Synthesis and characterization of derivatives including thiazolidine-2,4-dione/1-H- imidazole and evaluation of antimicrobial, antioxidant, and cytotoxic properties of new synthetic heterocyclic compounds

Article abstract of DOI:10.1007/s11164-021-04525-4

Several new derivatives of thiazolidine-2,4-dione and 1-H-imidazole were prepared using imidazole aldehydes 6a–6f in ethanol as a solvent. Products 7a–7f were obtained in reasonable yields and great purity. The antioxidant activity for finish products was

Full text of DOI:10.1007/s11164-021-04525-4

Research on Chemical Intermediates
https://doi.org/10.1007/s11164-021-04525-4
Synthesis and characterization of derivatives
including thiazolidine‑2,4‑dione/1‑H‑ imidazole
and evaluation of antimicrobial, antioxidant, and cytotoxic
properties of new synthetic heterocyclic compounds
Hadiseh Yazdani Nyaki1 · Nosrat O. Mahmoodi1
Received: 24 December 2020 / Accepted: 15 June 2021
© The Author(s), under exclusive licence to Springer Nature B.V. 2021
Abstract
Several new derivatives of thiazolidine-2,4-dione and 1-H-imidazole were pre-
pared using imidazole aldehydes 6a–6f in ethanol as a solvent. Products 7a–7f were
obtained in reasonable yields and great purity. The antioxidant activity for fnish
products was evaluated by DPPH radical scavenging activity and showed relatively
good activity against ascorbic acid. Compounds 7d, 7e, and 7f had the highest anti-
oxidant activity. Compound 7c showed the lowest amount of IC50 versus ascorbic
acid. The antimicrobial activity of these compounds against gram-positive bacteria
including Bacillus anthracis (B. anthracis) and Staphylococcus aureus (S. aureus)
and gram-negative bacteria including Escherichia coli (E. coli) and Pseudomonas
aeruginosa (P. aeruginosa) bacteria was evaluated by the inhibition zone diameter
assay method, and the compounds showed moderate to low antibacterial activity.
The toxicity properties of all synthesized compounds against cisplatin were inves-
tigated. Most of the compounds showed good activity against the positive control
group, and the toxicity of compound 7b was higher than that of other compounds.
*
Nosrat O. Mahmoodi
mahmoodi@guilan.ac.ir
1
Department of Organic Chemistry, Faculty of Science, University of Guilan, Rasht, Iran
Vol.:(0123456789)
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H. Y. Nyaki, N. O. Mahmoodi
Graphic abstract
Keywords 1-H-imidazole · Antimicrobial activities · Antioxidant activities · DPPH
radical · IC50 · Toxicity · Cisplatin
Introduction
In recent years, the entry of antibiotics into the pharmaceutical industry to fght
infectious diseases seemed to be sufcient and appropriate for treatment, but with
the indiscriminate and arbitrary use of antibiotics, bacteria resistance has increased
and has become a public health problem [1, 2]. The search for new antimicrobial
agents with strong antibacterial properties, reduced toxicity, and lower side efects
has prompted researchers to investigate [3–8].
Accordingly, heterocyclic compounds have received much attention. Heterocyclic
compounds play an essential role in medicinal chemistry and are central to synthetic
organic chemistry and have the highest practical and theoretical importance. These
compounds containing heteroatoms show signifcant changes in the cyclic molecular
structure due to the non-common electron pairs and the negative electron diference
between the heteroatoms and the carbon. Heterocyclic ring systems with special
shifts in the right positions have emerged as powerful scafolds for biological esti-
mation. In this context, heterocyclic systems containing sulfur and nitrogen exhibit a
variety of biological and pharmacological activities, in part due to their many simi-
larities between natural and synthetic molecules and known potentials.
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Synthesis and characterization of derivatives including…
In the environment, heterocyclic compounds are widely distributed, and many
heterocyclic compounds synthesized in laboratories have been used successfully as
clinical agents. Compounds containing aromatic polycyclic heterocycles are active
in various pharmaceutical felds. Among the most important and basic living com-
pounds containing heterocyclic groups that are based on aromatic heterocyclic sys-
tems, we can name DNA and RNA [9–14].
Thiazolidine-2,4-dione (TZD) is a fve-membered heterocyclic ring containing
sulfur and nitrogen, and its nucleus has two carbonyl moieties on the second and
fourth positions, and it is widely found in nature in various forms. TZD ring has
attracted a great deal of attention because of their diverse biological activities. The
main drugs with the TZD ring are found in the structure of diabetes drugs that are
prescribed to control blood sugar in patients. Clinical drugs include pioglitazone 1,
rosiglitazone 2, troglitazone 3, and rivoglitazone 4 [15]. Some well-known clinical
TZD drugs are mentioned in Fig. 1. Synthesized compounds containing a TZD ring
have been used for the treatment of such antimalarial, antimicrobial, anti-viral, anti-
oxidant, anti-convulsant, anti-HIV, anti-tubercular, anticancer, and anti-infamma-
tory agent [16–20].
Also, another fve-membered heterocyclic ring that has high therapeutic prop-
erties today and has been considered by chemists is imidazole (IMD). IMD has
increased the range of recovery of various drugs in clinical trials [21]. Some clinical
drugs with the IMD ring are shown in Fig. 1. Among the medicinal properties of
compounds containing IMD, we can mention antimicrobial, antibacterial, antifun-
gal, anticancer, and antioxidant [22–26].
The two rings of IMD and TZD and their derivatives, due to their excel-
lent ability against bacteria and also their remarkable antioxidant properties, have
been widely considered for the construction of new heterocycles [27–30]. One of
the well-known clinical drugs used to treat diabetes, which includes both rings, is
Fig. 1 Clinical drugs containing TZD and IMD ring
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H. Y. Nyaki, N. O. Mahmoodi
rivoglitazone 4, shown in Fig. 1. Accordingly, in this study, we created new syn-
thetic compounds by combining two rings of IMD and TZD and investigated the
antibacterial activity of these compounds against gram-positive bacteria including
Bacillus anthracis (B. anthracis) and Staphylococcus aureus (S. aureus) and gram-
negative bacteria including Escherichia coli (E. coli) & Pseudomonas aeruginosa
(P. aeruginosa) bacteria by inhibition zone diameter assay method, and antioxidant
activity was evaluated by DPPH radical scavenging properties of the newly synthe-
sized compounds.
Results and discussion
Chemistry
In this project, synthesize new compounds containing TZD and imidazole (IMD),
which is based on the use of IMD-aldehydes 6a–6f and TZD, and fnally, the tar-
get products (4,5-triphenyl-1H-imidazol-2-yl)benzylidene)thiazolidine-2,4-dione)
7a–s7f are completed. The synthesis steps of the fnishing compounds 7a–7f are
shown in Scheme 1, and the fnal structure compounds are depicted in Table 1. Our
results show that high-yield products are obtained and easily purifed using non-
chromatographic methods. The advantages of this method are simple adjustment
and product separation and reproducibility, use of cheap and minimal solvents.
Initially, hydroxyl-IMD 5a–5f was synthesized through a four-multi-compo-
nent reaction among benzyl 3, vanillin 1, aniline derivatives 4a–4f and NH4OAc
2 in the presence of glacial AcOH as catalyst and solvent under microwave irradia-
tion during a short reaction time (4–6 min) [31, 32]. As shown in Scheme 2, AcOH
increases the electrophilic strength of the carbonyl group of vanillin 1. Imine 8 is
then formed during a condensation reaction from an ammoniacal nucleophilic attack
derived from NH4OAc 2 to carbonyl and the removal of a H2O molecule. Subse-
quently, a nuclear attack of aniline 4a results in the formation of an intermediate of
9. Intermediate 9 during a compression reaction with benzil 3 forms an intermedi-
ate 11 via an intermediate 10 by removing a molecule of H2O in an acidic medium.
The stable aromatic product 5a is then produced.
Then, to synthesize IMD-aldehyde 6a–6f, the premade hydroxyl-IMD 5a–5f was
participated in the Duf reaction refuxed by using HMTA (hexamethylenetetramine)
and TFA (trifuoroacetic acid)), after which the medium is acidifed and the temper-
ature reaches 100 °C for additional 12-h refux. The IMD-aldehyde 6a–6f product
was obtained with very good yields [33]. The proposed mechanism for the synthe-
sis of compounds 6a–6f shown in Scheme 3 is that, frst, hexamethylenetetramine
(HMTA) 12 is protonated in the presence of trifuoroacetic acid (TFA), because
angular pressure causes rearrangement and production of iminium ion 14 through
ion 13. Intermediate 14 is then attacked by an ortho-carbon of the phenolic com-
pound 5 through a nucleophilic substitution reaction, producing a ketone interme-
diate 15. Intermediate 15 is rearranged in the presence of TFA ion (CF3COO−) to
form a more stable phenolic compound 16. Further protonation of the intermediate
16 and rearrangement leads to the formation of iminium ion 18 via fragmentation of
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Synthesis and characterization of derivatives including…
Scheme 1 The general method for the syntheses of compounds (IMD-TZD) 7a–7f
17, which produces an intermediate 19 during a hydride transfer. Finally, iminium
ion 19 is hydrolyzed in the presence of an aqueous solution of HCl to formulate the
product 6. Also, the rest of the structure related to HMTA is sequentially hydrolyzed
to ammonia and formaldehyde during these steps (Scheme 3).
To synthesize (4,5-diphenyl-1H-imidazol-2-yl)benzylidene)thiazolidine-2,4-di-
one) 7a–7f, the TZD ring according to the literature was premade. Mix the thiourea
and chloroacetic acid in water and HCl and refux for 12 h, and the reaction product
with high purity after recrystallization was achieved [34]. IMD-aldehyde 6a–6f and
TZD were dissolved in EtOH; then piperidine is added as a catalyst, and the mixture
was refuxed for 36 h and then acidifed and refned with Conc. AcOH and then
recrystallized to obtain highly purifed products. All steps are depicted in Scheme 1,
and the proposed mechanism for the synthesis of 7a–7f from 6a–6f via piperidine
took place through intermediates 20–25 as shown in Scheme 4. The structure,
molecular formula, MW, and MP of the fnal products 7a–7f are shown in Table 1.
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H. Y. Nyaki, N. O. Mahmoodi
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Synthesis and characterization of derivatives including…
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H. Y. Nyaki, N. O. Mahmoodi
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Synthesis and characterization of derivatives including…
Scheme 2 The proposed mechanism for the synthesis of compounds 5a–5f
Scheme 3 The proposed mechanism for the synthesis of compounds 6a–6f via HMTA and TFA
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H. Y. Nyaki, N. O. Mahmoodi
Scheme 4 The proposed mechanism for the synthesis of compounds 7a–7f
The structures of IMD-aldehydes 6a–6f and (4,5-diphenyl-1H-imidazol-2-yl)ben-
1
zylidene)thiazolidine-2,4-dione) (IMD-TZD) 7a–7f were determined by FT-IR, H
NMR, and 13C NMR spectra. In the FT-IR spectrum, of IMD-aldehyde derivatives,
6a–6f a carbonyl stretching band in the range of 1600–1700, was observed, while, in
the fnal product 7a–7f, two carbonyl stretching bands at the range of 1600–1750, the
N–H stretching vibration bands at 3393–3417 and the C=CH band at 1500–1600
were perceived, which confrmed the presence of the thiazolidine-2,4-dione moiety
in the structure of the desired products.
1
In H NMR spectra of 6a–6f in CDCl3, the presence of a single peak in the
range 9.70–9.82 ppm confrms the presence of aldehyde O=C–H. Also, the pres-
ence of a single peak region of about 11.10–11.32 ppm is related to the O–H sig-
nal. The OCH3 signal appears individually in the range of 3.60–3.85 ppm. Other
aromatic protons appeared in the expected range at 7.00–7.68 ppm. The products
(IMD-TZD) 7a–7f are dissolved in DMSO, as the olefn signal C=CH is expected
to appear in the range 7.90–8.10 ppm according to the literature [16] and the N–H
single in the range 10.2–10.81 ppm. The O–H signal appears to be in the range of
12.50–12.77 ppm individually and confrms that the TZD moiety has replaced the
aldehyde. In 13C NMR spectra, of 6a–6f in CDCl3 as a solvent, the H–C=O signal
appeared at 196.07–196.63 ppm. The OCH3 signal is in the range of 55.92–56.22
and other aromatic carbons appeared at 114.14–158.79 ppm. The product (IMD-
TZD) 7a–7f in DMSO provided the expected number and types of carbons. The
C=O peak in the TZD moiety appears in diferent signals due to its binding to other
atoms. The NH-C=O–C of the TZD ring appeared at 167.15–167.31 ppm, and the
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Synthesis and characterization of derivatives including…
NH–C=O–S appeared at 167.48–167.96 ppm. The signal at 55.87–56.14 is attrib-
uted to OCH3, and other aromatic carbons appeared at 114.14–158.79 ppm. Ele-
mental analysis was used to fnd the percentage of elements used in the synthesized
compounds.
Biological activities
Antimicrobial activity section
The antimicrobial activity of the newly synthesized compounds 7a–7f against the
target bacteria was evaluated qualitatively and quantitatively in the presence or
absence of inhibition zone diameter. Four bacterial strains examined by the cup plate
method were used for this method, from gram-positive bacteria including Bacillus
anthracis (B. anthracis) and Staphylococcus aureus (S. aureus) and gram-negative
bacteria including Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aer-
uginosa). Samples were prepared at a Conc. (5.0 mg/ml) in DMSO, and chloram-
phenicol was used as a standard antibiotic. Also, pioglitazone along with new com-
pounds was studied as a pharmacological compound with TZD ring antimicrobial
activity ring. The display results are shown in Table 2.
According to the results observed in Table 2 and Fig. 2, which shows the com-
parison of the antimicrobial activity of synthesized compounds 7a–7f in comparison
with chloramphenicol and pioglitazone, it can seem that all the investigated deriva-
tives displayed moderate to good activity. As shown in Fig. 2, newly synthesized
compound 7c is showed an inhibitory efect like that of chloramphenicol in bacteria
(B. anthracis) and can use as a standard.
In contrast to bacteria (S. aureus), only compounds 7c, 7d, and 7f exhibit activ-
ity that is moderately active, with activity 7d being good. The only compound that
is active against bacteria (E. coli) is compound 7d. All products are active against
Table 2 Antimicrobial activity
Compound
Antimicrobial activity (inhibition zone diameter
(mm))
of the newly synthesized
compounds (IMD-TZD) 7a–7f
Gram-positive
Gram-negative
B. anthracis S. aureus E. coli P. aeruginosa
7a
7b
7c
7d
7e
7f
15
14
22
18
14
19
–
–
9
15
–
10
24
–
–
–
–
12
–
–
24
–
9
9
9
16
9
8
26
10
Chloramphenicol 23
Pioglitazone
–
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H. Y. Nyaki, N. O. Mahmoodi
Fig. 2 Antimicrobial activity inhibition zone (mm) of synthesized compounds (IMD-TZD) 7a–7f
bacteria (P. aeruginosa), even pioglitazone, which was less active than other bacte-
ria, and compound 7d has better performance.
Antioxidant activity section
Since the main mechanism of antioxidant action in compounds is radical-scaveng-
ing, many methods have been developed in which the antioxidant activity is evalu-
ated by the scavenging of synthetic radicals in polar organic solvents such as MeOH
at r. t. In this study, the DPPH method was selected to evaluate the antioxidant activ-
ity of new compounds because it is one of the most efective methods for evaluating
the Conc. of radical-scavenging materials active by a chain-breaking mechanism.
Also, the DPPH radical is a stable free radical, and the DPPH radical-scavenging
activity was determined by the change in color from purple to colorless and decrease
in absorbance at 517 nm, due to reduction by the antioxidant (AH) or reaction with a
radical species to form a stable DPPH-H molecule, as follows (1) [35, 36]:
DPPH∙ + H∙ → DPPH − H
(1)
By comparing structural information and antioxidant activity, it was observed
that DPPH radical scavenging antioxidant activity depends on two parameters: the
functional groups on the aromatic ring and the position of functional groups on
the ring. Antioxidants donate hydrogen atoms to become stable free radicals. The
degree of stability and antioxidant potential is in direct relationship with the range
of delocalization. The antioxidant activities of compounds (IMD-TZD) 7a–7f were
screened at Conc. of 2000, 1000, 500, 250, 125 µg/mL at 517 nm for DPPH assay,
respectively Fig. 3.
Also, IC50 values (the Conc. of compounds to scavenge 50% of DPPH) were
calculated by plotting radical scavenging activity against Conc. and obtaining a line
equation in Fig. 4 Ascorbic acid was used as a standard in Table 3 [35].
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Synthesis and characterization of derivatives including…
Fig. 3 DPPH radical scavenging activity in diferent Conc. for the synthesis compounds 7a–7f
Fig. 4 IC50 values of synthesis
compounds (IMD-TZD) 7a–7f
by DPPH
Table 3 IC50 values for DPPH
Compound
DPPH assay
radical scavenging activity of
IC50(μM)
synthesis compounds 7a–7f
7a
7b
7c
998
1564
940
7d
7e
7f
1578
1768
1087
971
Ascorbic acid
As is depicted in Fig. 3, all of the investigated compounds demonstrated consider-
able free radical scavenging activities. Compounds 7b, 7d, 7e, and 7f showed higher
antioxidant activity at lower Conc. (500–125 μg/mL) in comparison with others and
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H. Y. Nyaki, N. O. Mahmoodi
were dose-dependent other compounds showed moderate activity. Also, IC50 values
of products (IMD-TZD) 7a–7f were calculated in as shown Fig. 4. The IC50 values
were in the range of 940–1768 µM for the DPPH assay in Table 3. Product 7c was
much more active than ascorbic acid, and products 7b, 7d and 7e were much weak
than standard in the DPPH assay.
Products 7a and 7f showed moderate activity than ascorbic acid. The IC50 value
of product 7c may be due to the presence of a p-OEt functional group in the struc-
ture of this compound.
Cytotoxic activity section
One way to treat cancer is to use strong chemical drugs or chemotherapy. Today,
several chemical drugs have been used and researched to treat cancer. Finding new
drugs that can fght cancer cells encouraged us to study the anticancer properties of
compounds 7a–7f. Accordingly, we investigated the cytotoxic efects of 7a–7f on
human breast cancer cell line proliferation (MCF-7) in the present work. Cells were
treated with diferent concentrations of the 7a–7f and cisplatin as a positive control
group in diferent amounts ranging from 0 to 200 μg/mL for 24 h. Cells were incu-
bated with 7a–7f, and cell viability was measured 18 h later by MTT assay. Inhibi-
tion of cell proliferation in each treatment is reported as a percentage of the number
of cells treated concerning the untreated control cells (Fig. 5).
Figure 6 shows the IC50 values of 7a–7f and cisplatin against the (MCF-7) cells.
The IC50 of cisplatin, as the positive control group, under all identical conditions,
was approximately 4.61 µg/mL, respectively. MTT assay results showed that 7b
had higher cytotoxicity than other compounds. However, all IC50 values showed
approximately reasonable activity for the compounds. Among the synthesis com-
pounds in this test, 7b, 7d and 7e showed the best anti-growth activity with IC50 of
113.3, 92.4 and 85.6 µg/mL, respectively.
Fig. 5 The anti-growth activity
of compounds 7a–7f against
(MCF-7) cells using MTT assay
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Synthesis and characterization of derivatives including…
Fig. 6 IC50 values of deriva-
tives 7a–7f and cisplatin against
the (MCF-7) cells
Examining the obtained results, it seems that the presence of chloride and nitrous
oxide groups in the structure of the compounds increases their toxicity and increases
their activity in inhibiting (MCF-7) cell growth. On this account, these compounds
show poorer performance against (MCF-7) cells compared to cisplatin as a positive
control group. The toxicity of other compounds in comparison with cisplatin drug
was found to be in order of: 7b>7e>7d>7f>7a>7c. Figure 7 shows a view of
(MCF-7) cells versus composition 7b and the efect of cisplatin as a positive control
group on the cells.
TZD ring has an important role in antioxidant activity [37, 38]. As it is depicted
in Scheme 5, the N–H of the TZD ring can readily donate hydrogen radical to DPPH
radical and form a radical of the test compound [39].
The new radical species makes it possible to create diferent and stable radi-
cal species through the TZD ring and the phenol ring and the IMD ring in the
structure of the compounds. In the phenol ring, the formation of the enol-ketone
group causes more radical stability, and it also seems that other parts of the
product structure also afect the radical activity. The most important efective
Fig. 7 Cellular death of (MCF-7) cells against for compound 7b and cisplatin as a positive control
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H. Y. Nyaki, N. O. Mahmoodi
Scheme 5 Proposed mechanism of radical scavenging activity
part can be attributed to the groups attached to the IMD ring that can increase
the antioxidant power. The high activity of compound 7e is probably due to the
NO2 group, which leads to radical instability, as shown in Scheme 5.
Experimental section
Material
The chemical reagents and solvents used in synthesis were purchased from
Merck, Fluka, and Aldrich. The purity of the synthesized compounds was
checked by thin-layer chromatography (TLC) using Merck silica gel 60F254 alu-
minum sheet.
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Synthesis and characterization of derivatives including…
Instrumentation
Melting points were determined on the 91100 s electric device, and are uncorrected.
The infrared (IR) spectra were recorded on a Shimadzu FT-IR-8400 spectrometer
in the region of 400–4000 cm−1in the KBr disk. A microwave oven (ETHOS 1600,
Milestone) with a power of 600 W specially designed for organic synthesis was used.
1H NMR and 13C NMR spectra were measured with Bruker 500, 400 MHz spec-
trometers in DMSO-d6 and CDCl3 as solvents. All chemical shifts were reported as
(ppm) values. The Mass spectra were recorded by (Agilent Technology-5973), mass
spectrometer operating at an ionization potential of 70 eV.
General procedure for the synthesis of (1,2,4,5‑tetraphenyl‑1H‑imidazole)derivatives
5a–5f
The hydroxyl-substituted imidazole derivatives 5a–5f were synthesized through
one-pot four-component reactions. A mix of aniline derivatives 4a–4f (1.1 mmol),
benzyl 3 (1 mmol, 0.210 g), vanillin 1 (1 mmol), and NH4OAc 2 (1 mmol) in glacial
AcOH (2.5 mL) was solved and heated in a stir when it was microwaved (230 W) for
4–6 min in a heat-resistant container.
The process of forming the fnal product 5a–5f can be examined by TLC. After
the reaction, (12 mL) of distilled water was added to the stirring solution and the pH
of the solution becomes quenched with NH4OH. Then, the precipitates were col-
lected by fltration and recrystallized, and fnally, the products 5a–5f were obtained
with good yields. The structures of the prepared compounds were confrmed by ana-
lyzing their spectral characteristics by FT-IR, 1HNMR, 13CNMR, and determination
of the substrates’ purity and reaction monitoring were accompanied by thin-layer
chromatography (TLC) [31, 40].
Spectra data for the synthesized products of 5a–5f
2‑methoxy‑4‑(1,4,5‑triphenyl‑1H‑imidazol‑2‑yl)phenol (5a) White solid; yield: 66%;
m.p.: 208.82 °C; FT-IR (KBr, υ/cm−1): 3449 (O–H stretch); 3054 (aromatic C–H
stretch); 1644, 1602 (C=N stretch); 1537, 1489 (C=C stretch); 1273 (C–O stretch);
1228 (C–N stretch); 764, 697 (aromatic C–H out of plane bend). 1H NMR (400 MHz,
DMSO-d6) δ: 9.29 (s, 1H), 7.50 (dd, J=8.2, 1.4 Hz, 2H), 7.38–7.34 (m, 3H), 7.33–
7.24 (m, 9H), 7.18 (tt, J=7.2, 1.7 Hz, 1H), 6.88 (dd, J=8.2, 2.1 Hz, 1H), 6.85 (d,
J=2.1 Hz, 1H), 6.69 (d, J=8.2 Hz, 1H), 3.52 (s, 3H). 13C NMR (100 MHz, DMSO-
d6)δ: 147.4, 147.3, 146.8, 137.5, 136.9, 135.1, 131.6, 131.1, 131.1, 129.6, 129.4,
129.0, 128.9, 128.8, 128.6, 126.9, 126.8, 121.9 (2C), 115.7, 112.8, 55.6. HRMS-ESI
(m/z) [M+] Calcd. for C28H22N2O2 418.1683, found 418.1676. Elemental analysis
Calcd. for C28H22N2O2 (%): C, 80.36; H, 5.30; N, 6.69; O, 7.65 Found: C, 80.45; H,
5.20; N, 6.67; O, 7.68.
4‑(1‑(4‑chlorophenyl)‑4,5‑diphenyl‑1H‑imidazol‑2‑yl)‑2‑methoxyphenol (5b) White
solid; yield: 72%; m.p.: 201.36 °C; FT-IR (KBr, υ/cm−1): 3449 (O–H stretch); 1637
(C=Nstretch);1535,1488(C=Cstretch);1430,1384;1274(C–Ostretch);1232(C–N
1 3

H. Y. Nyaki, N. O. Mahmoodi
stretch); 778, 698 (aromatic C–H out of plane bend). 1H NMR (400 MHz, DMSO-d6)
δ: 9.33 (s, 1H), 7.50 (dd, J=8.6, 1.4 Hz, 2H), 7.43 (d, J=8.6 Hz, 2H), 7.36–7.33 (m,
3H), 7.30 (d, J=8.6 Hz, 2H), 7.28–7.24 (m, 4H), 7.19 (tt, J=7.4, 1.7 Hz, 1H), 6.89
(d, J=2 Hz, 1H), 6.83 (dd, J=8.4, 2.2 Hz, 1H), 6.72 (d, J=8.4 Hz, 1H), 3.59 (s, 3H).
13C NMR (100 MHz, DMSO-d6)δ: 147.5, 147.5, 147.0, 137.0, 136.4, 134.9, 133.6,
131.6, 131.2, 131.0, 130.9, 129.6, 129.1, 129.0, 128.6, 126.9, 126.9, 122.1, 121.7,
115.7, 113.0, 55.7. HRMS-ESI (m/z) [M+] Calcd. for C28H21ClN2O2 452.1292, found
452.1288. Elemental analysis Calcd. for C28H21ClN2O2 (%): C, 74.25; H, 4.67; Cl,
7.83; N, 6.18; O, 7.06 Found: C, 74.21; H, 4.69; Cl, 7.80; N, 6.21; O, 7.09.
4‑(1‑(4‑ethoxyphenyl)‑4,5‑diphenyl‑1H‑imidazol‑2‑yl)‑2‑methoxyphenol (5c) Taupe
solid; yield: 73%; m.p.: 219.45 °C; FT-IR (KBr, υ/cm−1): 3417 (O–H stretch); 3055
(aromatic C-H stretch); 2980 (aliphatic C-H stretch); 1605 (C=N stretch); 1510, 1480
(C=C stretch); 1432; 1240 (C–O stretch); 832, 775, 696 (aromatic C–H out of plane
1
bend). H NMR (400 MHz, DMSO-d6) δ: 9.28 (s, 1H), 7.49 (dd, J=8.2, 1.4 Hz,
2H), 7.34–7.30 (m, 3H), 7.27–7.23 (m, 4H), 7.20–7.15 (m, 3H), 6.91–6.86 (m, 4H),
6.70 (d, J=8.4 Hz, 1H), 3.98 (q, J=7 Hz, 2H), 3.57 (s, 3H), 1.30 (t, J=7.1,2.3 Hz,
3H). 13C NMR (100 MHz, DMSO-d6) δ: 158.7, 147.4, 147.3, 147.0, 136.7, 135.2,
131.6, 131.4, 131.2, 130.5, 130.0, 128.9, 128.7, 128.6, 126.8, 126.7, 122.1, 121.8,
115.6, 115.0, 112.8, 63.8, 55.7, 15.0. HRMS-ESI (m/z) [M+] Calcd. for C30H26N2O3
462.1943, found 462.1936. Elemental analysis Calcd. for C30H26N2O3 (%): C, 77.90;
H, 5.67; N, 6.06; O, 10.38 Found: C, 78.00; H, 5.62; N, 6.07; O, 10.32.
4‑(4,5‑diphenyl‑1‑(p‑tolyl)‑1H‑imidazol‑2‑yl)‑2‑methoxyphenol (5d) White crys-
tal solid; yield: 77%; m.p.: 222.61 °C; FT-IR (KBr, υ/cm−1): 3457 (O–H stretch);
3033 (aromatic C–H stretch); 1603 (C=N stretch); 1516, 1481 (C=C stretch); 1434,
1383; 1264 (C–O stretch); 1230 (C–N stretch); 777, 700 (aromatic C-H out of plane
bend). 1H NMR (400 MHz, DMSO-d6) δ: 9.27 (s, 1H), 7.49 (dd, J=8.8, 1.4 Hz, 2H),
7.33–7.30 (m, 3H), 7.27–7.23 (m, 4H), 7.20–7.12 (m, 5H), 6.88 (dd, J=8, 2 Hz, 1H),
6.86 (d, J=2 Hz, 1H), 6.70 (d, J=8 Hz, 1H), 3.54 (s, 3H), 2.28 (s, 3H). 13C NMR
(100 MHz, DMSO-d6) δ: 147.3, 147.2 (d, J=8.0 Hz), 146.9, 138.5, 136.9, 135.1,
134.9, 131.6, 131.2 (2C), 130.1, 129.1, 128.9, 128.8, 128.6, 126.9, 126.8, 122.1 (d,
J=4.0 Hz), 121.9, 115.6 (d, J=9.0 Hz), 112.8, 55.6, 21.1. HRMS-ESI (m/z) [M]
Calcd. for C29H24N2O2 432.1838, found 432.1833. Elemental analysis Calcd. for
C29H24N2O2 (%): C, 80.53; H, 5.59; N, 6.48; O, 7.40 Found: C, 80.60; H, 5.62; N,
6.37; O, 7.41.
2‑methoxy‑4‑(1‑(3‑nitrophenyl)‑4,5‑diphenyl‑1H‑imidazol‑2‑yl)phenol (5e) Yellow
solid; yield: 70%; m.p.: 231.38 °C; FT-IR (KBr, υ/cm−1): 3427 (O–H), 3053 (aro-
matic C–H stretch), 1924 (aliphatic C–H stretch), 1602 (C=N stretch), 1530 (NO2
asymmetric stretch), 1486 (C=C stretch), 1445, 1350 (NO2 symmetric stretch), 1291
1
(C–O stretch), 1223 (C-N stretch), 779, 695 (aromatic C–H out-of-plane bend). H
NMR (400 MHz, CDCl3) δ: 9.45 (s, 1H), 7.68 (d, J=1.6 Hz, 1H), 7.62 (dd, J=8.4,
1.6 Hz, 2H), 7.41 (d, J=1.6 Hz, 1H), 7.32–7.22 (m, 7H), 7.20–7.16 (m, 4H), 7.02 (d,
J=8.4 Hz, 2H), 3.80 (s, 3H). 13C NMR (100 MHz, CDCl3) δ: 147.5, 147.5, 147.0,
1 3

Synthesis and characterization of derivatives including…
137.1, 136.8, 134.9, 132.6, 131.6, 131.5, 130.9, 130.8, 129.1, 129.0, 128.6, 126.9,
126.9, 122.1, 122.1, 121.7, 115.7, 113.0, 55.7. HRMS-ESI (m/z) [M+] Calcd. for
C28H21N3O4 463.1589, found 463.1582. Elemental analysis Calcd. for C28H21N3O4
(%): C, 72.56; H, 4.57; N, 9.07; O, 13.81 Found: C, 72.60; H, 4.63; N, 8.99; O, 13.78.
4‑(4,5‑diphenyl‑1H‑imidazol‑2‑yl)‑2‑methoxyphenol (5f) Color less crystal solid;
yield: 94%; m.p.: 261.21 °C; FT-IR (KBr, υ/cm−1): 3087 (aromatic C–H stretch);
1654, 1607 (C=N stretch); 1499 (C=C stretch); 1274 (C–O stretch); 1228 (C-N
stretch); 767, 697 (aromatic C–H out of plane bend). The structure of the product
was confrmed by FT-IR spectroscopy and comparison of the observed melting tem-
perature with the reported melting temperature ([41] 260 °C).HRMS-ESI (m/z) [M+]
Calcd. for C22H18N2O2 342.1435, found 342.1422. Elemental analysis Calcd. for
C22H18N2O2 (%): C, 77.17; H, 5.30; N, 8.18; O, 9.35 Found: C, 77.13; H, 5.33; N,
8.21; O, 9.33.
General procedure for the synthesis of aldehyde imidazole derivatives 6a–6f
Hexamethylenetetramine (HMTA) (4 mmol) was added to the solution dissolved
5a–5f (3.75 mmol) in trifuoroacetic acid (TFA) (7 mL), and the resulting solution
was refuxed for 12 h at 70 °C. Then 6 mL of HCl 3 M was added to it and refuxed
again for 30 min. The solution was cooled to r. t. and quenched with NH4OH. Then,
the precipitates were collected by fltration and washed with the AcOH solution, and
the imidazole aldehydes 6a–6f were obtained with good results.
Spectra data for the synthesized products of 6a–6f
2‑Hydroxy‑3‑methoxy‑5‑(1,4,5‑triphenyl‑1H‑imidazol‑2‑yl) benzaldehyde (6a) Tan
solid; yield: 76%; m.p: 176.31 °C; FT-IR (KBr, υ/cm−1): 3382 (O–H); 3051 (aro-
matic C–H stretching); 1670 (aldehyde C=O); 1599 (C=N stretch); 1477, 1430,
(C=C stretch); 1278, 1075 (C–O stretch); 1204 (C–N stretch); 769, 697 (aromatic
1
C–H out of plane bending). H NMR (500 MHz, CDCl3) δ (ppm): 11.18 (br, 1H),
9.74 (s, 1H), 7.60 (dd, J=8.6, 1.5 Hz, 2H), 7.37 (d, J=2.0 Hz, 1H), 7.36–7.32 (m,
3H), 7.31–7.22 (m, 6H), 7.15 (dd, J=8.0, 1.5 Hz, 2H), 7.13–7.11 (m, 3H), 3.65
(s, 3H). 13C NMR (125 MHz, CDCl3)δ: 196.56, 151.59, 147.82, 145.32, 138.16,
136.92, 133.84, 131.07, 131.01, 130.08, 129.44, 128.72, 128.50, 128.45, 128.26,
128.21, 127.51, 126.93, 125.22, 122.07, 120.26, 117.89, 55.99. HRMS-ESI (m/z)
[M+] Calcd. For C29H22N2O3 446.1681, found 446.1673. Elemental analysis Calcd.
For C29H22N2O3 (%): C, 78.01; H, 4.97; N, 6.27; O, 10.75 Found: C, 78.05; H, 4.91;
N, 6.23; O, 10.81.
5‑(1‑(4‑Chlorophenyl)‑4,5‑diphenyl‑1H‑imidazol‑2‑yl)‑2‑hydroxy‑3‑methoxyben‑
zaldehyde (6b) Dark yellow solid; yield: 75%; m.p.: 197.74 °C; FT-IR (KBr, υ/
cm−1): 3415 (O–H); 3063 (aromatic C-H stretching); 2844 (aliphatic C–H); 1656
(aldehyde C = O); 1600 (C = N stretch); 1492, 1469,1431 (C = C stretch); 1260,
1092 (C–O stretch); 1177 (C–N stretch); 962, 744, 719, 696 (aromatic C–H out
1 3

H. Y. Nyaki, N. O. Mahmoodi
1
of plane bending). H NMR (500 MHz, CDCl3) δ (ppm): 11.23 (br, 1H), 9.77 (s,
1H), 7.60 (d, J = 7.3 Hz, 2H), 7.32–7.23 (m, 9H), 7.16 (d, J = 6.8 Hz, 2H), 7.12 (s,
1H), 7.05 (d, J = 8.2 Hz, 2H), 3.71 (s, 3H). 13C NMR (125 MHz, CDCl3)δ: 196.42,
151.73, 147.98, 145.34, 138.54, 135.57, 134.62, 133.94, 131.05, 130.82, 130.03,
129.68, 129.61, 128.65, 128.40, 128.28, 127.33, 126.94, 125.05, 122.18, 120.28,
117.82, 56.05. HRMS-ESI (m/z) [M+] Calcd. For C29H21ClN2O3 480.1298, found
480.1291. Elemental analysis Calcd. For C29H21ClN2O3 (%): C, 72.42; H, 4.40; Cl,
7.37; N, 5.82; O, 9.98 Found: C, 72.46; H, 4.39; Cl, 7.35; N, 5.89; O, 9.91.
5‑(1‑(4‑Ethoxyphenyl)‑4,5‑diphenyl‑1H‑imidazol‑2‑yl)‑2‑hydroxy‑3‑methoxy‑
benzaldehyde (6c) Pale yellow solid; yield: 76%; m.p.: 114.68 °C; FT-IR (KBr,
υ/cm−1): 3411 (O–H); 3051 (aromatic C–H stretching); 2975, 2935 (aliphatic
C–H); 1661 (aldehyde C = O); 1606 (C = N stretch); 1511, 1476, 1441 (C = C
stretch); 1244, 1073 (C–O stretch); 1168 (C–N stretch); 723, 697 (aromatic C-H
1
out of plane bending). H NMR (500 MHz, CDCl3) δ (ppm): 9.75 (s, 1H), 7.59
(dd, J = 8.5, 1.5 Hz, 2H), 7.36 (d, J = 2.0 Hz, 1H), 7.30–7.23 (m, 6H), 7.21 (d,
J = 2.0 Hz, 1H), 7.16 (dd, J = 7.9, 1.7 Hz, 2H), 7.02 (d, J = 8.9 Hz, 2H), 6.82 (d,
J = 8.9 Hz, 2H), 4.00 (t, J = 7.0 Hz, 2H), 3.71 (s, 3H), 1.42 (t, J = 7.0 Hz, 3H).
13C NMR (125 MHz, CDCl3) δ: 196.63, 158.90, 151.55, 147.83, 145.46, 137.91,
133.90, 131.26, 131.08, 130.20, 129.49, 129.31, 128.43, 128.24, 128.14, 127.48,
126.87, 125.17, 122.20, 120.23, 117.98, 114.97, 63.78, 56.06, 14.64. HRMS-ESI
(m/z) [M+] Calcd. For C31H26N2O4 490.1958, found 490.1966. Elemental analysis
Calcd. For C31H26N2O4 (%): C, 75.90; H, 5.34; N, 5.71; O, 13.05 Found: C, 75.86;
H, 5.37; N, 5.77; O, 13.00.
5‑(4,5‑Diphenyl‑1‑(p‑tolyl)‑1H‑imidazol‑2‑yl)‑2‑hydroxy‑3‑methoxybenzaldehyde
(6d) Brown-green solid; yield: 70%; m.p.: 181.94 °C; FT-IR (KBr, υ/cm−1): 3415
(O–H); 3043 (aromatic C–H stretching); 2850 (aliphatic C–H); 1675 (aldehyde
C = O); 1602 (C = N stretch); 1511, 1476, 1434 (C = C stretch); 1280, 1078 (C–O
1
stretch); 1205 (C–N stretch); 751, 695 (aromatic C–H out of plane bending). H
NMR (500 MHz, CDCl3) δ (ppm): 11.21 (br, 1H), 9.76 (s, 1H), 7.61 (dd, J = 8.6,
1.4 Hz, 2H), 7.39 (d, J = 2.0 Hz, 1H), 7.31–7.29 (m, 3H), 7.27–7.21 (m, 3H),
7.17 (dd, J = 7.8, 1.6 Hz, 2H), 7.14–7.12 (m, 3H), 7.00 (d, J = 8.2 Hz, 2H), 3.66
(s, 3H), 2.36 (s, 3H). 13C NMR (125 MHz, CDCl3)δ: 196.63, 151.44, 147.73,
145.34, 138.70, 138.22, 134.44, 134.24, 131.08, 131.07, 130.40, 129.97, 128.40,
128.23 (2C), 128.07, 127.36, 126.75, 125.10, 122.59, 120.24, 117.88, 55.92,
21.12. HRMS-ESI (m/z) [M+] Calcd. For C30H24N2O3 460.1875, found 460.1901.
Elemental analysis Calcd. For C30H24N2O3 (%): C, 78.24; H, 5.25; N, 6.08; O,
10.42 Found: C, 78.30; H, 5.28; N, 6.12; O, 10.30.
2‑Hydroxy‑3‑methoxy‑5‑(1‑(3‑nitrophenyl)‑4,5‑diphenyl‑1H‑imidazol‑2‑yl)ben‑
zaldehyde (6e) Olive solid; yield: 69%; m.p.: 205.31 °C; FT-IR (KBr, υ/cm−1):
3421 (O–H); 3074 (aromatic C–H stretching); 1654 (aldehyde C = O); 1601
(C = N stretch); 1532, 1348 (NO2 symmetric stretching); 1466, 1446, 1393 (C= C
stretch); 1256, 1072 (C-O stretch); 1212 (C–N stretch); 962, 759, 700 (aromatic
1 3

Synthesis and characterization of derivatives including…
C–H out of plane bending). 1H NMR (500 MHz, CDCl3) δ (ppm): 11.18 (br, 1H),
9.73 (s, 1H), 8.20 (ddd, J = 8.1, 2.1, 1.1 Hz, 1H), 7.97 (t, J = 2.1 Hz, 1H), 7.61 (dd,
J = 8.5, 1.4 Hz, 2H), 7.52 (t, J = 8.1 Hz, 1H), 7.44 (ddd, J = 8.1, 2.1, 1.1 Hz, 1H),
7.34–7.28 (m, 5 H), 7.26 (tt, J = 7.2, 2.6 Hz, 1H), 7.21 (s, 2H), 7.17 (dd, J = 7.8,
1.5 Hz, 2H), 3.75 (s, 3H). 13C NMR (125 MHz, CDCl3) δ: 196.07, 152.07, 148.37,
148.30, 145.52, 138.82, 138.16, 134.32, 133.55, 131.10, 130.75, 130.24, 129.59,
128.90, 128.82, 128.34, 127.29, 127.16, 125.00, 123.44, 123.33, 121.69, 120.28,
117.94, 56.22. HRMS-ESI (m/z) [M+] Calcd. For C29H21N3O5 491.1562, found
491.1575. Elemental analysis Calcd. For C29H21N3O5 (%): C, 70.87; H, 4.31; N,
8.55; O, 16.28 Found: C, 70.92; H, 4.28; N, 8.60; O, 16.20.
5‑(4,5‑Diphenyl‑1H‑imidazol‑2‑yl)‑2‑hydroxy‑3‑methoxy benzaldehyde (6f) Dark
khaki solid; yield: 85%, m.p.: 167.82 °C; FT-IR (KBr, υ/cm−1): 3304 (N–H); 3054
(aromatic C–H stretching); 1648 (aldehyde C=O); 1468, 1445, 1397 (C=C stretch);
1261, 1092 (C–O stretch); 1205 (C–N stretch); 955, 760, 695 (aromatic C–H out of
plane bending). The product was too insoluble in any appropriate solvent for analysis
by NMR spectroscopy. HRMS-ESI (m/z) [M+] Calcd. For C23H18N2O3 370.1384,
found 370.1391. Elemental analysis Calcd. For C23H18N2O3 (%): C, 74.58; H, 4.90;
N, 7.56; O, 12.96 Found: C, 74.52; H, 4.93; N, 7.60; O, 12.95.
General procedure for the synthesis of thiazolidine‑2,4‑diones derivatives 7a–7f
To a mixture of TZD (0.6 mmol), 2-hydroxy-3-methoxy-5-(1,4,5-triphenyl-1H-im-
idazol-2-yl)benzaldehyde (6a, 0.6 mmol) in EtOH (5 mL) was added amount of
piperidine as catalytic; it was refuxed for 18–24 h. Then, the reaction mixture was
poured into cold H2O and AcOH was added dropwise until the solution became
acidic. After that, it was stirred for 30 min and the precipitates of the product were
fltered, washed with H2O and recrystallized with EtOH, to obtain pure (Z)-5-(2-
hydroxy-3-methoxy-5-(1,4,5-triphenyl-1H-imidazol-2-yl)benzylidene)thiazolidine-
2,4-dione derivative 7a as yellow solids. All the other compounds 7b–7f were
obtained in a similar reaction procedure of 7a in moderate to high yields (Scheme 1
and Table 1).
Spectra data for the synthesized products of 7a–7f
(Z)‑5‑(2‑hydroxy‑3‑methoxy‑5‑(1,4,5‑triphenyl‑1H‑imidazol‑2‑yl)benzylidene)thia‑
zolidine‑2,4‑dione (7a) Yellow solid; yield: 82%; m.p.: 232.59 °C; FT-IR (KBr) ν
cm−1: 3411 (N–H); 3059 (aromatic C–H stretching); 2933 (aliphatic C–H); 1740,
1703 (C=O); 1559 (C=N stretch); 1490, 1426 (C=C stretch); 1273, 1072 (C–O
1
stretch); 1159 (C–N stretch); 767, 695 (aromatic C-H out of plane bend). H NMR
(500 MHz, DMSO-d6) δ (ppm): 12.57 (s, 1H), 10.49 (s,1H), 7.93 (s, 1H,), 7.52–7.50
(d, J=7.8 Hz, 2H), 7.44–7.34 (ddd, J=8.3 Hz, 11H), 7.30–7.28 (d, J=8.3 Hz, 2H),
7.20 (s, 1H), 7.13 (s, 1H), 3.71 (s, 3H). 13C NMR (125 MHz, DMSO-d6) δ (ppm):
167.83, 167.21, 148.19, 147.58, 144.64, 134.97, 131.37, 131.17, 129.53, 129.40,
129.25, 128.63, 128.50, 128.11, 128.08, 127.15, 125.54, 123.64, 120.93, 120.23,
116.87, 114.40, and 56.02. 13C NMR-DEPT (135): CH (131.14, 130.54, 129.43,
1 3

H. Y. Nyaki, N. O. Mahmoodi
128.62, 128.31, 126.91, 126.48, 125.79) and CH3 (55.78). HRMS-ESI (mlz) [M+]
Calcd. For C32H23N3O4S 545.1412, found 545.1396. Exact mass [M+] (m/z)=346,
340(100), 252, 169, 128, 97. Elemental analysis Calcd. For C32H23N3O4S (%): C,
70.44; H, 4.25; N, 7.70; O, 11.73; S, 5.88 Found: C, 70.54; H, 4.20; N, 7.67; O,
11.70; S, 5.89.
(Z)‑5‑(5‑(1‑(4‑chlorophenyl)‑4,5‑diphenyl‑1H‑imidazol‑2‑yl)‑2‑hydroxy‑3‑meth‑
oxybenzylidene)thiazolidine‑2,4‑dione (7b) Pale yellow solid; yield: 78%; m.p.:
255.34 °C; FT-IR (KBr) ν cm−1: 3407 (N–H); 3058 (aromatic C–H stretching);
2955 (aliphatic C–H); 1743, 1706 (C=O); 1607 (C=N stretch); 1491, 1430 (C=C
stretch); 1269, 1076 (C–O stretch); 1156 (C–N stretch); 1011 (C–Cl); 834,776, 725,
1
699 (aromatic C–H out of plane bend). H NMR (500 MHz, DMSO-d6) δ (ppm):
12.53 (s, 1H), 10.24 (s, 1H,), 7.94 (s, 1H), 7.49–7.48 (d, J=8.4 Hz, 2H), 7.43–7.41
(d, J=8.4 Hz, 2H), 7.36–7.34 (m, 5H,), 7.28–7.21 (m, 5H), 7.13 (s, 1H), 6.99
(s, 1H), 3.73 (s, 3H). 13C NMR (125 MHz, DMSO-d6) δ (ppm): 167.75, 167.31,
152.81, 150.11, 148.90, 147.57, 133.65, 131.54, 131.19, 130.59, 129.67, 129.45,
128.76, 128.64, 128.30, 126.91, 126.53, 125.97, 123.03, 122.61, 119.96, and 55.87.
13C NMR-DEPT (135): CH (131.15, 129.55, 129.29, 128.65, 127.11, 125.39) and
CH3 (55.95). HRMS-ESI (mlz) [M+] Calcd. For C32H22ClN3O4S 579.1023, found
579.1041. Exact mass [M+] (m/z)=329, 317, 219, 195, 177, 168(100), 152, 130, 94.
Elemental analysis Calcd. For C32H22ClN3O4S (%): C, 66.26; H, 3.82; Cl, 6.11; N,
7.24; O, 11.03; S, 5.53 Found: C, 66.20; H, 3.86; Cl, 6.07; N, 7.29; O, 11.10; S, 5.48.
(Z)‑5‑(5‑(1‑(4‑ethoxyphenyl)‑4,5‑diphenyl‑1H‑imidazol‑2‑yl)‑2‑hydroxy‑3‑meth‑
oxybenzylidene)thiazolidine‑2,4‑dione (7c) Pale yellow solid; yield: 85%; m.p.:
161.88 °C; FT-IR (KBr) ν cm−1: 3407 (N–H); 3056 (aromatic C–H stretching); 2959,
2933 (aliphatic C–H); 1738, 1702 (C=O); 1605 (C=N stretch); 1511, 1480 (C=C
stretch); 1249, 1074 (C–O stretch); 1119 (C-N stretch); 838, 775, 697 (aromatic C-H
out of plane bend). 1H NMR (500 MHz, DMSO-d6) δ (ppm): 12.53 (s, 1H), 10.36 (s,
1H), 7.93 (s, 1H), 7.49–7.48 (d, J=7.4 Hz, 2H), 7.34–7.23 (m, 11H), 7.07 (s, 1H),
6.88–6.87 (d, J=8.7 Hz, 2H), 3.96–3.95 (d, J=8.7 Hz, 2H), 3.73 (s, 3H), 1.27–1.24
(t, J=8.7 Hz,3H). 13C NMR (125 MHz, DMSO-d6) δ (ppm): 167.86, 167.24, 158.79,
147.53, 144.84, 135.99, 131.55, 131.14, 129.89, 129.78, 128.98, 128.57, 128.47,
126.93, 125.77, 123.37, 120.37, 115.01, 114.30, 63.38, 55.95, and 14.37. 13C NMR-
DEPT (135): CH (131.13, 129.91, 129.79, 128.59, 128.49, 126.84, 125.67, 114.95,
114.77); CH2 (-62.13) and CH3 (55.90, 14.40). HRMS-ESI (mlz) [M+] Calcd. For
C34H27N3O5S 589.1743, found 589.1702. Exact mass [M+] (m/z)=346, 340(100),
279, 189,181, 171, 163, 158, 96. Elemental analysis Calcd. For C34H27N3O5S (%):
C, 69.26; H, 4.62; N, 7.13; O, 13.57; S, 5.44 Found: C, 69.30; H, 4.55; N, 7.16; O,
13.48; S, 5.51.
(Z)‑5‑(5‑(4,5‑diphenyl‑1‑(p‑tolyl)‑1H‑imidazol‑2‑yl)‑2‑hydroxy‑3‑methoxy‑
benzylidene)thiazolidine‑2,4‑dione (7d) Dark yellow solid; yield: 83%; m.p.:
252.69 °C; FT-IR (KBr) ν cm−1: 3398 (N–H); 3036 (aromatic C–H stretching);
2930 (aliphatic C–H); 1738, 1701 (C = O); 1600 (C = N stretch); 1511, 1478
1 3

Synthesis and characterization of derivatives including…
(C = C stretch); 1269, 1076 (C–O stretch); 1158 (C–N stretch); 774, 697 (aro-
1
matic C-H out of plane bend). H NMR (500 MHz, DMSO-d6) δ (ppm): 12.52
(s, 1H), 10.25 (s, 1H), 7.93 (s, 1H), 7.50–7.48 (d, J = 7.8 Hz, 2H), 7.33–7.30 (m,
5H), 7.26–7.23 (m, 5H), 7.20–7.16 (t, J = 8.1 Hz, 3H), 7.05 (s, 1H), 3.71 (s, 3H),
2.51 (s, 3H). 13C NMR (125 MHz, DMSO-d6) δ (ppm): 167.96, 167.26, 147.50,
144.95, 138.84, 131.31, 131.16, 130.00, 128.79, 128.53, 128.38, 128.35, 127.20,
126.93, 125.88, 123.26, 120.05, 114.14, 55.87, and 20.56. 13C NMR-DEPT (135):
CH (131.14, 130.01, 129.75, 128.78, 128.54, 128.36, 127.15, 126.67, 125.79) and
CH3 (55.79, 20.56). HRMS-ESI (mlz) [M+] Calcd. For C33H25N3O4S 559.1597,
found 559.1634. Exact mass [M+] (m/z) = 346, 340(100), 279, 189,181, 171, 165,
158,145, 116, 91. Elemental analysis Calcd. For C33H25N3O4S (%): C, 70.82; H,
4.50; N, 7.51; O, 11.44; S, 5.73 Found: C, 70.79; H, 4.53; N, 7.47; O, 11.46; S,
5.75.
(Z)‑5‑(2‑hydroxy‑3‑methoxy‑5‑(1‑(3‑nitrophenyl)‑4,5‑diphenyl‑1H‑imidazol‑2‑yl)
benzylidene)thiazolidine‑2,4‑dione (7e) Pale yellow solid; yield: 80%; m.p.:
240.77 °C; FT-IR (KBr) ν cm−1: 3417(N–H); 3059 (aromatic C–H stretching);
2959, 2933 (aliphatic C–H); 1738, 1702 (C = O); 1641, 1604 (C = N stretch);
1535, 1350 (NO2 symmetric stretch); 1488, 1425 (C = C stretch); 1270, 1075 (C-O
stretch); 1158 (C–N stretch); 860, 775, 697 (aromatic C-H out of plane bend). 1H
NMR (500 MHz, DMSO-d6) δ (ppm): 12.55 (s, 1H), 10.26 (s, 1H), 8.42–8.40
(d, J = 9.7 Hz, 1H), 8.24–8.22 (d, J = 9.3 Hz, 1H), 7.91 (s, 1H), 7.71–7.67 (t,
J = 8.7 Hz, 1H), 7.54–7.52 (d, J = 7.6 Hz, 2H), 7.41–7.33 (m, 10H), 7.01 (s, 1H),
3.74 (s, 3H). 13C NMR (125 MHz, DMSO-d6) δ (ppm): 167.48, 167.15, 156.39,
154.52, 154.25, 148.37, 147.78, 147.10, 147.10, 145.10, 136.97,135.40, 131.26,
131.21, 130.90, 129.48, 128.89, 128.86, 128.68, 127.05, 125.36, 123.92, 122.48,
121.44, 120.93, 120.19, 56.14. 13C NMR-DEPT (135): CH (135.41, 131.24,
131.19, 130.92, 129.57, 128.88, 128.74, 128.70, 127.05, 125.19, 124.52, 123.95,
120.92, 116.96, 114.56) and CH3 (56.10). HRMS-ESI (mlz) [M+] Calcd. For
C32H22N4O6S 590.1265, found 590.1331. Exact mass [M+] (m/z) = 346, 340(100),
279, 189,181, 171, 165, 158, 91. Elemental analysis Calcd. For C32H22N4O6S (%):
C, 65.08; H, 3.75; N, 9.49; O, 16.25; S, 5.43 Found: C, 65.11; H, 3.70; N, 9.53;
O, 16.17; S, 5.49.
(Z)‑5‑(5‑(4,5‑diphenyl‑1H‑imidazol‑2‑yl)‑2‑hydroxy‑3‑methoxybenzylidene)thia‑
zolidine‑2,4‑dione (7f) Shiny yellow solid; yield: 75%; m.p.: 200.13 °C; FT-IR
(KBr) ν cm−1: 3393 (N–H); 3059 (aromatic C–H stretching); 2959, 2930 (aliphatic
C–H); 1732, 1689 (C = O); 1650, 1603 (C = N stretch); 1483, 1446 (C = C stretch);
1261, 1075 (C–O stretch); 1164 (C–N stretch); 768, 697 (aromatic C–H out of
plane bend). 1H NMR (500 MHz, DMSO-d6) δ (ppm): 11.74 (s, 1H), 9.81 (s, 1H),
9.55 (s, 1H), 9.41 (s, 1H), 7.24–7.21 (d, J = 6.2 Hz, 1H), 6.95–6.91 (d, J = 8.2 Hz,
1H), 6.71–6.69 (d, J = 8.2 Hz, 4H), 6.60–6.57 (d, J = 7.5 Hz, 4H), 6.53–6.50 (d,
J = 7.6 Hz, 2H), 3.12–3.13 (s, 3H). 13C NMR (125 MHz, DMSO-d6) δ (ppm):
168.24, 167.39, 158.80, 148.07, 147.34, 144.65, 135.13, 128.59, 127.93, 126.61,
123.50, 120.53, 117.21, 125.54, 123.64, 120.93, 120.23, 113.88, 110.96, and 56.26.
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H. Y. Nyaki, N. O. Mahmoodi
13C NMR-DEPT (135): CH (128.60, 127.94, 127.70, 126.61) and CH3 (56.26).
HRMS-ESI (mlz) [M+] Calcd. For C26H19N3O4S 469.1095, found 469.1101. Exact
mass [M+] (m/z): 318, 268(100), 235, 218, 194, 178, 162, 151, 126, 93. Elemental
analysis Calcd. For C26H19N3O4S (%): C, 66.51; H, 4.08; N, 8.95; O, 13.63; S, 6.83
Found: C, 66.46; H, 4.12; N, 8.92; O, 13.71; S, 6.79.
Biolog
Antimicrobial activities by Inhibition zone diameter assay
Antibacterial activity of the synthesized compounds 7a–7b was determined, using a
slightly modifed cup plate method. Mueller Hinton agar was used for the growth of
bacterial strains such as gram-positive (B. anthracis & S. aureus) and gram-negative
(E. coli & P. aeruginosa). All of the test compounds were dissolved in DMSO at a
Conc. of 5 mg/ml. Each plate was inoculated with 20 μl of microbial suspension.
Thirty microliters of the test compounds was added to each cup. The plates contain-
ing bacteria were incubated at 37 °C for 24 h, the positive antimicrobial activity was
read based on the growth inhibition zone, and compared with Chloramphenicol was
used as a standard and pioglitazone as a drug, as shown in Table 2 and Fig. 2.
Antioxidant activity by DPPH assay
DPPH (2,2-diphenyl-1-picrylhydrazyl) is a stable free radical. MeOH solution of
DPPH is used to evaluate the antioxidant activity of several synthesized compounds.
Antioxidant on interaction with DPPH both transfers electron or hydrogen atom to
DPPH, thus neutralizing its free radical character. The degree of the scavenging
activity displays change in the color from purple to yellow. The change in absorb-
ance produced at 517 nm has been used as a measure of its antioxidant activity.
DPPH radical scavenging activity in percent (I %) was calculated as follows:
[
]
I % = (Ab − As) ∕Ab × 100
where Ab is the absorbance of blank reaction (DPPH+MeOH) and as the absorb-
ance of the test sample compounds.
The suitable amount of DPPH was dissolved in MeOH to give a Conc. of
6.25×10–5 M. The sample solutions at Conc. of 2000, 1000, 500, 250, and 125 µg/
mL in MeOH were prepared and ascorbic acid as a standard. To 0.5 mL of each
sample, the solution was added 3.5 mL of fresh DPPH solution and was shaken vig-
orously. Samples were kept in darkness for 30 min at 37 °C, and then their absorb-
ance was measured at 517 nm. The investigation of antioxidant activity revealed that
all the newly synthesized compounds showed potent to moderate radical scavenging
activity when compared with ascorbic acid as a standard; the results are shown in
Figs. 3, 4 and Table3.
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Synthesis and characterization of derivatives including…
Cytotoxic activity by MTT assay
Cell lines
The human breast cancer cells (MCF-7) were obtained from the Pasteur Institute
of Iran (Tehran, Iran). The cells were maintained at 37 °C in a humidifed atmos-
phere (90%) containing 5% CO2 and then cultured in DMEM (Dulbecco’s Modifed
Eagle’s Medium) with 10% (v/v) FBS (fetal bovine serum), 100 units/mL penicillin,
and 100 μg/mL streptomycin. The cells were seeded overnight and then incubated
with diferent concentrations of compounds 7a–7f and cisplatin.
Cell viability assay
Cell viability following exposure to synthetic compounds was estimated by using
the MTT (3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide) reduction
assay[42]. The (MCF-7) cells were seeded in 96-well plates and at 10,000 cells per
well containing 200 µL medium. After 24-h incubation at 37 °C, diferent concen-
trations of test compounds were added to the wells. The samples including 7a–7f
and cisplatin were tested at 25, 50, 75, 100, 125, 125, 150, 150, 175, and 200 μg/
mL concentrations. The samples were dissolved in dimethyl sulfoxide (DMSO) and
further diluted with cell culture medium. The fnal concentration of DMSO was
adjusted to 1% of the total volume of the medium in all treatment, including the
blank. A control medium without DMSO was also incubated. After the treatment,
5 mg/mL of MTT solution was added and incubated for 3 h at 37 °C in a dark place.
The absorbance of formazan creation was measured at a wavelength of 570 nm with
an enzyme-linked immunosorbent assay (ELISA) reader (Molecular Devices, Sun-
nyvale, CA, USA). The cell viability by MTT assay was calculated as a percentage
of the control value (untreated cells) (Fig. 5).
Conclusions
In this project, we were able to provide an easy and efcient method with rela-
tively high-efciency and high-purity products for the synthesis of compounds
7a–7f, which includes two rings of thiazolidine-2,4-dione and imidazole. Also,
the obtained products 7e, 7d, and 7f had high antioxidant properties, among which
the synthesized product 7e had stronger antioxidant properties due to the presence
of the NO2 group in the DPPH method. This presents the potential electron dona-
tion capacity of products besides their hydrogen atom transfer capacity. Among the
synthesized products, compound 7c had a lower IC50 than ascorbic acid. The IC50
value of product 7c may be due to the presence of a p-OEt functional group in the
structure of this compound. Compounds 7a–7f and pioglitazone were also microbial
evaluated and showed low to moderate antimicrobial activity against gram-positive
and gram-negative bacteria. Compound 7c, among other compounds, showed very
good inhibition of zone diameter assay compared to gram-positive (B. anthracis)
bacteria, and only product 7d showed inhibition of zone diameter assay against
1 3

H. Y. Nyaki, N. O. Mahmoodi
gram-negative (E. coli) bacteria, and the drug pioglitazone only shows inhibitory
activity against gram-negative (P. aeruginosa) bacteria. The cytotoxic efects of the
compounds against breast cancer cells (MCF-7) have been studied using the modi-
fed MTT method. The presence of chlorine and nitrogen dioxide groups in the
structure of the compound increased the growth inhibition of cancer cells, and com-
pound 7b had the best results.
Supplementary Information The online version contains supplementary material available at https://doi.
org/10.1007/s11164-021-04525-4.
Acknowledgements This probe was supported in part by the Research Committee of the University of
Guilan. We also thanks Dr. M. PasandidehNadamani for his useful synthetic advising and Dr. Esmaeel
Panahi Kokor for the Cytotoxic MTT assay
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