Facile route to synthesize Fe3O4?acacia-SO3H nanocomposite as a heterogeneous magnetic system for catalytic applications

Article abstract of DOI:10.1039/d0ra07986c

In this work, a novel catalytic system for facilitating the organic multicomponent synthesis of 9-phenyl hexahydroacridine pharmaceutical derivatives is reported. Concisely, this catalyst was constructed from acacia gum (gum arabic) as a natural polymeric

Full text of DOI:10.1039/d0ra07986c

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Facile route to synthesize Fe O @acacia–SO H
3
4
3
nanocomposite as a heterogeneous magnetic
Cite this: RSC Adv., 2020, 10, 40055
system for catalytic applications†
a
a
a
a
Reza Taheri-Ledari,
Mir Saeed Esmaeili, Zahra Varzi, Reza Eivazzadeh-Keihan,
a
bc
Ali Maleki * and Ahmed Esmail Shalan
*
In this work, a novel catalytic system for facilitating the organic multicomponent synthesis of 9-phenyl
hexahydroacridine pharmaceutical derivatives is reported. Concisely, this catalyst was constructed from
3 4
acacia gum (gum arabic) as a natural polymeric base, iron oxide magnetic nanoparticles (Fe O NPs), and
sulfone functional groups on the surface as the main active catalytic sites. Herein, a convenient
preparation method for this nanoscale composite is introduced. Then, essential characterization
methods such as various spectroscopic analyses and electron microscopy (EM) were performed on the
fabricated nano-powder. The thermal stability and magnetic properties were also precisely monitored via
thermogravimetric analysis (TGA) and vibrating-sample magnetometry (VSM) methods. Then, the
3 4 3
performance of the presented catalytic system (Fe O @acacia–SO H) was further investigated in the
Received 18th September 2020
Accepted 19th October 2020
referred organic reaction by using various derivatives of the components involved in the reaction.
Optimization, mechanistic studies, and reusability screening were carried out for this efficient catalyst as
well. Overall, remarkable reaction yields (94%) were obtained for the various produced derivatives of 9-
phenyl hexahydroacridine in the indicated optimal conditions.
DOI: 10.1039/d0ra07986c
rsc.li/rsc-advances
general properties of the catalytic systems such as the phys-
icomechanical features of the individual Fe O powder are
1
. Introduction
3
4
Recently, powder technology has received much attention in improved. In this regard, numerous studies have been per-
heterogeneous catalytic systems; powders have great potential formed, and it has been revealed that the efficiency of the Fe
to be applied in complex organic synthesis reactions and are powder can be signicantly modied through its composition
3 4
O
1
6–20
conveniently separated during the purication processes with other materials.
through their heterogeneity. One of the best-known members oxide, Fe O
3 4
For instance, a composition of graphene
and silver nanoparticles was prepared and applied
of this family of materials is magnetic nanoscale powder, which for enhanced photocatalytic degradation of phenols in the past
1,2
21
has been widely used for various scientic purposes such as drug year. Moreover, Javanbakht et al. composited magnetic nano-
delivery, disease diagnosis, water desalination, environment particles with a chitosan matrix for the efficient removal of lea-
3
4
5
6
7
22
cleaning, and chemical catalysis. In our previous work, we have d(II) from water resources. Here, we attempted to prepare
reported several different catalytic systems constructed with the a suitable composite of Fe nanoparticles and “acacia gum”
individual iron oxide (Fe O ) powder (in nanoscale) and applied powder, and we applied this composition to facilitate the organic
them in various catalytic processes. These nanoparticles could synthesis of 9-phenyl hexahydroacridine (HHA) pharmaceuticals.
also be composed of other brous materials and could be
Acacia gum, also called “gum arabic”, is obtained from wild
3 4
O
3
4
8–15
immobilized into polymeric matrices. Through this method, the trees, and its main origin is Somalia. From the organic chemical
aspect, there are several hydroxyl groups in the structure of this
polymer that can be used as appropriate sites for covalent binding
a
Catalysts and Organic Synthesis Research Laboratory, Department of Chemistry, Iran
23
and catalytic applications. From the physicomechanical aspect,
the suitable stability of acacia gum led us to apply it as an
appropriate substrate for immobilization of magnetic nano-
particles. Previously, acacia gum was used as a matrix for catalytic
University of Science and Technology (IUST), Tehran 16846-13114, Iran. E-mail:
maleki@iust.ac.ir; Fax: +98 21 73021584; Tel: +98 21 77240640-50
b
Central Metallurgical Research and Development Institute (CMRDI), P. O. Box 87,
Helwan, Cairo 11421, Egypt. E-mail: a.shalan133@gmail.com
c
BCMaterials, Basque Center for Materials, Applications and Nanostructures, Martina systems. For instance, Banerjee and Chen used this polymer to
Casiano, UPV/EHU Science Park, Barrio Sarriena s/n, Leioa 48940, Spain
design a nanoscale absorbent system for the removal of copper
†
Electronic supplementary information (ESI) available: The table of the materials
ions from water resources. They also magnetized acacia gum
through the composition of Fe O NPs for an easy separation from
and equipment applied in this project and the original spectra of the selected
synthesized 9-phenyl hexahydroacridine compounds. This section can be found
in the online version. See DOI: 10.1039/d0ra07986c
3
4
24
the mixture. In this work, we attempted to perform a chemical
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Fig. 1 (a) Chemical structure of the acacia gum polymer and (b) general structure of tetramethyl-9-phenyl-hexahydroacridine-1,8(2H,5H)-
dione.
modication of acacia gum by sulfonation of the hydroxyl func- impregnated sulfonated carbon composite was recently reported
3
0
tional groups and use the product as an acidic catalytic system for as an acidic catalytic system for assisting the alkylation of phenol.
the facilitated synthesis of HHA derivatives. The chemical struc- In this study, our aim was to sulfonate acacia gum and apply it to
ture of the acacia gum polymer is presented in Fig. 1(a). facilitate the multicomponent synthesis reactions of tetramethyl-9-
To date, various types of hydroacridine derivatives have been phenyl-hexahydroacridine-1,8(2H,5H)-dione. The general structure
developed and investigated for their therapeutic properties. For of these pharmaceuticals is presented in Fig. 1(b).
example, it has been revealed that 5,6-dihydroacridine derivatives
Concisely, we introduce a convenient method to synthesize
25,26
possess antidiabetic and antioxidant properties.
Therefore, it is an Fe O @acacia–SO H heterogeneous magnetic catalytic
3
4
3
highly important to prepare appropriate conditions for fast and system. Then, it is clearly shown that the synthesis of HHA
direct synthesis of hydroacridine derivatives. Generally, HHAs and derivatives is highly facilitated through applying this efficient
a wide spectrum of active pharmaceutical ingredients (APIs) are catalyst. 87–94% reaction yields were obtained for different
synthesized via multicomponent coupling reactions. Today, to derivatives of HHA in reaction times of less than two hours.
obtain purer products with high reaction yields and to shorten the Moreover, convenient separation and excellent reusability were
reaction time, many strategies are being introduced and applied. observed for this system through its magnetic properties.
One of the most effective strategies is to use heterogeneous
27–29
metallic catalytic systems.
Briey, through the existence of
heteroatoms in the structure of the preliminary reactants of 2. Results and discussion
multicomponent reactions, constructive electronic interactions
provide suitable conditions for chemical bonding. In this regard,
sulfonated polymeric networks appear to be efficient for catalysis
2
.1. Preparation method of the Fe
3 4 3
O @acacia–SO H nano-
powder
As presented in Fig. 2, iron(II) and iron(III) chloride salts were
dissolved in deionized water at room temperature. Then, acacia
of organic synthesis reactions. For instance,
a polymer-
Fig. 2 Schematic of the preparation route of the Fe
3
O
4 3
@acacia–SO H nano-powder.
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Fig. 3 (a) Fourier-transform infrared spectra of (i) the neat acacia gum, (ii) Fe
3
O
4
@acacia binary composite, and (iii) Fe
O
3 4
3
@acacia–SO H nano-
powder; (b) energy-dispersive X-ray spectra of (i) the Fe
O
3 4
@acacia binary composite and (ii) the fabricated Fe
3
4 3
O @acacia–SO H nano-powder.
gum powder was added and was also dissolved. In the next structures. In the case of sulfone groups, they are most likely cova-
32
stage, iron ions were precipitated via co-deposition and lently attached to the acacia and Fe
produced Fe nanoparticles, which were well composed with stage, aer completion of the addition of sulfonic acid and stirring
the polymeric texture of acacia. Via this in situ method, a better for 120 min, the particles of Fe
composition was obtained, and the dark particles of Fe O were magnetically separated, washed, and dried in an oven.
3 4
O nanoparticles. In the next
3 4
O
31
3 4 3
O @acacia–SO H composite were
3
4
well immobilized. For this purpose, ammonia solution was
used to raise the pH value. Moreover, aer separation and
drying of the precipitate, the particles of Fe O @acacia were
3 4
dispersed in chloroform and the temperature was reduced by an
ice bath. Due to the exothermic reaction of sulfonic acid, gentle
addition of this material at cool temperatures is required.
2
.2. Characterization of the Fe
3 4 3
O @acacia–SO H nano-
powder
2.2.1. FT-IR and EDX studies. To investigate the presence
of essential functional groups in the structure of the
3 4
During the preparation process, the Fe O nanoparticles appear to
Fe O @acacia–SO H nano-powder, Fourier-transform infrared
3
4
3
electrostatically combine with the acacia textures because both
species contain several hydroxyl groups in their chemical
(
FT-IR) spectra of the neat acacia gum (spectrum i), Fe O @-
3 4
3 4 3
acacia binary composite (spectrum ii), and Fe O @acacia–SO H
3 4
Fig. 4 (a) Thermogravimetric analysis curves and (b) room-temperature M–H curves of the (i) Fe O @acacia binary composite and (ii) fabricated
Fe @acacia–SO H nano-powder.
O
3 4
3
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nano-powder (spectrum iii) were acquired and are presented in
Fig. 3(a). As can be seen in the spectra, the presence of the O–
3
H, C–H (hybridation sp ), and C–O bands was conrmed by
ꢀ
1
the peaks appearing at 3400, 2929, 1050 and 1250 cm
,
respectively. Also, it appears that some of the hydroxyl groups
in the structure of the acacia gum were converted to C]O.
ꢀ1
This claim is proven by the peak that appeared at ꢁ1660 cm
in the spectrum (i). The composition of the Fe NPs was
3
1
O
4
ꢀ
conrmed by the peak appearing at ꢁ590 cm in the spec-
trum (ii), which is related to the Fe–O bond. As observed in
the spectrum (ii), the sharp broad peak of hydroxyl groups in
the structure of acacia gum became deformed; this result
may be due to the physicochemical composition of the Fe
3 4
O
NPs. According to literature, the peak related to the S]O
ꢀ
1
bond is appeared in the range of 1000–1200 cm . Accord-
ingly, as shown in the spectrum (iii), this peak appeared and
conrmed the successful sulfonation of the Fe O @acacia
3 4
binary composite. To obtain more conrmation of the
successful execution of the sulfonation process, energy-
dispersive X-ray (EDX) analysis was also performed. As
Fig. 3(b) shows, 5.3% of the total weight of the Fe
3 4
O @-
acacia–SO H nanocomposite was formed of sulfur aer
3
carrying out the sulfonation process. The existence of the
other essential elements, such as carbon, oxygen, and iron,
Fig. 5 X-ray diffraction patterns of (a) neat acacia gum, (b) the Fe
NPs, and (c) the fabricated Fe @acacia–SO H nano-powder.
3 4
O
3
O
4
3
related to the desired structures of the Fe
3 4
O @acacia binary
composite and Fe O @acacia–SO H nano-powder are also
3
4
3
proven by EDX analysis.
.2.2. TGA and VSM studies. To check thermal stability of
our prepared Fe @acacia–SO H nano-powder, thermogravi-
Fe
ꢁ4.0 emu g ) aer performing the sulfonation process. The
most probable reason is removal of some of the Fe magnetic
3 4
O @acacia binary composite (curve i) decreased slightly
2
ꢀ
1
(
3
O
4
3
3 4
O
metric analysis (TGA) was performed in a thermal range of 0–
NPs that were not strongly attached to the polymeric bers
during the sulfonation process. However, magnetic saturation
for the fabricated Fe O @acacia–SO H nano-powder occurred
ꢂ
3
500 C (Fig. 4(a)). This method also gives some information
3 4
about the combination of the Fe O NPs and the sulfonated
acacia via monitoring of the decomposition process. For the
3
4
3
ꢀ1
at ꢁ23.5 emu g by applying a magnetic eld with 10 000 (Oe)
power, and this value is enough to perform a convenient
magnetic separation process.
Fe O @acacia binary composite (curve i), it can be clearly
3
4
observed that proportional to the temperature rise, two distinct
ꢂ
ꢂ
shoulders in the thermal ranges of 0–700 C and 800–1700 C
2.2.3. XRD study. The X-ray diffraction (XRD) pattern of the
appeared; then, the weight percentage gradually decreased from
prepared Fe @acacia–SO H nano-powder was also investi-
3
O
4
3
ꢂ
ꢁ
1700 C onwards. The rst shoulder can be related to the
gated to check the effects of the composited ingredients on the
dehydroxylation process of the acacia gum. Reportedly, the
organic layers and the hydroxyl groups are separated from the
structure as hydrate molecules up to 700 C. In the next stage,
in which ꢁ55% of the total weight was lost, the acacia gum
likely decomposed and the individual Fe O NPs started to
general crystal structure (Fig. 5). With a quick look at the
ꢂ
spectrum, the presence of a broad peak starting from 2q ¼ 20
ꢂ
33
ꢂ
and continuing to 40 is conrmed. According to the literature,
this broad peak is related to the crystal structure of neat acacia
3
4
34
gum. This result indicates that the acacia polymeric network
ꢂ
collapse from ꢁ1700 C. In curve (ii), which belongs to the
does not include a well-dened crystal structure in comparison
with the inorganic components. Also, there are some other
peaks in the XRD spectrum that are relatively sharp and can be
considered as indicative signals of the Fe O inorganic crystal
3 4
structure. Via a comparison with the reference pattern of the
fabricated Fe @acacia–SO H nano-powder, it can be clearly
3
O
4
3
observed that the stability of the organic functional groups was
signicantly enhanced and the dehydroxylation process was
ꢂ
ꢂ
prolonged to ꢁ1500 C instead of 700 C. Then, the decompo-
ꢂ
sition process started from ꢁ1600 C, and the weight was
Fe O NPs (JCPDS #99-0073), it was revealed that the peaks
3
4
gradually reduced. It can also be seen that only 40% of the total
ꢂ
appearing at 2q ¼ 30.7, 36.2, 43.4, 57.7, and 63.4 belong to the
crystal structure of the composited Fe NPs. These peaks are
also associated with the Miller indices (2 2 0), (3 1 1), (4 0 0), (5 1
), and (4 4 0), respectively.
.2.4. EM study. One of the most preferred methods for
ꢂ
weight was lost up to 3500 C; this indicates that the general
3 4
O
stability of the fabricated nano-powder was enhanced via the
composition process. The magnetic property of the desired
product was also studied by vibrating-sample magnetometry
1
2
3 4
(VSM), and a comparison was made with the Fe O @acacia
investigating the sizes, morphologies, and compositions of
microscale and nanoscale materials is electron microscopy
binary composite through their magnetic-hysteresis (M–H)
curves (Fig. 4(b)). As shown, the magnetic property of the
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(
EM). This is because EM gives direct information from the 2.3. Catalytic application of the Fe O @acacia–SO H nano-
3 4 3
samples without any need for further interpretation or inac- powder in the organic synthesis of 9-phenyl
curate estimations. Fig. 6 illustrates the eld-emission scan- hexahydroacridine pharmaceutical derivatives
ning electron microscopy (FESEM) (images a and b) and
As discussed in the Introduction section, the main goal of the
design and fabrication of the Fe O @acacia–SO H nano-powder
3 4 3
transmission electron microscopy (TEM) images (images c and
d) of the fabricated Fe @acacia–SO H nano-powder at
different magnications. As can be observed in all the images,
the mean size of the captured Fe NPs between the acacia
3
O
4
3
was to provide a suitably active substrate with high heteroge-
neity to increase the convenience of the organic synthesis of 9-
phenyl hexahydroacridine pharmaceutical derivatives. Here, it
is clearly demonstrated that high reaction yields were obtained
through applying the present catalytic system. Moreover, the
reaction time signicantly decreased in comparison with the
catalyst-free conditions. A brief comparison was made between
our novel designed catalytic system and other recently reported
systems that highlights the high efficiency of the present
nanocomposite in organic catalysis (Table 1). Scheme 1 pres-
ents a general view of the targeted organic reaction that was
intended to be catalyzed by the Fe O @acacia–SO H nano-
3 4
O
textures is around 86 nm. Also, high uniformity in the sizes
and shapes of the particles as well as a monotonous distri-
bution onto the acacia gum bers are nicely illustrated in
image (a). Obviously, this good dispersion of the particles
provides an extremely active surface area for catalytic appli-
cations. The TEM images also clearly disclosed that the
spherical-shaped NPs were entrapped in the polymeric matrix.
This composition may lead to higher mechanical stability in
catalytic systems. This stability will be better highlighted in
the recycling process investigation.
3
4
3
powder.
Fig. 6 (a and b) Field-emission scanning electron microscopy and (c and d) transmission electron microscopy images of the fabricated Fe
@acacia–SO H nano-powder.
3
-
O
4
3
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2
.3.1. Optimization. Concisely, various conditions, assessment of the desired products, melting point measure-
including catalyst-free reactions, reactions catalyzed by the neat ments were used. Then, some of the products were selected and
Fe
NPs and acacia gum powder individually, and catalytic identied via spectroscopic methods. Table 2 reports the
systems with different amounts of Fe @acacia–SO
H, various synthesized products via the presented catalytic process.
3 4
O
3
O
4
3
reaction media and different reaction times were precisely
monitored in the synthesis reaction of 9-(4-methoxyphenyl)- Fe
2.3.3. Suggested mechanism of the catalytic activity of the
@acacia–SO H nano-powder. The Fe @acacia–SO
nano-powder is an acidic catalytic system in which the catal-
3
O
4
3
3
O
4
3
H
3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydroacridine-1,8(2H,5H)-
dione, which was considered as a model reaction. Table 1 briey ysis proceeds via H-bonding interactions with the involved
reports the obtained results from each case and also shows that ingredients in the synthesis reactions. As a plausible mecha-
9
4% yield was obtained through using 0.02 g of Fe
SO H nanocomposite under reux conditions.
.3.2. Synthesis of 9-phenyl hexahydroacridines catalyzed by performing a nucleophilic attack on the activated aldehyde
by Fe @acacia–SO
H nano-powder. To investigate the cata- (stage 2). Next, a p-conjugated system is formed during
lytic performance of the fabricated Fe O @acacia–SO H nano- a dehydration process (stage 3). Aerward, in stage four,
3
O
4
@acacia– nism, Fe
3 4 3
O @acacia–SO H starts with activation of the alde-
hyde component in the rst stage. Dimedone enters the cycle
3
2
3
O
4
3
3
4
3
catalyst, various derivatives of the aldehyde component, another dimedone performs a nucleophilic attack on the
including bromine, chlorine, methyl, methoxy, and nitro structure of the conjugated compound; then, NH enters the
4
groups, were studied under the optimal conditions. For initial cycle and forms the structure of the target 9-phenyl
Table 1 Optimization information for the catalyzed synthesis reaction of 9-(4-methoxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahy-
a
droacridine-1,8(2H,5H)-dione
ꢂ
b
Entry
Cat. system
Cat. weight (g)
Medium
Temp. ( C)
Time (min)
Yield (%)
1
2
3
4
5
6
7
8
9
—
—
Fe
—
—
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
25
75
75
75
75
75
75
75
50
80
130
35
130
75
110
90
Reux
110
110
110
110
110
110
300
110
110
110
110
110
110
110
55
N.R.
N.R.
Trace
Trace
88
94
94
94
91
62
75
79
76
3
O
4
NPs
0.02
0.02
0.01
0.02
0.02
0.03
0.03
0.02
0.02
0.02
0.02
0.02
0.01
0.02
0.05
Acacia gum
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
3
3
3
3
3
3
3
3
3
3
O
O
O
O
O
O
O
O
O
O
4
4
4
4
4
4
4
4
4
4
@acacia–SO
@acacia–SO
@acacia–SO
@acacia–SO
@acacia–SO
@acacia–SO
@acacia–SO
@acacia–SO
@acacia–SO
@acacia–SO
3
3
3
3
3
3
3
3
3
3
H
H
H
H
H
H
H
H
H
H
c
10
11
12
13
14
15
16
17
H
2
O
DMF
DCM
Toluene
CH
3
CN
79
Nano-Fe
Fe @SiO
Cell-Pr-NHSO
3
O
4
–TiO
2
–SO
3
H
Solvent free
Solvent free
Ethanol
86 (ref. 35)
90 (ref. 36)
88 (ref. 37)
3
O
4
2
–MoO
3
H
40
48
3
H
a
Abbreviations: Cat.: catalyst; Temp.: temperature, DMF: dimethylformamide; DCM: dichloromethane; N.R.: no reaction. The reaction progress
was controlled by thin-layer chromatography, and the desired hexahydroacridine product was puried via ash-column chromatography.
b
c
Isolated yield. Optimum conditions.
Scheme 1 General schematic of the organic synthesis reaction of the 9-phenyl hexahydroacridine derivatives catalyzed by the Fe
SO H nanocatalyst.
3 4
O @acacia–
3
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Table 2 Various derivatives of 9-phenyl hexahydroacridine synthesized via the catalytic process using the Fe
O
3 4
3
@acacia–SO H nanocatalyst
ꢂ
Melting point ( C)
a
Entry
Product structure
Product code
Time (min)
Yield (%)
Found
Reported
Ref.
38
1
a
110
93
279–281
277–279
2
b
145
87
264–266
263–264
39
3
c
135
91
290–292
295–297
40
4
d
150
87
318–320
319–321
41
5
e
125
91
211–213
210–213
41
6
f
120
92
301–303
300–302
42
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Table 2 (Contd.)
ꢂ
Melting point ( C)
a
Entry
Product structure
Product code
Time (min)
Yield (%)
Found
Reported
Ref.
7
g
150
86
86
94
286–288
281–283
288–290
287–289
36
8
h
150
282–284
43
9
i
110
287–290
44
1
0
j
140
90
321–324
322–324
45
a
Isolated yield.
hexahydroacridine. Scheme 2 schematically presents the analyses, it was clearly revealed that no signicant changes
4
6–51
explained catalytic cycle. occurred in the structure of the Fe
3 4 3
O @acacia–SO H catalytic
2
.3.4. Recyclability of the Fe O @acacia–SO H catalytic system. As can be observed in Fig. 7(b and c), all of the distinct
3 4 3
system. The stability of the fabricated catalytic system was indicative peaks appeared in both spectra. Moreover, induc-
precisely investigated by successive running of the catalytic tively coupled plasma (ICP) analysis was performed to investi-
process in the synthesis reaction of product i. As can be seen in gate the metal leaching from the system. Aer completion of the
Fig. 7(a), acceptable reaction yields were obtained in a total of catalytic process (aer run 1), the particles were separated and
ten runs of the reaction. Aer recycling and reusing the nano- the supernatant was ltered and analyzed. Briey, it was
particles ten times, FT-IR and EDX spectra of the recovered observed that only 0.15 mg of the iron element leached from
nanocomposite were prepared and investigated. From these 0.05 g of the catalytic system.
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Scheme 2 Plausible mechanism of the catalytic activity of the fabricated Fe
3
4 3
O @acacia–SO H nanocatalyst in the synthesis reactions of 9-
phenyl hexahydroacridine derivatives.
(
1.0 mmol and 2.0 mmol, respectively) were dissolved in deionized
3
. Experimental
water (10 mL) via vigorous stirring at room temperature. Then,
acacia gum powder (0.6 g) was added in several portions and also
3.1. Materials and equipment
All commercially available chemicals, solvents, reagents and were dissolved. In the next stage, the reaction mixture was gradually
ꢂ
purchased from Sigma-Aldrich and Merck Company. All the heated to around 80 C under a neutral atmosphere of N
2
. Then,
applied materials and equipment are summarized in Table S1.† ammonia solution (13 mL) was added dropwise until the pH value
reached ꢁ12. The dark mixture was then stirred under the same
conditions for an additional 1 h. Finally, the magnetic particles
were collected via holding an external magnet at the bottom of the
3.2. Practical methods

ask aer cooling to room temperature. The particles were washed
3
.2.1. Preparation of Fe O @acacia binary composite. In
3
4
ꢂ
with ethanol and water several times and dried in an oven at 60 C.
a round bottom ask (50 mL), FeCl $4H O and FeCl $6H O salts
2
2
3
2
Fig. 7 (a) Recycling diagram, (b) Fourier-transform infrared spectrum, and (c) energy-dispersive X-ray spectrum of the recovered Fe
acacia–SO H catalytic system.
3 4
O @-
3
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3
.2.2. Preparation of Fe
a round bottom ask (50 mL), the particles of Fe
g) were dispersed in chloroform (10 mL), and the temperature 130.0, 129.5, 126.7, 115.4, 47.0, 46.9, 46.3, 31.7, 31.2, 28.9, 27.8.
3
O
4
@acacia–SO
3
H nano-powder. In (m, 2H), 2.34 (d, 2H), 2.32 (d, 2H), 2.31 (d, 2H), 1.14 (s, 6H), 1.07
1
3
3 4
O
@acacia (0.6 (s, 6H). C NMR (75 MHz, DMSO), d (ppm): 189.8, 135.3, 134.1,
was reduced by an ice bath. In a separate ask, chlorosulfonic
9-(3-Methylphenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahy-
acid (99%) (2.0 mL) was mixed with chloroform (2.0 mL), and droacridine-1,8(2H,5H)-dione (product e): M. P ( C): 211–213.
ꢂ
1
the resulting solution was added dropwise to the main reaction
ask with stirring. Aer completion of the addition, the ice bath 7.09–7.11 (d, 1H), 7.03–7.08 (m, 1H), 6.86–6.88 (d, 1H), 5.05 (s,
was removed, and vigorous stirring was continued for an 1H), 2.32–2.40 (m, 2H), 2.26 (d, 2H), 2.22 (d, 2H), 2.16 (d, 2H),
H NMR (300 MHz, DMSO), d (ppm): 8.07 (s, 1H), 7.26 (s, 1H),

1
3
additional 2 h at room temperature. Ultimately, the product was 1.05 (s, 6H), 0.95 (s, 6H). C NMR (75 MHz, DMSO), d (ppm):
magnetically separated, washed, and dried as described above. 196.1, 149.5, 146.7, 137.3, 129.1, 128.0, 126.9, 125.2, 113.3, 51.1,
3
.2.3. General procedure for the catalyzed synthesis of 9- 40.8, 33.6, 32.7, 29.8, 27.2, 21.8.
phenyl hexahydroacridine pharmaceutical derivatives. In
9-(3-Methoxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahy-
a round bottom ask (25 mL), aldehyde (1.0 mmol), dimedone droacridine-1,8(2H,5H)-dione (product f): M. P ( C): 301–303. H
2.0 mmol), ammonium acetate salt (1.1 mmol), and Fe O @- NMR (300 MHz, DMSO), d (ppm): 8.94 (s, 1H), 7.25 (s, 1H), 7.22
ꢂ
1
(
3
4
acacia–SO H nano-powder (0.02 g) were mixed in ethanol (2.0 (d, 1H), 7.01 (m, 1H), 6.98 (d, 1H), 5.07 (s, 1H), 3.91 (s, 3H), 2.22–
3
mL), and the mixture was reuxed. Aer the appropriate time 2.27 (m, 2H), 2.17 (d, 2H), 2.11 (d, 2H), 2.04 (d, 2H), 1.12 (s, 6H),
1
3
had passed (110 min), the particles of the catalytic system were 0.95 (s, 6H). C NMR (75 MHz, DMSO), d (ppm): 196.1, 158.72,
magnetically removed and the desired product was puried via 149.9, 143.8, 134.9, 128.5, 127.7, 125.2, 112.8, 50.8, 40.2, 33.0,
1
13

ash-column chromatography. The original H and C-NMR 32.3, 29.4, 27.9, 20.9.
spectra of the selected products are shown in Fig. S1–S20 in
the ESI† section.
9-(4-Nitrophenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahy-
droacridine-1,8(2H,5H)-dione (product g): M. P ( C): 286–288.
ꢂ
3
.2.4. Recycling of the catalyst. Aer completion of the rst 1H NMR (300 MHz, DMSO), d (ppm): 9.90 (s, 1H), 7.19–7.21 (d,
round, the Fe O @acacia–SO H particles were magnetically 2H), 7.12–7.14 (d, 2H), 4.76 (s, 1H), 2.42–2.49 (d, 4H), 2.14–2.32
3
4
3
1
3
separated and the rest were separated via decanting. Then, the (d, 2H), 1.95–1.98 (d, 2H), 0.99 (s, 6H), 0.84 (s, 6H). C NMR (75
particles were washed well with deionized water and ethanol (20 MHz, DMSO), d (ppm): 194.4, 149.5, 146.1, 129.9, 129.5, 127.5,
mL) four successive times. Aerward, the particles were died in 115.5, 111.1, 50.1, 40.0, 32.6, 32.2, 29.0, 26.4.
a vacuum oven for 24 h. To reuse the particles, redispersion was
3,3,6,6-Tetramethyl-9-(3-nitrophenyl)-3,4,6,7,9,10-hexahy-
initially performed by an ultrasound cleaner bath (50 kHz, droacridine-1,8(2H,5H)-dione (product h): M. P ( C): 281–283.
ꢂ
ꢀ
1
1
2
00 W L ); then, the reactants were added to the ask.
H NMR (300 MHz, DMSO), d (ppm): 9.31 (s, 1H), 8.00–8.01 (d,
H), 7.65–7.66 (d, 1H), 7.54–7.57 (t, 1H), 4.65 (s, 1H), 2.50–2.59
2
(
(
dd, 4H), 2.27–2.30 (d, 2H), 2.08–2.12 (d, 2H), 1.04 (s, 6H), 0.91
s, 6H). C NMR (75 MHz, DMSO), d (ppm): 196.0, 149.4, 149.0,
3.3. Spectral data for selected products
13
3
1
,3,6,6-Tetramethyl-9-phenyl-3,4,6,7,9,10-hexahydroacridine-
,8(2H,5H)-dione (product a): M. P ( C): 279–281. H NMR (300
131.1, 129.7, 122.3, 112.9, 51.0, 40.9, 33.9, 32.8, 29.7, 27.3, 21.1.
9-(4-Methoxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahy-
ꢂ
1
ꢂ
1
MHz, DMSO), d (ppm): 9.30 (s, 1H), 7.00–7.13 (m, 5H), 4.60 (s, droacridine-1,8(2H,5H)-dione (product i): M. P ( C): 288–290. H
1
0
1
2
H), 2.40–2.48 (m, 2H), 2.27 (d, 2H), 2.12 (d, 2H), 2.00 (d, 2H), NMR (300 MHz, DMSO), d (ppm): 9.20 (s, 1H), 7.05–7.07 (t, 2H),
.98 (s, 6H), 0.83 (s, 6H). C NMR (75 MHz, DMSO), d (ppm): 6.76–6.80 (t, 2H), 4.46 (s, 1H), 3.70 (s, 3H), 2.56 (d, 2H), 2.49–
94.3, 149.3, 147.1, 127.6, 127.5, 125.4, 111.4, 50.2, 32.9, 32.2, 2.51 (m, 2H), 2.27 (d, 2H), 2.09 (d, 2H), 1.03 (s, 6H), 0.91 (s, 6H).
1
3
1
3
9.1, 26.4.
-(2-Chlorophenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahy-
droacridine-1,8(2H,5H)-dione (product b): M. P ( C): 264–266.
C NMR (75 MHz, DMSO), d (ppm): 196.2, 157.5, 149.6, 139.2,
9
128.8, 125.2, 113.0, 50.8, 40.36, 32.6, 32.4, 29.5, 26.9.
9-(4-Bromophenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahy-
H NMR (300 MHz, DMSO), d (ppm): 9.59 (s, 1H), 7.25–7.27 (d, droacridine-1,8(2H,5H)-dione (product j): M. P ( C): 321–324. H
H), 7.10–7.20 (m, 1H), 7.04–7.08 (m, 1H), 6.99–7.01 (m, 1H), NMR (300 MHz, DMSO), d (ppm): 9.33 (s, 1H), 7.23–7.26 (dd,
2H), 6.87–6.92 (m, 2H), 4.73 (s, 1H), 2.26–2.46 (m, 4H), 2.19–2.22
NMR (75 MHz, DMSO), d (ppm): 196.4, 152.4, 142.6, 132.0, (m, 2H), 2.15 (m, 4H), 1.10 (s, 6H), 0.99 (s, 6H). C NMR (75
ꢂ
1
ꢂ
1
1
5
1
3
.05 (s, 1H), 2.71–2.10 (m, 8H), 0.98 (s, 6H), 0.92 (s, 6H).
C
1
3
129.7, 128.2, 115.2, 50.6, 40.8, 32.2, 31.4, 29.3, 27.2.
MHz, DMSO), d (ppm): 194.4, 149.6, 149.3, 147.1, 127.9, 127.8,
9
-(4-Chlorophenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahy-
126.0, 111.9, 50.7, 32.2, 31.2, 29.2, 27.3.
ꢂ
droacridine-1,8(2H,5H)-dione (product c): M. P ( C): 290–292.
H NMR (300 MHz, DMSO), d (ppm): 9.92 (s, 1H), 7.27–7.30 (d,
H), 7.18–7.19 (d, 2H), 4.50 (s, 1H), 2.50–2.59 (dd, 4H), 2.25–2.28
d, 2H), 2.07–2.10 (d, 2H), 1.04 (s, 6H), 0.90 (s, 6H). C NMR (75 In this work, we designed and fabricated a novel catalytic
1
4. Conclusions
2
(
1
3
MHz, DMSO), d (ppm): 196.1, 149.3, 147.1, 131.7, 129.6, 129.3, system with high heterogeneity and magnetic features to facil-
1
28.2, 113.1, 50.2, 33.6, 32.8, 29.1, 27.3.
itate the MCR synthetic reactions of 9-phenyl hexahy-
droacridine pharmaceutical derivatives. A combination of
9-(2,4-Dichlorophenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hex-
ꢂ
ahydroacridine-1,8(2H,5H)-dione (product d): M. P ( C): 318– acacia gum (gum arabic) with iron oxide magnetic particles on
1
3
1
20. H NMR (300 MHz, DMSO), d (ppm): 9.95 (s, 1H), 7.34 (s, the nanoscale was used as a magnetized natural matrix. From
H), 7.28–7.33 (d, 1H), 7.19–7.22 (d, 1H), 5.58 (s, 1H), 2.38–2.43 the physicochemical aspect, through effective H-binding
40064 | RSC Adv., 2020, 10, 40055–40067
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interactions, the organic and inorganic ingredients were rmly
7 A. Maleki, F. Hassanzadeh-Afruzi, Z. Varzi and
M. S. Esmaeili, Magnetic dextrin nanobiomaterial: an
organic–inorganic hybrid catalyst for the synthesis of
biologically active polyhydroquinoline derivatives by
asymmetric Hantzsch reaction, Mater. Sci. Eng., C, 2020,
109, 110502.
8 A. Maleki, R. Taheri-Ledari and M. Soroushnejad, Surface
functionalization of magnetic nanoparticles via palladium-
catalyzed Diels-Alder approach, ChemistrySelect, 2018, 3,
13057–13062.

xed and combined well with each other. EM imaging
approaches indeed disclosed the composition of the composite.
Then, the prepared Fe O @acacia binary composite was
3
4
equipped with sulfone groups, which are considered to be the
main active catalytic sites. Aerward, the high catalytic perfor-
mance of the formed cluster-shaped composite was investigated
in the organic synthesis reactions of 9-phenyl hexahy-
droacridine derivatives. The mechanical and thermal stability
of the fabricated Fe O @acacia–SO H nano-powder was also
3
4
3
studied, and this substantial stability was highlighted in the
recycling process. Overall, herein, we have made an effort to
9 A. E. Shalan, M. Rasly and M. M. Rashad, Organic acid
precursor synthesis and environmental photocatalysis
applications of mesoporous anatase TiO2 doped with
different transition metal ions, J. Mater. Sci.: Mater.
Electron., 2014, 25(7), 3141–3146.
comprehensively study the structural features of the Fe
acacia–SO H nano-powder and demonstrate the catalytic
performance of this product. Due to the high convenience of the
3 4
O @-
3
synthesis process and the low prices of the used raw materials, 10 S. Parvaz, R. Taheri-Ledari, M. S. Esmaeili, M. Rabbani and
this product is recommended for industrial applications.
A. Maleki, A brief survey on the advanced brain drug
administration by nanoscale carriers: with a particular
focus on AChE reactivators, Life Sci., 2020, 240, 117099.
1 A. Maleki, R. Taheri-Ledari, J. Rahimi, M. Soroushnejad and
Z. Hajizadeh, Facile peptide bond formation: effective
interplay between isothiazolone rings and silanol groups at
silver/iron oxide nanocomposite surfaces, ACS Omega,
2019, 4, 10629–10639.
Conflicts of interest
1
The authors declare no conict of interest.
Acknowledgements
1
2 A. Maleki, R. Taheri-Ledari, R. Ghalavand and R. Firouzi-
The authors gratefully acknowledge the partial support from the
Research Council of the Iran University of Science and Tech-
nology (IUST). Furthermore, AES is grateful for the National
Research grants from MINECO “Juan de la Cierva” [FJCI-2018-
Haji,
functionalized
Palladium-decorated
Fe O /SiO
o-phenylenediamine-
magnetic nanoparticles:
3
4
2
a promising solid-state catalytic system used for Suzuki–
Miyaura coupling reactions, J. Phys. Chem. Solids, 2020,
037717].
136, 109200.
13 R. Taheri-Ledari, A. Maleki, E. Zolfaghari, M. Radmanesh,
H. Rabbani, A. Salimi and R. Fazel, High-performance
sono/nano-catalytic system: Fe O @Pd/CaCO -DTT core/
3 4 3
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catalyst for the preparation of 1,8-
40066 | RSC Adv., 2020, 10, 40055–40067
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RSC Adv., 2020, 10, 40055–40067 | 40067