Phosphotungstic acid supported on SiO2@NHPhNH2 functionalized nanoparticles of MnFe2O4 as a recyclable catalyst for the preparation of tetrahydrobenzo[b]pyran and indazolo[2,1-b]phthalazine-triones

Article abstract of DOI:10.1016/j.poly.2019.01.065

MnFe₂O₄@SiO₂@NHPhNH₂–phosphotungstic acid was synthesized by the reaction of diamine-modified silica coated manganese ferrite nanoparticles with H₃PW₁₂O₄₀, the Keggin-type hetero

Full text of DOI:10.1016/j.poly.2019.01.065

Accepted Manuscript
Phosphotungstic acid supported on SiO2@NHPhNH2 functionalized nanopar-
ticles of MnFe2O4 as a recyclable catalyst for the preparation of tetrahydroben-
zo[b]pyran and indazolo[2,1-b]phthalazine-triones
Roya Mozafari, Fariba Heidarizadeh
PII:
S0277-5387(19)30087-7
https://doi.org/10.1016/j.poly.2019.01.065
POLY 13738
DOI:
Reference:
Polyhedron
To appear in:
Received Date:
Revised Date:
Accepted Date:
31 December 2018
22 January 2019
27 January 2019
Please cite this article as: R. Mozafari, F. Heidarizadeh, Phosphotungstic acid supported on SiO2@NHPhNH2
functionalized nanoparticles of MnFe2O4 as a recyclable catalyst for the preparation of tetrahydrobenzo[b]pyran
and indazolo[2,1-b]phthalazine-triones, Polyhedron (2019), doi: https://doi.org/10.1016/j.poly.2019.01.065
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Phosphotungstic acid supported on SiO2@NHPhNH2 functionalized nanoparticles of
MnFe2O4 as a recyclable catalyst for the preparation of tetrahydrobenzo[b]pyran and
indazolo[2,1-b]phthalazine-triones
Roya Mozafaria, Fariba Heidarizadeha,*
a
Chemistry Department, College of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran. E-mail:
heidarizadeh@scu.ac.ir; Tel: (+98) 6135743169
MnFe2O4@SiO2@NHPhNH2- phosphotungstic acid was synthesized by the reaction of
diamine-modified silica coated manganese ferrite nanoparticles with H3PW12O40, the Keggin-
type heteropoly acid. This is the first time that H3PW12O40 supported on diamine
functionalized MnFe2O4 nanoparticles has been reported. The synthesized catalyst was
characterized by various techniques, including Fourier Transform Infrared Spectroscopy
(FTIR), Transmission electron-microscopy (TEM), X-ray Powder Diffraction (XRD),
Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Spectroscopy (EDX),
Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), Thermogravimetric
Analysis (TGA), and Vibrating Sample Magnetometer (VSM). The synthesized nanoparticle
was examined as the heterogenous nanocatalyst for the synthesis of tetrahydrobenzo-[b]-
pyran derivatives and 2H-indazolo-[2, 1-b]-phthalazine-triones under the solvent-free heating
or ultrasonic irradiation conditions.This method offers several advantages including high
yield, low reaction times, and the simple work-up procedure due to the presence of the
magnetic nanoparticles in this catalyst, so that, it can be easily recovered and reused for at
least six successive times without the loss of its high catalytic activity, suggesting its great
Potential for industrial applications.
Keywords: phosphotungstic acid, Keggin-type heteropoly acid, ferrite nanoparticles, 2H-
indazolo-[2, 1-b]-phthalazine-triones, tetrahydrobenzo-[b]-pyran
1. Introduction
The magnetic nanoparticles (MNPs) have attracted great interest because of their magnetic
and electrical properties, and the tremendous surface area-to-volume ratio which make a
unique compound with wide applications in drug delivery system, targeted gene therapy,
magnetic resonance imaging, biosensors, ion exchange separation, magnetic data storage and
environmental remediation and catalysis [1].

The utilizing of an efficient support, could significantly improve the activity, selectivity,
recycling, and reproducibility of the catalyst systems [2]. In recent years, MNPs have
appeared as attractive solid supports for immobilization of homogeneous catalysts [3].
Furthermore, the magnetic nanoparticles can be well dispersed in the reaction mixtures and
after the completion of the reaction can be isolated efficiently from the product solution
through a simple magnetic separation process [4]. The MNPs have been grafted onto
inorganic and organic materials supports to amend their stabilization and recycling ability.
magnetic nanoparticles can be used in a wide range of the catalytic reactions including
condensation, oxidation, esterification, acylation, epoxidation, hydration, and hydrogenation
[5]. Among the various magnetic nanoparticles, Fe3O4 presents the most interesting magnetic
substance as the catalyst support; however, Fe3O4 is quite chemically unstable [6]. On the
contrary, manganese ferrite (MnFe2O4) which is a typical ferromagnetic oxide has high
thermal constancy, moderate magnetization, mechanical rigidity, and the significant chemical
stability [7].
More recently, polyoxometalate functionalized magnetic nanoparticles have emerged much
broadly and been widely used as active species in organic reactions catalysis [8].
Polyoxometalate, with the molecular formula of [XM12O40]n−,where X = P5+, As5+, Si4+, or
Ge4+ and M = Mo6+, or W6+, have been utilized as catalysts for various organic reactions due
to their unique physicochemical properties [9]. Lately, the phosphotungstic acid (PTA), has
been attracted the considerable attention because of its super strong Brønsted acidity and also
its ease of preparation. However, it should be immobilized on the proper support to eliminate
its very low surface area, and instability in polar solvents [10]. The supported PTA has a
greater number of surface acid sites than its bulk form and therefore show higher catalytic
activity [11]. On the other hand, most of the acidic protons of the bulk phosphotungstic acid
are in the interior of the solid which are inaccessible for catalysis of non-polar hydrocarbon
reactions [12]. This kind of keggin-type heteropoly acid has more properties such as high
thermal stability, ease of handling, stronger acidity properties compared to the homogeneous
acid catalysts, low toxicity, capability of the clean technologies development and low cost
[13]. Pyran derivatives have received significant attention due to their important biological
and pharmacological properties [14]. Among the pyrans, the substituted tetrahydrobenzeno-
[b]-pyran have a special importance among the 6-membered oxygen containing heterocycles
as they have been utilized in the synthesis of blood anticoagulant [15]. In addition, they have
been used as anticancer and antimicrobial agents [16], and the photoactive materials [17].
Moreover, phthalazine and its derivatives are very useful compounds in various fields of
chemistry, biology and pharmacology [18]. Some of these compounds exhibit antimicrobial
[19], anticonvulsant [20], antifungal [21], anticancer [22], and anti-inflammatory activity [23]
and can be incorporated for hypertensive treatment. The photophysical properties of some
selected derivatives have also been studied showing medium to strong optical behaviour [24].
Therefore, several methods have been reported for improving the preparation of these
compounds, but most of these methods suffer from some drawbacks [25]. Consequently, to

overcome these drawbacks, a great deal of efforts is directed to develop an efficient catalytic
system for the synthesis of these compounds.
Followed by the efforts done by this research group to utilize the green condition in organic
synthesis, MnFe2O4@SiO2@NHPhNH2-PTA was synthesized and used as a magnetic
hereocatalyst for the synthesis of tetrahydrobenzo-[b]-pyrans and 2H-indazolo-[2,1-b]-
phthalazine-triones from the simple and easily available starting materials under a very
simple condition.
2. Experimental
2.1. Materials and methods
All the chemicals were of analytical grade and used without further purification.
Manipulation and reactions were carried out in air without the protection of inert gas.
Phosphotungstic acid was synthesized according to the literature. Fourier transform infrared
(FT-IR) spectra were obtained using potassium bromide pellets in the range of 400–4000 cm 1
1
with a FT BOMEM MB102 spectrophotometer. H NMR and 13C NMR spectra were
recorded on a Brucker spectrometer at 400 MHz and 100 MHz, respectively, with tetra
methylsilane as an internal standard. X-ray diffraction (XRD) patterns of the synthesized
samples were taken with a Philips X-ray diffractometer (modelPW1840) over a 2θ range
from 10 to 80° using Cu Kα radiation(λ = 1.54056 A°). The FESEM images were obtained
using a Hitachi Japan S4160 scanning electron microscope. The magnetic proper-ties of the
fabricated MnFe2O4@SiO2@NHPhNH2-PTA composite as well as other samples were
studied using vibrating sample magnetometer (VSM) of Meghnatis Daghigh Kavir Company.
The TGA curve of the MnFe2O4@SiO2@NHPhNH2-PTA was recordedon a BAHR, SPA 503
o
at heating rates of 10 C min−1. The surface properties of the samples were determined by
nitrogen adsorption/ desorption isotherms at - 197ᵒC using a micromeritics ASAP 2000
instrument and the surface area and the pore size distribution were investigated by the
Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) analysis. The content of
metal in the catalyst was measured by inductively coupled plasma-optical emission
spectrometry (ICP-OES). The thermal behavior was studied by heating 1–3 mg of samples in
aluminum-crimped pans under airflow, over the temperature range of 25–800 oC.
2.2. Synthesis of MnFe2O4
First, the mixture of MnSO4 (11.24 g, 0.02 mol) and FeSO4 (2.77 g, 0.01 mol) was dissolved
in 100 ml deionized water and magnetically stirred. Sodium hydroxide (10%) solution was
added dropwise under constant stirring to raise pH to 10. Then, the mixture was stirred for 30
minutes. 1 g of Polyvinylpyrrolidone (PVP) was add to the liquid precipitate and it was
brought to reaction temperature of 100 °C and stirred for 2 h. Synthesized nano MnFe2O4
(dark brown precipitate) was separated by a permanent magnet from the reaction media and

washed with distilled water-ethanol mixture solution several times to remove impurities.
Finally, the product (light brown powder) was dried at 80 °C for 12 h.
2.3. Synthesis of diamine-functionalized modified silica coated manganese ferrite
nanoparticles (MnFe2O4@SiO2@NHPhNH2)
1 g of magnetic MnFe2O4 was dispersed in a mixture of 84 mL ethanol, 24 mL deionized
water, and 25 mL concentrated ammonia aqueous solution (25%) by stirring for 30 min.
Subsequently, 2 mL of tetraethyl orthosilicate (TEOS) was added dropwise. After being
stirred for 24 h at room temperature, the resulted solid was magnetically separated, washed
twice with water and twice with ethanol, and then dried at 100 °C for 2 h.
Then for the linkage of 3-chloropropyl unit to the surface of the obtained support, 0.7 g of
MnFe2O4 were dispersed in 100 mL anhydrous toluene, with ultrasonication for 25 min and
1 mL of 3-chloropropyltrimethoxysilane was added dropwise into the dispersion and
o
ultrasonicated for 15 min. Subsequently, the mixture was refluxed at 110 C under constant
stirring for 24 h. The products were magnetically separated and washed two times with
toluene and two times with ethanol and then dried at 60 oC.
The prepared MnFe2O4@SiO2-Cl (0.7 g) was dispersed into 70 mL of acetonitrile and
ultrasonicated for 20 min. Then, KI (7 mmol, 1.162 g) and K2CO3 (7 mmol, 0.967 g) were
added into the dispertion and ultrasonicated for 20 min. Subsequently 1,4-phenylenediamine
(20 mmol, 2.16 g) was added to a solution and the mixture was stirred under reflux condition
for 24h. The obtained solid was then magnetically collected from the solution and washed
o
abundantly with water/ethanol and dried at 60 C. The attachment of 1,4-phenylenediamine
group onto the surface of Manganese ferrite was confirmed according to FT-IR spectra.
2.4. Synthesis of diamine modified silica coated manganese ferrite polyoxometalte
nanoparticles(MnFe2O4@SiO2@NHPhNH2PTA)
0.3 g of MnFe2O4@SiO2@NHPhNH2 was dispersed in 50 mL of deionized water and
ultrasonicated for 25 min. Then, a solution of H3PW12O40.6H2O (0.42 mmol, 1.254 g)
in 20 mL deionized water was added dropwise into the solution and ultrasonicated for
25 min and the mixture was stirred for 24h at room temperature. Finally, the formed
(MnFe2O4@SiO2@NHPhNH2-PTA) was magnetically separated and washed twice
with water and dried at 60 oC.
2.5 General procedure for the synthesis of 2H-indazolo[2,1b]phthalazine-triones
In a 5 ml round-bottom flask, to a mixture of dimedone (1 mmol), phthalhydrazide (1 mmol),
aldehyde (1mmol) and MnFe2O4@SiO2@NHPhNH2-PTA (0.030 g) was heated under solvent
o
o
–free conditions at 80 C or under sonicated at 80 C in presence of H2O for an appropriate
period of time as indicated in Table 2. After the reaction was completed (monitored by TLC),
the catalyst separated by an external magnet. Finally, the obtained organic layer was
extracted with ethyl acetate to afford the pure [b]pyrans derivatives by removing solvent in

good to high yield. The desired pure product(s) was characterized by comparison of their
physical data with those of known 2H-indazolo[2,1-b]phthalazine-triones.
2.6 General procedure for the synthesis of tetrahydrobenzo[b]pyrans
In a typical experiment, to a mixture of the aromatic aldehyde (1 mmol), malononitrile (1.2
mmol), dimedone (1 mmol), and MnFe2O4@SiO2@NHPhNH2-PTA (0.040 g) was heated
o
o
under solvent–free conditions at 80 C or under sonicated at 80 C in presence of H2O as a
green solvent for the time specified in Table 4. After complete consumption of starting
material as judged by TLC (n-hexane/ethyl 10:5), 5 mL EtOAc was added and the magnetic
catalyst was concentrated on the sidewall of the reaction vessel using an external magnet. The
solid residue was isolated with EtOAc (10 ml) and dried with anhydrous Na2SO4. After
evaporation of EtOAc the crude product was by recrystallization in hot EtOH. The desired
pure product(s) was characterized by comparison of their physical data with those of known
4H-benzo[b]pyrans. The residual catalyst in the reaction vessel was washed and dried and
then subjected to the next run directly.
2.7 Selected spectral data
3,4-Dihydro-3,3-dimethyl-13-(3-flourophenyl)-2-H-indazolo[2,1-b]phthalazine1,6,11(13H)-
trione (Table 3, entry 7)
IR (KBr) v ( cm−1): 2957, 2877, 1663, 1629, 1603, 1471, 1357, 1314, 1271, 1142, 778, 701,
684. 1H NMR (DMSO-d6, 400 MHz): δ= 1.11 (s, 3H), 1.13 (s, 3H), 2.27 (s, 2H), 3.18 (AB
system, dd, 1H, J = 19.1 Hz and J = 2.2 Hz), 3.33 (AB system, d, 1H, J = 19.2 Hz), 6.31 (s,
1H), 7.08–7.12 (pt, 1H), 7.31–7.39 (m, 3H), 7.96–7.98 (m, 2H), 8.01–8.12 (m, 1H), 8.26–
8.29 (m, 1H). 13C NMR (DMSO-d6, 100.6 MHz): δ = 28.3, 28.4, 34.7, 37.7, 50.7, 64.3,
114.7, 115.2, 117.0, 124.1, 127.5, 129.0, 129.7, 130.5, 134.2, 135.0, 140.8, 152.9, 154.3,
155.9, 161.3, 163.7, 192.3
3,4-Dihydro-3,3-dimethyl-13-(4-hydroxyphenyl)-2-H-indazolo[2,1-b]phthalazine1,6,11
(13H)-trione (Table 3, entry 9)
IR (KBr) v( cm−1): 3363(OH), 2960, 1674, 1657, 1634, 1362, 1271, 847, 704
1H NMR (DMSO-d6, 400 MHz): δ = 1.10 (s, 3H), 1.14 (s, 3H), 2.27 (d, 2H), 3.16 (AB
system, dd, 1H, J = 17.8 Hz and J = 2.0 Hz), 3.32 (AB system, d, 1H, J = 17.2 Hz), 6.20 (s,
1H), 6.86 (d, 2H), 7.22 (d, 2H), 7.94–7.99 (m, 2H), 8.10–8.12 (m, 1H), 8.25–8.27 (m, 1H),
9.47 (br, 1HOH). 13C NMR (DMSO-d6, 100.6 MHz): δ = 28.4, 28.5, 34.7, 37.7, 50.8, 64.4,
115.2, 115.3, 118.0, 127.1, 127.9, 128.1, 129.2, 129.4, 134.1, 134.9, 151.4, 154.0, 155.8,
157.7, 192.4.
3,4-Dihydro-3,3-dimethyl-13-(4-nitrophenyl)-2-H-indazolo[2,1-b]phthalazine-1,6,11(13H)-
trione (Table 3, entry 4)
IR (KBr) v( cm−1): 2973, 1697, 1617, 1660, 1525, 1368, 1148, 1102, 858, 701
1H NMR (DMSO-d6, 400 MHz): δ = 1.10 (s, 3H), 1.14 (s, 3H), 2.27 (s, 2H), 3.20 (AB
system, dd, 1H, J = 18.8 Hz and J = 2.0 Hz), 3.32 (AB system, d, 1H, J = 18.8 Hz), 6.44 (s,
13
1H), 7.79–7.82 (m, 2H), 7.96–8.01 (m, 2H), 8.09–8.12 (m, 4H). C NMR (DMSO-d6,

100.6 MHz): δ = 28.3, 28.4, 34.8, 37.7, 50.6, 64.2, 116.8, 123.8, 127.2, 128.0, 128.9, 129.2,
129.7, 134.3, 135.0, 145.3, 147.6, 152.3, 154.4, 155.9,192.3.
2-Amino-3-cyano-4-(2-chlorophenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8tetrahydrobenzo
[b]pyran (Table 5, entry 3)
IR (KBr) υ (cm–1): 1150, 1414, 1645, 1688, 2230, 2963, 3327, 3390.
1H NMR (CDCl3, 400 MHz) δ (ppm): 1.08, 1.13 (s, 6H, 2CH3), 2.20 and 2.26 (2H, CH2),
2.43 and 2.49 (2H, CH2), 4.63 (bs, 1H, CH), 7.14-7.33 (m, 4H, CHAr), 7.35 (bs, 2H, NH2).
13C NMR (100 MHz, DMSO-d6) δ: 27.7, 33.1, 36.7, 40.4, 50.0, 62.0, 113.0, 120.0, 126.0,
129.4, 131.4, 143.5, 159.15, 161.5, 193.0
2-Amino-3-cyano-4-(4-methylphenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo
[b]pyran (Table 5, entry 2)
IR (KBr) υ (cm–1): 1414, 1470, 1603, 1681, 1683, 2199, 2875, 2959, 3197, 3330, 3471.
1H NMR (DMSO, 400 MHz) δ (ppm): 0.99 (s, 6H, 2CH3), 1.98 (1H, CH2), 2.03, (1H, CH2),
2.47 (2H, CH2), 2.94 (bs, 3H, CH3), 4.479 (s, 1H, CH), 7.62-7.94 (m, 4H, CHAr), 7.21 (bs,
13
2H, NH2). C NMR (100 MHz, DMSO-d6) δ: 23.2, 29.2, 29.2, 30.7, 36.0, 40.4, 53.2, 56.7,
113.8, 120.2, 126.0, 131.8,134.6 141.0, 159.2, 163.0, 198.8
2-Amino-3-cyano-4-(3-nitrophenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8tetrahydrobenzo [b pyran
(Table 5, entry 4)
IR (KBr) υ (cm–1): 1349, 1374, 1599, 1595, 1661, 1679, 2186, 2871, 2956, 3202, 3336, 3431.
1H NMR (400 MHz, DMSO-d6) δ: 1.03 (s, 3H, CH3), 1.08 (s, 3H, CH3), 2.4 (2H, CH2), 2.7
(2H, CH2), 4.7 (dd, 1H, CH), 7.2 (s, 2H, NH2), 7.2-7.34 (m, 4H, CHAr) 13C NMR (100 MHz,
DMSO-d6) δ: 28.5, 30.7, 37.0, 46.6, 50.0, 60.2, 113.0, 119.6, 122.5, 126.0, 130.8,135.1
145.9, 159. 9, 163.0, 198.1
2-Amino-3-cyano-4-(2-nitrophenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran
(Table 5, entry 9)
IR (KBr) υ (cm–1): 1380, 1518, 1595, 1647, 1683, 2196, 2957, 3257, 3311.
1H NMR (DMSO-d6, 400 MHz) δ (ppm): 1.03 (s, 6H, 2CH3), 2.03 and 2.21, (2H, CH2), 2.83
13
(2H, CH2) 4.83 (bs, 1H, CH), 7.14-7.33 (m, 4H, CHAr), 7.21 (bs, 2H, NH2). C NMR (100
MHz, DMSO-d6) δ: 28.2, 28.7,. 32.6, 36.0, 40.4, 58.7, 61.0, 113.0, 117.8, 120.04, 126.0,
130.4,131.4 143.5, 159. 5, 162.6, 194.2
3 Results and discussion
In order to design and synthesize of a new and highly efficient catalyst system, The
manganese ferrite -polyoxometalate hybrid nanomaterials, MnFe2O4@SiO2@NHPhNH2-
PTA, were fabricated via a straight forward four-step procedure.(Scheme 1) Manganese
ferrite, as the magnetic core of the composite, was made by the co-precipitation of Mn2+, and
Fe3+ ions in the basic solution leading to the formation of MnFe2O4 magnetic nanoparticles
[26], and then coated with a thin layer of silica. The treatment of the silanol group of
MnFe2O4@SiO2 with 3-Chloropropyltrimethoxysilane (CPTMS) afforded MnFe2O4@SiO2-
Cl. MnFe2O4@SiO2-NHPhNH2 was carried out by the reaction of 1, 4-phenylenediamine

with chloropropyl-grafted MnF2O4@SiO2. The final step involved the reaction of
MnFe2O4@SiO2@NHPhNH2 amine groups with H3PW12O40 to yield
MnFe2O4@SiO2@NHPhNH2-PTA. Protonation of diamine group yields the positively
charged cations which bounds electrostatically to the heteropolyanions. It has been proven
that the heteropoly anion salts of the organic cations are generally insoluble in water [27].
Thus, the excess heteropoly acids can be removed by washing the resulting materials with
water.
Scheme. 1 Step-by-step synthesis of MnFe2O4@SiO2@NHPhNH2-PTA
3.5 Catalyst characterization
The obtained MnFe2O4@SiO2@NHPhNH2-PTA catalyst has been characterized by FT-IR,
XRD ,FESEM, TEM, TGA, EDX, ICP-AES and VSM techniques.
Fig. 1 represents the results of field emission scanning electron micrograms (FESEM) in
order to investigate the particle shape, surface morphology and architecture of the MnFe2O4,
MnFe2O4@SiO2 and MnFe2O4@SiO2@NHPhNH2-PTA. Also, FESEM images of the
particles showed spherical core–shell structured magnetic nanocomposite with nano
dimension ranging under 50 nm. As shown in Fig. 3, grafting heteropoly acid onto the
nanoparticle shell did not lead to the significant change in the structure and morphology of
nanoparticles, indicating that the magnetic core remained intact during the immobilization
and functionalization process on the surface of nanocomposite.

b
a
Fig. 1. SEM image of MnFe2O4 (a), MnFe2O4@SiO2 (b), and MnFe2O4@SiO2@NHPhNH2-PTA (c)
In order to obtain some information on the elemental composition and distribution on the
surface of the sample, MnFe2O4@SiO2@NHPhNH2-PTA was characterized by using EDX
analysis and Mn, Fe, O, Si, C, N, P, W were detected (Fig. 2). Based on the above results, it
is demonstrated that H3PW12O40 was immobilized onto the surface of the phenylenediamine
functionalized
MnFe2O4
nanoparticles.
Also,
the
loading
of
PTA
in
MnFe2O4@SiO2@NHPhNH2-PTA was calculated by the ICP-AES atomic emission
spectroscopy technique. The exact amount of PTA loaded onto the diamine functionalized

silica coated MnFe2O4 was found to be 0.77 mmol g−1. The amount of Mn and Fe was
checked by ICP-AES analysis and their 2:1 ratio was confirmed. The amount of H+ in the
MnFe2O4@SiO2@NHPhNH2-PTA determined by acid-base titration was 0.88 mmol g−1.
Fig. 2. EDX spectrum of MnFe2O4@SiO2@NHPhNH2-PTA nanoparticles
Transmission electron-microscopy (TEM) studies of the of MnFe2O4@SiO2@NHPhNH2-
PTA organic–inorganic composites (Fig. 3) confirmed that the particles have almost spherical
morphology .The images indicate that MnFe2O4 (dark spots) was encapsulated by silica,
amine and heteropoly acid, and particles exhibit a size distribution of 26 nm, similar to the
sizes obtained from the FESEM measurements.

Fig. 3 TEM image of MnFe2O4@SiO2@NHPhNH2-PTA
The XRD patterns of MnFe2O4, MnFe2O4@SiO2 and MnFe2O4@SiO2@NHPhNH2-PTA are
displayed in Fig. 4. The diffraction peaks related to Bragg’s reflections from (2 2 0), (3 1 1),
(4 0 0), (4 2 2), and (3 3 3) planes correspond to the standard spinel structure of MnFe2O4
(JCPDS 02-8517) with a space group of Fd3m ( Fig. 4A)[28]. The crystallite size of
MnFe2O4 nanoparticles was about 27nm, as measured by using the well-known Debye–
Scherrer formula 29. After coating with silica, an additional weak peak in the XRD pattern of
MnFe2O4@SiO2 at 2θ = 20 is attributed to the amorphous silica shell formed around the
magnetic core (Fig. 4B). In the XRD pattern of MnFe2O4@SiO2@NHPhNH2-PTA, the
characteristic peaks of MnFe2O4 did not change, but some peaks related to phosphotungstic
acid have been added. (Fig. 4C)
Fig. 4. XRD patterns of MnFe2O4 (A), MnFe2O4@SiO2(B), MnFe2O4@SiO2@NHPhNH2-PTA(C)
The FT-IR spectrum of MnFe2O4 shows two peaks at 400 cm−1 and 505 cm−1 which are
attributed to Fe-O stretching in the tetrahedral and octahedral sites of MnFe2O4, respectively
(Fig. 5a) [29]. The bands located at 1091 cm−1 and 798 cm−1 in the spectrum of
MnFe2O4@SiO2, are ascribed to the symmetrical and asymmetrical vibration modes of the Si-
O-Si bonds in SiO2 (Fig. 5b) [30]. C–H stretching vibrations appeared at 2925 cm−1 and 2846
cm−1 confirming the presence of the anchored propyl group of MnFe2O4@SiO2-Cl
nanoparticles (Fig 5c). Fig. 5d, shows the peaks in the range of 1400 to 1634 cm-1 assigned to
the phenylenediamine ring and also N-H bending at 3400 cm-1 for the synthesized
MnFe2O4@SiO2@NHPhNH2
is
clearly
observed
[31].
In
the
case
of
MnFe2O4@SiO2@NHPhNH2-PTA nanoparticles, typical FT-IR spectra of H3PW12O40 show
four characteristic vibration peaks at 1081 cm−1, 985 cm−1, 897 cm−1, and 803 cm−1, attributed

to the stretching vibration modes of P-O, W-O and W-O-W bonds of the Keggin unit,
respectively (Fig. 5e) [32]. As compared to the starting Keggin unit, the peak at 1080 cm−1
overlapped the Si–O–Si stretching vibration, however, new peaks and non-overlapped bands
at 980 cm−1, 896 cm−1 and 809 cm−1 are observed in the FT-IR spectra of
MnFe2O4@SiO2@NHPhNH2-PTA, indicating that H3PW12O40 was successfully anchored to
MnFe2O4@SiO2@NHPhNH2.
Fig. 5. FT-IR spectra of MnFe2O4 (a), MnFe2O4@SiO2 (b), MnFe2O4@SiO2-Cl (c),
MnFe2O4@SiO2@NHPhNH2(d), and MnFe2O4@SiO2@NHPhNH2-PTA(e)
the thermogravimetric analysis (TGA) curves of, MnFe2O4, MnFe2O4@SiO2 and
MnFe2O4@SiO2@NHPhNH2-PTA nanocatalyst indicates the weight loss of the organic
material as they decompose upon heating (Fig. 6). The first weight loss of 4.6% below 180
°C which might be due to the loss of the adsorbed water as well as dehydration of the surface

o
OH groups. The weight loss of 5.28% about 180– 410 C attributed to the decomposition of
the organic species, i.e. diamine group. The weight loss of 7.60% in around 480 was due to
the break down and decomposition of H3PW12O40 structure. On the basis of this result, the
well grafting of organic and inorganic groups on the MnFe2O4 is verified.
)c)
Fig. 6. The TGA curves of MnFe2O4 (a), MnFe2O4@SiO2 (b) and MnFe2O4@SiO2@NHPhNH2-PTA(C)
Magnetic properties of MnFe2O4@SiO2@NHPhNH2-PTA and MnFe2O4@SiO2@NHPhNH2-
PTA were investigated using a vibrating sample magnetometer (VSM) with a field of −10000
Oe to 10000 Oe at room temperature. As shown in (Fig. 7), the M(H) hysteresis loop for the
sample was completely reversible, which indicated their superparamagnetic characteristics.
The catalyst MnFe2O4@SiO2@NHPhNH2-PTA demonstrated saturation magnetization
values of 20 emu. g−1 , while the MnFe2O4 nanoparticle had the value of 78.98 emu. g−1. The
reason may be attributed to the grafting of silica, diamine groups and H3PW12O40 over
MnFe2O4. However, the lower value of (Fig 7b) is still enough to ensure the readily recovery
of the catalyst from reaction mixture using external magnetic force.

Fig. 7. Magnetization curves for MnFe2O4(a) and MnFe2O4@SiO2@NHPhNH2-PTA (b) at room temperature
Fig. 8 represent the low temperature nitrogen adsorption–desorption isotherms and pore
volume and pore size distribution of MnFe2O4@SiO2@NHPhNH2-PTA sample which exhibit
a type III curve with a hysteresis loop. Type III isotherms correspond to a mesoporous
material. According to the report in Table 1 about Brunauer–Emmett–Teller (BET) surface
area, pore volume and pore size of (BET: 19.64 m2/g, pore volume: 6.99 cm3/g and pore size:
29 nm), decrease in surface area, pore volume and pore diameter after loading
Phosphotungstic acid on MnFe2O4@SiO2@NHPhNH2 is due to this fact that the PTA unites
were immobilized dispersed on the surface of MnFe2O4@SiO2.
Fig. 8. pore size distributions (left) and Nitrogen adsorption–desorption isotherms (right) of
MnFe2O4@SiO2@NHPhNH2-PTA
Table 1 Specific surface area (BET), diameter pore and total pore volume of MnFe2O4@SiO2@NHPhNH2-PTA
Sample
BET surface
area (m2/g)
Pore volume
(cm3/g)
Pore size (nm)
MnFe2O4@SiO2@NHPhNH2-
PTA
19.64
6.99
29
3.2. Catalytic studies

Due to the ability of MnFe2O4@SiO2NHPhNH2-PTA as a mild and efficient acid catalyst, in
this study, it was decided to apply this catalyst for the synthesis of phthalazine (Scheme 2)
and pyran (Scheme 4) derivatives. At the first stage, to obtain the best reaction conditions, the
reaction of dimedone, benzaldehyde and phthalhydrazide in the presence of 0.03 g of
o
MnFe2O4@SiO2NHPhNH2-PTA as a model reaction at 80 C and under the solvent-free
conditions and a variety of solvents such H2O, EtOH, EtOAc, CH2Cl2 and CH3CN was
examined. The represented data in Table 2, showed that the reaction proceeded efficiently
o
under the solvent-free conditions at 80 C and resulted in high yields of the desired product
(Table 2, entry 9). This three-component condensation was also accomplished in protic
solvent such as EtOH and H2O under the reflux condition and gave the corresponding product
in 90% yield after a longer time (Table 2, entries 1 and 6). Moreover, aprotic solvents such as
CH2Cl2, EtOAc, CH3CN afforded the desired product in lower yields and longer reaction
times (Table 2, entries 2, 3and 4). Then the best amount of catalyst under the solvent-free
conditions at 80 oC was checked and the best result was obtained in the presence of 0.03 g of
catalyst. The effect of temperature was also studied by carrying out the model reaction under
o
o
the solvent-free condition and 0.03 g of catalyst at room temperature, 60 C, and 80 C. The
yield increased when the reaction temperature was increased (Table 2, entry 9). The reaction
was also checked in the absence of the catalyst in which the reaction did not proceed even
after 3 hours (Table 2, entry 5). These observations established the crucial role of
MnFe2O4@SiO2NHPhNH2-PTA for the expedition of the reaction time and the product yield.
For the investigation of the ultrasonic irradiation ability for the acceleration of the organic
reactions, the model reaction under the ultrasonic irradiation at 80ᵒC in the presence of H2O
as a green solvent and various amounts of catalyst was examined. The excellent yield of the
three-component coupling product was obtained under the optimized condition using 0.03 g
of catalyst in water as the solvent in 8 minutes.
Scheme 2 Preparation of indazolo [2,1-b] phthalazine-triones by MnFe2O4@SiO2NHPhNH2-PTA
Table
2
Optimization of various parameters for the synthesis of phthalazine-triones by
MnFe2O4@SiO2NHPhNH2-PTAa
Entry
Catalyst
Solvent
Condition
Time(min)
Yield(%)b

amount(g)
0.03
EtOH
CH2Cl2
CH3CN
EtOAc
reflux
60
100
100
100
180
60
87
30
1
2
0.03
0.03
reflux
reflux
35
3
0.03
reflux
45
4
None
0.03
-
reflux
trace
90
5
H2O
reflux
6
0.03
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
H2O
rt
100
45
60
7
0.03
60
80
80
8
0.03
25
96
9
0.025
0.015
None
0.015
0.025
0.03
80
25
93
10
11
12
13
14
80
35
88
Sonication/ rt
Sonication/ 80
Sonication/ 80
Sonication/80
25
tace
65
H2O
18
H2O
14
89
H2O
8
95
15
aReaction Conditions: bezaldehyde( 1mmol), dimedone( 1 mmol), phthalhydrazide (1 mmol), under solvent-free
, MnFe2O4@SiO2NH-NH2-PTA(0.03 g) or water( 5ml, ultrasonic irradiation)
After optimizing the reaction conditions, the generality of this catalytic system was
confirmed by employment of a series of aldehydes. The results are summarized in Table 3.
Table 3 Synthesis of derivatives of 2H-indazolo[2,1-b]phthalazine-1,6,11(13H)-trione derivatives in the
presence of MnFe2O4@SiO2@NH-NH2-PTAa
Solvent-
Ultrasonic
/H2O/80 oC
free/80 oC
Entry
Product
Time
Yield
Time
Yield
M.p. oC
Found/
Aldehyde
Reported
25
94
8
92
208-209
(203205)
[33]
1

220-221
(219-221)
[34]
30
89
12
87
2
25
20
91
96
10
90
93
266-268
(264-266)
[35]
3
4
6
268-270
(270-272)
[36]
20
96
6
95
226-230
(223-225)
[37]
5
6
25
93
12
89
221-223-
(220-222)
[38]
25
20
90
95
10
88
95
216-218
(217-219)
[39]
7
8
8
265-268
(265-267)
[37]

30
88
12
86
226-228
(225-227)
[40]
9
aReaction Conditions: bezaldehyde( 1mmol), dimedone( 1 mmol), phthalhydrazide (1 mmol), under solvent-free
, MnFe2O4@SiO2NH-NH2-PTA(0.03 g) or water( 5ml, ultrasonic irradiation)
As shown in Table 3, the aldehydes with both electron donating and withdrawing groups
were participated in the condensation reaction with the equal efficiency and excellent yields
without the formation of any byproducts. The meta-substituted aromatic aldehydes (Table 3,
entry 4) as well as the sterically hindered ortho-substituted aromatic aldehydes (Table 3, entry
3), both undergo the condensation reactions without any difficulties.
A proposed mechanism for the synthesis of indazolo[2,1-b]phthalazine-triones is was
outlined in Scheme 3 .Based on this mechanism, as shown theintermediate (1) is produced
upon initial condensation of aldehyde with dimedone under the catalytic activity of
MnFe2O4@SiO2@NHPhNH2-PTA. Subsequent nucleophilic addition of phthalhydrazide the
intermediate (1) followed successively by intramolecular cyclization to the intermediate
(2),and rearrangement to furnish the corresponding product.

Scheme. 3 Proposed mechanism for the synthesis of indazolo[2,1-b]phthalazine-triones
The reusability of the catalyst is an important benefit especially for commercial applications.
Thus, the activity constancy of the catalyst, catalytic reusability of
MnFe2O4@SiO2@NHPhNH2-PTA was investigated for synthesis of 2H-indazolo[2,1-b]
phthalazine-1,6,11(13H)-trione under

Fig. 9 Recycl ability of MnFe2O4@SiO2@NHPhNH2-PTA in the synthesis of 2H-indazolo[2,1-b]phthalazine-
1,6,11(13H)-trione
Encouraged by these results, the phthalylhydrazide with malonitrile was replaced, in order to
explore its further applications toward the synthesis of the tetrahydrobenzo-[b]-pyrans
derivatives. Initially, the reaction conditions were optimized. For this purpose, the reaction of
benzaldehyde, malonitrile and dimedone was chosen as a model reaction and then the model
o
reaction was carried out under the solvent-free conditions at 80 C in the presence of 0.04 g
of MnFe2O4@SiO2NHPhNH2-PTA and the variety of solvents such H2O, EtOH, EtOAc,
CH2Cl2 and CH3CN were examined. The results are summarized in Table 4. The best result
in terms of the reaction time (30 min) and the yield (95%) was obtained when the reaction
time carried out under the solvent-free condition at 80 oC (Table 4, entry 8).
o
In addition, the model reaction in the presence of 0.04 g catalyst at 60 C was examined and
the corresponding product was formed in longer reaction time and lower yield (Table 4,
entries 7).
It was found that in the absence of nanomagnetic acid catalyst, only a trace of the desired
product was observed on the Thin Layer Chromatography (TLC) plate even after 3 hours of
heating (Table 4, entry 5). The result clearly showed that the catalyst is effective for this
transformation and in its absence, the reaction did not take place even after the higher
reaction time.
scheme for the of synthesis tetrahydrobenzo-[b]-pyrans by MnFe2O4@SiO2NHPhNH2-PTA
Table
4
Optimization of various parameters for the synthesis of tetrahydrobenzo[b]pyran by
a
MnFe2O4@SiO2NHPhNH2-PTA
Entry
Catalyst
Solvent
Condition
Time(min) Yield(%)b
amount(g)
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.04
0.03
None
EtOH
CH2Cl2
CH3CN
EtOAc
reflux
reflux
reflux
reflux
rt
60
100
90
73
40
1
2
48
3
100
180
60
69
4
None
trace
90
5
H2O
reflux
60
6
Solvent free
Solvent free
Solvent free
H2O
40
85
7
80
30
95
8
80
35
91
9
Sonication/ rt
30
tace
10

0.02
0.03
0.04
H2O
H2O
H2O
Sonication/ 80
Sonication/ 80
Sonication/80
25
20
10
78
89
94
11
12
13
aReaction Conditions: bezaldehyde( 1mmol), dimedone( 1 mmol), malononitrile (1.2 mmol), under solvent-free
, MnFe2O4@SiO2NH-NH2-PTA (0.04 g) or water (5ml, ultrasonic irradiation)
The optimum conditions were applied to a series of aromatic aldehydes carrying either
electron-donating or electron-withdrawing substitutions in the ortho, meta, and para
positions. The results are shown in Table 5.
Table 5 Synthesis of derivatives of 2-amino-5-oxo-5,6,7,8-tetrahydro-4-H-benzo[b]pyran derivatives in the
presence of MnFe2O4@SiO2@NH-NH2-PTAa
Solven-free/
80oC
Ultrasonic/
H2O/80oC
Entry
Ar
Product
Time
Yield
Time
Yielda
M.p. oC
Found/
Reported
235-237
30
95
10
92
(236-239)[41]
1
210-212
35
30
86
91
12
10
85
90
(214-216)[41]
2
214-216
(212-213)[42]
3

30
92
10
93
208-209
4
(210)[43]
25
95
8
94
180-182
5
(180-182)[44]
35
88
12
85
203-205
6
(198-202)[42]
189-190
7
25
25
93
95
10
90
94
(190-192)[43]
8
265-268
(265-267)[42]
8
9
30
89
12
87
236-238
(238-239)[42]
aReaction Conditions: bezaldehyde( 1mmol), dimedone( 1 mmol), malononitrile (1.2 mmol), under solvent-free
, MnFe2O4@SiO2NH-NH2-PTA (0.04 g) or water (5ml, ultrasonic irradiation)

It was observed that the electron-withdrawing groups gave rise to the excellent yields of
o
products under both the solvent-free condition at 80 C and the ultrasonic irradiation. The
1
structures of products were determined from their analytical and spectral [IR, H and 13C,
Nuclear Magnetic Resonance (NMR)] data and by direct comparison with authentic samples.
The formation of the products were also confirmed by the comparison of their melting points
with the products prepared by the previously reported methods. As can be seen from Tables 3
and 5, the catalytic system worked exceedingly well in both phthalazine-triones and
tetrahydrobenzo-[b]-pyran and the expected products were obtained in short times and in
good to high yields.
A plausible reaction mechanism for the synthesis of tetrahydrobenzo-[b]-pyran is shown in
Scheme 5. Initially, both aldehyde and malononitrile were activated in the presence of
MnFe2O4@SiO2NHPhNH2-PTA. After condensation and elimination of a water molecule, the
product reacts with dimedone via Michael addition to afford the desired
tetrahydrobenzo[b]pyran derivative. The mechanism clearly explains the role of
heteropolyacid active sites.
Scheme 5 Proposed mechanism for the synthesis of tetrahydrobenzo[b]pyran
The reusability of catalysts is one of the most important benefits of heterogeneous catalytic
systems from economic, and environmentally point of view. The recyclability of nanocatalyst
was investigated for the one-pot three-component reaction between aldehyde, malononitrile
and dimedone by carrying out six consecutive cycles using the same reaction conditions.
After each run, the catalyst was recovered without filtration since the
MnFe2O4@SiO2NHPhNH2-PTA was rapidly concentrated as soon as an external magnet was
set close to the sidewall of the reaction vessel, then washed with EtOH (10 mL), CH2Cl2 (10

mL). The solid catalyst dried under vacuum after each cycle, and then reused for the next
reaction (Fig. 10).
Fig. 10 Recycl ability of MnFe2O4@SiO2@NHPhNH2-PTA in the synthesis of 2-amino-5-oxo-5,6,7,8-
tetrahydro-4-H-benzo[b]pyran
It was observed that the MnFe2O4@SiO2@NHPhNH2-PTA indicated excellent activity for
the three-component reaction even after the six run. TGA, XRD, BET, FT-IR and TEM
analyses of reused catalyst after six run indicated that no detectable changes of the catalyst
occurred during the reaction the recycling stages (Fig. 11)

Fig. 11 TGA, XRD, BET, FT-IR and TEM analyses of reused catalyst after six run
A comparison for the efficiency of the catalytic activity of MnFe2O4@SiO2NHPhNH2-PTA
for the synthesis of indazolo-[2, 1-b]-phthalazine-triones (Table 6, entries 1–7) and
tetrahydrobenzo-[b]-pyran condensation (Table 6, entries 8–13), with several previously
reported methods is presented. The results show that this method is superior to some
previously reported methods in terms of yields, reaction times, the amount of the reagent
used, and the avoidance of toxic catalysts, organic volatile solvents and the easy separation of
the catalyst.
Table 6 Comparison of the efficacy of MnFe2O4@SiO2@NH-NH2-PTA catalyst with some various catalysts in
the synthesis of 3,4-Dihydro-3,3-dimethyl-13-(4-chlorophenyl)-2H-indazolo[2,1-b]phthalazine-1,6,11(13H)-
trione (1) and 2-Amino-4-(4-chlorophenyl)-5-oxo-5,6,7,8-tetrahydro-4H chromene-3-carbonitrile condensation
(2).
Enty Catalyst
product
Catalyst
loading
0.075 g
Time
(min)
35
Condition
Yield
(%)
88
Ref.
Fe3O4@silica sulfuric acid
1
1
1
1
1
1
1
2
2
solvent-
[40]
1
2
3
4
5
6
7
8
9
free,100 ᵒ C
solvent-
Ceric ammonium nitrate
0.027 g
15mol%
0.03mol%
15 mol%
0.03 g
120
26
20
20
20
8
94
85
92
93
95
[45]
free,50 ᵒC
80 ᵒ C
β-CD (β-Cyclodextrin ) /
[33]
H2O.
Citric acid
solvent-
[46]
free,80 ᵒ C
solvent-
[Dsim][HSO4]
[47]
free,100 ᵒC
solvent-
MnFe2O4@SiO2NH-NH2-
PTA
This work
This work
[48]
free,80 ᵒ C
MnFe2O4@SiO2NH-NH2-
PTA
0.03 g
Sonication/ 95
H2O 80 ᵒ C
H2PO4-SCMNPs
0.03 g
20
25
solvent-
89
free,80 ᵒ C
Fe3O4@Ph-SO3H
0.2 mol%
Sonication/ 90
H2O.
[49]
Nano ZnO
2
2
2
10 mol%
0.03 g
0.04
30
60
25
80 ᵒ C
95
78
95
[50]
10
11
12
Fe3O4/SiO2/Met
MnFe2O4@SiO2NH-NH2-
PTA
Reflux
[51]
solvent-
free,80 ᵒ C
This work
MnFe2O4@SiO2NH-NH2-
PTA
2
0.04
8
Sonication/ 94
13
This work
H2O 80 ᵒ C
In view of the leaching problems observed with tungsten supported on heteropoly acid
catalyst, quantitative analysis using AAS was employed to determine the amount of metal in

the reaction. The heterogeneity of the MnFe2O4@SiO2NHPhNH2-PTA catalyst was examined
by carrying out a hot filtration test using dimedone, malononitrile and benzaldehyde as model
substrates. No tungsten could be detected in the liquid phase using AAS and, more
significantly, after hot filtration,the reaction of the residual mixture was completely stopped.
4 Conclusions
In Conclusion, an easy, green methodology and highly efficient method was
developed for the synthesis of 2H-indazolo-[2,1-b]-phthalazine-triones and
tetrahydrobenzo-[b]-pyran derivatives via one-pot three-component reaction in the
presence of MnFe2O4@SiO2@NHPhNH2-PTA nanoparticles as the efficient and
o
magnetic catalyst under the solvent-free condition at 80 C or the ultrasonic
irradiation conditions in water.
This method gives notable advantages such as easy preparation, heterogeneous nature,
clean and simple procedure, thermal stability and the easy separation of the catalyst,
easy product separation and purification, excellent yields, short reaction time, lower
loading of the catalyst compared with the other methods, and avoidance of using
hazardous organic solvents that makes this method an instrumental alternative to the
previous methodologies for the scale up of these one-pot three-component reactions.
Furthermore, the catalyst is magnetically separable and eliminates the requirement of
catalyst filtration after the completion of the reaction, which represents a major
advantage for reactions from an economic and environmental point of view.
Acknowledgements
This work was supported by the Research Council at the Shahid Chamran University of
Ahvaz.
References
[1] M. Esmaeilpour, J. Javidi,F. Nowroozi Dodeji and M. Mokhtari Abarghoui, Transition
Met. Chem. 39 (2014) 797.
[2] J. Mondal, T. Sen, A. Bhaumik, Dalton Trans. 4 (2012) 6181.
[3] (a) S. Shylesh, V. Schunemann, W.R. Thiel, Angew. Chem. Int. Ed. 49 (2010) 3428.
(b) C.W. Lim, I.S. Lee, Nano Today. 5 (2010) 412.
[4] J. Govan, Y. Gun’ko, Nanomaterials. 4 (2018) 222.
[5] (a) Y. Zhu, L.P. Stubbs, F. Ho, R. Liu, C.P. Ship, J.A. Maguire, N.S. Hosmane,
ChemCatChem. 2(2010) 365. (b) P. Wang, H. Liu, J. Niu, R. Li, J. Ma, Catal. Sci. Technol. 4

(2014) 1333.(c) R.B. Nasir Baig, R.S. Varma, Chem. Commun.49 (2013) 752.(d) T. Cheng,
D. Zhang, H. Li, G. Liu, Green Chem. 16 (2014) 3401.
[6] A. Kong, P. Wang, H. Zhang, F. Yang, S.P. Huang, Y. Shan, Appl. Catal. A. 417 (2012)
183
[7] B. JansiRani, M. Ravina, B. Saravana kumar, G. Ravi, V. Ganesh, S. Ravichandran, R.
Yuvakkumar, Nano-Structures & Nano-Objects. 14 (2018) 84.
[8] O, Makrygenni, E. Secret, A. Michel, D. Brouri, V. Dupuis, A. Proust, J.M. Siaugue, R.
Villanneau, Journal of Colloid and Interface Science 514 (2018) 4.
[9] (a) A.M.I. lnicka, E. Bielanska, L.L. Dobrzynska, A. Bielanski, Appl. Catal. A. 421-422
(2012) 91; (b) A. Ciftci, D. Varisli, C.K. Tokay, N.A. Sezgi, T. Dogu, Chem. Eng. J. 207–
208 (2012) 85; (c) A. Kumar, P. Singh, S. Kumar, R. Chandra, S. Mozumdar, J. Mol. Catal.
A: Chem. 276 (2007) 95.
[10] T. Jihuai, L. Tingting, Zh.Jinwen, X. Bingxue, Ch.Muhua, Zh. Xinbao, Journal of the
Taiwan Institute of Chemical Engineers. 000 (2018) 1.
[11] (a) L. T.Aany Sofia, A. Krishnan, M. Sankar, N. K. Kala Raj, P. Manikandan, P. R.
Rajamohanan and T.G. Aithkumar, J. Phys. Chem. 113 (2009) 21114; (b) J. Javidi, M.
Esmaeilpour and F. Nowroozi Dodeji, RSC Adv. 5 (2015) 308; (c) M. Esmaeilpour, J.Javidi,
F. Nowroozi Dodeji, New J. Chem. 38 (2014) 5453.
[12] A. Khodadadi Dizaji, B. Mokhtarani, H. R, Mortaheb, Fuel. 236 (2019) 717.
[13] (a) M. A. Schwegler, H. Bekkum, N. Munck, Appl. Catal. A. 74 (1991) 191; (b) E.
Rafiee, N. Nobakht, Journal of Molecular Catalysis A: Chemical. 398 (2015) 17 ; (c) Y. Wei,
Y. Chen, R. Wang, Fuel Processing Technology 178 (2018) 262.
[14] A.T. Khan, M. Lal, S. Ali, M.M. Khan, Tetrahedron Lett. 52 (2011) 5327.
[15] (a) B. Karami, S. Khodabakhshi, K. Eskandari, Tetrahedron Lett. 53 (2012) 1445; (b)
C.Wiener, C. H. Schroeder, B. D. West and K. P. Link, J. Org. Chem. 27 (1962) 3086.
[16] (a) Z. Chen, Q. Zhu, W. Su, Tetrahedron Lett. 52 (2011) 2601; (b) A. Hasaninejad, M.
Shekouhy, N. Golzar, A. Zare, M.M. Doroodmand, Appl. Catal.A: Gen. 402 (2011) 11.
[17] S. F Hojati, M. Moosavifar, T. Ghorbanipoor, Comptes Rendus Chimie. 5 (2017) 520.
[18] R.G. Vaghei, R.K. Nami, Z.T. Semiromi, M. Amiri, M. Ghavidel, Tetrahedron. 67
(2011) 1930.
[19] R. Tayebee, M. Fattahi Abdizadeh, B. Maleki, E. Shahri, Journal of Molecular Liquids.
241 (2017) 447.
[20] F. M. Awadallah, W. I. EI-Eraky, D. O. Saleh, European Journal of Medicinal
Chemistry, 52 (2012)14.
[21] P. Sagar Vijay Kumar, L. Suresh, G. V. P. Chandramouli, Journal of Saudi Chemical
Society 3 (2017 ) 306.
[22] K. Kong, J. Zhang, P. Zhao, H. Lu, Y. Chen, Tetrahedron 48 (2017) 6742.
[23] Da-Ch. Liu,G-H. Gong, Ch-X. Wei, X-J. Jin, Zh-Sh. Quan, Bioorganic & Medicinal
Chemistry Letters. 6 (2016) 1576.
[24] D. S. Raghuvanshi, K. N. Singh, Tetrahedron Letters. 52 (2011) 5702.
[25] (a) G. Shukla, R.K. Verma, G.K. Verma, M.S. Singh, Tetrahedron Lett. 52 (2011) 7195;
(b) G. Karthikeyana, A. Pandurangan, J. Mol. Catal. A: Chem. 361-362 (2012) 58.

[26] I. Malaescu, A. Lungu, C. N. Marin, P. Vlazan, P. Sfirloaga, G. M. Turi, Ceramics
International. 15 (2016) 16744.
[27] I.V. Kozhevnikov, Catalysis for Fine Chemicals, Catalysis by Polyoxometalates, vol. 2,
Wiley, Chichester, (2002) 175 pp.
[28] G. Singh, S. Chandra, International Journal of Hydrogen Energy. 43 (2018) 4058.
[29] K. Ashwini, H. Rajanaika, K.S. Anantharaju, H. Nagabhushanad,P. Adinarayana Reddy,
K. Shetty, K.R. Vishnu Mahesh, Materials Today: Proceedings 4 (2017) 11902.
[30] M. Arshad, M. Abbas, S. Ehtisham-ul-Haque, M. Akhyar Farrukh, M. Iqbal, Journal of
Molecular Structure. 1180 (2019) 244.
[31] Y. Lin, H. Chen, K. Lin, B. Chen, C. Chiou, J. Environ. Sci. 23 (2011) 44.
[32] F. Mahmoudi, S. Farhadi, P. Machek, M. Jarosova, Polyhedron 158 (2019) 423.
[33] A. V. Chate, P. K .Bhadke, M. A .Khande, J. N .Sangshetti, Ch. H. Gill, Chinese
Chemical Letters. 7 (2017) 1577.
[34] R. Tayebee, M. Jomei, B. Maleki, M. Kargar Razi, H. Veisi, M. Bakherad, Journal of
Molecular Liquids. 206 (2015) 119.
[35] M. Abedini, F. Shirini, J. M, Alinejad Omran, Journal of Molecular Liquids. 212 (2015)
405.
[36] B. Afzalian, J. T.Mague, M. Mohamadi, S. Y. Ebrahimipour, B. Pouramiri, E.
Tavakolinejad Kermani, Chinese Journal of Catalysis.7 (2015) 1101.
[37] F. Shirini, M. Safarpoor, N. Langarudi, O.Goli-Jolodar, Dyes and Pigments. 123 (2015)
186.
[38] M. Saha, S. Phukan, R. Jamatia, S. Mitra, A.K. Pal, RSC Adv. 3 (2013) 1714.
[39] H.R. Shaterian, S. Sedghipour, E. Mollashahi, Res. Chem. Intermed. (2014)
[40] A.R. Kiasat, J. Davarpanah, Journal of Molecular Catalysis A: Chemical. 373 (2013) 46.
[41] M. Rastgoo Yousefi, O. Goli-Jolodar, F. Shirini, Bioorganic Chemistry. 81 (2018) 326.
[42] S. M. Baghbanian, N. Rezaeia and H. Tashakkorian, Green Chem. 15 (2013) 95.
[43] B. Maleki and S. S.Ashrafi, RSC Adv. 4 (2014) 42873.
[44] A. r Hasaninejada, N. Golzar, M. Beyrati,A. Zare, M. M. Doroodmand, Journal of
Molecular Catalysis A: Chemical 372 (2013) 137.
[45] K. Mazaahir, C. Ritika, J. Anwar, Chin. Sci. Bull. 57 (2012) 2273.
[46] M. A. Zolfigol, M. Mokhlesi, Sh. Farahmand, J IRAN CHEM SOC. 10 (2013) 577.
[47] F. Masihpour, A. Zare, M. Merajoddin, A.r. Hasaninejad, Journal of Chemical
Technology and Metallurgy, 54 (2019) 23.
[48] H.R. Saadati-Moshtaghin, F.M. Zonoz ,Materials Chemistry and Physics 199 (2017)
159.
[49] D. Elhamifar, Z. Ramazani, M. Norouzi, R. Mirbagheri, Journal of Colloid and Interface
Science 511 (2018) 392.
[50] M. Hosseini-Sarvari, S. Shafiee-Haghighi, Chem. Heterocycl. Compd. 48 ( 2012) 1307.
[51] A. Alizadeh, M. M. Khodaei, M. Beygzadeh, D. Kordestani, M. Feyzi, Bull. Korean
Chem. Soc. 33 (2012) 2546.

The present work describes the synthesis of a new ionic compound based on polyoxometalate anion
supported on silica coated nanoparticle MnFe2O4 as a novel scaffold for the preparation of
tetrahydrobenzo[b]pyran and indazolo[2,1-b]phthalazine-triones. The structure and composition
ofthe nanocomposite was performed by different methods and analyzed by FT-IR, FE-SEM, TEM,
TGA, XRD, BET, ICP and VSM. This catalyst show high activity and give excellent yields. The catalyst
can be easily separated from the reaction mixture and reused several time. The results show that
the particles are mostly spherical in shape and have an average size of approximately <30 nm.