Preparation of Polydopamine Sulfamic Acid-Functionalized Silica Gel as Heterogeneous and Recyclable Nanocatalyst for Acetylation of Alcohols and Amines Under Solvent-Free Conditions

Article abstract of DOI:10.1007/s10562-018-2486-1

To fabricate SiO₂/PDA–SO₃H nanocatalyst, a suitable method is designed for the loading of sulfonic acid groups on the surface of polydopamine (PDA)-encapsulated SiO₂ nanoparticles. To bridge the gap between heterogeneous and homogeneous catalysis, surface functionalization of silica gel is an elegant procedure. The morphology, structure, and physicochemical features were specified using different analytical techniques including field emission scanning electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FT-IR), high resolution-transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDX), X-ray photoelectron spectroscopy (XPS), and back titration. The SiO₂/PDA–SO₃H nanoparticles are efficient nanocatalysts for the acetylation of many alcohols, phenols, and amines with acetic anhydride under solvent-free conditions in good to excellent yields. Moreover, the reuse and recovery of the catalyst was shown seven times without detectible loss in activity. Graphical Abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s10562-018-2486-1

Catalysis Letters
https://doi.org/10.1007/s10562-018-2486-1
Preparation of Polydopamine Sulfamic Acid-Functionalized Silica
Gel as Heterogeneous and Recyclable Nanocatalyst for Acetylation
of Alcohols and Amines Under Solvent-Free Conditions
Hojat Veisi1 · Saba Vafajoo1 · Kiumars Bahrami2,3 · Bita Mozafari4
Received: 25 May 2018 / Accepted: 8 July 2018
© Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract
To fabricate SiO2/PDA–SO3H nanocatalyst, a suitable method is designed for the loading of sulfonic acid groups on the sur-
face of polydopamine (PDA)-encapsulated SiO2 nanoparticles. To bridge the gap between heterogeneous and homogeneous
catalysis, surface functionalization of silica gel is an elegant procedure. The morphology, structure, and physicochemical
features were specified using different analytical techniques including field emission scanning electron microscopy (FESEM),
Fourier transformed infrared spectroscopy (FT-IR), high resolution-transmission electron microscopy (HR-TEM), energy
dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDX), X-ray photoelectron spectroscopy
(XPS), and back titration. The SiO2/PDA–SO3H nanoparticles are efficient nanocatalysts for the acetylation of many alcohols,
phenols, and amines with acetic anhydride under solvent-free conditions in good to excellent yields. Moreover, the reuse
and recovery of the catalyst was shown seven times without detectible loss in activity.
Graphical Abstract
R XH
R = alkyl, aryl
X = NH, O
HO
H2N
R XAc
N
H
HO
HO
NH
Ac2O
r.t.
N
H
HO
NHSO3H
NHSO3H
HO
OH
HO
OH
HO3SHN
PDA
HO3SHN
NHSO3H
NHSO3H
NHSO3H
HO
HO
NH2
HO3SHN
HO3SHN
Tris, pH = 8.5
ClSO3H
SiO2
HO3SHN
NHSO3H
SiO2/PDA
NHSO3H
SiO2/PDA-SO3H
Keywords Silica gel · Polydopamine · Sulfonic acid · Acetylation · Amine · Alcohol
Extended author information available on the last page of the article
Vol.:(0123456789)
1 3

H. Veisi et al.
SiO2-supported catalysts indicate great dispersion and
reactivity with a high chemical stability degree. Different
catalysts and ligands have been immobilized on these par-
ticles through employing these privilages of silica nano-
particles over other supporting materials [27]. In recent
years, heterogeneous sulfonic acids have served as impor-
tant functional materials in chemical reactions because of
their superacidity, high activity at low temperatures, and
nontoxicity [28–33].
1 Introduction
The “green chemistry” principles of chemical reactions
have persuaded using reusable strong solid acids as
options for unrecyclable “liquid acids” catalysts includ-
ing nitric acid, sulfuric acid, etc. Although applying new
solid acid catalysts has been developed extensively, new
methodologies should be discovered for the immobiliza-
tion of sulfonic acid. These solid acids are economically
and industrially appropriate alternatives due to their par-
ticular features involving the use of less toxicity and avail-
able precursors, simple and non-energy-intensive proce-
dures for reuse and recovery of catalyst [1]. Hence, using
nanoparticles as heterogeneous catalysts has attracted sig-
nificant attention due to the structural features and great
catalytic activity levels related to these materials [2]. In
addition, nanoparticle materials are a bridge between het-
erogeneous and homogeneous catalysts [3]. Also, using
transition metal nanoparticles as catalysts for organic reac-
tions is crucial since nanoparticle-based catalytic systems
can show superior catalytic activities compared with the
corresponding bulk materials. Transition metal oxides are
efficient catalysts in organic reactions. These high reactivi-
ties are because of high surface areas which are combined
with unusual reactive morphologies.
In this study, a novel reusable solid acid composite was
prepared using PDA. At first, in aqueous solution through
catechol and nitrogen-containing groups, a PDA layer was
coated on the silica gel surfaces via in situ spontaneous
oxidative polymerization to enhance the SiO2 dispersion.
Afterwards, sulfonated-polydopamine coated SiO2 nano-
composite (SiO2/PDA) was provided as an efficient solid
acid nanocatalyst using chlorosulfonic acid (Scheme 1).
The major purpose of this catalytic synthesis was to present
a new and efficient acidic nanocomposite on the basis of
silica gel to broaden the application of these composites for
organic reactions. To examine the catalytic activity of this
nanocatalyst, acetylation of alcohols, phenols and amines
with acetic anhydride were selected as prominent synthetic
compounds (Scheme 1).
Acetylation of phenols, alcohols, and amines is a mostly
used transformation in synthetic chemistry and employed
widely as protecting group in multi-step pharmaceuti-
cal synthesis and cosmetic or food industries [4, 5]. The
hydroxyl and amino groups acetylation has been done
through acetyl chloride or acetic anhydride in the presence
of either base [6–9] or acid catalysts [10–16]. Although
there are different acetylation ways, the majority of proto-
cols to date had innate shortcoming such as harsh condi-
tions, harmful organic solvents, long reaction times, and
tedious work-up methods [17–19]. A promising solution to
these problems is possibly the use of insoluble and green
nanocatalysts or eco-friendly solvent-free conditions.
Generally, these premises are employed for the usage of
nano-materials and supported nanoparticles as catalysts in
different chemistries types. Accordingly, using supported
silica materials has been applied efficiently as heterogene-
ous catalysts. The prominent merit of a catalytic system
according to silica nanoparticles is that the nanoparticles
can be separated efficiently from the reaction mixture via
a simple filtration after completion of reaction [20, 21].
On the other hand, nanoparticles are effective alternative
support materials for the immobilization homogeneous
catalyst [22, 23]. Because of their high surface area, these
nanoparticles possess a wide range of potential usages in
biomedicine, physics, material science, biotechnology,
and catalysis support applications [24–26]. Moreover, the
2 Experimental
2.1 Preparation of SiO2/PDA and SiO2/PDA–SO3H
Nanoparticles
Silica gel (1 g) were dispersed in 500 mL Tris buffer
(10 mM, pH 8.5), then dopamine (1 g) was added, and the
mixture solution was mechanically stirred for 24 h at room
temperature. After reaction, the SiO2/PDA nanoparticles
were filtrated and washed with deionized water and anhy-
drous ethanol and dried at 40 °C to give SiO2/PDA.
In the next step, the SiO2/PDA was sulfonated using
chlorosulfonic acid (ClSO3H). The SiO2/PDA composite
(1 g) were dispersed in dry CH2Cl2 (50 mL) by ultrasonic
bath for 20 min. Subsequently, chlorosulfonic acid (0.8 mL)
was added dropwise over a period of 30 min at room tem-
perature. Upon completion of the addition, the mixture was
stirred for 5 h at room temperature. The resulted nanocata-
lyst was separated from the suspension by centrifugation,
washed several times with CH2Cl2 and ethanol (50%) and
then dried at 40 °C to give SiO2/PDA–SO3H (Scheme 1).
The content of acid sites of SiO2/PDA–SO3H nanocompos-
ite was estimated by back titration using HCl (0.337 N). 10 mL
of NaOH (0.130 N) was added to 0.1 g of this composite and
stirred for 30 min. The catalyst was separated and washed with
deionized water. The excess amount of NaOH was titrated with
1 3

Preparation of Polydopamine Sulfamic Acid-Functionalized Silica Gel as Heterogeneous and…
R XH
R = alkyl, aryl
X = NH, O
HO
H2N
R XAc
N
HO
NH
H
HO
Ac2O
r.t.
N
H
HO
NHSO3H
NHSO3H
HO
OH
HO
OH
HO3SHN
PDA
HO3SHN
NHSO3H
NHSO3H
NHSO3H
HO
HO
NH2
HO3SHN
HO3SHN
Tris, pH = 8.5
ClSO3H
SiO2
HO3SHN
NHSO3H
SiO2/PDA
NHSO3H
SiO2/PDA-SO3H
Scheme 1 Preparation of SiO2/PDA–SO3H and its application for acetylation of alcohols, phenols and amines
HCl (0.337 N) in the presence of phenolphthalein as indicator.
The acid site content was 0.32 mmol g−1.
solution (pH 8.5) with constant stirring. The prosperous
produced SiO2/PDA nanostructure was sulfonated further
using chlorosulfonic acid to obtain polydopamine sulfamic
acid-functionalized silica nanoparticles (SiO2/PDA–SO3H)
as a new heterogeneous solid acid nanocatalyst (Scheme 1).
FT-IR, HR-TEM, FESEM, WDX, EDX, and XPS analyses
were performed to characterize the obtained nanocatalyst.
Figure 1 displays the comaprison of the FT-IR spectra of
SiO2/PDA–SO3H and SiO2. The FT-IR spectrum of SiO2
(Fig. 1a) shows solid bands in the low-frequency region of
500–1000 cm−1 because of the silica skeleton, which is in
line with the silica spectrum. The Si–O and O–H character-
istic bands are seen at 1082 and 3200–3500 cm−1, respec-
tively [34]. The peaks at 3400, 2930, 1480, and 1465 cm−1
can be attributed to O–H stretching, C–H stretching, C=C
stretching, and C–N stretching which correspond to the func-
tional groups –OH of phenol and –C=C–NH– in the SiO2/
PDA [35], while the peaks at 1635 and 1512 cm−1 can be
assigned to the benzene ring skeleton vibration [35]. These
findings reveal that PDA polymer is immobilized success-
fully on the silica gel surface through physical and chemical
adsorption. In addition, the prosperous NH groups’ sulfona-
tion by ClSO3H was approved by a 1000–1300 cm−1 band,
indicating SO3H groups [36].
2.2 General Procedure for Acylation Reaction
A 25 mL ballon containing a magnetic stir bar was charged
with phenol/alcohol/amine (1 mmol) and acetic anhydride
(2 mmol), SiO2/PDA–SO3H (30 mg, 1 mol% H+) as catalyst.
The reaction mixture was stirred at room temperature and the
reaction progress was monitored on thin-layer chromatography
(TLC). After completion of the reaction, the reaction mix-
ture was diluted with ethyl acetate and catalyst was separated
from reaction mixture by centrifugation. The reaction mixture
was washed with sat. NaHCO3 solution (1×15 mL) and the
product was extracted with ethyl acetate (3×10 mL) and dried
over Na2SO4 and evaporated under vacuum. All the obtained
products are well known in the literature.
2.3 Procedure for Reusing the Catalyst
After the reaction time, the catalyst SiO2/PDA–SO3H was
separated by centrifugation and washed several times with
EtOH, water and acetone. Then, the recovered dried catalyst
under vacuum was used for another run.
The morphology and size of SiO2/PDA–SO3H was inves-
tigated using scanning electron microscopy. The FESEM
image of (a) SiO2 and (b) SiO2/PDA–SO3H showed that the
catalyst was made in nanometer-sized particles as quasi-
spherical with mean diameter of 10 5 nm (Fig. 2a, b).
Compared with Fe3O4, a continuous layer of polymer can
be detected on the SiO2/PDA–SO3H catalyst surface. The
presence of PDA shell on the silica NPs surface was also
3 Results and Discussion
3.1 Characterization
The silica gel modification with polydopamine was obtained
through in situ polymerization of dopamine in tris-buffer
1 3

H. Veisi et al.
Fig. 1 FT-IR spectra of a SiO2
and b SiO2/PDA–SO3H
approved by the EDX detector coupled to FESEM, indicat-
ing Si, C, N, S, and O (Fig. 2c).
with exhibition of a single S 2s peak corresponding to SO3H
groups at 231.5 eV (2%) [38].
Wavelength-dispersive X-ray spectroscopy (WDX) can
prepare qualitative data on the distribution of various chemi-
cal elements in the catalyst matrix in combination with scan-
ning electron microscopy (SEM). Figure 3 depicts images
of representative SEM and corresponding elemental maps
(WDX) for the synthesized catalyst. The sulfur particles are
dispersed adequately in the composite. The selected-area
elemental analysis figure shows homogeneously C, N, S, O,
and Si in the sample, confirming the regular uniformity of
the sample.
3.2 Catalytic Application of SiO2/PDA–SO3H
in the N/O‑Acetylation
Its catalytic activity was studied as a new heterogeneous
solid acid nanocatalyst for acetylation of alcohols, phenols,
and amines with acetic anhydride after structural charac-
terization of the obtained silica-polymer composite (SiO2/
PDA–SO3H) (Scheme 1) [39–53].
The phenol’s reaction with acetic anhydride as acetylating
agent was selected as a model reaction and carried out in
various states in the presence of the SiO2/PDA–SO3H nano-
catalyst to indicate the optimum conditions for this transfor-
mation. Several solvents were tested for the acetylation of
phenol, and it was revealed that the reaction did not com-
plete. Finally, the acetylation reaction was done under sol-
vent free conditions. Table 1 (entry 7) indicates that, under
solvent free conditions, the optimal catalyst loading (40 mg,
20 mol%) was the optimal one for the synthetic process and
brought about the highest product yield (95%). When the
catalyst amount was lower, the product yield decreased
(Table 1, entry 8), while increasing the catalyst concentra-
tion did not significantly enhance the product yield (Table 1,
entry 9). Even after prolonged reaction time, no product was
seen in the absence of catalyst (Table 1, entry 10).
HR-TEM measurement confirmed the SiO2/PDA–SO3H
nanostructure. Figure 4 shows that a clear PDA coat (nearly
10 nm-in-thickness) is immobilized on the silica nanoparti-
cles’ surface. The polydopamine layer’s encapsulation shell
and partly aggregation of silica particles during encapsula-
tion process is observed in the images of HR-TEM.
The SiO2/PDA–SO3H catalyst was characterized by
XPS (Fig. 5). The characteristic peaks related to carbon (C
1s), nitrogen (N 1s), silica (Si 2p), and Sulfur (S 2s) are
visible in XPS elemental survey. High resolution XPS of
the materials in C 1s region approved existence of carbon
via appearance of six peaks at 284.5, 285.7, 287.1, 289.0,
291.9, and 293.2 eV, respectively, corresponding to C–C/
C=C, C–N, C–O, C–O–C, O–C–O, and C–N–S forms of
carbon [37]. The XPS spectra proved successful sulfonation
1 3

Preparation of Polydopamine Sulfamic Acid-Functionalized Silica Gel as Heterogeneous and…
Fig. 2 FESEM images of a SiO2; b SiO2/PDA–SO3H; and c EDX spectrum of SiO2/PDA–SO3H
Assuming the optimal conditions for alcohols’ acetyla-
tion, a broad range of various alcohols was screened, such as
benzylic, primary, secondary, and tertiary alcohols. Table 2
indicates that these reactions showed that all alcohols were
converted to the corresponding acetates in considerable
yields under the optimized conditions. Benzylic alcohols
with electron-donating groups were the most reactive sub-
strate and were converted to the corresponding acetates in
the shortest reaction times. Moreover, the reaction occurred
at a slower rate for aromatic substrates with an electron-
withdrawing group (Table 2, entries 2–4). On the other
hand, phenols with strong electron-withdrawing groups
such as 4-nitrophenol, and phenol with amino groups such
2-aminophenol acetylated in good yields (Table 2, entries
6–8). The tertiary alcohol 1-adamantanol was acetylated in
high yield to provide the corresponding acetylated material
(Table 2, entry 14). Additionally, cinnamyl alcohol, an allyl-
lic alcohol, was converted selectively to the corresponding
acetate, and during the acetylation reaction, the carbon dou-
ble bond was intact (Table 2, entry 9).
To examine the potentiality of this catalytic system, the
acetylation of different phenols and amines was investigated
in solvent free conditions (Table 2). Generally, phenols’
acetylation developed slowly in comparison with amines.
Acetylation of benzylic amines and aliphatic amines was
indicated to be more rapid than anilines and needed shorter
reaction times.
Using a mixture of phenol and benzyl alcohol, the chem-
oselectivity was assessed. An equimolar mixture of phenol
and 4-chlorobenzyl alcohol reacted with acetic anhydride in
1 3

H. Veisi et al.
Fig. 3 SEM image of SiO2/PDA–SO3H shows the presence of C, N, S, O, and Si atoms in the catalyst
Fig. 4 HR-TEM images of
SiO2/PDA–SO3H
the presence of SiO2/PDA–SO3H catalyst, revealing that it
proceeded with absolute chemoselectivity towards 4-chlo-
robenzyl alcohol (Scheme 2). Thus, this method could be
beneficial in the presence of phenols for the chemoselective
acetylation of benzylic alcohols. Moreover, the reaction of
tertiary alcohols with acetic anhydride under determined
conditions was studied. Considerable chemoselectivity
was observed for the secondary alcohols’ conversion when
1 3

Preparation of Polydopamine Sulfamic Acid-Functionalized Silica Gel as Heterogeneous and…
Fig. 5 XPS spectrum of the SiO2/PDA–SO3H in the Si 2p, C 1s, N 1s and S 2s regions
tertiary alcohols were present including 1-admantanol
(Scheme 2).
Table 1 Optimization conditions on the acetylation of phenol in the
Scheme 3 shows the catalytic mechanism of SiO2/
PDA–SO3H. In acetic anhydride, the catalyst can protonate
the carbonyl and render it more reactive towards the nucleo-
philic attack of N or O groups. The acetate is made with the
release of proton to rebuild the catalyst structure through
transfer of proton.
presence of the SiO2/PDA–SO3H
Entry
Solvent
Catalyst
(mol%)
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
9
MeOH
H2O
CH3Cl
CH2Cl2
Toluene
CH3CN
–
–
–
–
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.5
2.0
–
6
6
6
4
5
3
2
3
2
8
55
45
65
70
50
80
95
85
95
0.0
The heterogeneous catalysts reusability is crucial,
particularly for commercial uses. To examine the reus-
ability and recyclability of the catalyst, the acetylation of
aniline with acetic anhydride was evaluated under identi-
cal reaction conditions. With completion of the reaction,
the catalyst could be isolated through centrifugation and
reemployed similarly for forthcoming experiments (seven
times). The product yield and reaction time remained the
same, revealing the reusability and recyclability of the
catalyst without losing its activity (Fig. 6). The FESEM
10
Reaction conditions: phenol (1 mmol), acetic anhydride (2 mmol),
room temperature, and solvent (3 mL)
1 3

H. Veisi et al.
Table 2 O,N-acetylation
with Ac2O under solvent-free
conditions in the presence of
SiO2/PDA–SO3H
Entry Substrate
1
Product
Time (h) Yield (%)a References
0.5
96
[54]
OH
OAc
2
0.5
96
[54]
OH
OH
OH
OAc
Br
Br
3
0.5
0.5
2.0
96
96
95
[55]
[54]
[18]
OAc
Cl
Cl
4
OAc
Cl
Cl
Cl
Cl
5
6
OH
OAc
OH
OAc
3.0
4.0
6.0
90
90
65
[54]
[54]
[17]
Cl
Cl
7
8
OH
OAc
NO2
NO2
OH
OH
NH2
NHAc
9
2.0
1.0
90
90
[54]
[54]
OH
OAc
10
OH
OAc
11
12
OH
OAc
1.0
1.5
96
85
[54]
[54]
OH
OAc
13
14
OH
OAc
2.0
5.0
90
75
[54]
[54]
OH
OAc
1 3

Preparation of Polydopamine Sulfamic Acid-Functionalized Silica Gel as Heterogeneous and…
Table 2 (continued)
Entry Substrate
15
Product
Time (h) Yield (%)a References
0.2
96
[39]
NH2
NHAc
16
0.2
96
[39]
NH2
NHAc
H3C
H3C
17
0.3
1.0
96
96
[54]
[17]
NH2
NHAc
H3CO
H3CO
18
19
NH2
NH2
CH3
NHAc
NHAc
CH3
2.0
90
[54]
20
21
1.0
0.5
96
96
[54]
[54]
N
H
N
Ac
H
N
Ac
N
N
N
H
Ac
NH2
NH
Ac
22
0.2
96
[54]
H2N
AcH
N
Reaction conditions: substrate (1 mmol), catalyst (1 mol%), acetic anhydride (2 mmol) at room temperature
under solvent free conditions
aIsolated yields
Scheme 2 Chemoselectivity of
the acetylation in presence of
SiO2/PDA–SO3H
OH
OAc
OH
SiO2/PDA-SO3H
Ac2O, r.t.
OAc
+
Cl
+
+
Cl
0%
Only product
OH
OAc
OH
OAc
SiO2/PDA-SO3H
Ac2O, r.t.
+
0%
Only product
and HR-TEM images (Fig. 7) of the catalyst after the
7th runs indicated the preservation of the catalyst’s
nanostructure.
catalyst had one or more disadvantages such as low yield
of products, non-reusability, toxicity, and longer reaction
time.
The reaction of benzyl alcohol with acetic anhy-
dride was performed to compare the synthesized SiO2/
PDA–SO3H efficiency with previously reported catalyst
for acetylation reaction (Table 3). The previously reported
1 3

H. Veisi et al.
Scheme 3 Plausible reaction
mechanism of SiO2/PDA–
SO3H-catalyzed acetylation
O
S
O
OH
OH
O
O
O
O
O
R
SiO2/PDA-SO3H
X
R
O
S
O
OH
O
OH
O
O
S
O
O
X
H
O
O
O
R
XH
R = alkyl, aryl
X = NH, O
4 Conclusion
A new heterogeneous solid acid nanocatalyst was devel-
oped through loading of sulfonic acid groups on the sur-
face of polydopamine (PDA)-encapsulated silica nanopar-
ticles. The catalytic use of the synthesized nanocatalyst
was demonstrated at room temperature for the acetylation
of different alcohols, phenols, and amines under solvent
free conditions with considerable yields. The catalyst was
recyclable for numerous times with no loss of catalytic
activity. The easy preparation, mild reaction conditions,
high yields, solvent free conditions, and compatibility to
different functional groups are privileges of this protocol.
In addition, the merits of this new nanocatalyst compared
with other catalysts are as following: (a) easy separation
of the catalyst after reaction by centrifugation; (b) high
catalytic activity under mild reaction conditions, and (c)
Fig. 6 Recyclability of SiO2/PDA–SO3H
Fig. 7 a HR-TEM; and b
FESEM images of reused cata-
lyst after the 7th run
1 3

Preparation of Polydopamine Sulfamic Acid-Functionalized Silica Gel as Heterogeneous and…
Table 3 Comparison efficiency
Entry
Reaction conditions
Time
Yield (%)
References
of SiO
2/PDA–SO3H with
some reported catalysts for the
acetylation reactions of benzyl
alcohol
1
2
3
4
5
6
7
8
9
SiO2/PDA–SO3H, r.t., solvent-free
ZnCl2, r.t., solvent-free
Borated zirconia, 110 °C, toluene
SiO2–ZnCl2, 80 °C, CH3CN
Silica sulfamic acid, r.t., solvent-free
Yttria-zirconia, 110 °C, solvent-free
Copper zirconium phosphate NPs, 60 °C, solvent-free
Nano γ-Fe2O3, sonication, r.t., solvent-free
CuO–ZnO, r.t., CH2Cl2
30 min
3 h
14 h
3 h
15 min
6 h
30 min
1 h
15 min
96
63
25
90
93
94
91
64
92
This work
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[17]
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[56]
[19]
[57]
[58]
[59]
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loss in the product yield.
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Acknowledgements We are thankful to Payame Noor University, Teh-
ran, Iran, for partial support of this work.
28. Veisi H, Taheri S, Hemmati S (2016) Green Chem 18:6337
29. Zhang M, Liu P, Liu YH, Shang ZR, Hu HX, Zhang ZH (2016)
RSC Adv 6:106160–106170
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Affiliations
Hojat Veisi1 · Saba Vafajoo1 · Kiumars Bahrami2,3 · Bita Mozafari4
3
* Hojat Veisi
Nanoscience and Nanotechnology Research Center (NNRC),
hojatveisi@yahoo.com
Razi University, Kermanshah 67149‐67346, Iran
4
Department of Pharmaceutical Chemistry, Faculty
of Pharmaceutical Chemistry, Pharmaceutical Sciences
Branch, Islamic Azad University, (IAUPS), Tehran, Iran
1
Department of Chemistry, Payame Noor University,
Tehran 19395-4697, Iran
2
Department of Organic Chemistry, Faculty of Chemistry,
Razi University, Kermanshah 67149‐67346, Iran
1 3