The influence of the polymerization approach on the catalytic performance of novel porous poly (ionic liquid)s for green synthesis of pharmaceutical spiro-4-thiazolidinones

Article abstract of DOI:10.1039/d0ra08647a

Although poly (ionic liquids) (PILs) have attracted great research interest owing to their various applications, the performance of nanoporous PILs has been rarely developed in the catalysis field. To this end, a micro-mesoporous PIL with acid-base bifunc

Full text of DOI:10.1039/d0ra08647a

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The influence of the polymerization approach on
the catalytic performance of novel porous poly
(ionic liquid)s for green synthesis of pharmaceutical
spiro-4-thiazolidinones†
Cite this: RSC Adv., 2020, 10, 44159
ab
Zahra Elyasi,a Javad Safaei Ghomi,
Gholam Reza Najafia
*
and Mohammad Reza Zand Monfareda
Although poly (ionic liquids) (PILs) have attracted great research interest owing to their various applications,
the performance of nanoporous PILs has been rarely developed in the catalysis field. To this end, a micro–
mesoporous PIL with acid–base bifunctional active sites was designed and fabricated by two different
polymerization protocols including hydrothermal and classical precipitation polymerization in this paper.
Based on our observations, hydrothermal conditions (high temperature and pressure) enabled the
proposed sonocatalyst to possess a great porous structure with a high specific surface area (SBET: 315 m2
ꢀ1) and thermal stability (around 450 ꢁC for 45% weight loss) through strengthening cross-linking. In
a comparative study, the preferred nanoporous PIL was selected and utilized as the sonocatalyst in
a multicomponent reaction of isatins, primary amines, and thioglycolic acid. In the following, a variety of
new and known pharmaceutical spiro-4-thiazolidinone derivatives were synthesized at room
temperature and obtained excellent yields (>90%) within short reaction times (4–12 min) owing to the
substantial synergistic effect between ultrasound irradiation and magnetically separable catalyst.
g
Received 10th October 2020
Accepted 23rd November 2020
DOI: 10.1039/d0ra08647a
rsc.li/rsc-advances
Radical-initiated polymerization processes, including
dispersion, suspension, and emulsion polymerization, are
1. Introduction
traditional protocols for the construction of synthetic polymers
owing to the polymer materials separation and ease of heat
removal.14–16
The indole scaffold is known as one of the most important
structures in heterocyclic chemistry owing to its widespread
pharmacological and bioavailability applications, such as anti-
inammatory, antimicrobial, anti-hypertensive, anti-cancer,
and anti-diabetic (Fig. 1).1–6 In addition, 4-thiazolidinone
derivatives are privileged heterocyclic compounds with signi-
cant potential pharmaceutical performance, especially in the
design of various anticancer agents.7–9 Therefore, several
methods have been investigated for the synthesis of spiro
[indole-thiazolidinones] compounds by reacting isatins with
mercaptoacetic acid and amines under various conditions.10–13
However, many reported methods suffer from drawbacks, such
as longer reaction times, high reaction temperature, use of
ammable solvents, tedious workup, lower yields of the prod-
ucts, and expensive catalysts. Therefore, introducing an envi-
ronmentally benign and straightforward synthetic strategy for
the preparation of spiro[indolethiazolidinones] is an essential
goal.
In these heterogeneous polymerizations, polymeric surfac-
tants or emulsiers are used to stabilize the latex particles or
monomer droplets. In recent decades, the precipitation poly-
merization has developed and in which any added surfactant or
stabilizer is absent compared to traditional polymerization
protocols.17 However, a low monomer concentration (<5 wt%)
leads to heavy consumption of solvent and low relative yield
(<50%). Recently, several new methods have been investigated
to overcome these limitations, including solvothermal precipi-
tation
polymerization,
redox-initiated
precipitation
aDepartment of Chemistry, Qom Branch, Islamic Azad University, Post Box:
37491-13191, Qom, I. R. Iran. E-mail: safaei@kashanu.ac.ir; Fax: +98 31
55552935; Tel: +98 31 55912385
bDepartment of Organic Chemistry, Faculty of Chemistry, University of Kashan, Iran
† Electronic supplementary information (ESI) available. See DOI:
10.1039/d0ra08647a
Fig.
compounds.
1 Indole scaffold in pharmacologically and biologically
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polymerization, and photoinitiated precipitation polymeriza- efficiency of the prepared catalyst. Based on the observations,
tion.18–22 Ionic liquids bearing polymerizable groups could be prepared porous PIL is highly sensitive to the polymerization
polymerized under different conditions to form a new class of process. The catalyst obtained from the hydrothermal precipi-
polyelectrolytes, which are named poly (ionic liquids) (PILs).23,24 tation polymerization is in the class of nanoscale materials with
They are able to provide the properties of both the ionic liquids high porosity structure. The high specic surface area in
and conventional polymers. Therefore, they opened up a wide combination with porous morphology, and thermal stability
window to various range of applications, such as catalysts, supply catalysis application. Finally, the preferred catalyst was
surface active materials, fuel cells, and membranes.25–29 used to facilitate the one-pot synthesis of spiro-2,3-
Recently, the interest in their applications and synthesis kept disubstituted-4-thiazolidinones in an aqueous system under
growing, particularly those made from N-vinyl imidazolium- ultrasound condition.
based monomers.30 Typically, imidazolium-based PILs are
great metal-free catalysts due to their remarkable properties like
2.1. Structural and textural analysis of Co3O4@crosslinked p
[AVIM]Br nanocatalyst
good stability, tunable structure, and low vapor pressure.
However, many PILs catalysts, reported in the literature, have
low active site concentrations and poor porosities.31,32 There-
fore, there is a challenge to synthesize porous PILs with a large
amount of porosity and high specic surface areas. On the other
hand, the stability of the porous materials is an important
prerequisite for their various applications. The broad applica-
tion rang of zeolites is attributed to their great hydrothermal
and thermal stabilities.33,34 Although Metal Organic Frame-
works (MOFs) have uniform pore sizes (due to their crystallinity)
compared to zeolites, their applications are limited by their
sensitivity to moisture, particularly in the presence of base or
acid chemicals.35,36 While, porous ionic polymers (PIPs) con-
taining chemically stable covalent bonds exhibited high
hydrothermal, chemical, and thermal stabilities. Therefore,
PIPs could be selected as efficient heterogeneous catalysts
owing to their excellent stabilities which can facilitate the reuse
and recovery of catalysts.37,38 Mesoporous PILs (as the main
branch of the PIPs category) could be fabricated to possess
intrinsic networks with exchangeable anions and porous
structure among proper polymerization processes.39,40 Immo-
bilization of PILs onto the magnetic supports is another prac-
tical procedure for improving the reusability and stability.41 In
continuation of our investigations about introducing synthetic
methodologies in the presence of efficient nanocatalyst,42–46
a new type of porous poly ionic liquid has been fabricated under
two comparative polymerization methods. We designed and
synthesized a new hypercrosslinked PIL immobilized on vinyl
functionalized Co3O4 nanoparticles as a high effective catalyst
for green preparation of spiro[indole-thiazolidinone]
derivatives.
In order to obtain more accurate information, the FT-IR analysis
of the Co3O4 NPs, Co3O4@MPS, [AVIM]Br monomers, and
Co3O4@crosslinked p[AVIM]Br was performed. As shown in
(Fig. 2a), the strong peaks at 655 and 575 cmꢀ1 are attributed to
the characteristic peaks of spinel Co3O4. The peaks at 655 cmꢀ1
belong to the stretching vibration of metal–O in which M is
Co2+. While the absorption band at 575 cmꢀ1 can be attributed
to the metal–O in which M is Co3+. Coating of MPS onto the
Co3O4 NPs surface is also conrmed by peaks at 1100, 1540, and
1740 cmꢀ1 which respectively belong to stretching vibrations of
Si–O, C]C, and steric C]O (Fig. 2b). As it can be seen in
(Fig. 2c), the stretching and bending vibration of the vinyl group
2. Results and discussion
Proving appropriate reaction conditions for NPs' surfaces is
known as one of their most important modication. Having
high magnetic behavior can also increase their importance due
to the fact that they are generally absorbed to the magnet along
with the magnetically stirring. In order to overcome this chal-
lenge, Co3O4 NPs were selected as the magnetic core instead of
Fe3O4 NPs. In addition, the surface of MNPs has been modied
by MPS before the polymerization process which caused gra-
ing of polymeric networks on MNPs by covalent bonding. On
the other hand, two different methods were applied to study the
Fig. 2 The FT-IR spectra of (a) Co3O4, (b) Co3O4@MPS, (c) ionic
effect of polymerization protocol on the morphology and monomer, and (d) crosslinked Co3O4@p[AVIM]Br.
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Table 1 Textural property of the Co3O4@crosslinked p[AVIM]Br
a
b
c
SBET
VP
Dav
Entry PIL
(m2 gꢀ1) (cm3 gꢀ1) (nm)
1
2
Hydrothermal
315
110
0.29
0.37
3.1
precipitation polymerization
Classical precipitation
polymerization
10.7
a
BET surface area. b Total pore volume. c Average pore size.
obvious porous and crosslinked polymeric network was formed
in both methods. As shown in Fig. 3, autoclaving temperature
and pressure have a signicant effect on the morphology in
contrast. Based on the observations, hydrothermal conditions
(high temperature and pressure) enabled the PIL to possess
great porous structure through strengthening crosslinking.
Actually, the diameter of particles increased as the temper-
ature decreased. Increasing the temperature from 80 ꢁC (reux)
to 150 ꢁC (autoclave) leads to the formation of a crosslinked
magnetic core and polymeric shell structures with 25–50 nm
(Fig. 4f). While classical precipitation polymerization provides
the magnetic core diameter of ꢂ527 nm (Fig. 4c). Notably, the
growth of particles is occurred due to their paramagnetic
behavior and lack of enough energy force (temperature and
pressure) for good dispersion. Moreover, the uniform porous
structure of the Co3O4@crosslinked p[AVIM]Br was determined
through Fig. 4d.
The porous structure is a key characteristics factor in the
world of catalysts which affects their chemical and physical
properties. As shown in FE-SEM images, the type of polymeri-
zation process extremely changed their morphology and struc-
ture which could have signicant effects on the surface
properties of the catalyst.
The N2 isotherm of the hydrothermal sample illustrated the
type IV behavior with an obvious H2 type hysteresis loop in the
pressure ranges from 0.65 to 1.00, implying the presence of
Fig. 3 Comparative FESEM images of Co3O4@p[AVIM]Br, under (A)
hydrothermal treated, and (B) classical precipitation polymerization in
2 mm.
of the imidazole ring have respectively appeared at 1648 cmꢀ1
and 932–1020 cmꢀ1. These mentioned peaks are not seen in the
Co3O4@crosslinked p[AVIM]Br spectrum conrming polymeri-
zation (Fig. 2d).
Moreover, the characteristic peaks of N–C–N at 660 cmꢀ1 and
1228 cmꢀ1 are retained aer the polymerization process in the
spectrum as well. The imidazole H–C–C & H–C–N bending
vibration also appears at 1168 cmꢀ1 while the peak at 824 cmꢀ1
corresponds to the in-plane imidazole ring bending.47 Notably,
these mentioned peaks were observed in both IL monomer and
PILs spectra. The doublet around 2850–3000 cmꢀ1 corresponds
to symmetric ns(CH2) and asymmetric nas(CH2) of the IL
monomers. The broad peak at about 3300 cmꢀ1 to 3530 cmꢀ1
also belongs to the quaternary nitrogen of imidazolium with
bromide.47 As shown in Fig. 2d, the observed strong peak at
1670 cmꢀ1 is attributed to the characteristic peak of carbonyl
groups of N,N0-methylenebisacrylamide.
Fig. 3 and 4 show the FE-SEM images for porous PILs
synthesized by hydrothermal precipitation and classical
precipitation polymerization process. As it can be seen, an
Fig. 4 FE-SEM images of sonocatalyst obtained through (a–c) clas-
sical
precipitation,
and
(d–f)
hydrothermal
precipitation Fig. 5 Pore size distributions and nitrogen adsorption desorption
polymerization.
isotherms of Co3O4@p[AVIM]Br catalyst.
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microporous and mesoporous. Moreover, the classical sample
of Co3O4@crosslinked p[VIM]Br showed the type IV isotherm
with a distinctive H1 type hysteresis loop in the relative pressure
ranges from 0.4 to 1.00, conrming the characteristic meso-
porous structure. The specic surface area of prepared PIL
through classical precipitation polymerization (ꢂ110.0 m2 gꢀ1
)
was less than one-third compared to the one that was obtained
through hydrothermal precipitation polymerization (ꢂ315.0 m2
gꢀ1). Moreover, their pore size distributions and total pore
volumes were quite different as demonstrated in Table 1. As it
can be seen in Fig. 5, the absence of a step change in the pore
size distribution of samples revealed that the distribution is
non-zero <60 nm. Therefore, there are many pores in the
network in which N2 gas is not condensed at the highest pres-
sure. For the PIL obtained through classical precipitation
polymerization, most pores were over 10 nm with a wide range
distribution. Hydrothermal condition provided a higher degree
of cross linking that led to more porous structure and smaller
pore size distribution.
Thus, fabricated Co3O4@crosslinked p[AVIM]Br through
hydrothermal polymerization resulted in a much higher proper
pores structure and specic surface area which not only stem
from the co-existence of random micro and mesoporous but
also can greatly enhance their catalytic activity in organic
synthesis.
Fig. 7 XRD pattern of sonocatalyst.
weight loss) indicating the rapid decomposition of structure
through classical method. It was assumed that a difference in
the network forces (different degree of crosslinking) or
morphology may explain the difference obtained in the thermal
stability of samples. Thus, fabricated Co3O4@crosslinked p
[AVIM]Br through hydrothermal polymerization illustrated
more thermal stability.
The Co3O4@crosslinked p[AVIM]Br structure was investi-
gated by the measurements of powder X-Ray Diffraction (XRD)
(Fig. 7). The XRD pattern of the proposed catalyst clearly illus-
trated 9 reection peaks at 2q ¼ 19.45, 31.701, 37.263, 38.97,
45.174, 56.11, 59.773, 65.629, and 69.41. All of the appeared
peaks were consistent with the peak positions of face-centered
cubic Co3O4 (fcc, Fd3m, JCPDS card no. 01-080-1533). A broad
peak around 20ꢁ belongs to the amorphous silica around the
Co3O4 core. These experimental results showed that the modi-
cations did not cause a phase change in the Co3O4 particles.
Energy-Dispersive X-ray spectroscopy (EDX) analysis and
elemental mapping images of Co3O4@crosslinked p[AVIM]Br
are presented in (Fig. S2†). In the EDX spectrum of the prepared
PIL, expected elements (C, O, N, Co, Si, Br) have appeared in
their regions. Elemental mapping results clearly determined
that all the related elements, from PILs, are well distributed
throughout the Co3O4@crosslinked p[AVIM]Br slices.
Thermo Gravimetric Analysis (TGA) of the Co3O4@-
crosslinked p[AVIM]Br was separately investigated for Co3-
O4@crosslinked p[AVIM]Br catalyst under hydrothermal
precipitation and classical precipitation polymerization
methods to determine the effect of polymerization approach on
thermal stability. The initial weight loss at low temperature
(<200 ꢁC) is attributed to the evaporation of physically adsorbed
water owing to the hydrophilic nature of ionic liquid units
(Fig. 6). The onset thermal degradation temperature (Td) value
for Co3O4@crosslinked p[AVIM]Br was about 420 ꢁC under
hydrothermal condition. The hydrothermal treated Co3O4@p
[AVIM]Br showed a drastic weight loss of 45% between the
temperature 420–500 ꢁC which can be due to the decomposition
of the major bond between cross-linking and ionic moꢁnomers.
Co3O4@p[AVIM]Br shows a fast weight loss up to 380 C (70%
Vibrating sample magnetometer was investigated to conrm
the magnetic behavior of the catalyst at room temperature.
According to the linear magnetization diagram (Fig. S3†), the
prepared catalyst has paramagnetic behavior. The magnetiza-
tion was 0.48 emu gꢀ1 at 14 000 Oe. It is worth mentioning that
the nal catalyst magnetization is enough and therefore it can
be separated from the reaction mixture using an external
magnet.
2.2. Measurement of catalytic activity of MNP@crosslinked
p[AVIM]Br through the one-pot synthesis of spiro[indoline-
3,20-thiazolidinones]
In order to screen the catalytic activity of the prepared Co3-
O4@crosslinked p[AVIM]Br, a one-pot multicomponent reac-
tion between isatin, aniline, and thioglycolic acid was rst
Fig. 6 TGA analysis of Co3O4 NPs, prepared Co3O4@p[AVIM]Br under
hydrothermal and classical precipitation methods.
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Table 2 Screening of different condition for the synthesis of desired product 4aa
Entry
Solvent
Catalyst
Condition
Time (min)
Yield%b
1
2
3
4
5
6
7
8
H2O
H2O
H2O
H2O
H2O
H2O
H2O
EtOH
EtOH/H2O
CH3CN
CH2Cl2
THF
Toluene
MeOH
DMF
—
US
US
US
US
US
US
D
20
8
6
15
5
5
90
10
10
10
15
30
30
10
20
20
18
48
94
88
80
93
92
90
92
89
85
80
60
91
62
55
Co3O4 NPs (10 mol%)
(10 mol%)
Classical-Co3O4@p[AVIM]Br
(5 mol%)
(15 mol%)
(10 mol%)
(10 mol%)
(10 mol%)
(10 mol%)
(10 mol%)
US
US
US
US
US
US
US
US
US
9
10
11
12
13
14
15
16
(10 mol%)
(10 mol%)
(10 mol%)
(10 mol%)
Dioxane
(10 mol%)
a
Reaction conditions: isatin (1 mmol), aniline (1 mmol) and thioglycolic acid (1 mmol) in the presence of hydrothermal treated MNP@crosslinked
p[AVIM]Br. b Isolated yield.
chosen as a model reaction. The reaction was optimized under cause a reaction to take place rapidly. Next, the effect of solvents
various conditions and the experimental results are summa- was variably investigated in the synthesis of (4a) as a model
rized in Table 2. Initially, the model reaction was carried out in compound. Ethanol, acetonitrile, methanol, and THF afforded
H2O as the greenest solvent in the presence of different catal- medium yields and more times (Table 2, entries 8, 10, 12, and
ysis. Based on the data, the reaction, which was done without 14). When the reaction was done in dioxane, toluene and DMF,
any catalyst, resulted in trace yield (Table 2, entry 1). According the product yields were respectively about 55, 60, and 62%.
to the empirical results, although the Co3O4@crosslinked p Based on the results, H2O is an optimum solvent for the prep-
[AVIM]Br obtained through classical precipitation polymeriza- aration of 4a. As a result, the use of 10 mol% of the
tion was efficient (Table 2, entry 4), the hydrothermal Co3- hydrothermal-treated Co3O4@crosslinked p[AVIM]Br catalyst in
O4@crosslinked p[AVIM]Br was the best one (Table 2, entry 3). H2O as solvent under US condition can be considered as the
The signicant effect of hydrothermal precipitation polymeri- optimal condition (40 kHz, 100 W).
zation on the textural and structural properties (surface area,
Subsequently, to demonstrate the scope and applicability of
porosity, particle size, thermal stability) led to greater efficiency this catalyst in the one-pot three-component synthesis of spiro-
of Co3O4@crosslinked p[AVIM]Br. To adjust the amount of 2,3-disubstituted-4-thiazolidinone derivatives, the reaction was
catalyst, different experiments were conducted. Accordingly, by extended to other substituted isatins, and various primary
increasing the amount of sonocatalyst from 5 to 10 mol%, the amines (Tables 3 and 4). All the prepared compounds have been
1
yield was increased from 80 to 94% while more nanocatalyst characterized by IR, HNMR, 13CNMR, and elemental analysis.
amount (15 mol%) did not improve the reaction yield (Table 2, The above results clearly showed that the present catalytic
entry 6). In order to determine the effect of ultrasonic agitation, procedure is extendable to a great diversity of substrates to
the reaction was carried out in H2O as solvent by mechanical make
a variety-oriented library of spiro-4-thiazolidinone.
stirring under silent condition (Table 2, entry 7). The obtained Changing the electronic structure of the substituents (C5 of
result showed that the reaction yield is lower than sonication isatins) was also acceptable with high yields. An aryl amine
within a longer time. As could be guessed, there is a meaningful including electron-donating substituents (methoxy, methyl,
synergistic effect among catalyst (active catalytic sites) and US and hydroxy) reacted well with thioglycolic acid and isatin
waves. Actually, collapsing the cavitation bubbles provided derivatives generated the desired spiro products in excellent
localized ‘‘hot spots” with high pressures that were responsible yields whereas the amines have less reactive electron with-
for the required bonding energy and molecular fragmentation. drawing substituents, such as (chloro, and uoro) that were
From the physical aspect, US irradiation facilitated the disper- found to be sluggish good yields. While the reactions of various
sion of the nanocatalyst in the media and therefore higher isatins and thioglycolic acid with benzylamine were afforded
active surface area was generated. All of these phenomena can the products in higher yields.
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Table 3 Scope of catalytic activity of hydrothermal treated Co3O4@crosslinked p[AVIM]Br for synthesis of spiro-4-thiazolidinonesa
Entry
X
Amine
Product
Time (min)
Yield%b
1
2
3
4
5
6
7
8
H
H
H
H
H
H
H
Cl
Cl
Cl
Cl
Br
Br
Me
Me
Me
Aniline
4a
4b
4c
4d
4e
4f
4g
4h
4i
4j
4k
4l
4m
4n
4o
4p
6
8
6
7
10
6
7
4
4
7
4
6
6
10
9
94
92
96 NEW
96
92
98
96
97
95
96
98 NEW
95
95
92
4-Chloroaniline
4-Methoxyaniline
Benzylamine
4-Fluoroaniline
2-Chloro-5-(triuoromethyl)aniline
4-Aminophenol
Aniline
4-Methylaniline
Benzylamine
4-Methoxyaniline
Aniline
9
10
11
12
13
14
15
16
Benzylamine
Aniline
4-Methylaniline
4-Fluoroaniline
93
90
12
a
Reactions conditions: isatin (1 mmol), amine (1 mmol) and thioglycolic acid (1 mmol), in the presence of hydrothermal treated
Co3O4@crosslinked p[AVIM]Br (0.01 g). b Isolated yield.
Table 4 Scope of catalytic activity of hydrothermal treated Co3-
derivatives. As shown in Table 5, the highest yield and short-
est reaction times belong to prepared porous PIL under mild
O4@crosslinked p[AVIM]Br for synthesis of spiro-4-thiazolidinonesa
and green conditions.
The proposed reaction pathway mechanism for the prepa-
ration of spiro[indoline-3,20-thiazolidinones] in the presence of
prepared PIL is shown in Scheme 1. Herein, we introduce a new
porous PIL including two different catalytic natures. Applied
PIL including different acidic and basic active sites, can activate
reaction via different routes by noncovalent interactions
between two ionic groups of opposite charge (approaching
isatin and aniline to initiate reaction). On the other hand,
hydrogen bonding (a branch of noncovalent interactions)
Entry
X
Amine
Product
Time (min)
Yield%b
makes carbonyl group of isatin more susceptible to aniline
nucleophilic addition. According to literatures,50,51 at the initial
step of the catalytic pathway, the sonocatalyst facilitated the
condensation of primary amine and isatin for the generation of
the protonated Schiff base A through dual acid-basic sites.
Then, imine (A) reacts with thioglycolic acid to generate the
carbon–sulfur bond. The gem-diol compound generates
through an intramolecular cyclization, and the desired product
(4a) was obtained aer the release of a water molecule.
Furthermore, ultrasound irradiations have a signicant role in
multicomponent reactions. In general, asymmetric collapse
form micro liquid jet with high speed enhanced the heat and
mass transfer among the pores in the presence of ultrasound
waves. This liquid jets activated the heterogeneous magnetic
catalyst and improved the mass transfer by the disruption of the
interfacial boundary layers.
1
2
3
4
5
6
7
8
9
H
(I)
(I)
(I)
(II)
(II)
(II)
(IV)
(IV)
(IV)
(III)
4q
4r
4s
4t
4u
4v
4w
4x
4y
4z
5
5
8
92
96
93
95
7
91
95
98
92
96
Br
Me
H
Cl
Me
H
Cl
Me
H
6
98
10
6
5
8
10
7
a
Reactions conditions: isatin (1 mmol), amine (1 mmol) and
thioglycolic acid (1 mmol), in the presence of hydrothermal treated
Co3O4@crosslinked p[AVIM]Br (0.01 g). b Isolated yield.
In addition, a comparative study was performed between
synthesized Co3O4@p[AVIM]Br and previously reported catalyst
for the synthesis of spiro-2,3-disubstituted-4-thiazolidinone
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Table 5 Comparative study between reported catalyst and Co3O4@crosslinked p[AVIM]Br
Product
Catalystref.
Condition
Yield%
Time
Acetic acid48
Co3O4@p[AVIM]Br
Benzene/reux
US/water
75%
92%
10 h
8 min
DBSA10
Co3O4@p[AVIM]Br
Room temperature/water
US/water
81%
97%
30 h
4 min
CTAB49
Co3O4@p[AVIM]Br
US/water
US/water
90
92
45 min
5 min
Recoverability is known as one of the most important prop- reused directly with fresh substrates. It was shown that the
erties of the fabricated catalyst. At the end of the reaction, the hydrothermal treated Co3O4@crosslinked p[AVIM]Br could be
nanocatalyst was magnetically separated and then the catalyst recovered from the eight runs without any noticeable loss of its
was washed three times with ethanol and H2O, dried 24 h, and activity (Fig. 8). Next, to explore the probable change of
Scheme 1 The catalytic cycle for the synthesis of spiro-4-thiazolidinones (4a).
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using Barrett–Joyner–Halenda (BJH) method. FE-SEM images
were prepared with MIRA3TESCAN-XMU. Elemental analyses
(EDS) were obtained on a PerkinElmer analyzer. Vibrating
Sample Magnetometer (VSM) was made by MDK-I. R. Iran. NMR
spectra were recorded on a Bruker 300 MHz spectrometer with
TMS as an internal standard and DMSO-d6 as solvent.
3.2. Synthesis of vinyl functionalized Co3O4 NPs
Co3O4 NPs were prepared based on our previously reported
procedure.52 Cobalt(II) nitrate hexahydrate (8.60 g) was
dispersed in ethanol (100 mL) at room temperature for 30 min.
Then, oxalic acid (2.14 g)ꢁwas swily added and the mixture was
stirred for 90 min at 40 C. The obtained pink precipitate was
calcined at 400 ꢁC for 2 h. A mixture of Co3O4 MNP (1 g) in
50 mL ethanol was prepared and the ammonia solution (2 mL)
was then added to it. Next, 3-(trimethoxysilyl)propyl methacry-
late (MPS) (10 mmol) was slowly added and the solution was
stirred under reux condition for 24 h. Finally, the MPS coated
Co3O4 NPs (MNP@MPS) were separated by an external magnet
and washed with ethanol (3 ꢃ 30 mL) to remove the unreacted
Fig. 8 Recyclability of sonocatalyst.
sonocatalyst morphology, the FESEM images of the recovered
Co3O4@crosslinked p[AVIM]Br aer eight reaction runs were
recorded for two different polymerization methods (Fig. 9). As
shown, recycling did not signicant change the morphology of
hydrothermal treated sample (Fig. 9A), so the propose catalyst
has high chemical stability.
ꢁ
compounds and then was dried overnight at 45 C.
3.3. Synthesis of the ionic monomer
1-Aminopropyl-3-vinylimidazolium bromide ([AVIM]Br) was
prepared under ultrasound condition for the rst time. Briey,
1-vinyl imidazole (3 mmol) and 10 mL ethanol were added to
a two-necked ask equipped and then 3-bromopropylamine
hydrobromide (3 mmol) was added into the ask and sonicated
under nitrogen atmosphere. Finally, [AVIM]Br$HBr (5 mmol)
was dissolved in the water (10 mL) and then equimolar sodium
hydroxide was added and sonicated for 10 min at room
temperature to form the isolated [AVIM]Br. The chemical
structure of the product was determined using the FTIR, 1H
NMR, and 13C NMR analysis ([AVIM]Br yield ¼ 90%). White
solid, yield: 90%; IR (CHCl3) nmax: 3440, 2930, 2845, 1648, 1228,
3. Experimental
3.1. Chemicals and apparatus
1-Vinylimidazole (Alfa Aesar, 99%), 3-bromopropylamine
hydrobromide (99%), ethyl acetate (ACS reagent, $99.5%), and
4,40-azobis(4-cyanopentanoic acid) ($98%) were obtained from
Aldrich Chemical. All other chemical compounds were chosen
from Merck Chemical. Fourier transform infrared spectra were
recorded on an ABB Bomem MB-100 FTIR spectrometer. The
XRD pattern was recorded on a Brucker AXS D8 diffractometer
(Cu-Ka radiation). Thermo Gravimetric Analysis (TGA) was
performed using a TGA Q 50 analyzer under the nitrogen
atmosphere. The pore size distribution curves and nitrogen
sorption isotherms were checked on a BELSORP-MINI analyzer
while the samples were degassed at 473 K for 3 h. The specic
surface area of samples was determined by Brunauer–Emmett–
Teller (BET) calculation. Pore size distributions were estimated
1
1168, 1020, 932, 824, 660 cmꢀ1, H NMR (300 MHz, DMSO-d6)
d (ppm): 7.95 (s, 1H), 7.54 (s, 1H), 7.01 (s, 1H), 5.50–5.77 (d, 2H),
5.18 (s, 1H), 4.84–4.80 (t, 1H), 3.60–3.5 (t, 2H), 2.90–2.84 (t, 2H),
2.10–2.05 (m, 2H). 13C NMR (100 MHz, DMSO-d6) d (ppm):
139.7, 124.5, 114.0, 107.5, 35.0, 33.3, 29.3.
3.4. Fabrication of porous poly ionic liquid through the
precipitation polymerizations
Co3O4@MPS (0.5 g), 1-aminoethyl-3-vinylimidazolium bromide
(0.45 g, 0.005 mol) and N,N0-methylenebis acrylamide (0.46 g,
0.003 mol) as crosslinker were dissolved into 10 mL dry meth-
anol. The preparation procedure was followed by the addition of
ACPA (1% mol, 0.029 g) which was reuxed for 3 h. Next, the
obtained gray powder was washed with water (2 ꢃ 20) and dried
ꢁ
at 40 C for about 18 h.
3.5. Fabrication of porous poly ionic liquid through the
hydrothermal precipitation polymerization
Fig. 9 FE-SEM images of the recovered sonocatalyst after eight
reaction run under the optimum reaction condition; (A) hydrothermal,
and (B) classical precipitation polymerization.
As a typical procedure, Co3O4@MPS (0.5 g), 1-aminoethyl-3-
vinylimidazolium bromide (0.45 g, 0.005 mol), N,N0-
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methylenebis acrylamide (0.46 g, 0.003 mol), and ACPA 6.74–7.35 (m, 8H, Ar–H), 10.92 (s, 1H, NH). 13C NMR (100 MHz,
(1% mol, 0.029 g) were mixed in 10 mL deionized water. Aer DMSO-d6) d/ppm: 176.83, 163.86, 156.92, 145.94, 133.90, 126.96,
vigorous stirring at ambient temperature for 2 h, the mixture 123.93, 122.26, 120.37, 116.47, 115.20, 113.94, 87.96, 55.76,
ꢁ
was transferred into steel autoclave at 100 C for 24 h. Finally, 32.96. Anal. calcd for C17H14N2O3S, % C, 62.56; H, 4.32; N, 8.58.
the dark monolithic solid was collected and kept in a vacuum Found, %: C, 62.57; H, 4.35; N, 8.60.
ꢁ
drying oven at 40 C for 12 h. The specic fabrication rout of
30-Benzyl-spiro[indoline-3,20-thiazolidine]-2,40-dione
(4d).
1
ꢁ
porous PIL is shown in Scheme 2.
Mp 180–182 C (MeOH). H NMR (300 MHz, DMSO-d6) d/ppm:
2.41–2.48 (2H, CH2), 3.71 (2H, CH2), 6.71–7.63 (m, 9H, Ar–H),
10.25 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d/ppm: 177.6,
170.6, 144.3, 140.4, 134.6, 127.6, 125.4, 119.9, 115.1, 111.9, 75.3,
55.7, 22.2. Anal. calcd for C17H14N2O2S, % C, 65.79; H, 4.55; N,
9.03. Found, %: C, 65.78; H, 4.51; N, 9.01.
3.6. General preparation of spiro-4-thiazolidinones
A mixture of isatin (1 mmol), thioglycolic acid (1 mmol), various
primary amines (1 mmol), and synthesized Co3O4@crosslinked
p[AVIM]Br as catalyst were dissolved in water and sonicated in
30-(4-Fluorophenyl)-spiro[3H-indole-3,20-thiazolidine]-2,40-
ꢁ
an ultrasonic bath at 25 C for appropriate times. The comple-
1
(1H) dione (4e). Mp 245–244 ꢁC (MeOH). H NMR (300 MHz,
tion of the reaction was monitored by TLC and the catalyst was
then magnetically separated. Finally, the crude precipitate was
ltered and then recrystallized from EtOH to obtain a pure solid
product. The products were characterized by 1H NMR, 13C NMR,
IR, and elemental analysis (spectral data of compounds
mentioned in ESI†).
DMSO-d6) d/ppm: 3.78 (d, 1H, CH), 4.39 (d, 1H, CH), 6.69–7.56
(m, 8H, Ar–H), 9.97 (s, 1H, NH). 178.4, 167.9, 155.4, 151.2, 148.4,
140.5, 133.3, 132.4, 130.6, 126.8, 123.2, 122.6, 118.1, 116.5, 72.7,
36.5. Anal. calcd for C16H11FN2O2S, %: C, 61.14; H, 3.53; N, 8.91.
Found, %: C, 61.11; H, 3.51; N, 8.90.
30-(5-Triuoromethyl-2-chlorophenyl)-spiro-[3H-indole-3,20-
1
ꢁ
thiazolidine]-2,40-(1H)-dione (4f). Mp 145 C (MeOH). H NMR
3.7. Spectral data of the all compounds
(300 MHz, DMSO-d6) d/ppm: 3.87 (d, 2H, CH2), 6.78–7.31 (m,
7H, Ar–H), 9.19 (s, 1H, NH). 13C NMR (75.47 MHz, DMSO-d6) d/
ppm: 179.9, 174.4, 146.0, 135.1, 134.1, 130.5, 129.2, 125.7, 125.0,
122.5, 120.4, 117.9, 113.5, 112.7, 100.0, 70.2, 21.0. Anal. calcd for
17H10ClF3N2O2S; % C, 51.20; H, 2.53; N, 7.02. Found C, 51.17;
H, 2.52; N, 7.04.
30-(4-Hydroxyphenyl)-spiro[3H-indole-3,20-thiazolidine]-2,40-
(1H)-dione (4g). Mp > 230 ꢁC (MeOH). 1H NMR (300 MHz,
DMSO-d6) d/ppm: 3.56 (2H, CH2), 6.51–7.63 (m, 8H, Ar–H), 9.04
(s, 1H, OH), 10.21 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d/
ppm: 180.1, 168.2, 162.2, 159.5, 143.2, 138.3, 136.3, 127.5, 124.9,
122.7, 112.8, 109.8, 108.9, 78.4, 33.0. Anal. calcd for
30-Phenyl-spiro[3H-indole-3,20-thiazolidine]-2,40-(1H)-dione
(4a). Mp 233 ꢁC (MeOH). 1H NMR (300 MHz, DMSO-d6) d/ppm:
3.46 (d, 2H, CH2), 6.34–7.60 (m, 9H, Ar–H), 11.16 (s, 1H, NH).
13C NMR (100 MHz, DMSO-d6) d/ppm: 172.1, 167.1, 142.4, 136.0,
134.0, 126.1, 125.2, 123.5, 119.7, 116.8, 108.7, 70.9, 31.2. Anal.
calcd for C16H12N2O2S, % C, 64.85; H, 4.08; N, 9.45. Found, %:
C, 64.84; H, 4.05; N, 9.43.
C
30-(4-Chlorophenyl)-spiro[3H-indole-3,20-thiazolidine]-2,40-
(1H)-dione (4b). Mp 170–173 ꢁC (MeOH). H NMR (300 MHz,
1
DMSO-d6) d/ppm: 2.48 (2H, CH2), 6.75–7.22 (m, 8H, Ar–H), 10.38
(s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d/ppm: 173.8, 170.9,
145.9, 133.9, 124.6, 123.9, 122.2, 120.0, 115.2, 113.5, 111.1, 71.8,
31.2. Anal. calcd for C16H11ClN2O2S, % C, 58.09; H, 3.35; N, 8.47.
Found, %: C, 58.08; H, 3.33; N, 8.50.
C
16H12N2O3S, % C, 61.53; H, 3.87; N, 8.97. Found, %: C, 61.55;
H, 3.85; N, 9.00.
5-Chloro-30-phenylspiro[indoline-3,20-thiazolidine]-2,40-
dione (4h). Mp 306 ꢁC (MeOH). 1H NMR (300 MHz, DMSO-d6) d/
ppm: 4.03 (d, 2H, CH2), 6.76–7.69 (m, 8H, Ar–H), 10.90 (s, 1H,
NH). 13C NMR (100 MHz, DMSO-d6) d/ppm: 176.2, 171.9, 140.4,
136.2, 131.3, 129.6, 128.7, 128.2, 127.2, 127.0, 126.6, 112.4, 69.6,
32.5. Anal. calcd for C16H11ClN2O2S, % C, 58.09; H, 3.35; N, 8.47.
Found, %: C, 58.05; H, 3.35; N, 8.42.
30-(4-Methoxyphenyl)-spiro[3H-indole-3,20-thiazolidine] 2,40-
(1H)-dione (4c). Mp 168–170 ꢁC. IR (CHCl3) nmax: 3280, 2833,
1738, 1612, 1500, 1462, 1333, 752 cmꢀ1 1H NMR (300 MHz,
,
DMSO-d6) d/ppm: 2.48 (s, 3H, CH3), 3.75–3.81 (q, 2H, CH2),
30-(4-Methyl)-5-chlorospiro[3H-indole-3,20-thiazolidine]-2,40-
(1H)-dione (4i). Mp 185–186 ꢁC (MeOH). 1H NMR (300 MHz,
DMSO-d6) d/ppm: 2.35 (s, 3H, CH3), 3.30 (d, 2H, CH2), 6.38–7.40
(m, 7H, Ar–H), 11.07 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6)
d/ppm: 179.5, 161.7, 159.0, 152.9, 149.5, 143.3, 137.7, 127.6,
125.0, 123.5, 111.1, 109.7, 76.3, 50.8, 32.1. Anal. calcd for C17-
H13ClN2O2S, % C, 59.21; H, 3.80; N, 8.12. Found, %: C, 59.25; H,
3.82; N, 8.12.
30-Benzyl-5-chlorospiro[indoline-3,20-thiazolidine]-2,40-dione
1
ꢁ
(4j). Mp 186–188 C (MeOH). H NMR (300 MHz, DMSO-d6) d/
ppm: 3.31 (d, 2H, benzyl CH2), 4.00 (d, 2H, CH2), 6.71–8.00 (m,
8H, Ar–H), 10.54 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d/
ppm: 175.8, 172.1, 142.0, 135.5, 131.3, 128.08, 128.0, 127.4,
126.3, 123.6, 122.3, 110.6, 68.5, 46.1, 32.1. Anal. calcd for
Scheme 2 Schematic representation of the fabrication of Co3O4@-
crosslinked p[AVIM]Br under two different polymerization approach.
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C17H13ClN2O2S, % C, 59.21; H, 3.80; N, 8.12. Found, %: C, 59.20;
H, 3.78; N, 8.11.
C
21H18N4O3S; % C, 62.05; H, 4.46; N, 13.78. Found % C, 62.09;
H, 4.45; N, 13.79.
30-(4-Methoxyphenyl)-5-chloro-30-phenylspiro[3H-indole-3,20-
5-Bromo-30-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyr-
thiazolidine]-2,40-(1H)-dione (4k). Mp 186–188 ꢁC (MeOH). IR azol-4-yl)-spiro[3H-indole-3,20-thiazolidine]-2,40-(1H) dione (4r).
(CHCl3) nmax: 3448, 3224, 2931, 2835, 1736, 1608, 1597, 1504, Mp 333 ꢁC (MeOH). 1H NMR (300 MHz, DMSO-d6) d/ppm: 2.50
1462, 1292, 1254, 1034, 837 cmꢀ1, 1H NMR (300 MHz, DMSO-d6) (s, 3H, CH3), 3.04 (s, 3H, N–CH3), 3.99 (d, 2H, CH2), 6.76–7.79
d/ppm: 2.48 (s, 3H, CH3), 3.79 (q, 2H, CH2), 6.83–7.41 (m, 7H, (m, 8H, Ar–H), 10.93 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6)
Ar–H), 11.08 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d/ppm: d/ppm: 178.2, 173.7, 169.9, 163.8, 162.3, 159.4, 157.1, 154.7,
173.8, 163.8, 157.9, 145.9, 133.9, 124.6, 123.9, 122.2, 120.0, 148.5, 146.8, 131.1, 129.8, 128.3, 126.6, 124.3, 123.2, 70.1, 37.4,
115.2, 113.9, 87.9, 55.8, 32.5. Anal. calcd for C17H13ClN2O3S, % 17.0, 16.7. Anal. calcd for C21H17BrN4O3S; % C, 51.97; H,
C, 56.59; H, 3.63; N, 7.76. Found, %: C, 56.57; H, 3.62; N, 7.74. 3.53; N, 11.54. Found % C, 51.89; H, 3.56; N, 11.59.
5-Bromo-30-phenylspiro[indoline-3,20-thiazolidine]-2,40-
5-Methyl-30-(2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-
dione (4l). Mp 306 ꢁC (MeOH). 1H NMR (300 MHz, DMSO-d6) d/ pyrazol-4-yl)-spiro[3H-indole-3,20-thiazolidine]-2,40-(1H) dione
1
ꢁ
ppm: 3.8 (s, 2H, CH2), 6.92–8.16 (m, 8H, Ar–H), 11.17 (s, 1H, (4s). Mp 328–330 C (MeOH). H NMR (300 MHz, DMSO-d6) d/
NH). 13C NMR (100 MHz, DMSO-d6) d/ppm: 179.6, 174.4, 154.9, ppm: 2.67 (s, 3H, CH3), 2.73 (s, 3H, N–CH3), 4.44 (d, 2H, CH2),
140.4, 135.0, 134.6, 129.6, 125.2, 119.4, 114.1, 111.2, 110.9, 72.1, 6.74–7.97 (m, 8H, Ar–H), 10.65 (s, 1H, NH). 13C NMR (100 MHz,
38.5. Anal. calcd for C16H11BrN2O2S, % C, 51.21; H, 2.95; N, DMSO-d6) d/ppm: 177.7, 173.6, 165.4, 161.7, 157.8, 152.0, 149.3,
7.47. Found, %: C, 51.25; H, 2.93; N, 7.42.
132.2, 131.9, 129.8, 129.7, 129.2, 124.8, 116.0, 115.6, 97.9, 69.5,
49.0, 31.1, 18.1, 14.2. Anal. calcd for C22H20N4O3S; % C, 62.84;
30-Benzyl-5-bromospiro[indoline-3,20-thiazolidine]-2,40-
dione (4m). Mp 190–192 ꢁC (MeOH). 1H NMR (300 MHz, DMSO- H, 4.79; N, 13.32. Found % C, 62.85; H, 4.76; N, 13.39.
d6) d/ppm: 3.31 (d, 2H, benzyl CH2), 4.00 (d, 2H, CH2), 6.71–8.00
30-(1H-Benzimidazol-2-yl)-spiro-[3H-indole-3,20-thiazoli-
(m, 8H, Ar–H), 10.54 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) dine]-2,40-(1H)-dione (4t). Mp 250 ꢁC (MeOH). 1H NMR (300
d/ppm: 178.5, 175.3, 152.3, 148.0, 146.3, 136.2, 135.9, 130.9, MHz, DMSO-d6) d/ppm: 4.81 (d, 2H, CH2), 6.72–8.35 (m, 8H, Ar–
125.3, 124.2, 115.0, 108.8, 80.6, 38.9, 31.1. Anal. calcd for C17
-
H), 10.75 (s, 1H, NH), 10.89 (s, 1H, NH). 13C NMR (100 MHz,
H13ClN2O2S, % C, 59.21; H, 3.80; N, 8.12. Found, %: C, 59.20; H, DMSO-d6) d/ppm: 177.6, 167.6, 157.8, 146.6, 141.5, 137.6, 131.0,
3.78; N, 8.11.
129.5, 129.3, 128.4, 126.0, 120.9, 104.9, 72.9, 32.9. Anal. calcd for
C17H12N4O2S; % C, 60.70; H, 3.60; N, 16.66. Found C, 60.71; H,
5-Methyl-30-phenylspiro[indoline-3,20-thiazolidine]-2,40-
dione (4n). Mp > 300 ꢁC (MeOH). 1H NMR (300 MHz, DMSO-d6) 3.55; N, 16.69.
d/ppm: 2.08 (s, 3H, CH3), 3.25 (d, 2H, CH2), 6.47–8.06 (m, 8H,
5-Chloro-30-(1H-benzimidazol-2-yl)-spiro-[3H-indole-3,20-
Ar–H), 10.94 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d/ppm: thiazolidine]-2,40-(1H)-dione (4u). Mp 265 ꢁC (MeOH). 1H NMR
180.0, 170.8, 157.0, 154.0, 146.8, 143.6, 125.8, 121.1, 118.3, (300 MHz, DMSO-d6) d/ppm: 3.38 (d, 1H, CH), 4.39 (d, 1H, CH),
117.8, 114.9, 108.7, 102.9, 71.8, 29.2. Anal. calcd for 6.72–7.78 (m, 7H, Ar–H), 10.12 (s, 1H, NH), 12.89 (s, 1H, NH).
C
17H14N2O2S, % C, 65.79; H, 4.55; N, 9.03. Found, %: C, 65.75; 13C NMR (100 MHz, DMSO-d6) d/ppm: 171.4, 167.6, 150.9, 145.0,
H, 4.54; N, 9.02.
139.2, 132.0, 130.2, 128.0, 127.2, 126.0, 123.8, 122.4, 118.0,
30-(4-Methyl)-5-methylspiro[3H-indole-3,20-thiazolidine]-2,40- 108.0, 65.3, 29.8. Anal. calcd for C17H11ClN4O2S; % C, 55.06; H,
1
(1H)-dione (4o). Mp 187–189 ꢁC (MeOH). H NMR (300 MHz, 2.99; N, 15.11. Found C, 55.01; H, 2.97; N, 15.09.
DMSO-d6) d/ppm: 1.68 (s, 3H, CH3), 2.48 (s, 3H, CH3), 3.76 (d,
5-Methyl-30-(1H-benzimidazol-2-yl)-spiro-[3H-indole-3,20-
2H, CH2), 6.56–7.41 (m, 7H, Ar–H), 11.08 (s, 1H, NH). 13C NMR thiazolidine]-2,40-(1H)-dione (4v). Mp 240 C (MeOH). H NMR
1
ꢁ
(100 MHz, DMSO-d6) d/ppm: 177.4, 165.9, 152.4, 150.4, 148.4, (300 MHz, DMSO-d6) d/ppm: 2.40 (s, 3H, CH3), 4.81 (d, 2H, CH2),
141.7, 134.1, 133.0, 130.0, 124.8, 124.2, 121.6, 117.3, 116.6, 71.7, 6.44–8.35 (m, 7H, ArH), 10.74 (s, 1H, NH), 10.98 (s, 1H, NH). 13
C
36.5, 31.0. Anal. calcd for C18H16N2O2S, % C, 66.64; H, 4.97; N, NMR (100 MHz, DMSO-d6) d/ppm: 174.2, 166.2, 164.4, 164.1,
8.64. Found, %: C, 66.65; H, 4.82; N, 8.62.
155.7, 155.4, 152.3, 150.5, 132.7, 128.4, 127.7, 124.7, 117.4,
116.5, 115.3, 105.4, 77.5, 35.7, 30.9. Anal. calcd for C18H14N4O2S,
30-(4-Fluorophenyl)-5-methylspiro[3H-indole-3,20-thiazoli-
dine]-2,40-(1H)-dione (4p). Mp 190–192 ꢁC (MeOH). 1H NMR % C, 61.70; H, 4.03; N, 15.99. Found, %: C, 61.65; H, 4.01; N,
(300 MHz, DMSO-d6) d/ppm: 1.68 (s, 3H, CH3), 2.68 (d, 2H, CH2), 15.92.
6.71–7.28 (m, 7H, ArH), 11.66 (s, 1H, NH). 13C NMR (100 MHz,
30-(1,3-Benzothiazol-2-yl)-spiro-[3H-indole-3,20-thiazolidine]
DMSO-d6) d/ppm: 20.9, 24.6, 32.6, 73.1, 116.08–140.34, 150.8, 2,40-(1H)-dione (4w). Mp 168 ꢁC (MeOH). 1H NMR (300 MHz,
167.2, 170.5, 118.02, 63.05. Anal. calcd for C17H13FN2O2S, % C, DMSO-d6) d/ppm: 4.41 (d, 1H, CH), 4.86 (d, 1H, CH), 6.97–7.65
62.18; H, 3.99; N, 8.53. Found, %: C, 62.15; H, 3.88; N, 8.52.
(m, 8H, Ar–H), 10.95 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6)
30-(2,3-Dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)- d/ppm: 175.6, 170.6, 156.8, 143.6, 141.5, 136.6, 130.0, 129.5,
spiro[3H-indole-3,20-thiazolidine]-2,40-(1H) dione (4q). Mp 127.3, 126.4, 126.0, 121.9, 108.9, 74.9, 32.1. Anal. calcd for
1
ꢁ
320 C (MeOH). H NMR (300 MHz, DMSO-d6) d/ppm: 2.50 (s,
C17H11N3O2S2; C, 57.77; H, 3.14; N, 11.89. Found C, 57.70; H,
3H, CH3), 3.41 (s, 3H, N–CH3), 4.05 (d, 2H, CH2), 6.70–8.12 (m, 3.13; N, 11.85.
9H, Ar–H), 10.63 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d/ 5-Chloro-30-(1,3-benzothiazol-2-yl)-spiro-[3H-indole-3,20-
1
ꢁ
ppm: 175.8, 173.8, 165.6, 155.8, 148.4, 144.3, 143.8, 133.2, 131.7, thiazolidine]-2,40-(1H)-dione (4x). Mp 171 C (MeOH). H NMR
121.9, 121.0, 115, 9, 108.8, 72.4, 29.6, 22.0, 15.5. Anal. calcd for (300 MHz, DMSO-d6) d/ppm: 4.47 (d, 1H, CH), 4.84 (d, 1H, CH),
6.89–7.75 (m, 7H, Ar–H), 10.59 (s, 1H, NH). 13C NMR (100 MHz,
44168 | RSC Adv., 2020, 10, 44159–44170
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DMSO-d6) d/ppm: 175.5, 169.3, 159.2, 144.6, 142.2, 137.7, 136.9,
132.8, 129.0, 128.1, 127.0, 123.7, 122.6, 122.3, 107.7, 65.0, 25.7.
Anal. calcd for C17H10ClN3O2S2; % C, 52.64; H, 2.60; N, 10.83.
Found % C, 52.70; H, 2.62; N, 10.86.
4 S. Mishra, M. Kaur, S. Chander, S. Murugesan, L. Nim,
D. S. Arora and P. Singh, Eur. J. Med. Chem., 2018, 155,
658–669.
5 P. S. S. Gupta, H. Rasool Bhat, S. Biswal and M. Kumar Rana,
J. Mol. Liq., 2020, 114375.
6 Z. Bakherad, M. Safavi, A. Fassihi, H. Sadeghi-Aliabadi,
M. Bakherad, H. Rastegar, J. B. Ghasemi, S. Sepehri,
L. Saghaie and M. Mahdavi, Res. Chem. Intermed., 2019, 45,
2827–2854.
7 S. Holota, A. Kryshchishyn, H. Derkach, Y. Trun,
I. Demchuk, A. Gzella, P. Grellier and R. Lesyk, Bioorg.
Chem., 2019, 86, 126–136.
5-Methyl-30-(1,3-benzothiazol-2-yl)-spiro-[3H-indole-3,20-
1
ꢁ
thiazolidine]-2,40-(1H)-dione (4y). Mp 163 C (MeOH). H NMR
(300 MHz, DMSO-d6) d/ppm: 2.24 (s, 3H, CH3), 3.87 (d, 1H, CH),
4.51 (d, 1H, CH), 7.06–7.66 (m, 7H, Ar–H), 8.30 (s, 1H, NH). 13
C
NMR (100 MHz, DMSO-d6) d/ppm: 178.4, 169.9, 160.6, 141.9,
140.7, 134.7, 132.2, 131.4, 130.6, 129.5, 129.0, 127.7, 128.4,
123.7, 122.2, 66.0, 20.9. Anal. calcd for C18H13N3O2S2; % C,
58.84; H, 3.57; N, 11.44. Found % C, 58.76; H, 3.55; N, 11.42.
30-(6-Chloro-1,3-benzothiazol-2-yl)-spiro-[3H-indole-3,20-
8 A. Deep, B. Narasimhan, S. M. Lim, K. Ramasamy,
R. K. Mishra and V. Mani, RSC Adv., 2016, 6, 109485–109494.
9 M. Mushtaque, F. Avecilla, Z. B. Hafeez and M. M. A. Rizvi, J.
Heterocycl. Chem., 2019, 56, 1794–1805.
1
ꢁ
thiazolidine]-2,40-(1H)-dione (4z). Mp 170 C (MeOH). H NMR
(300 MHz, DMSO-d6) d/ppm: 3.43 (d, 2H, CH2), 6.93–8.21 (m,
7H, Ar–H), 10.87 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6) d/
ppm: 175.8, 171.7, 157.2, 154.2, 147.8, 143.1, 127.8, 125.1, 120.7, 10 A. Preetam and M. Nath, Tetrahedron Lett., 2016, 57, 1502–
118.2, 117.8, 112.1, 102.7, 70.0, 21.2. Anal. calcd for C17H10 1506.
ClN3O2S2; % C, 52.64; H, 2.60; N, 10.83. Found % C, 52.70; H, 11 R. Singh, A. Singh and D. Bhardwaj, ChemistrySelect, 2019, 4,
-
2.62; N, 10.86.
9600–9607.
12 D. P. Anekal and J. S. Biradar, Arabian J. Chem., 2017, 10,
S2098–S2105.
13 M. P. Thakare, P. Kumar, N. Kumar and S. K. Pandey,
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4. Conclusions
In this study, a nanoporous poly (ionic liquid) is proposed to
facilitate the synthesis of the pharmaceutical spiro-4-
thiazolidinone library. In practice, two different methods were
applied to study the effect of polymerization protocol on
morphology and efficiency of prepared sonocatalyst. According
to the obtained results, hydrothermal precipitation polymeri-
zation provided a higher degree of cross linking and as a result
achieved more thermal stability, and porous structure (smaller
pore size distribution) which are known as the key characteristic
parameters in the catalysis eld. On the other hand, the
synergistic effect between US irradiation and magnetically
separable catalyst play a vital role in the straightforward
synthesis of spiro-4-thiazolidinones.
14 Y. Jiang, Y. Zhang, L. Ding, J. A. De, L. Cruz, B. Wang,
X. Feng, Z. Chen, Z. Mao and X. Sui, Carbohydr. Polym.,
2019, 223, 115079.
15 H. Gao, Chin. Chem. Lett., 2019, 30, 1996–2002.
16 Z. Dastjerdi, E. D. Cranston, R. Berry, C. Fraschini and
M. A. Dube, Macromol. React. Eng., 2019, 13, 1800050.
17 W. V. Smith and R. H. Ewart, J. Chem. Phys., 1948, 16, 592–
599.
18 J. Chen, C. Zhao, H. Huang, M. Wang and X. Ge, Polymer,
2016, 83, 214–222.
´
19 C. G. Gutierrez, G. Caceres Montenegro, R. J. Minari,
J. R. Vega and L. M. Gugliotta, Macromol. React. Eng., 2019,
13, 1900007.
20 H. Yang, H. Kang, B. Wang and R. Liu, Colloids Surf., A, 2020,
587, 124315.
21 R. Zeng, Y. Chen, L. Zhang and J. Tan, Polym. Chem., 2020,
11, 4591–4603.
Conflicts of interest
There are no conicts to declare.
22 J. Tan, Y. Bai, X. Zhang, C. Huang and D. Liu, Macromol.
Rapid Commun., 2016, 37, 1434–1440.
23 A. Eekhari and T. Saito, Eur. Polym. J., 2017, 90, 245–272.
24 J. Yuan, D. Mecerreyes and M. Antonietti, Prog. Polym. Sci.,
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25 Z. Wang, Y. Si, C. Zhao, D. Yu, W. Wang and G. Sun, ACS
Appl. Mater. Interfaces, 2019, 11, 27200–27209.
26 P. Pillai and A. Mandal, J. Mol. Liq., 2020, 302, 112553.
27 B. Lin, W. Yuan, F. Xu, Q. Chen, H. Zhu, X. Li, N. Yuan,
F. Chu and J. Ding, Appl. Surf. Sci., 2018, 455, 295–301.
28 G. Yang, Q. Huang, H. Huang, J. Chen, Y. Lei, F. Deng,
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Acknowledgements
The authors acknowledge a reviewer who provided helpful
insights. The authors are grateful to the Islamic Azad University,
Qom Branch, Qom, I. R. Iran for supporting this work.
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