) 1249-1256.
49] V. Polshettiwar, R.S. Varma, Org. Biomol. Chem. 7 (2009) 37-40.
50] M. Szávuly, S.D. Szilvási, R. Csonka, D. Klesitz, G. Speier, M. Giorgi, J. Kaizer, Journal of
Molecular Catalysis A: Chemical 393 (2014) 317-324
[
[
[
[
[
[
51] S. Rayati, F. Nejabat, S. Zakavi, Inorganic Chemistry Communications 40 (2014) 82-86.
52] P. Gogoi, M. Kalita, T. Bhattacharjee, P. Barman, Tetrahedron Letters 55 (2014) 1028-1030
53] X.T. Zhou, H.B. Ji, Catalysis Communications 53 (2014) 29-32.
54] B. Yu, C.X. Guo, C.L. Zhong, Z.F. Diao, L.N. He, Tetrahedron Letters 55 (2014) 1818-1821.
55] Y. Imada, T. Kitagawa, S. Iwata, N. Komiya, Takeshi Naota, Tetrahedron 70 (2014) 495-501.
56] H. Zhang, G. Wang, Tetrahedron Letters 55 (2014) 56-58.
17

[
57] Y. Kon, T. Yokoi, M. Yoshioka, S.Tanaka, Y. Uesaka,T. Mochizuki, K. Sato, T. Tatsumi,
Tetrahedron 70 (2014) 7584-7592
[
[
[
58] T.H. Chen, Z. Yuan, A.Carver, R. Zhang, Applied Catalysis A: General 478 (2014) 275-282.
59] M. Aslam, S. Li, and V. P. Dravid, J. Am. Ceram. Soc. 90 [3] (2007) 950-956.
60] H.E.B. Lempers, R.A. Sheldon, J. Catal. 175 (1998) 62-69.
18

Figures caption
Scheme 1. Synthesis of magnetic metallic cobalt nanoparticles in water
Fig. 1. XRD patterns of Co nanoparticles coated with silica layer (a) and catalyst (b).
Fig. 2. EDAX analyses of Co@SiO nanoparticles and catalyst Co@SiO2@[Mn(III)SB].
2
Fig. 3. FT-IR spectra of magnetic metallic Co NPs, Schiff base ligand and synthesized magnetic.
Fig. 4. TEM image of Co NPs , silica-coated cobalt nanoparticles and the magnetic catalyst
Co@SiO
Fig. 5. AGFM analysis of Co@SiO
Fig 6. XPS analyses of the Co@SiO
2
@[Mn(III)SB].
2
and catalyst Co@SiO
2
@[Mn(III)SB].
2
and high resolution TEM image of Co@SiO .
2
Fig. 7. The effect of temperature on the oxidation of benzyl alcohol by Co@SiO
and number of recycling of the catalyst (b).
2
@Mn(III)SBC (a)
19

Scheme 1
Fig. 1.
2
0

Fig. 2.
2
1

Fig. 3.
2
2

Fig. 4.
2
3

Fig. 5.
24

Fig. 6.
2
5

Fig. 7.
2
6

Table 1. Effect of reflux time on loading of metal content on magnetic support.
Entry
Reflux
time (min) (Co@SiO
Support Anchoring group
Catalyst
Metal
loaded
2
)
(Mn(II)SBC)
(
wt%)
4.34
5.87
6.17
7.18
7.19
1
2
3
4
5
120
180
240
300
360
0.3 g
0.3 g
0.3 g
0.3 g
0.3 g
0.4 g
0.4 g
0.4 g
0.4 g
0.4 g
Co@SiO
Co@SiO
Co@SiO
Co@SiO
Co@SiO
2
@[Mn(II)SBC]
2
@[Mn(II)SBC]
2
@[Mn(II)SBC]
2
@[Mn(II)SBC]
2
@[Mn(II)SBC]
Table 2. The optimized amounts of the catalyst and oxidant in oxidation reaction.
Initial test
Entry Co@SiO
1
2
@[Mn(III)SB]
H
2
O
2
(30%)
Product
Selectivity Isolated
Yield %
µl, (mmol)
30, (0.293 mmol) benzaldehyde
0.02 g
100
32
Experiments to obtain optimized conditions
2
3
4
5
6
7
8
9
0.02 g
0.02 g
0.02 g
0.03 g
0.03 g
0.03 g
0.03 g
0.03 g
40, (0.391 mmol)
50, (0.489 mmol)
60, (0.587 mmol)
60, (0.587 mmol)
70, (0.685 mmol)
80, (0.783 mmol)
90, (0.881 mmol)
benzaldehyde
benzaldehyde
benzaldehyde
benzaldehyde
benzaldehyde
benzaldehyde
benzaldehyde
100
100
100
100
100
100
100
100
100
44
51
63
72
81
89
92
94
4
100, (0.979 mmol) benzaldehyde
90, (0.881 mmol) benzaldehyde
1
0
Not used
The amount of metal loaded on magnetic support and calculation of TON and TOF numbers
a
-1 b
Entry
Catalyst
The amount of Metal loaded (wt %) TON
TOF (h )
1
1
Co@SiO @Mn(III)SBC
2
7.19 95
87
Reaction conditions: benzyl alcohol (0.6 mmol), temperature 45 °C, solvent: ethyl acetate 3ml.
a
Moles of substrate converted per moles of metal in the catalyst ([substrate]/[metal]×100).
27

Table 3. The effect of various solvents on the oxidation of benzyl alcohol to benzaldehyde.
Entry
catalyst
solvent
product
Time
min)
Selectivity Isolated
(
(%)
100
100
100
Yield
81
91
88
2
3
4
Co@SiO
2
2
2
@Mn(III)SBC
Acetone
Acetonitrile
DMF
benzaldehyde 40-45
benzaldehyde 40-45
benzaldehyde 40-45
Co@SiO
Co@SiO
@Mn(III)SBC
@Mn(III)SBC
5
Co@SiO
@Mn(III)SBC Ethyl acetate benzaldehyde 40-45
2
100
94
Reaction conditions: benzyl alcohol (0.6 mmol), temperature 45 °C, 90 µl H
mmol).
O
2 2
(30%) (0.881
Table. 4. Oxidation of the variety of aromatic and aliphatic alcohols in the presence of the
catalyst Co@SiO @[Mn(III)SBC].
2
Entry
Sulfides
Catalyst
product
Time Selectivit Isolated
(
min)
y
%
yield %
1
2
3
4
CSMn(III)S
B
40-45
40-45
40-45
40-45
100
100
100
100
92
CSMn(III)S
B
90
CSMn(III)S
B
87
CSMn(III)S
B
86
-O
O
OH
N+
5
6
CSMn(III)S
B
40-45
40-45
100
100
90
98
CSMn(III)S
B
28

7
8
9
CSMn(III)S
B
40-45
40-45
40-45
100
100
100
94
87
89
CSMn(III)S
B
CSMn(III)S
B
Amount of catalyst CSMn(III)SB 0.03 g, Substrate: Benzyl alcohol (0.6 mmol), 90 µl H
0.881 mmol), temperature 45 °C, solvent: Ethyl acetate.
2
O 30%
2
(
Table 5. Oxidation of methyl phenyl sulfide using an aqueous solution of hydrogen peroxide
0%.
3
a
Entry
Catalyst
amount (mg)
H
2
O
2
Time
(min)
40-45
40-45
40-45
40-45
40-45
40-45
40-45
40-45
Sulfoxide Sulfone
µl, (mmol)
60, (0.587 mmol)
70, (0.685 mmol)
90, (0.881 mmol)
100, (0.979 mmol)
110, (1.07 mmol)
120, (1.17 mmol)
130, (1.27 mmol)
100, (0.979 mmol)
%
42
51
60
76
87
92
93
7
%
N.P
b
1
2
3
4
5
6
7
8
30
40
40
40
40
40
40
No
N.P
N.P
N.P
N.P
N.P
N.P
N.P
Substrate (1 mmol), catalyst: Co@SiO
Isolated yield. No Product.
2
@[Mn(III)SBC], Ethyl acetate (3ml), temperature 45 °C.
a
b
29