Gd0.7Sr0.3MnO3 perovskite as a novel and efficient catalyst for synthesis of dioxodecahydroacridine derivatives

Article abstract of DOI:10.1080/15533174.2016.1186058

In this work, perovskite-type material Gd_0.7Sr_0.3MnO₃ was fabricated by sol-gel method. To prepare this nanopowder, metal salts, citric acid as the complexing agent, and water as solvent were used. A series of common analy

Full text of DOI:10.1080/15533174.2016.1186058

Synthesis and Reactivity in Inorganic, Metal-Organic, and
Nano-Metal Chemistry
ISSN: 1553-3174 (Print) 1553-3182 (Online) Journal homepage: http://www.tandfonline.com/loi/lsrt20
Gd0.7Sr0.3MnO3 perovskite as a novel and efficient
catalyst for synthesis of dioxo-decahydroacridine
derivatives
Haman Tavakkoli, Tayebeh Sanaeishoar & Maryam Moeinirad
To cite this article: Haman Tavakkoli, Tayebeh Sanaeishoar & Maryam Moeinirad
(2016): Gd0.7Sr0.3MnO3 perovskite as a novel and efficient catalyst for synthesis of dioxo-
decahydroacridine derivatives, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-
Metal Chemistry, DOI: 10.1080/15533174.2016.1186058
To link to this article: http://dx.doi.org/10.1080/15533174.2016.1186058
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Published online: 27 Jul 2016.
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Date: 29 July 2016, At: 01:15

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Gd0.7Sr0.3MnO3 perovskite as a novel and efficient catalyst for synthesis of dioxo-
decahydroacridine derivatives
Haman Tavakkoli*, Tayebeh Sanaeishoar, and Maryam Moeinirad
Department of Chemistry, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
*Corresponding author. E-mail address: htavakkoli59@gmail.com
ABSTRACT
In this work, perovskite-type material Gd0.7Sr0.3MnO3 was fabricated by sol-gel method. To
prepare this nanopowder, metal salts, citric acid as the complexing agent and water as solvent
were used. A series of common analytical techniques were used to characterize the crystallinity,
morphology, specific surface area and grain size of the nanopowders. The composition and
morphology of the nanopowders by energy dispersive X-Ray spectrometer (EDX) and scanning
electron microscopy (SEM) is studied. BET analysis for surface accurate area of sample and
Fourier transform infrared (FTIR) spectra were used to study the structure of nanopowders. Also
X-Ray diffraction (XRD) patterns show that single perovskite phase is completely formed after
calcination treatment. Moreover, in this study, 1,8-dioxo-decahydroacridine derivatives were
generated via one-pot four-component condensation, under solvent-free conditions at the
presence of a perovskite as a new, efficient, heterogeneous, green and recyclable catalyst with
excellent yields.
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Keywords
Perovskite, Nanopowder, Heterogeneous catalyst, Hantzsch-type condensation, Four-component
reactions
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1. Introduction
Multicomponent reactions (MCRs) have emerged as efficient and powerful tools in modern
synthetic organic chemistry because the syntheses of complex organic molecules from simple
and readily available substrates can be achieved in a very fast and efficient manner without the
isolation of any intermediate [1-5]. MCRs have emerged as efficient, atom economic, time saving
and powerful tools in modern synthetic organic chemistry for the synthesis of pharmacologically
and biologically important targets as they increase the efficiency of the reaction and avoid the
multiple steps along with saving solvents and chemicals [6]. 1,8-Dioxodecahydroacridines and
their derivatives are polyfunctionalized 1,4-dihydropyridine derivatives that contain a large
family of medicinally important compounds that have attracted much attention because of their
[8]
diverse pharmacological and therapeutic properties, such as antimalarial [7], antitumor
,
[9]
[10-13]
anticancer
,
bronchodilator, anti-atherosclerotic and antidiabeticagents
.
1,4-
Dihydropyridines and their derivatives were synthesized with the Hantzsch procedure, which
involves the three component condensation of an aromatic aldehyde, dimedone and ammonium
acetate or amines in the presence of several catalysts such as p-dodecylbenezenesulfonic acid
(DBSA) [14], tris(pentafluorophenyl)borane [15], acidic ionic liquids [16], proline [17], ceric
[18]
ammonium nitrate (CAN)
and triethylbenzylammonium chloride (TEBAC) [19]. However,
most of these reported procedures have disadvantages such as use of hazardous organic solvents,
long reaction times, and low yields and harsh reaction conditions. Thus, the development of
efficient, easy, and environmentally friendly methods using new heterogeneous and reusable
catalysts for the synthesis of 1,8-dioxodecahydroacridines is still necessary.
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Traditional ABO3 perovskite-type mixed oxides have been known as catalysts or catalyst
precursors for several organic reactions at very low catalyst loadings [20-23]. The great stability of
the perovskite structure allows partial substitution at the A sites and/or the B sites modifying the
catalytic, structural and redox properties. Generally speaking, A-site replacement mainly affects
the amount of sorbed oxygen, whereas B-site replacement influences the nature of sorbed oxygen
[24,25]. The large variety of properties displayed by perovskite oxides is due to the ability of the
framework to accommodate cations of various sizes and valences and to tolerance towards
anionic and cationic vacancies. Perovskites have many possible applications, e.g., in membranes
for gas separation [26] as catalysts [27,28], as promising adsorbents [29,30], in electrical devices [31], as
ferromagnetic material [32], and in sensors [33]. The redox properties of the B ions, the nature and
concentration of oxygen adspecies, and the existence of lattice defects are generally believed to
be responsible for the good catalytic activity of these perovskite-type oxides [34,35]. In general,
perovskite with a partial substitution of the A or B cations (AxA'1-xBO3) / (AB1-xB'xO3) have
received much attention in catalysis.
In the present study, Gd0.7Sr0.3MnO3 nanopowders (GSMO NPs) fabricated by sol-gel method
show the best catalytic performance for synthesis of 1,8-dioxo-decahydroacridine derivatives.
Moreover, the effect of different solvents was investigated and the catalytic efficiency was
compared with traditional catalyst under similar conditions.
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2. Experimental
2.1. General remarks
All chemicals were available commercially and used without additional purification. A series of
common analytical techniques were used to characterize the crystallinity and morphology of the
nanopowders. The FT-IR spectra were recorded on a Perkin-Elmer BX-II IR spectrometer. For
structural investigation of calcined powder at 700°C XRD measurements were carried out in the
angle region of (2θ = 20 to 70°) using CuKα radiation on a Rigaku D/MAXRB XRD
diffractometer equipped with a curved graphite monochromator. The composition and
morphology of the nanopowders by energy dispersive X-Ray spectrometer (EDX) and scanning
electron microscopy (SEM) was studied. The SEM of the type LEO 1450VP (V = 30 kV) was
equipped with an EDX spectrometer of the type Inca 400 (Oxford Instruments). The surface
accurate area of sample was calculated using BET method from the nitrogen adsorption
isotherms obtained at 77 K on samples out gassed at 250°C with the use of a Micromeritics
Accusorb 2100E apparatus. The melting points of products were determined with an
Electrothermal 9200 melting point apparatus.
2.2. Synthesis of catalyst
The perovskite precursors in this work were prepared by sol-gel method. Appropriate amounts of
Gadolinium nitrate Gd(NO3)3.6H2O, strontium nitrate Sr(NO3)2, Manganese acetate
Mn(CH3COO)2, citric acid and distilled water were used as starting materials. The molar ratio of
citric acid to metal ions was 4:1. Metal nitrates were dissolved in distilled water and then citric
acid was added slowly to the metal solution at room temperature under constant magnetic
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stirring. The solution was refluxed with stirring for 2h to convert it to a stable complex. To make
a gel, it was heated at 50°C for 2h on a heater. A dry gel was obtained by placing the sol in an
oven and heating slowly to 110°C for 12 h and then calcined at 700°C for 6h to obtain the
nanopowders using perovskite-type oxides.
2.3. Typical procedure for the synthesis of 1,8-Dioxodecahydroacridines
A mixture of dimedone (2 mmol), aromatic aldehyde (1 mmol), ammonium acetate or aromatic
amines (1 mmol), and nanoparticle catalysts (0.001g) was heated in the oil bath at 120°C for the
appropriate time. During the procedure, the reaction was monitored by TLC. After the
completion of the reaction, the reaction mixture was cooled to room temperature and hot ethanol
was added. The catalyst was insoluble in hot ethanol and it could therefore be recycled by a
simple filtration. The product was then collected from the filtrate .After that it cooled to room
temperature and recrystallized from distilled water to give compounds 4a-k in high yields.
3. Results and Discussion
3.1. FT-IR spectroscopy
Fourier transform infrared spectra were obtained as a powerful method to determine the structure
and measurement of chemical species. Fig. 1 show the FTIR spectra of the GSMO NPs in the
range of 400--4000 cm--1, calcined at 700°C for 6h in air. The FTIR spectrum is similar to the
most other ABO3-type perovskite compounds which have common BO6 oxygen-octahedral
structure [36-38]. Relatively strong peak show the typical M--O--C pair vibrations around 1400-
1600 cm1 [39]. An intermediate absorption band about 1081 and 1201 cm1 corresponded to C--O
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[40]

bond
and the anti-symmetric NO3 stretching vibration [41], respectively. The characteristic
band is observed at 1726 cm1 and corresponds to the C = O bond. The FTIR spectra of calcined
samples show the vanishing of bands related to complexing agent. The strong band at 523 cm1
in the far IR spectra corresponds to the M--O stretching vibration mode and this peak is
characteristics of perovskite oxides.
3.2. X-ray diffraction
Fig. 2 shows the XRD patterns of the GSMO NPs prepared by sol--gel method and calcined at
700°C for 6 h. The diffractograms reveal that the crystalline perovskite structure is the main
phase for synthesized catalyst. The diffraction peaks at 2θ angels appeared at 22.8, 33.1,41,48,
59.3 and 69.6 can be assigned to scattering from the (100), (110), (111), (200), (211) and
(220).XRD data shows GSMO NPs crystallizes in an orthorhombic phase with a = 5.42, b = 5.56
and c = 7.62 [42]. The crystallite grain size of the monophase samples was determined the full
width at half-maximum width (FWHM) of the XRD (2θ = 33.1o) peak using the Scherrer
formula:
0.96λ
Dhkl

hklcoshkl
Where Dhkl(nm) is the particle size perpendicular to the normalline of (hkl) plane, βhkl is the full
width at half maximum, θhkl(Rad) is the Bragg angle of (hkl) peak, and λ (nm) is the wavelength
of X-ray. The crystallite size of GSMO NPs calcinated at 700°C was about 17nm.
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3.3. Morphology, pore structure and surface area
Scanning electron microscopy (SEM) of perovskite oxide (GSMO) prepared by the sol--gel
method and calcined at 700°C is shown in Fig. 3. Based on the SEM images, porosity of the
surface is evident and it seems that the particles have grown with uniform size. The particles size
of GSMO NPs that were propagated on the surface seems to be in the range of 25--63 nm. The
surface looks rough with relatively large holes that probably caused by a sudden removal of a
large amount of gas when the sample was directly inserted in to the hot furnace of 700°C.
Energy-dispersive X-ray (EDX), as shown in Fig. 4, indicates the existence of Gd, Sr, Mn and O
elements as well as the phase purity in these nanoparticles. The specific surface area of the
nanocatalyst was measured by the Brunauer-Emmett-Teller (BET) method (Fig. 5). Results
showed that the average of specific surface area and mean pore diameter of GSMO NPs were
98.66 m2/g and 28.782 nm, respectively. So, it seems that the large specific surface area of
GSMO nanoparticles is an advantage for the catalytic synthesis of 1,8- dioxodecahydroacridines
and their derivatives. Several methods to calculate the mesopore size distribution from
adsorption isotherm data have been developed [43,44]. Most computational methods are based on
the BJH model by Barrett, Joyner and Halenda [45]. The pore size distribution of GSMO catalyst
is shown in Fig.6. A result showed that radius of the pore as to peak was 12.24 nm. Therefore the
relatively large pore sizes can facilitate the transport of reactants and products through the porous
structure of GSMO NPs, which is a characteristic of the porous materials.
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3.4. Catalytic application in synthesis of 1,8-dioxodecahydroacridines
The one-pot synthesis of 1,8-dioxodecahydroacridines was achieved by the three-component
condensation of aromatic aldehydes, dimedone and ammonium acetate in the presence a
heterogeneous catalyst(Scheme 1). At first, to optimize the reaction conditions, the reaction was
carried out by heating a mixture of benzaldehyde (1 mmol), dimedone (2 mmol), and ammonium
acetate (1 mmol) at different catalysts and different loading of the catalyst. Effective catalysis
was demonstrated down to 0.4mol% (0.001 g) of GSMO NPs (table 1). A further increase in the
amount of catalyst did not have any significant effects on the product yield, as well as in the
absence of catalyst a very low amount of the desired product was formed (entry 1). However
other catalysts such as Kf.γAl2O3, NH4OAc.Al2O3, FeCl3.SiO2 and ZnCl2.SiO2Al2O3 were
examined, but GSMO NPs can act as high efficiency catalyst with fast time and excellent yields
of the obtained products (entry7). Moreover, the reaction was carried out in various solvents and
under solvent-free conditions. As shown in Table 2, solvent-free condition gave the best result in
terms of reaction time and yield. Also we conducted this reaction in different temperatures; it
was observed that taking reaction in the room temperature gave low yields of the desired
products (table 3, entry 1). The yield increased sharply when the temperature was raised from
room temperature to 120°C. It should be noted that increasing the reaction temperature did not
improve the yield. Thus, a range of 1,8-dioxodecahydroacridinesunder was prepared under the
optimized reaction conditions using various aromatic aldehydes (1), dimedone (2) and
ammonium acetate (3). All desired products were formed as shown in table 4. The results
showed that the reactions of electron-withdrawing aldehydes have higher yields compared to the
reactions of electron donating aldehydes.
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3.4.1. A plausible mechanism for synthesis of 1,8-dioxo-decahydroacridine
A proposed mechanism for the condensation of an aromatic aldehyde, dimedone and ammonium
acetate in the presence of GSMO NPs as a Brönsted acidic catalyst for the synthesis of
1,8‐dioxodecahydroacridines is shown in Scheme 2. Initially; aromatic aldehyde (1) and
dimedone (2) coordinates to the Lewis acidic site present at the catalyst surface (I,II). Then, the
elimination of the water leads to intermediate (7) via Knoevenagel condensation (III). On the
other hand, the condensation reaction between dimedone and ammonium acetate leads to
intermediate (8, IV). Formation of intermediate (9) takes place through a Hantzsch-like
mechanism via conjugate addition of the intermediate (8) to the intermediate (7, V). Finally,
intra-molecular nucleophilic attack of nitrogen to carbon containing hydroxyl group leads to final
product (4).
3.4.2. Reusability of catalyst
To evaluate the stability of catalytic activity, reusability of the catalyst was also investigated. For
this purpose, we again studied the same model reaction under optimized conditions. When the
reaction was completed, the reaction mixture was cooled to room temperature, and hot ethanol
was added. The catalyst was separated by filtration, dried at 70°C under vacuum, and reused for a
similar reaction. As shown in Fig.7, GSMO NPs could be reused at least five times without
significant loss of activity.
4. Conclusions
In summary, nanoparticles of perovskite type Gd0.7Sr0.3MnO3 were synthesized using sol--gel
method in the presence of citric acid as complexing agents. A study of the morphological,
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structural and catalytic properties of the Gd0.7Sr0.3MnO3 NPs was carried out by means of various
analytical techniques. XRD and microscopic analyses indicated that the GSMO NPs prepared by
calcinating the gel precursor at 700°C for 6 h, have suitable crystallinity with the orthorhombic
perovskite structure. In addition, GSMO NPs were successfully used as a new, green, non-
volatile, efficient recyclable heterogeneous catalyst for the synthesis of 1,8-
dioxodecahydroacridines under solvent-free conditions. Catalytic activity results revealed that
the, GSMO NPs exhibited excellent catalytic performance in the condensation of various
aromatic aldehydes, dimedone and ammonium acetate. Because of its small particle size and
high specific surface area, the GSMO NPs provides a favorable surface for the reactants and the
reaction completes successfully in terms of excellent yield. We have found that the reactions of
electron-withdrawing aldehydes have higher yields and short reaction times compared to the
reactions of electron donating aldehydes. High yields, short reaction times, high performance of
catalyst even after five runs and very low loading of catalyst (0.001 g) are some of the
advantages of this protocol.
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Table 1.Condensation reaction of benzaldehyde, dimedone and ammonium acetate in the
presence of different catalysts and different loading of the catalysta.
Entry
Catalyst
-
Kf.γAl2O3
Catalyst loading (g)
Time (h)
40
Yield (%)b
1
2
3
4
5
6
7
8
-
30
65
60
85
85
80
92
92
0.001
0.001
0.001
0.001
0.0005
0.001
0.002
20
20
20
20
20
20
20
NH4OAc.Al2O3
FeCl3.SiO2
ZnCl2.SiO2
Gd0.7Sr0.3MnO3
Gd0.7Sr0.3MnO3
Gd0.7Sr0.3MnO3
aReaction conditions: benzaldehyde (1mmol), dimedone (2mmol) and ammonium acetate
(1mmol) at 120C.
bIsolated yields.
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Table 2.Initial solvent effect studies for synthesis of 1,8-dioxo-decahydroacridines in the
presence of Gd0.7Sr0.3MnO3.a
Entry
Solvent
H2O
CH3CN
EtOH
MeOH
Temp (◦C)
Reflux
Reflux
Reflux
Reflux
Reflux
Reflux
120
Time (h)
120
Yield (%)b
1
2
3
4
5
6
7
80
30
70
65
-
300
300
300
300
300
20
Ethyl acetate
n-Hexane
Solvent-free
80
92
aReaction conditions: benzaldehyde (1mmol), dimedone (2mmol) and ammonium acetate
(1mmol) 0.4 mol% nano-Gd0.7Sr0.3MnO3 in 2 mL solvent, stirring.
bIsolated yields.
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Table 3.Optimization of temperature for synthesis of 1,8-dioxo-decahydroacridines under
solvent-free conditionsa.
Entry
Temp (◦C)
Time (h)
120
20
Yield (%)b
1
2
3
4
5
6
7
8
-
50
70
90
100
110
120
130
50
40
50
65
72
85
92
92
20
20
20
20
20
20
aReaction conditions: benzaldehyde (1mmol), dimedone (2mmol) and ammonium acetate
(1mmol) 0.4 mol% nano-Gd0.7Sr0.3MnO3.
bIsolated yields.
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Table 4.Synthesis of various 1,8-dioxo-decahydroacridines in the presence of nano-
a
Gd0.7Sr0.3MnO3 .
Entry
1
Ar
Product
Time(min)
20
Yields
(%)b
mp (◦C)
C6H5
92
274-276
(279-281) [46]
O
O
N
H
4a
2
4-C6H4Cl
15
94
303-305
Cl
(300-302) [47]
O
O
N
H
4b
3
4-C6H4Br
15
95
315-318
Br
(312-316) [48]
O
O
N
H
4c
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4
3-O2NC6H4
NO2
O
15
94
294-296
(288-291) [47]
O
N
H
4d
5
4-MeC6H4
Me
20
90
274-276
(269-271) [47]
O
O
N
H
4e
OH
6
4-OHC6H4
20
88
308-3011
(307-309) [46]
O
O
N
H
4f
NO2
7
4-O2NC6H4
15
93
284-288
(286-289) [47]
O
O
N
H
4g
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OMe
8
4-MeOC6H4
20
88
272-274
(288-291) [47]
O
O
N
H
4h
9
2-ClC6H4
15
93
222-225
(221-223) [47]
Cl
O
O
N
H
4i
NMe2
10
4-Me2NC6H4
20
86
263-265
(264-266) [48]
O
O
N
H
4j
OMe
11
3,4-
15
82
259-263
(MeO)2C6H3
(260-263) [48]
OMe
O
O
N
H
4k
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aReaction conditions: benzaldehyde (1mmol), dimedone (2mmol) and ammonium acetate
(1mmol) 0.4 mol% nano-Gd0.7Sr0.3MnO3 (0.001g), stirring at 120C.
bIsolated yields.
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(a)
(b)
Fig.1. FT-IR spectra of GSMO NPs before (a) and after (b) calcination at 700°C.
23
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Fig.2. XRD pattern of GSMO NPs calcined at 700°C.
24
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Fig.3. SEM images of GSMO NPs.
25
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Fig.4. Energy dispersive X-ray (EDX) spectrum of the GSMO NPs.
26
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Fig.5. N2 adsorption--desorption isotherm of GSMO NPs is calcinated at 700°C.
27
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Fig.6. BJH plot of GSMO is calcinated at 700°C.
28
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100
90
80
70
60
50
92
90
80
80
40
30
20
10
0
75
Fresh
nd2
rd3
th4
th5
Run
Fig.7. Yield refers to isolated products from the benzaldehyde (1mmol), dimedone (2mmol) and
ammonium acetate (1mmol) 0.4 mol% nano-Gd0.7Sr0.3MnO3 (0.001g), under solvent-free
conditions.
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