Preparation of Ag-doped g-C3N4 Nano Sheet Decorated Magnetic γ-Fe2O3@SiO2 Core–Shell Hollow Spheres through a Novel Hydrothermal Procedure: Investigation of the Catalytic activity for A3, KA2 Coupling Reactions and [3?+?2] Cycloaddition

Article abstract of DOI:10.1002/aoc.4413

Taking advantageous of both g-C₃N₄ and magnetic core-shell hollow spheres, for the first time a heterogeneous and magnetically separable hybrid system was prepared through a novel and simple hydrothermal procedure and used for immobilization of bio-synthesized Ag(0) nanoparticles. The hybrid system was fully characterized by using SEM/EDS, FTIR, VSM, TEM, XRD, TGA, DTGA, ICP-AES, BET and elemental mapping analysis. The catalytic utility of the obtained system, h-Fe₂O₃@SiO₂/g-C₃N₄/Ag, for promoting ultrasonic-assisted A³, KA² coupling reactions and [3?+?2] cycloaddition has been confirmed. The results established that the catalyst could efficiently catalyze the reaction to afford the corresponding products in high yields in short reaction times. The reusability study confirmed that the catalyst could be recovered and reused for at least five reaction runs with only slight loss of the catalytic activity. The hot filtration test also proved low silver leaching, indicating the heterogeneous nature of the catalysis.

Full text of DOI:10.1002/aoc.4413

Received: 6 November 2017
DOI: 10.1002/aoc.4413
Revised: 2 March 2018
Accepted: 25 March 2018
F U L L P A P E R
Preparation of Ag‐doped g‐C3N4 Nano Sheet Decorated
Magnetic γ‐Fe2O3@SiO2 Core–Shell Hollow Spheres through
a Novel Hydrothermal Procedure: Investigation of the
Catalytic activity for A3, KA2 Coupling Reactions and [3 + 2]
Cycloaddition
Samahe Sadjadi1
| Masoumeh Malmir2 | Majid M. Heravi2
1 Gas Conversion Department, Faculty of
Petrochemicals, Iran Polymer and
Petrochemical Institute, PO Box 14975‐
112, Tehran, Iran
2 Department of Chemistry, School of
Science, Alzahra University, PO Box
1993891176, Vanak, Tehran, Iran
Taking advantageous of both g‐C3N4 and magnetic core‐shell hollow spheres,
for the first time a heterogeneous and magnetically separable hybrid system
was prepared through a novel and simple hydrothermal procedure and used
for immobilization of bio‐synthesized Ag(0) nanoparticles. The hybrid system
was fully characterized by using SEM/EDS, FTIR, VSM, TEM, XRD, TGA,
DTGA, ICP‐AES, BET and elemental mapping analysis. The catalytic utility
of the obtained system, h‐Fe2O3@SiO2/g‐C3N4/Ag, for promoting ultrasonic‐
assisted A3, KA2 coupling reactions and [3 + 2] cycloaddition has been con-
firmed. The results established that the catalyst could efficiently catalyze the
reaction to afford the corresponding products in high yields in short reaction
times. The reusability study confirmed that the catalyst could be recovered
and reused for at least five reaction runs with only slight loss of the catalytic
activity. The hot filtration test also proved low silver leaching, indicating the
heterogeneous nature of the catalysis.
Correspondence
Majid Heravi, Department of Chemistry,
School of Science, Alzahra University, PO
Box 1993891176, Vanak, Tehran, Iran.
Email: mmh1331@yahoo.com;
m.heravi@alzahra.ac.ir
Samahe Sadjadi, Gas Conversion
Department, Faculty of Petrochemicals,
Iran Polymer and Petrochemical Institute,
PO Box 14975‐112, Tehran, Iran.
Email: s.sadjadi@ippi.ac.ir;
samahesadjadi@yahoo.com
KEYWORDS
[3 + 2] cycloaddition, A3 and KA2 coupling, g‐C3N4, magnetic nanoparticles
1 | INTRODUCTION
responsible for multifunctional catalytic activity.
Recently, Ong and his co‐workers reviewed the signifi-
In the last decade, graphitic carbon nitride (g‐C3N4) as a
novel form of metal‐free polymeric semiconductor mate-
rial has attracted great attention due to its exceptional
electronic, morphological, and optical and (photo) cata-
lytic activities.[1–4] Meanwhile, bulk g‐C3N4 can be facilely
prepared via poly condensation reaction of organic avail-
able precursors, such as, cyanamide,[5] dicyandiamide,[6]
melamine,[7] urea, thiourea[8] etc. Generally, g‐C3N4 has
a robust structure because of the creation of strong cova-
lent bonds between nitrogen and carbon atoms, which is
cance of the graphitic carbon nitride (g‐C3N4)‐based
photo catalysts for artificial photosynthesis and environ-
mental remediation.[9] On the other hand, the recent
researches have shown that g‐C3N4 is a unique support
for metal nanocatalysts with high thermal and chemical
stability and excellent catalytic performance in organic
reactions.[10–13] Unfortunately, these materials suffered
from some drawbacks such as, poor harvesting of the vis-
ible‐light irradiation, low surface area, inherent low elec-
trical conductivity and difficult recycling from the treated
Appl Organometal Chem. 2018;e4413.
wileyonlinelibrary.com/journal/aoc
Copyright © 2018 John Wiley & Sons, Ltd.
1 of 18
https://doi.org/10.1002/aoc.4413

2 of 18
SADJADI ET AL.
solutions. Many efforts have been devoted to circumvent
these issues mostly through hybridization of g‐C3N4 with
inorganic materials.[10,11,14,15]
condition is still remained a hot topic. In continuation of
our research on the design and preparation of heteroge-
neous catalysts[44,45] and development of environmentally
benign procedures for the synthesis of chemicals,[44,46–49]
recently, we focused on the utility of magnetic hollow
spheres for developing hybrid magnetically separable het-
erogeneous catalysts.[35,50,51] In this line, we developed
efficient catalysts by decorating magnetic hollow spheres
with organic functionalities such as dopamine and cyclo-
dextrin and doping silver nanoparticles.[50,51] Further-
more, we disclosed the use of bio‐based approach for
reduction of silver nanoparticles.[35,51] In all designed cat-
alysts, the synergistic effects among the magnetic hollow
spheres, organic moiety and silver nanoparticles were
observed and led to promising catalysts with high catalytic
activities and reusability. To further explore the hybrid
catalysts based on magnetic hollow spheres, herein we
wish to report for the first time, hybridization of silica‐
core‐shell magnetic hollow spheres with g‐C3N4 through
a novel hydrothermally‐assisted procedure to develop a
support for immobilization of Ag(0) nanoparticles derived
from bio‐based approach (Scheme 1). The catalytic activity
and reusability of h‐Fe2O3@SiO2/g‐C3N4/Ag for promot-
ing ultrasonic‐assistedA3, KA2 coupling reactions and
[3 + 2] cycloaddition was also investigated.
The utility of magnetic nanoparticles (MNPs) as cost‐
effective and easily separable catalysts has been
proved.[16] Among various types of MNPs, hollow mag-
netic nanoparticles consisting of an iron oxide core with
unique hollow structure have achieved more attention
because of their exclusive separable features, low density,
easy recovery, high surface area, self‐supporting capacity
and surface permeability.[17] Nano magnetic γ‐Fe2O3 hol-
low sphere particles have wide range of applications such
as drug delivery and catalysis. Silver as an efficient cata-
lyst has been extensively employed as a heterogeneous
catalysts for promoting a range of chemical reactions
including coupling reactions such ascycloadditions,
cycloisomerizations, sigmatropic rearrangements, and
nitrene transfer reactions.[18]
Three‐component reactions of amines, alkynes and
ketones or aldehydes are referred to KA2 and A3coupling
reactions respectively. The importance of these reactions
lies in the fact that they can be applied for the synthesis
of important key intermediates, propargylamines, which
can be used for the synthesis of diverse range of com-
pounds such as natural products, complex nitrogen con-
taining chemicals with biological activities such as
fungicides and herbicides and heterocycles such as pyr-
roles, quinolines and indolizines.[19–23] Notably, due to
the advantageous of KA2 and A3coupling reactions, they
have been considered as potent alternative for classic
methodologies for the synthesis of propargylamines such
as propargylictriflates, direct amination of propargyl
halides and propargylic phosphates.[21,24,25] These cou-
pling reactions proceed in the presence of a catalyst such
as gold, zinc, copper, silver, iron‐based catalysts.[21,26–28]
Recently, development of novel and efficient catalysts for
promoting KA2 and A3coupling reactions received grow-
ing attention and various catalysts including magnetic cat-
alysts such as Fe3O4@Au nanoparticles,[29] magnetically
2 | EXPERIMENTAL SECTION
2.1 | General remarks
All chemicals and reagents including, trisodium citrate
dihydrate, sodium acetate trihydrate, FeCl3·6H2O, TEOS,
urea, toluene, acetone, ethanol, deionized water, chloro-
form, dimethylformamide (DMF), ethylene glycol (EG),
AgNO3, NH3.H2O, derivatives of aromatic and aliphatic
aldehydes,
aliphatic
ketones,
phenylacetylenes,
benzonitriles and sodium azide in high purity were pur-
chased from Merck and Sigma‐Aldrich and used as
received without further purification.
separable CuO nanoparticles supported on graphene
The progress of the organic reaction were monitored
by TLC on commercial aluminum‐backed plates of silica
gel 60 F254, visualized, using ultraviolet light. Melting
points were determined in open capillaries using an Elec-
trothermal 9100 without further corrections. 1H NMR
and 13C NMR spectra were detailed using a Bruker
DRX‐400 spectrometer at 400, 300 and 100, 75 MHz
respectively. The h‐Fe2O3@SiO2/g‐C3N4/Ag was charac-
terized by various analytical techniques including, Fou-
rier transform infrared (FT‐IR) spectroscopy, X‐ray
diffraction (XRD), transmission electron microscopy
(TEM), field‐emission scanning electron microscopy com-
bined with electron dispersive spectrometry (FE‐SEM‐
EDS), thermogravimetric analysis (TGA, DTGA), N2
oxide,[30] Cu2O/nano‐CuFe2O4
and hybrid catalysts
[31]
such as Cu(II) Schiff base complex immobilized on
graphene oxide,[32] sulfonate‐based Cu(I) metal–organic
frameworks,[33] copper nanoparticles supported on starch
micro particles,[34] have been reported.[35] Similarly,
tetrazoles are one of the most significant intermediates
used for the synthesis of more complicated compounds.
They can be prepared by [3 + 2] cycloaddition reaction
starting from nitriles. Generally, diverse synthetic
methods have been considered for this conversion.[36–43]
Despite significant advances in this research field, devel-
opment of a novel efficient, non‐toxic heterogeneous cata-
lyst which could promote these reactions under green

SADJADI ET AL.
3 of 18
SCHEME 1 The possible rout to the synthesis of h‐Fe2O3@SiO2/g‐C3N4/Ag hollow spheres
adsorption–desorption, Inductively coupled plasma
atomic emission spectroscopy (ICP‐AES) and vibrating
sample magnetometry (VSM) were used to identify and
characterize the prepared catalyst.
The magnetic properties of h‐Fe2O3@SiO2/g‐C3N4/Ag
and h‐Fe2O3 were measured by using a vibrating sample
magnetometer (VSM, Lakeshore 7407) at room tempera-
ture. BET surface area was recorded on a BELSORP Mini
II instrument. The degassing process was performed by
heating h‐Fe2O3@SiO2/g‐C3N4/Ag at 423 K for 3 h.
Thermo‐gravimetric analyses were conducted with a
METTLER TOLEDO thermo gravimetric instrument
under N2 atmosphere at a heating rate of 10 °C min−1
from 50 to 800 °C. The ultrasonic apparatus used for in
this work was Bandelin HD 3200 with output power of
150 W and tip TT13. Transmission electron microscope
images were taken with a CM30300Kv field emission
transmission electron microscope.
FTIR spectra of the fresh and reused h‐Fe2O3@SiO2/
g‐C3N4/Ag were obtained from potassium bromide pellets
in the range of 400–4000 cm−1 using PERKIN‐ELMER‐
Spectrum 65 instrument. X‐ray diffraction was detected
by using a Siemens, D5000. CuKα radiation from a sealed
tube. Scanning electron Microscopy, electron dispersive
spectrometry and scanning electron microscopy, analyses
were performed using Tescanvega II XMU Digital Scan-
ning Microscope and Tescan instrument, using Au‐coated
samples and acceleration voltage of 20 kV, respectively.

4 of 18
SADJADI ET AL.
Notably, all of compounds were known and were
resulting light yellow product 3 was obtained and used
identified by comparison of their physical properties and
spectroscopic data with those of reliable compounds and
were found identical. However, we compared all com-
pounds by their melting points. Additionally, 1H and
13CNMR spectra of selected compounds were recorded
and given as ESI.
in subsequent studies.
2.2.4 | Synthesis of h‐Fe2O3@SiO2/g‐C3N4
(4)
In order to synthesize h‐Fe2O3@SiO2/g‐C3N4 core‐shell,
750 mg of h‐Fe2O3@SiO2 and 150 mg of g‐C3N4 were
mixed together in deionized water (50 ml) and dispersed
under ultrasonic irradiation. After 1 h, the mixture trans-
ferred to 100 ml autoclave and heated at 100 °C for 12 h.
Subsequently, the brown product 4 was magnetically col-
lected, washed for several times with EtOH/H2O and
dried in oven at 60 °C overnight.
2.2 | Preparation of h‐Fe2O3@SiO2/g‐C3N4/
Ag
2.2.1 | General procedure for the Prepara-
tion of nanomagnetic Fe2O3 hollow sphere
(1)
Hollow magnetic γ‐Fe2O3 was prepared via solvothermal
method.[50] Typically, 5 mmol of ferric chloride hexahy-
drate was dissolved in 70 ml of ethylene glycol in a flask
and then, 1.5 mmol of trisodium citrate dehydrate along
with 30 mmol of sodium acetate and 17 mmol of urea
was added to the solution under vigorous stirring. After
0.5 h, the as‐prepared mixture was transferred into the
Teflon‐lined stainless‐steel autoclave (150 ml capacity)
and kept at 220 °C overnight. Upon completion of the
hydrothermal process, the autoclave was cooled and then
the precipitate was separated by an external magnet,
washed with EtOH/H2O repeatedly, and dried at 80 °C
overnight in oven to obtain the brown product 1.
2.2.5 | Preparation of Ephedra procera
plant extracts (5)
Fresh leaves of Ephedra procera plant were collected
around Arak City, Iran. In the first step, the collected
Ephedra procera plant (5 g) was washed with deionized
water, crushed in porcelain mortar to achieve soft pow-
der. After that, it was mixed thoroughly with 100 ml
deionized water and boiled at 80 °C during 1 h. After sim-
ple filtration, the fresh extract 5 was collected and used
for more experiments on reduction of silver nitrate to
obtain Ag (0) nanoparticles.
2.2.2 | General procedure for the Prepara-
tion of h‐Fe2O3@SiO2Core shell (2)
2.2.6 | Loading of Ag(0) nanoparticles on
h‐Fe2O3@SiO2/g‐C3N4: synthesis of h‐
Fe2O3@SiO2/g‐C3N4/Ag (6)
The silica shell was formed around the h‐Fe2O3 according
to the procedure reported in the literature with slight
modification.[52] Typically, h‐Fe2O3 (1 g) was suspended
in a mixture of ethanol (50 ml), deionized water (20 ml)
and NH3.H2O (6 ml) and then sonicated at ambient tem-
perature by keeping the pH value at ca. 11. After 0.5 h,
TEOS (2 g) was introduced into the mixture under contin-
uous stirring at room temperature in air. After 12 h, the
as‐prepared 2 was collected by using an external magnet,
washed several times with EtOH/H2O to remove un‐
The immobilization and trapping of silver nanoparticles
onto the surface of h‐Fe2O3@SiO2/g‐C3N4 was performed
by a novel, bio‐based and green procedure. In this line, to
the stirring mixture of h‐Fe2O3@SiO2/g‐C3N4 (1 g) in
20 ml deionized water, a solution of AgNO3 (0.1 g) in
20 ml deionized water was added at room temperature.
After 0.5 h, the Ag+ ions were adsorbed onto the surfaces
of h‐Fe2O3@SiO2/g‐C3N4 through the electrostatic inter-
action. To reduce silver salt and obtain Ag(0) nanoparti-
cles, Ephedra procera was used as a reducing and
stabilizing agent. To this purpose, the fresh extract
(1 ml) was added into the stirred suspension for 12 h.
Upon completion of the process; the black product 6
was magnetically collected, washed three times with
EtOH/H2O and dried at 60 °C for 12 h.
reacted silica, and dried at 80 ̊C for 12 h in oven.
2.2.3 | General procedure for the synthesis
of g‐C3N4 Nano‐sheet (3)
The g‐C3N4 nano‐sheet was prepared using urea pyrolysis
as described in the literature with little modification.[53]
In detail, 10 g of urea was grounded into powder and then
All steps of the procedure led to the formation of
nanomagnetic h‐Fe2O3@SiO2/g‐C3N4/Ag as a catalyst
are illustrated in Scheme 1.
calcined at 500 °C for 4 h at a heating rate of 5 °C min−1
.
After cooling of the crucible to room temperature, the

SADJADI ET AL.
5 of 18
2.2.7 | General procedure for the synthesis
of propargylamine (A3 Coupling reaction):
(5 l)
3 | RESULTS AND DISCUSSION
3.1 | Characterization of the catalyst
3.1.1 | FT‐IR Spectra
The amount of 20 mg of h‐Fe2O3@SiO2/g‐C3N4/Ag as a
catalyst was added to a mixture of phenyl acetylene
(1.1 mmol), aldehyde (1.0 mmol) and amine (1.0 mmol)
in 10 ml H2O as a green solvent. The resulting mixture
was then subjected to ultrasonic radiation of 80 W for
suitable reaction time (monitored by TLC). After comple-
tion of the reaction, the mixture was cooled to room tem-
perature and diluted with hot ethanol (10 ml). The
catalyst was magnetically separated, washed with etha-
nol, dried in air and re‐used for a consecutive run. The
resulting product was purified by recrystallization (hot
ethanol) to obtain the excellent yield.
The FTIR spectroscopy was used to confirm the forma-
tion of g‐C3N4 and h‐Fe2O3@SiO2/g‐C3N4/Ag, Figure 1.
The FTIR spectrum of g‐C3N4 exhibited a characteristic
band at 3000–3500 cm−1 which is representative of N‐H
and O‐H groups. Moreover, the observed band at 1200–
1600 cm−1 is indicative of C‐N group. This spectrum is in
good accordance with the previous reports in the litera-
ture.[54] To further confirm the formation of g‐C3N4, the
spectra of pure urea and g‐C3N4 were compared, Figure 1.
As depicted, the two FTIR spectra are markedly distin-
guished. Urea exhibited a sharp band at 1610 cm−1 which
is representative of C=O group. The absence of this band
in the FTIR spectrum of g‐C3N4 can proves its successful
formation.
The FTIR spectrum of the h‐Fe2O3@SiO2/g‐C3N4/Ag,
Figure 1, showed sharp absorption bands at 470–590 cm−1
which can be related to Fe‐O stretching vibration, indicat-
ing the formation of magnetic NPs.[50] Furthermore, the
characteristic band at 1089 cm−1 is representative of Si–O
stretching and can confirm the presence of silica shell.
The absorption bands at 976, 825 and 475 cm−1 can be
attributed to the bending vibrations of the Si–O–Si bond.[55]
The bands at range of 1225–1645 cm−1, which are the char-
acteristic bands of g‐C3N4 are present in both spectra of h‐
Fe2O3@SiO2/g‐C3N4/Ag and g‐C3N4 and can indicate the
conjugation of g‐C3N4.
2.2.8 | General procedure for the synthesis
of 1H‐tetrazoles ([3 + 2] Cycloaddition):
(9a)
The amount of 30 mg of h‐Fe2O3@SiO2/g‐C3N4/Ag was
added to a mixture of nitrile (1.0 mmol) and NaN3
(1.5 mmol) in DMF (5 ml). The mixture was sonicated
with power of 100 W for appropriate reaction time until
the reaction was completed (monitored by TLC). After
completion of reaction, the mixture was cooled to room
temperature and diluted with ethyl acetate (10 ml) and
5 N HCl (20 ml). The catalyst was magnetically separated
by using an external magnet, washed with ethanol, dried
in oven and re‐used for a consecutive run. Furthermore,
the organic layer was separated, and the aqueous layer
was extracted with ethyl acetate (20 ml). The combined
ethyl acetate layer was washed with water, dried over
anhydrous Na2SO4. The residue was purified by recrystal-
lization and short column chromatography on silica gel
to obtain the main products.
3.1.2 | SEM‐EDS images
Initially, the formation of g‐C3N4 was confirmed by
SEM‐EDS analyses, Figure 2. The observed morphology
FIGURE 1 The FTIR spectra of a) pure
urea, b) pure g‐C3N4 and c) h‐
Fe2O3@SiO2/g‐C3N4/Ag

6 of 18
SADJADI ET AL.
FIGURE 2 The FE‐SEM‐EDS analysis of a,b) h‐Fe2O3, the SEM‐EDS analysis of b,c) pure g‐C3N4 and e,f) h‐Fe2O3@SiO2/g‐C3N4/Ag
of g‐C3N4 is in good agreement with previous reports.[56]
The EDS analysis also contains only C and N atoms,
indicating the formation of g‐C3N4. To study the mor-
phology of h‐Fe2O3@SiO2/g‐C3N4/Ag and elucidate
whether the formation of silica shell and incorporation
of g‐C3N4 and Ag nanoparticle could alter the morphol-
ogy, the FE‐SEM‐EDS images of h‐Fe2O3 as well as
SEM‐EDS images of the h‐Fe2O3@SiO2/g‐C3N4/Ag
were recorded and compared, Figure 2. As expected,[50]
h‐Fe2O3 possessed the spherical morphology (Figure 2b).
The h‐Fe2O3@SiO2/g‐C3N4/Ag also showed a spherical
morphology, however, its morphology was more aggre-
gated. Considering the morphology of g‐C3N4, it can be
clearly detected that the spherical magnetic
nanoparticles are surrounded with g‐C3N4. This observa-
tion can confirm that the spherical morphology of mag-
netic nanoparticles did not change upon decoration
with g‐C3N4 and Ag nanoparticle. However, the presence
of g‐C3N4 on the surface of the nanoparticles kept them
more closed and packed.
The EDS image of h‐Fe2O3@SiO2/g‐C3N4/Ag clearly
shows the presence of Fe and O atoms which can be rep-
resentative of magnetic nanoparticles (Figure 2e). The
presence of Si and O atoms can also confirm the forma-
tion of silica shell. Moreover, the observation of C and
N in EDS can be indicative of g‐C3N4. Finally, the incor-
poration of silver nanoparticles can be confirmed by
observing Ag atom in EDS.

SADJADI ET AL.
7 of 18
as F) were in good agreement with the {220}, {311},
{400}, {422}, {511}, {440} and {533} planes of the typical
cubic structure hematite (JCPDS card no. 39–1346)[50]
and confirm the formation of magnetic nanoparticles.
The peaks at 2θ = 38.0, 44.1, 64.3, 77.8, 81.0° (labeled as
A) are indicative of formation of Ag(0) nanoparticles
(JCPDS card no. 04–0783). It is worth noting that the
broad halo present at 2θ = 5.0–27.0° (labeled as *) can
be assigned to the amorphous silica and g‐C3N4.
3.1.3 | Elemental mapping analysis
In Figure 3, the elemental mapping analysis of h‐
Fe2O3@SiO2/g‐C3N4/Ag is depicted. As shown, the disper-
sions of C and N atoms are almost uniform, indicating that
g‐C3N4 has successfully covered the magnetic core‐shell h‐
Fe2O3@SiO2. Additionally, Ag atoms are also well‐dis-
persed on the surface of the catalyst and no aggregation
is detected. This observation can confirm the efficiency
of g‐C3N4 for having electrostatic interactions with silver
nanoparticles and preventing them from aggregation.
3.1.5 | Vibrating sample magnetometer
(VSM) analysis
3.1.4 | XRD analysis
Next, the magnetic properties of h‐Fe2O3@SiO2/g‐C3N4/
Ag was studied by room temperature vibrating sample
magnetometer (VSM) and compared with that of h‐
Fe2O3, Figure 5. Interestingly, the results established that
incorporation of nanomagnetic SiO2 shell, g‐C3N4 and
The formation of desired phases in h‐Fe2O3@SiO2/g‐
C3N4/Ag was confirmed by obtaining X‐ray diffraction
pattern, XRD, Figure 4. The observed peaks at
2θ = 30.0, 35.5, 43.2, 54.7, 57.1, 63.8 and 74.0° (labeled
FIGURE 3 The Map analysis of a) pure g‐C3N4 and b) h‐Fe2O3@SiO2/g‐C3N4/Ag

8 of 18
SADJADI ET AL.
FIGURE 4 XRD analysis of h‐
Fe2O3@SiO2/g‐C3N4/Ag
FIGURE 5 VSM analyses of the a) h‐
Fe2O3 and b) h‐Fe2O3@SiO2/g‐C3N4/Ag
Ag(0) nanoparticles only led to a slight decrease in the
maximum saturation magnetization (Ms) values of h‐
fe2o3 (from 45.25 emu g−1 to 39.26 emu g−1) and the hys-
teresis loops of h‐Fe2O3@SiO2/g‐C3N4/Ag exhibited a
super paramagnetic behavior and could be separated sim-
ply by using an external magnet. This finding can be con-
sidered very important as mostly introduction of
nanomagnetic components to a magnetic nanoparticle
could reduce the Ms remarkably.[35] Notably, no signifi-
cant change in the coercivity from the enlarged view of
the central loop of the h‐Fe2O3 and h‐Fe2O3@SiO2/g‐
C3N4/Ag was observed.
weight loss, occurred at about 200 °C, can be assigned to
the loss of adsorbed H2O molecules and/ or surface
hydroxyl groups. The other observed weight losses can be
assigned to the degradation of organic component of h‐
Fe2O3@SiO2/g‐C3N4/Ag. Using this analysis, the content
of organic component in h‐Fe2O3@SiO2/g‐C3N4/Ag was
calculated to be 20.622 w/w%.
Subsequently, the weight percentage of Ag in h‐
Fe2O3@SiO2/g‐C3N4/Ag was studied by using ICP‐AES
analysis. To this purpose, a known amount of h‐
Fe2O3@SiO2/g‐C3N4/Ag was digested in concentrated
HNO3 and HCl solution. The analysis of the obtained
extract by ICP‐AES showed that the Ag content was
about 0.8 w/w%.
3.1.6 | Thermogravimetric analysis (TGA)
The thermal stability of the h‐Fe2O3@SiO2/g‐C3N4/Ag was
also investigated by thermogravimetric analyses (TGA and
DTGA), Figure 6. As depicted in Figure 6, the thermogram
of the catalyst exhibited five degradation steps over the
range of 30–800 °C. According to the literature,[50] the first
3.1.7 | N2 adsorption–desorption
In Figure 7, the nitrogen adsorption–desorption isotherm
of h‐Fe2O3@SiO2/g‐C3N4/Ag is depicted. The surface
area of h‐Fe2O3@SiO2/g‐C3N4/Ag was calculated to be

SADJADI ET AL.
9 of 18
FIGURE 6 The TGA and DTGA
analyses of the h‐Fe2O3@SiO2‐CD/Ag
experimental results, isotherm of type IV confirms the
presence a typical hysteresis loop of mesoporous adsor-
bents with a pore size diameter between 2 nm and
50 nm with a maximum around 3 nm.
3.1.8 | TEM analysis
h‐Fe2O3@SiO2/g‐C3N4/Ag was also studied by TEM,
Figure 8. As shown, core‐shell spheres can be observed
in which the darker core is the magnetic nanoparticle
while the lighter shell is silica with an average thickness
of about 40 nm. Ag nanoparticles can be detected as small
dark spots with an average diameter of about less than
10 nm. The formation of g‐C3N4 can clearly confirmed
by observing the sheets on the sphere.
3.2 | Catalytic activity of the h‐
Fe2O3@SiO2/g‐C3N4/Ag
3.2.1 | A3 and KA2 coupling reactions
FIGURE
7
The N2 adsorption–desorption, BET and BJH
isotherms of the h‐Fe2O3@SiO2/g‐C3N4/Ag
In the next step, the catalytic activity of the h‐
Fe2O3@SiO2/g‐C3N4/Ag was investigated. To this pur-
pose, the three‐component reaction of amines, phenyl
acetylene and aldehydes or ketones, A3 and KA2, which
is one of the most important approaches for the synthesis
of propargylamines, were selected as the model organic
transformations. To develop a green, eco‐friendly and
rapid procedure, the use of ultrasonic irradiation was
targeted. Initially, the reaction of phenyl acetylene, benz-
aldehyde, and morpholine was selected as a model reac-
tion, Scheme 2. To establish the necessity of the
30 m2 g−1. Moreover, the value of the total pore volume,
average pore diameter and pore size of the catalyst were
0.22 cm3 g−1, 29.3 and nm respectively, Table 1. It is
concluded that the catalyst possesses a porous structure.
Furthermore, based on to IUPAC classification the iso-
therm showed type IV nitrogen adsorption–desorption
isotherms with H3 hysteresis loops[57] which was usually
found on solids, indicating the presence of large
mesopores with a broad size distribution. Regarding to
TABLE 1 Textural property of h‐Fe2O3@SiO2/g‐C3N4/Ag
Catalyst
SBET (m2 g−1
)
Total pore volume (cm3 g−1
)
Average pore diameter (nm)
Pore size (nm)
h‐Fe2O3@SiO2/g‐C3N4/Ag
30
0.22
29.3
3.28

10 of 18
SADJADI ET AL.
FIGURE 8 The TEM images of h‐Fe2O3@SiO2/g‐C3N4/Ag
irradiation from 40 W to 80 W increased the yield of the
desired product while further increase in this value had
a detrimental effect and lower yields were obtained using
power of 100 W. This observation can be attributed to the
acceleration of the formation of some side‐products upon
using high ultrasonic powers. Using all these results, the
optimum reaction condition was selected to be using
20 mg catalyst in water as solvent under ultrasonic power
of 80 W.
Having the optimum reaction variables in hand, the
generality of the protocol was studied by using various
amines, aldehydes and ketones, Tables 2 and 3. As shown
in Tables 2 and 3, this protocol exhibited high substrate
scope and various substrates with different electron den-
sities and satiric properties can be successfully used in
this protocol to lead to the corresponding products in
high yields in short reaction times.
SCHEME 2 Model reaction of propargylamine
presence of the catalyst for promoting the synthesis of
propargylamines, the model reaction was performed in
the absence of the catalyst. The result established that
the reaction did not proceed without the catalyst. Next,
the reaction variables were optimized by performing the
model reaction by using different ultrasonic power (40–
100 w) in the presence of various amounts of the catalyst
(10–30 mg), in various solvents including (ethanol, water,
chloroform, DMF) and solvent free condition, Figure 9.
The results demonstrated that increasing the catalyst
amount from 10 mg to 20 mg led to the increase in the
yield of the model product. However, further increase of
the catalyst to 30 mg had no positive effect on the yield
of the desired product. Moreover, water was selected as
the solvent of the choice. It was also shown that the
power of ultrasonic irradiation can clearly affect the yield
of the product. Increasing the power of ultrasonic
Plausible Reaction Mechanism
The plausible reaction mechanism for A3 and KA2
coupling reactions is depicted in Scheme 3. Based on
the previous reports,[50,58] the reaction can initiate by the
formation of Ag‐acetylide I which can be obtained through
activation of terminal C‐H bond of phenylacetylene by
silver nanoparticles of h‐Fe2O3@SiO2/g‐C3N4/Ag.

SADJADI ET AL.
11 of 18
FIGURE 9 Effects of loading of
catalyst, duration of reaction and solvent
for the synthesis of propargylamine
Subsequently, the formed intermediate can undergo reac-
tion with imnium ion, II, produced from condensation
reaction of aldehyde and amine to furnish h‐
Fe2O3@SiO2/g‐C3N4/Ag and the desired product.
with sodium azide and formation of intermediate II
and cyclization, Scheme 5.
3.3 | Reusability of the catalyst
The simple recovery and reusability are requisites of het-
erogeneous catalysts with industrial use. Hence, investi-
gation of the catalysts is imperative. To study the
reusability of the h‐Fe2O3@SiO2/g‐C3N4/Ag, the yields
of two model reactions were obtained using fresh cata-
lyst. Upon completion of the reaction, the catalyst was
separated magnetically, washed and reused for succes-
sive reaction runs. The results, Figure 11, established
that the catalyst exhibited high reusability and could be
reused for several reaction runs with only slight loss of
the catalytic activity. Comparing the reusability of the
catalyst for two model reactions, demonstrated that the
catalyst showed superior reusability for the synthesis of
propargylamine (the catalyst could be reused for seven
reaction runs) than synthesis of 1H‐tetrazole (the cata-
lyst preserved its catalytic activity for five reaction runs).
This observation can be attributed to the use of higher
ultrasonic power for the synthesis of 1H‐tetrazole, which
may induce the leaching of Ag(0) nanoparticles. To con-
firm this speculation, the leachings of the silver nano-
particles for both model reactions were studied via
ICP‐AES for the catalyst reused for fifth and seventh
reaction runs. The results showed that up to five reuse,
the leaching of silver was negligible for both reactions.
However, the leaching after seventh reuse for the syn-
thesis of 1H‐tetrazole was much higher than that of syn-
thesis of propargylamine. This observation not only
established the dependency of reusability of the catalyst
on the reaction condition, indicated that the nature of
the catalysis is heterogeneous and the catalytic reaction
3.2.2 | [3 + 2] cycloaddition
Motivated by high catalytic activity of h‐Fe2O3@SiO2/g‐
C3N4/Ag, we further investigated its performance for
promoting synthesis of 5‐substituted 1H‐tetrazoles
through two component reaction of nitriles and sodium
azide. Similar to the propargylamine synthesis, the ultra-
sonic‐assisted procedure was selected and the reaction
condition was optimized by choosing a model reaction,
the reaction of benzonitriles and sodium azide
(Scheme 4), and varying the reaction variables, i.e. cata-
lyst amount, ultrasonic power and solvent, Figure 10.
As shown in Figure 10, the optimum reaction condition
was using 30 mg catalyst in DMF under ultrasonic irradi-
ation of power 100 W. Next, the generality of the proto-
col was confirmed by using various nitriles, Table 4. As
shown, this protocol exhibited broad substrate scope
and aromatic, heterocyclic and aliphatic substrates can
tolerate the reaction to furnish the corresponding prod-
ucts. In the case of benzonitrile, the presence of elec-
tron‐donating substituents on the aromatic ring led to
sluggish reactions due to the reduced the electrophilic
character of benzonitrile.
Plausible Reaction Mechanism
According to the previous reports,[59] the plausible mech-
anism for the synthesis of 1H‐Tetrazoleis initial activa-
tion of nitrile groups by silver nanoparticles of h‐
Fe2O3@SiO2/g‐C3N4/Ag which can serve as a Lewis acid
and formation of intermediate I followed by reaction

12 of 18
SADJADI ET AL.
TABLE 2 Synthesis of three‐component reaction of derivatives aldehyde, secondary‐ amines and terminal alkynes catalyzed by h‐
Fe2O3@SiO2/g‐C3N4/Aga [50]
Time
(min)
Yieldb
(%)
R1
R2
R3
R4
Product
1a: C6H5
3a: ‐(CH2)5‐
4a: C6H5
5a
5b
5c
15
15
20
15
20
18
16
25
12
20
25
12
15
18
16
20
15
13
15
15
18
20
25
20
15
18
17
20
95
88
89
92
90
86
93
90
94
88
83
98
91
90
90
92
80
73
90
83
88
90
75
85
85
75
79
75
1b: p‐Cl‐C6H4
3a
4a
1c: o‐Cl‐C6H4
3a
4a
1d: p‐Br‐C6H4
3a
4a
5d
5e
5f
1e: p‐Me‐C6H4
3a
4a
1f:p‐MeO‐C6H4
3a
4a
1 g:o‐Thiophen
3a
4a
5 g
5 h
5i
1 h: p‐OHCC6H4
3a
4a
1i: o‐Naphthyl
3a
4a
1a
3a
4b:p‐CH3−C6H4
5j
1a
3a
4c:p‐F‐C6H4
5 k
5 l
5 m
5n
5o
5p
5q
5r
1a
3b(CH2)2‐O‐(CH2)2‐
4a
4a
4a
4a
4b
4a
4a
4a
4b
4a
4a
4a
4c
4a
4a
4a
4a
1b
3b
1e
3b
1d
3b
1a
3b
1a
3c: ‐(CH2)4‐
1a
3d:C2H5
3a
C2H5
2a: C6H11
6a
6b
6c
2a
3b
2a
3b
2a
3c
6d
6e
6f
2a
3d
2a
3a
2b: ‐(CH2)2‐Me
3a
6 g
6 h
6i
2b
2b
2b
3b
3c
3d
6j
aReaction conditions: aliphatic or arylaldehydes (1 mmol), amines (1 mmol), alkynes (1.1 mmol), h‐Fe2O3@SiO2/g‐C3N4/Ag (20 mg) in water at 80 W and room
temperature.
bIsolated yield.
did not proceed through leached silver nanoparticles.
Finally, the stability of the catalyst in the course of the
catalytic process was studied by comparing the FTIR
spectra of the fresh and the reused catalyst after five
reaction runs, Figure 12. The results established that
both FTIR spectra were almost similar, indicating that

SADJADI ET AL.
13 of 18
TABLE 3 Synthesis of the three‐component reaction of aliphatic ketones, secondary‐ amines and terminal alkynes catalyzed by h‐
Fe2O3@SiO2/g‐C3N4/Aga[50]
Time
(min)
Yieldb
(%)
R5, R6
R3, R4
R4
Product
7a: ‐(CH2)4‐
3a: ‐(CH2)5‐
4a: C6H5
8a
8b
8c
8d
8e
8f
30
35
40
43
50
40
50
38
30
92
90
80
85
80
90
91
90
84
7a
3b: ‐(CH2)2‐O‐(CH2)2‐
4a
7a
3c: ‐(CH2)4‐
4a
7b: ‐(CH2)5‐
3a
3a
3b
3b
3c
3b
4a
7b
7b
7b
7b
7b
4b:p‐CH3−C6H4
4a
4b
8 g
8 h
8i
4a
4c:p‐F‐C6H4
aReaction conditions: ketones (1.5 mmol), amines (1 mmol), alkynes (1.5 mmol), h‐Fe2O3@SiO2/g‐C3N4/Ag (20 mg) in water at 80 W and room temperature.
bIsolated yield.
be preserved upon recycling, the XRD pattern of the
recycled catalyst was recorded and compared with that
of the fresh one, Figure 13. The comparison of two XRD
patterns showed their similarity, indicating that the mag-
netic nanocatalyst would not be destructed upon
recycling.
3.4 | Comparison of catalytic activity of h‐
Fe2O3@SiO2/g‐C3N4/Ag with other recently
reported
Finally, to study the merits of h‐Fe2O3@SiO2/g‐C3N4/Ag,
the catalytic activities of this catalyst for promoting two
model reactions for the synthesis of propargylamines
and 1H‐tetrazole were compared with those of some pre-
viously reported catalysts, Table 5. As shown, in the case
SCHEME 3 Plausible mechanism of the A3‐coupling reaction by
h‐Fe2O3@SiO2/g‐C3N4/Ag
of synthesis of model propargylamine various catalysts
under different reaction conditions have been reported
(Table 5, entries 1–14). Comparing the magnetic catalysts,
entries 1–5, It can be clearly concluded that the catalytic
activity of Ag(0) doped organic–inorganic hybrids of h‐
Fe2O3 is superior to bare Fe2O3. Moreover, the catalytic
activities of the magnetic Ag(0) doped hybrids are com-
parative, indicating the efficiency of these systems as cat-
alysts. Other catalysts reported for the synthesis of
propargylamines led to lower yields. Additionally, com-
pared to h‐Fe2O3@SiO2/g‐C3N4/Ag, the reaction times
SCHEME 4 The model reaction of 1H‐Tetrazole
the structure of the catalyst was almost preserved in the
course of the reaction.
To further investigate the nature of the recycled cata-
lyst and verify whether the structure of the catalyst would

14 of 18
SADJADI ET AL.
FIGURE 10 Effects of loading of
catalyst, duration of reaction and solvent
for the synthesis of 1H‐Tetrazole
TABLE 4 Synthesis of 5‐substituted‐1H‐tetrazole from deriva-
tives of aryl cyanide and sodium azide catalyzed by h‐Fe2O3@SiO2/
g‐C3N4/Aga[50]
Time
(h:min)
Yield
(%)b
R
Product
C6H5
9a
1:30
1:15
2
94
88
85
80
80
75
85
88
90
85
88
85
90
75
80
p‐O2N‐C6H4
p‐CH3‐C6H4
p‐OCH3‐C6H4
β‐Naphtol
9b
9c
9d
9e
2:40
1:15
2
SCHEME 5 Plausible mechanism for the synthesis of 5‐
Substituted 1H‐Tetrazoles by h‐Fe2O3@SiO2/g‐C3N4/Ag
Α‐Naphtol
m‐Cl‐C6H4
p‐Cl‐C6H4
9f
9 g
9 h
9i
1:30
1:45
1:20
3
with some reported catalysts, Table 5, entries 15–23,
showed that h‐Fe2O3@SiO2/g‐C3N4/Ag could promote
the reaction in shorter reaction times to afford the desired
product in higher or comparative yield. All these results
established that h‐Fe2O3@SiO2/g‐C3N4/Ag could be con-
sidered as an efficient catalyst for catalyzing organic
transformations.
p‐Br‐C6H4
p‐OH‐C6H4
p‐CN‐C6H4
2‐Pyridine
4‐Pyridine
CH2‐C6H5
9 J
9 k
9 l
9 m
9n
9o
1
1:10
1
3:30
2:45
o‐NH2‐m‐NO2‐C6H4
3.5 | Spectral data of some selected
compound
aReaction condition: nitriles (1.0 mmol), Sodium azide (1.5 mmol), h‐
Fe2O3@SiO2/g‐C3N4/Ag (30 mg), DMF (5 ml), at 100
W and room
temperature.
1‐(1,3‐diphenylprop‐2‐ynyl)piperidine (Table 2, 5a):
Pale yellow oily liquid; 1H NMR (400 MHz, CDCl3,
ppm) δ 1.45–1.49 (m, 2H), 1.58–1.65 (m, 4H), 2.59 (t,
4H), 4.81 (s, 1H), 7.31–7.40 (m, 6H), 7.53–7.55 (m, 2H),
7.65–67 (d, J = 7.6 Hz, 2H).
bYields are after work‐up.
for most of those protocols were very long. The compari-
son of the catalytic activities of h‐Fe2O3@SiO2/g‐C3N4/Ag
for promoting the synthesis of the model 1H‐tetrazole

SADJADI ET AL.
15 of 18
FIGURE 11 Reusability of the h‐
Fe2O3@SiO2/g‐C3N4/Ag catalyst for the
synthesis of propargylamine (a) and 1H‐
tetrazole (b)
FIGURE 12 The comparison of FTIR
analysis for fresh h‐Fe2O3@SiO2/g‐C3N4/
Ag and after seven runs
7.00 (dd, J1 = J2 = 3.6 Hz, 1H), 7.25–7.30 (m, 1H), 7.31
(d, J = 4.4 Hz, 2H).7.36–7.38 (m, 3H), 7.54–7.57 (m,
2H); 13C NMR (100 MHz, CDCl3, ppm) δ 24.4, 26.1,
50.6, 58.2, 85.3, 86.9, 123, 125.3, 125.8, 126.2, 128.2,
128.3, 131.8, 144.
1‐(3‐phenyl‐1‐(4‐(3‐phenyl‐1‐(piperidin‐1‐yl)prop‐
2‐ynyl)phenyl)prop‐2‐ynyl)piperidine (Table 2, 5h):
White solid; mp 157‐159 °C (Lit.[50] 158‐160 °C); 1H
NMR (400 MHz, CDCl3, ppm) δ 1.47 (m, 2H), 1.59–1.63
(m, 4H), 2.59 (m, 4H), 4.81 (s, 1H), 7.33–7.35 (m, 3H),
7.52–7.55 (m, 2H), 7.63 (s, 2H).
1‐(1‐(naphthalen‐3‐yl)‐3‐phenylprop‐2‐ynyl)
piperidine (Table 2, 5i): Yellow oil; 1H NMR (400 MHz,
CDCl3, ppm) δ 1.47–1.51 (m, 2H), 1.60–1.67 (m, 4H), 2.64
(t, 4H), 4.97 (s, 1H), 7.36–7.40 (m, 3H), 7.48–7.52 (m, 2H),
7.58–7.61 (m, 2H), 7.79 (dd, J1 = J2 = 8.4 Hz, 1H), 7.85–
7.91 (m, 3H), 8.11 (s, 1H); 13C NMR (100 MHz, CDCl3,
ppm) δ 24.4, 26.2, 50.8, 62.5, 86, 88.1, 123.3, 125.8,
125.9, 126.7, 127.2, 127.5, 127.7, 128.1, 128.12, 131.8,
132.9, 133.1, 136.3.
FIGURE 13 The comparison of the XRD patterns of fresh and
recycled catalysts
1‐(3‐phenyl‐1‐(thiophen‐2‐yl)prop‐2‐ynyl)piperi-
dine (Table 2, 5g): Yellow solid; mp 50‐51 °C (Lit.[50] 52‐
1
53 °C); H NMR (400 MHz, CDCl3, ppm) δ 1.48–1.52 (m,
2H), 1.63–1.70 (m, 4H), 2.62–2.71 (m, 4H), 5.03 (s, 1H),

16 of 18
SADJADI ET AL.
TABLE 5 Comparison of h‐Fe2O3@SiO2/g‐C3N4/Ag with other recently reported metal catalysts for the synthesis of propargylaminea
(Entry 1–14) and 1H‐tetrazoleb (Entry 15–23)
Reaction
conditions
Time Catalyst
(min) amount
Yield
(%)
Entry Catalyst
[Ref]
1
h‐Fe2O3@SiO2/g‐C3N4/Ag
H2O / r.t./U.S
H2O/ r.t./ U.S
S.F./ 90 °C
12
20 mg
98
96
96
97
75
89
89
65
59
91
89
87
95
93
95
83
97
90
95
This work
[35]
2
h‐Fe2O3@SiO2‐IL/Ag
12
25 mg
[50]
[51]
3
h‐Fe2O3@DA/Ag
60
10 mg
4
h‐Fe2O3@SiO2‐CD/Ag
H2O/ r.t./ U.S
H2O/ r.t./ U.S
Stirrer/ 90 °C
Reflux/ H2O
H2O/ 40 °C
8
20 mg
5
h‐Fe2O3
12
25 mg
This work
[23]
6
ZnO nano particles
120
240
720
10 mol%
10 mol%
5 mg
[60]
[61]
[62]
[19]
[63]
[33]
[64]
[31]
[34]
[32]
[54]
[37]
[41]
[59]
[43]
[50]
7
Immobilized Silver on Surface‐modified ZnO NPs
Ag‐CIN‐1c
AgI‐Pc‐Ld
8
9
Toluene/MW/ 150 °C 20
3 mol%
0.5 mol%
10 mol%
20 mg
10
11
12
13
14
15
16
17
18
19
20
21
22
23
CuNPs/TiO2
Neat/ 70 °C
420
ZnS
Reflux/ CH3CN
Reflux/EtOH, 90 °C
270
1440
90
sulfonate‐based Cu(I) metal–organic frameworks
CuI catalysts supported on protonated trititanate nanotubes Solvent‐free, 70 °C
20 mg
Cu2O/nano‐CuFe2O4
Solvent‐free, 90 °C
THF, 60 °C
40
10 mg
copper nanoparticles supported on starch micro particles
1200
900
360
840
60
0.3 mol%
20 mg
Cu(II) Schiff base complex immobilized on graphene oxide
Water, reflux, N2
PEG, 120 °C
Cu(II) immobilized on Fe3O4@SiO2@L‐Arginine
30 mg
CoY Zeolite
DMF, 120 °C
DMSO, 120 °C
DMF, 110 °C
DMF, 100 °C
DMF, 110 °C
DMF, r.t./ U.S
29 mg
CAESe
1 mol%
(NH4)2Ce(NO3)6
MCMBSAf
360
480
420
90
10 mmol% 97
5 mg
85
94
94
h‐Fe2O3@DA/Ag
h‐Fe2O3@SiO2/g‐C3N4/Ag
30 mg
30 mg
This work
aReaction conditions: morpholine (1 mmol), benzaldehyde (1 mmol), phenylacetylene (1.1 mmol) in the presence of different conditions.
bReaction condition: benzonitrile (1 mmol), Sodium azide (1.5 mmol) in the presence of different conditions.
cAg‐grafted covalent imine network material.
dAg(I)(Pyridine‐Containing Ligand) Complexes.
eCu(II) immobilized on aminatede pichlorohydrin activated silica.
fbenzylated MCM‐41 solfunic acid.
N,N‐diethyl‐1,3‐diphenylprop‐2‐yn‐1‐amine
(Table 2, 5r): Pale yellow oily liquid; 1H NMR (400 MHz,
CDCl3, ppm) δ 1.04 (m, 6H), 2.36–2.62 (m, 4H), 5.19 (s,
1H), 7.15–7.27 (m, 4H), 7.29–7.38 (m, 3H), 7.39–7.41
(m, 2H).
4‐(1‐phenylhex‐1‐yn‐3‐yl)morpholine (Table 2,
6 h): Yellow oil; H NMR (400 MHz, DMSO‐d6, ppm) δ
0.97 (m, 3H), 1.45–1.75 (m, 4H), 2.67–2.70 (m, 2H),
2.79–2.83 (m, 2H), 3.82–4.13 (m, 1H), 4.15–4.17 (m, 4H),
7.46–7.50 (m, 3H), 7.62–7.64 (m, 2H).
1
1‐(1‐cyclohexyl‐3‐phenylprop‐2‐ynyl)pyrrolidine
(Table 2, 6d): Colorless liquid; 1H NMR (400 MHz,
CDCl3, ppm) δ 1.05–1.36 (m, 5H), 1.56–1.63 (m, 2H),
1.75–1.79 (m, 6H), 1.82–2.10 (m, 4H), 2.5–2.98 (m, 4H),
3.36–3.38 (d, J = 7.6 Hz, 1H), 7.14–7.33 (m, 3H), 7.50–
7.63 (m, 2H). 13C NMR (100 MHz, CDCl3, ppm) δ 24.9,
26.9, 27.1, 28.3, 32.7, 33, 42.9, 51.1, 61.1, 86.1, 88.9,
125.9, 128.9, 129.8, 132.6.
4‐(1‐(2‐phenylethynyl)cyclohexyl)morpholine
(Table 3, 8f): Pale yellow oily liquid; 1H NMR
(400 MHz, CDCl3, ppm) δ 1.28–1.30 (m, 1H), 1.52 (m,
2H), 1.63–1.67 (m, 3H), 1.73 (br.s, 2H), 2.03–2.05 (m,
2H), 2.74 (br.s, 4H), 3.78 (br.s, 4H), 7.27 (m, 3H), 7.44–
7.45 (m, 2H), 13C NMR (100 MHz, CDCl3, ppm) δ22.7,
25.7, 35.4, 46.6, 58.8, 67.4, 86.4, 89.8, 123.4, 127.7,
128.1, 131.7.

SADJADI ET AL.
17 of 18
4‐(1‐((4‐fluorophenyl)ethynyl)cyclohexyl)
4 | CONCLUSION
morpholine (Table 3, 8i): Yellow oil;1H NMR
(400 MHz, DMSO‐d6, ppm) δ 1.26–1.34 (m, 1H), 1.57–
1.62 (m, 2H), 1.69–1.78 (m, 3H), 1.80–1.86 (m, 2H),
2.00–2.02 (m, 2H), 2.78 (s, 4H), 3.70 (br.t,
J = 4.2 Hz, 4H), 6.97–7.00 (t, J = 8.6 Hz, 2H), 7.32–
7.40 (m, 2H);
For the first time, a novel and simple hydrothermal
procedure is disclosed for the incorporation of g‐C3N4 to
h‐Fe2O3@SiO2. Additionally, an efficient catalyst, h‐
Fe2O3@SiO2/g‐C3N4/Ag, was prepared through extract‐
assisted reduction of silver precursor and immobilization
of Ag(0) nanoparticles on h‐Fe2O3@SiO2/g‐C3N4. The
hybrid system exhibited excellent catalytic activity for
promoting ultrasonic‐assisted A3, KA2 coupling reactions
and [3 + 2] cycloaddition. Moreover, the catalyst was
highly reusable and showed only slight Ag leaching upon
five recycling tests. High yields, low reaction times, broad
substrate scope and eco‐friendly nature were the merits of
this developed protocol.
5‐Phenyl‐1H‐tetrazole (Table 4, 9a): White solid;
mp 213–215 °C (Lit.[50] 214–215 °C); 1H NMR
(400 MHz, DMSO‐d6, ppm) δ 7.68 (s, 3H, Ph), 7.92 (s,
2H, Ph); 13C NMR (100 MHz, DMSO‐d6, ppm) δ 126.6,
128.6, 130.3, 134.6, 155.
5‐(4‐Nitrophenyl)‐1H‐tetrazole (Table 3, 9b): Yel-
1
low solid; mp 218–219 °C (Lit.[50] 220‐222 °C); H NMR
(400 MHz, DMSO‐d6, ppm) δ8.30 (d, 2H, J = 8.4, Ph),
8.39 (d, 2H, J = 8.8, Ar‐H); 13C NMR (100 MHz, DMSO‐
d6, ppm) δ 127.6, 129.1, 131, 149.5.
5‐(4‐Methylphenyl)‐1H‐tetrazole (Table 3, 9c):
White solid; mp 249‐251 °C (Lit.[50] 247‐249 °C); 1H
NMR (250 MHz, DMSO‐d6, ppm) δ 2.35 (s, 3H, CH3),
ACKNOWLEDGMENT
The authors appreciate partial financial supports from
Alzahra University and Iran Polymer and Petrochemical
Institute. MMH is also thankful to Iran National Science
Foundation for the Individual given grant.
7.37 (d, 2H,
J
=
7.6 Hz, Ph), 7.90 (d, 2H,
J = 7.5 Hz, Ph).
5‐(3‐Chlorophenyl)‐1H‐tetrazole (Table 3, 9 g):
White solid; mp138‐140 °C (Lit.[50] 137‐139 °C); 1H
NMR (250 MHz, DMSO‐d6, ppm) δ7.55 (m, 2H, Ph),
7.96 (d, 1H, J = 7.6, Ph), 7.99, (s, 1H); 13C NMR
(62.9 MHz, DMSO‐d6, ppm) δ 125.4, 126.2, 126.4, 130.7,
131.1, 133.9, 154.6.
ORCID
Samahe Sadjadi http://orcid.org/0000-0002-6884-4328
Majid M. Heravi http://orcid.org/0000-0003-2978-1157
5‐(4‐Chlorophenyl)‐1H‐tetrazole (Table 3, 9 h):
White solid; mp 251‐253 °C (Lit.[50] 251‐252 °C); 1H
NMR (400 MHz, DMSO‐d6, ppm) δ7.61 (d, 2H, J = 8.4,
Ph), 8.09 (d, 2H, J = 8.8, Ph).
REFERENCES
[1] Y. Li, J. Zhang, Q. Wang, Y. Jin, D. Huang, Q. Cui, G. Zou,
J. Phys. Chem. B 2010, 114, 9429.
[2] X. Zhang, X. Xie, H. Wang, J. Zhang, B. Pan, Y. Xie, J. Am.
Chem. Soc. 2013, 135, 18.
5‐(4‐Hydroxyphenyl)‐1H‐tetrazole (Table 3, 9j):
1
White solid; mp 235 °C (Lit.[50] 233‐234 °C); H NMR
[3] J. Wen, J. Xie, X. Chen, X. Li, Appl. Surf. Sci. 2017, 391, B, 72.
[4] G. Mamba, A. K. Mishra, Appl. Catal. B 2016, 198, 347.
[5] F. Su, M. Antoniettia, X. Wang, Sci. Technol. 2012, 2, 1005.
(400 MHz, DMSO‐d6, ppm) δ 6.91 (d, 2H, J = 8.4, Ph),
7.58 (d, 2H, J = 8.4, Ph), 10.11 (s broad, OH); 13C NMR
(100 MHz, DMSO‐d6, ppm) δ 116.1, 117.4, 128.8,
153.2, 159.8.
4‐(1H‐tetrazol‐5‐yl)‐benzonitrile(Table 3, 9 k):
White solid; mp 257‐259 °C (Lit.[50] 258‐260 °C); 1H
NMR (250 MHz, DMSO‐d6, ppm) δ8.06 (d, 2H, J = 7.1,
Ph), 8.19 (d, 2H, J = 8.6, Ar‐H); 13C NMR (62.9 MHz,
DMSO‐d6, ppm) δ 113.3, 118.1, 127.6, 128.7, 133.1,
155.2, 162.2.
[6] X. J. Ye, Y. J. Cui, X. Q. Qiu, X. C. Wang, Appl. Catal. B 2014,
152‐153, 383.
[7] X. S. Zhang, J. Y. Hu, H. Jiang, Chem. Eng. J. 2014, 256, 230.
[8] D. J. Martin, K. P. Qiu, S. A. Shevlin, A. D. Handoko, X. W. Chen,
Z. X. Guo, J. W. Tang, Angew. Chem. Int. Ed. 2014, 53, 9240.
[9] W.‐J. Ong, L.‐L. Tan, Y. H. Ng, S.‐T. Yong, S.‐P. Chai, Chem.
Rev. 2016, 116, 7159.
[10] M. N. Nadagouda, R. B. Nasir Baig, R. S. Varma, S. Verma, ACS
Sustainable Chem. Eng. 2016, 4, 1661.
2‐(1H‐tetrazol‐5‐yl)pyridine (Table 3, 9 l): White
solid; mp 210‐213 °C (Lit.[50] 211‐212 °C); 1H NMR
(400 MHz, DMSO‐d6, ppm) δ 7.75 (s, 1H, Ph), 8.07 (s,
1H, Ph), 8.20 (d, 1H, J = 8.4 Ph), 8.63 (s, 1H).
4‐(1H‐tetrazol‐5‐yl)pyridine (Table 3, 9 m): White
solid; mp 256‐258 °C (Lit.[50] 256‐258 °C); 1H NMR
(250 MHz, DMSO‐d6, ppm) δ 8.10 (d, 2H, J = 6.0, Ph),
8.77 (d, 2H, =J 6.5, Ph); 13C NMR (62.9 MHz, DMSO‐d6,
ppm) δ 120.9, 121.3, 133.8, 149.9, 165.7.
[11] R. A. Molla, M. A. Iqubal, K. Ghosh, S. M. Islam, Green Chem.
2016, 18, 4649.
[12] R. A. Molla, M. A. Iqubal, K. Ghosh, Kamaluddin, S. M. Islam,
Dalton Trans. 2015, 44, 6546.
[13] xX. Su, A. Vinu, S. S. Aldeyab, L. Zhong, Catal. Lett. 2015, 145, 1388.
[14] S. Kumar, A. Baruah, S. Tonda, B. Kumar, V. Shanker, B.
Sreedhar, Nanoscale 2014, 6, 4830.

18 of 18
SADJADI ET AL.
[15] Z. Zhu, Z. Lu, D. Wang, X. Tang, Y. Yan, W. Shi, Y. Wang, N.
[45] M. M. Heravi, E. Hashemi, Y. Shirazi Beheshtiha, S. Ahmadi,
Gao, X. Yao, H. Dong, Appl. Catal. B 2016, 182, 115.
T. Hosseinnejad, J. Mol. Catal. A. 2014, 394, 74.
[46] S. Sadjadi, M. M. Heravi, M. Daraie, Res. Chem. Intermed. 2017,
43, 2201.
[16] R. B. Nasir Baig, R. S. Varma, Chem. Commun. 2013, 49, 752.
[17] X. Wang, J. Feng, Y. Bai, Q. Zhang, Y. Yin, Chem. Rev. 2016,
116, 10983.
[47] S. Sadjadi, M. Eskandari, Ultrason. Sonochem. 2013, 20, 640.
[48] S. Sadjadi, M. M. Heravi, RSC Adv. 2017, 7, 30815.
[49] S. Sadjadi, M. M. Heravi, RSC Adv. 2016, 6, 88588.
[18] M. Harmata, Organic Mechanisms: Reactions, Stereochemistry
and Synthesis, Springer, 2010.
[19] M. J. Albaladejo, F. Alonso, Y. Moglie, M. Yus, Eur. J. Org.
Chem. 2012, 2012, 3093.
[50] A. Elhampour, M. Malmir, E. Kowsari, F. A. Boorboor, F.
Nemati, RSC Adv. 2016, 6, 96623.
[20] G. Villaverde, A. Corma, M. Iglesias, F. Sanchez, ACS Catal.
2012, 2, 399.
[51] S. Sadjadi, M. Malmir, M. M. Heravi, RSC Adv. 2017, 7, 36807.
[52] T. K. H. Ta, M.‐T. Trinh, N. V. Long, T. T. M. Nguyen, T. L. T.
Nguyen, T. L. Thuoc, B. T. Phan, D. Mott, S. Maenosono, H.
Tran‐Van, V. H. Le, Asp. 2016, 504, 1.
[21] S. V. Katkar, R. V. Jayaram, RSC Adv. 2014, 4, 47958.
[22] N. Salam, S. K. Kundu, A. Singha Roy, P. Mondal, S. Roy, A.
[53] M. Tahir, N. Mahmood, L. Pan, Z.‐F. Huang, Z. Lv, J. Zhang, F.
K. Butt, S. G, X. Zhang, S. X. Dou, J.‐J. Zou, J. Mater. Chem. A
2016, 4, 12940.
Bhaumik, S. Manirul Islam, Catal. Sci. Technol. 2013, 3, 3303.
[23] K. V. V. Satyanarayana, P. Atchuta Ramaiah, Y. L. N. Murty, M.
R. Chandra, S. V. N. Pammi, Catalysis Commun. 2012, 25, 50.
[54] S. C. Yan, Z. S. Li, Z. G. Zou, Langmuir 2009, 25, 10397.
[55] X. Zhang, Y. Niu, Y. Yang, Y. Li, J. Zhao, New J. Chem. 2014, 38, 4351.
[24] L. F. Bobadilla, T. Blasco, J. A. Odriozola, Phys. Chem. Chem.
Phys. 2013, 15, 16927.
[56] S. Wang, C. Li, T. Wang, P. Zhang, A. Li, J. Gong, J. Mater.
Chem. A 2014, 2, 2885.
[25] M. Hosseini‐Sarvari, F. Moeini, New J. Chem. 2014, 38, 624.
[26] B. J. Borah, S. J. Borah, K. L. Saikia, D. K. Dutta, Catal. Sci.
Technol. 2014, 4, 4001.
[57] P. Yuan, P. D. Southon, Z. Liu, M. E. R. Green, J. M. Hook, S. J.
Antill, C. J. Kepert, J. Phys. Chem. C 2008, 112, 15742.
[27] T. Zeng, W.‐W. Chen, C. M. Cirtiu, A. Moores, G. Song, C.‐J. Li,
Green Chem. 2010, 12, 570.
[58] L. Shi, Y.‐Q. Tu, M. Wang, F.‐M. Zhang, C.‐A. Fan, Org. Lett.
2004, 6, 1001.
[28] T.‐W. Hui, J.‐F. Cui, M.‐K. Wong, RSC Adv. 2017, 7, 14477.
[59] P. Mani, A. C. Sharma, S. Kumar, S. K. Awasthi, J. Mol. Catal.
A: Chem. 2014, 392, 150.
[29] A. M. Munshi, M. Shi, S. P. Thomas, M. Saunders, M. A.
Spackman, K. S. Iyer, N. M. Smith, Dalton Trans. 2017, 46, 5133.
[60] F. Movahedia, H. Masrouria, M. Z. Kassaee, J. Mol. Catal. A.
2014, 395, 52.
[30] M. Mirabedini, E. Motamedi, M. Z. Kassaee, Chin. Chem. Lett.
2015, 26, 1085.
[61] N. Salam, S. K. Kundu, R. A. Molla, P. Mondal, A. Bhaumik, S.
[31] F. Nemati, A. Elhampour, H. Farrokhi, M. Bagheri Natanzi,
M. Islam, RSC Adv. 2014, 4, 47593.
Catal. Commun. 2015, 66, 15.
[62] M. Trose, M. Dell'Acqua, T. Pedrazzini, V. Pirovano, E. Gallo,
E. Rossi, A. Caselli, G. Abbiati, J. Org. Chem. 2014, 79, 7311.
[32] S. Kumari, A. Shekhar, D. D. Pathak, RSC Adv. 2016, 6, 15340.
[33] P. Li, S. Regati, H.‐C. Huang, H. D. Arman, B.‐L. Chen, J. C.‐G.
Zhao, Chin. Chem. Lett. 2015, 26, 6.
[63] N. P. Eagalapati, A. Rajack, Y. L. N. Murthy, J. Mol. Catal. A.
2014, 381, 126.
[34] M. Gholinejad, F. Saadati, S. Shaybanizadeh, B. Pullithadathil,
[64] B. R. Prasad Reddy, P. V. Govardhana Reddy, M. V. Shankar, B.
RSC Adv. 2016, 6, 4983.
N. Reddy, Asian J. Org. Chem. 2017, 6, 712.
[35] S. Sadjadi, M. M. Heravi, M. Malmir, Appl. Organomet. Chem.
2017.
SUPPORTING INFORMATION
[36] T. Hashimoto, K. Maruoka, Chem. Rev. 2015, 115, 5366.
Additional supporting information may be found online
in the Supporting Information section at the end of the
article.
[37] V. Rama, K. Kanagaraj, K. Pitchumani, J. Org. Chem. 2011, 76, 9090.
[38] M. Tajbakhsh, H. Alinezhad, M. Nasrollahzadeh, T. A. Kamali,
Monatsh. Chem. 2016, 147, 2135.
[39] A. Kumar, S. Kumar, Y. Khajuria, S. K. Awasthi, RSC Adv.
2016, 6, 75227.
How to cite this article: Sadjadi S, Malmir M,
Heravi MM. Preparation of Ag‐doped g‐C3N4 Nano
Sheet Decorated Magnetic γ‐Fe2O3@SiO2 Core–
Shell Hollow Spheres through a Novel
[40] A. Ghorbani‐Choghamarani, L. Shiri, L. Azadi, RSC Adv. 2016,
6, 32653.
[41] N. Razavi, B. Akhlaghinia, RSC Adv. 2015, 5, 12372.
[42] S. Kumar, S. Dubey, N. Saxena, S. K. Awasthi, Tetrahedron Lett.
2014, 55, 6034.
Hydrothermal Procedure: Investigation of the
Catalytic activity for A3, KA2 Coupling Reactions
and [3 + 2] Cycloaddition. Appl Organometal
Chem. 2018;e4413. https://doi.org/10.1002/aoc.4413
[43] A. N. Chermahini, M. K. Omran, H. A. Dabbagh, G.
Mohammadnezhad, A. Teimouri, New J. Chem. 2015, 39, 4814.
[44] S. Sadjadi, M. M. Heravi, M. Daraie, J. Mol. Liq. 2017, 231, 98.