Synthesis, characterization and biological activities evaluation of novel sulfanyl derivatives

Article abstract of DOI:10.1080/10426507.2019.1672692

A novel series of 1-(3-Methyl-3-mesityl)-cyclobutyl-2-{[5-(2-fluorophenyl)-4-(aryl-alkyl)-4H-[1,2,4]triazol-3-yl]sulfanyl}-ethanone compounds were synthesized by a condensation reaction. The new compounds were characterized by elemental analyses, FT-IR an

Full text of DOI:10.1080/10426507.2019.1672692

Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: https://www.tandfonline.com/loi/gpss20
Synthesis, characterization and biological activities
evaluation of novel sulfanyl derivatives
Kamuran Saraç, Cahit Orek & Metin Koparir
To cite this article: Kamuran Saraç, Cahit Orek & Metin Koparir (2019): Synthesis,
characterization and biological activities evaluation of novel sulfanyl derivatives, Phosphorus,
Sulfur, and Silicon and the Related Elements, DOI: 10.1080/10426507.2019.1672692
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PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
https://doi.org/10.1080/10426507.2019.1672692
Synthesis, characterization and biological activities evaluation of novel
sulfanyl derivatives
Kamuran Sarac¸a, Cahit Orekb,c, and Metin Koparird
b
aDepartment of Chemistry, Faculty of Arts and Science, Bitlis Eren University, Bitlis, Turkey; Department of Genetics and Bioengineering,
c
Faculty of Engineering and Architecture, Kastamonu University, Kastamonu, Turkey; Research and Application Center, Kastamonu University,
d
ꢀ
Kastamonu, Turkey; Faculty of Science, Department of Chemistry, Firat University, Elazıg, Turkey
ABSTRACT
ARTICLE HISTORY
Received 19 March 2019
Accepted 23 September 2019
A novel series of 1-(3-Methyl-3-mesityl)-cyclobutyl-2-{[5-(2-fluorophenyl)-4-(aryl-alkyl)-4H-[1,2,4]tria-
zol-3-yl]sulfanyl}-ethanone compounds were synthesized by a condensation reaction. The new
1
compounds were characterized by elemental analyses, FT-IR and H, 13C NMR techniques. The anti-
KEYWORDS
oxidant and antibacterial properties of the synthesized compounds were also investigated. The in
vitro antioxidant and antibacterial activities of the newly synthesized compounds were measured,
and they were found to exhibit significantly high antioxidant activity.
Sulfanyl compounds;
1,2,4-Triazole; IR and NMR
spectroscopy; biological
effects
GRAPHICAL ABSTRACT
Introduction
of 1-(3-Methyl-3-mesityl)-cyclobutyl-2-{[5-(2-fluorophenyl)-
4-(aryl-alkyl)-4H-[1, 2, 4]triazol-3-yl]sulfanyl}-ethanone.
The ring-closure reaction of carbohydrazide is well known. The
ring systems of these structures are typically planar 6p–electron
aromatic systems and are used as starting materials for the synthe-
sis of many heterocycles.[1–4] The chemistry of 1,2,4-triazoles has
received considerable attention owing to their synthetic utility and
wide spectrum of biological activities. Many studies have shown
that 1,2,4-triazoles have potent biological characteristics such as
antimicrobial,[5,6] antifungal,[7,8] antibacterial,[9–12] anticancer,[13]
antimycobacterial, antiviral,[14,15] antimycotic activity,[16–18] antitu-
bercular,[19] anticonvulsants,[20] antinociceptive,[21] antioxi-
dant,[22–24] anti-inflammatory and analgesic [25] characteristics.
This study focuses on a detailed study of the synthesis,
Results and discussion
Chemistry
The reaction sequences employed for the synthesis of the
title compounds are shown in Figure 1.[26]
Reaction analysis of the title compounds (4a–d)
In the first step of this study, which was planned in two stages,
four thiosemicarbazides (3a–d) were obtained in total by the
characterization, and antioxidant and antibacterial activities interaction of 2-fluorobenzo hydrazide (1) with four different
CONTACT Kamuran Sarac¸
ksarac@beu.edu.tr
Department of Chemistry, Faculty of Arts and Science, Bitlis Eren University, Bitlis 13000, Turkey.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/gpss.
Supplemental data for this article is available online at https://doi.org/10.1080/10426507.2019.1672692.
ß 2019 Taylor & Francis Group, LLC

2
K. SARAC¸ ET AL.
Figure 1. Synthesis and the structures of the compounds.
isothiocyanate derivatives (2a–d). KOH was subsequently Reaction analysis of sulfanyl compounds containing tri-
added to the reaction medium to obtain 4-substituted-5-(2-flu-
orophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thiones (4a–d).[26]
Carboxylic acid hydrazide derivatives form thiosemicarbazide
derivatives by reacting to nucleophilic substitution with substi-
tuted isothiocyanates. The proposed reaction mechanisms of
thiosemicarbazide derivatives are given in Figure 2.[27]
azole and cyclobutane ring (6a–d)
In the second step of the study, the compounds (4a–d) were
reacted with 2-chloro-1-(3-methyl-3-mesitylcyclobutyl) (5)
in dry acetone containing K2CO3 to give cyclobutane ring-,
4-substituted 1,2,4-triazole sulfanyl compounds (6a–d). The
reaction mechanism of 6a–d is given in Figure 4.[29]
The nonbonding electrons in the nitrogen atom of the
thiosemicarbazide in the basic medium cause the ring clos-
ure reaction by the thiosemicarbazide attacking the number
one acyl carbonyl, and 4-substituted-1,2,4-triazole-3-thione
derivatives (4a–d) are formed by the separation of one-mole
water from the structure. The proposed mechanism of the
formation of 4a–d is given in Figure 3.[28]
FT-IR analysis of synthesized compounds
When the FT-IR spectra of the synthesized 4-substituted
1,2,4-triazoles were examined, it was found that the C¼O
peak in the carboxylic acid hydrazides between 1650 and

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
3
Figure 2. Reaction mechanism of thiosemicarbazide derivatives.
Figure 3. Mechanism of formation of 4a–d.
Figure 4. Mechanism of formation of 6a–d.
1690 cmꢀ1 disappeared. Instead of this peak, N–C¼S peaks at C–H between 2987 and 3103 cmꢀ1, aliphatic C–H between
1574, 1268, 1074, and 990 cmꢀ1 appeared. The N–C¼S vibra- 2852 and 2998 cmꢀ1, and C¼N peaks around 1625 cmꢀ1
tion frequencies of 4-benzyl-5-(2-fluorophenyl)-2,4-dihydro-3H- appeared in 4-substituted 1,2,4-triazole derivatives.
1,2,4-triazole-3-thione are shown in Figure S1 (Supplemental
In these synthesized compounds, the C¼O stretching
Materials). In addition to these characteristic peaks, aromatic vibration appeared between 1705 and 1720 cmꢀ1. The

4
K. SARAC¸ ET AL.
C–S–C stretching vibration of the structure was around one of the characteristic peaks in the 4-substituted 1,2,4-tri-
720 cmꢀ1. Some other important peaks were at Ar–H azole sulfanyl compounds was the signal that the nine –CH3
between 2950 and 3100 cmꢀ1, aliphatic CH between 2860
protons in the mesitylene ring formed. This signal appeared
and 2920 cmꢀ1, C–C peaks at 1160 cmꢀ1 at the cyclobutane
as a singlet at about 2.14 ppm and was found to be equiva-
lent to nine hydrogens. Another signal in the cyclobutane
ring, C¼C peaks of the mesityl ring around 1450 cmꢀ1
.
ring was the –CH3 signal, which was a singlet at about
1
1.50 ppm. The Supplemental Materials contains sample H-
1H and 13C-NMR analysis of synthesized compounds
NMR spectra for the products (known compounds) 6a–d
(Figures S14, S17, S20 and S23).
The most characteristic peak of the synthesized 4-substituted
1,2,4-triazoles was the SH/NH peak, which appeared as a
singlet in the range of 14.10–14.24 ppm. The SH/NH peak
for products 4a–d are given in Figure S2 (Supplemental
Materials). In addition to this characteristic peak of SH/NH,
there were some characteristic peaks in the substituents
attached to the 1,2,4-triazole ring. The first example of these
substituents was the ethyl fragment. The –CH2– protons of the
N–CH2–CH3 in the 4-position were found to give a quartet
peak at 3.86 ppm. The J value of this quartet peak was 7.1 Hz.
The –CH3 peaks showed triplet peak at 1.09 ppm. The J value
of this triplet peak was 7.1 Hz. The carbons in the 13C NMR
spectrum of the ethyl group were at about 13.6 ppm for CH3
and 39.6 ppm for CH2. Because of the high electronegativity of
the nitrogen atom, carbon, and hydrogen atoms close to the
nitrogen atom appeared to be downfield. Thus, the electron
charge density shifted from these atoms toward the nitrogen
atom, and these atoms resonated in downfield.
The second example of these substituents is the allyl frag-
ment. The peaks of the protons (N–CH2–) adjacent to the
–N–CH2–CH2–CH2 nitrogen atom were observed at 4.52 ppm
as a multiplet. (CH) proton of the –CH2–CH ¼ CH2 was
observed to peak between 5.64 and 5.70 ppm as a doublet of
doublet of triplets (ddt). Trans proton of CH2 in the
–CH2–CH ¼ CH2 appeared as a doublet at 4.73 ppm, and cis
proton of CH2 in the –CH2–CH ¼ CH2 appeared as a doublet
at 5.00 ppm.
Biological
Biological activities of the synthesized compounds
After the synthesis of the compounds, we elucidated their
biological activities with analytical and spectroscopic meth-
ods. Antibacterial activities were carried out according to
the standard broth dilution method prescribed by the
Clinical and Laboratory Standards Institute (CLSI).[30]
The Minimum Inhibition Concentration (MIC) values of
the synthesized compounds were calculated against B. subti-
lis (ATCC 6633), Listeria monocytogenes Scott A strains as
Gram-positive bacteria, Proteus vulgaris (FMC 1), S. typhi-
murium (NRRL B 4420) as Gram-negative bacteria, and
these values are given in Table S1 (Supplemental Materials).
It was observed that the antibacterial effects of the com-
pounds varied between 64 and 1024 mg mLꢀ1. Among the
compounds synthesized, the compound with the highest
antibacterial activity (6b) was effective against L. monocyto-
genes and P. vulgaris strains at 64 mg mLꢀ1. Considering the
substituents on the most active compounds against L. mono-
cytogenes and P. vulgaris, the presence of the phenyl com-
pound (6c) is particularly striking. Despite the very similar
structures of all the compounds, different antibacterial
effects suggest that they were due to the presence of differ-
ent substituents. The antioxidant activity of the compound
synthesized in the study was assessed using the free radical
scavenging activity method. The reduction ability of DPPH
radicals was determined by a decrease in absorbance at
517 nm induced by antioxidants and calculated percent
inhibition values. The obtained findings are given in Table
S2. It was determined that 6c showed better activity than
the standard antioxidant BHT. On the other hand, it was
found that it had a close activity relative to the a-tocopherol
standard. According to this, it can be said that 6c has a
good radical scavenging activity. This result can show that
our test compound has good activity as a hydrogen donor
because the antioxidants’ effect on DPPH radical cleansing
is thought to be due to their hydrogen donor capabilities.[31]
The third example of these substituents is the phenyl frag-
ment. The protons of the phenyl group appeared as a multiplet
signal between 7.36 and 7.54 ppm. The final example of these
substituents is the benzyl fragment. When 1H-NMR of the
benzyl group hydrogens is interpreted, aliphatic N–CH2–Ph
hydrogens and aromatic hydrogens can be evaluated as two
separate groups. The aliphatic protons appeared as singlets at
5.16 ppm downfield, which was considered to be low compared
to other aliphatic protons, as they are both adjacent to the
nitrogen atom high electronegativities and to the aromatic phe-
nyl group. Protons in the meta positions from the aromatic
hydrogens of the benzyl group appeared as multiple signals
between 6.88 and 6.90 ppm, a proton in the para position
appeared as a triplet at about 7.31 ppm, and hydrogens in the
ortho positions appeared as triplets around 7.27 ppm.
1
Experimental
Another characteristic peak in the H-NMR spectrum of
the 4-substituted 1,2,4-triazole sulfanyl compound was pro-
tons in the –S–CH2–CO fragment. These hydrogens
appeared as a signal at about 4.32 ppm. The hydrogen that
appeared as a pentet signal in the cyclobutane ring was one
Chemistry assays
Melting points were determined on Gallenkamp melting
point apparatus. The IR spectra were measured with a
of the characteristic peaks in these structures. This proton, Perkin–Elmer Spectrum one FT-IR spectrophotometer. The
which interacts with four hydrogens in the cyclobutane ring, 1H and 13C-NMR spectra were recorded on Bruker AC-400
1
appeared as a signal of about 3.58 ppm. On the other hand, NMR spectrometer operating at 400 MHz for H, 100 MHz

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
5
for 13C-NMR. Compounds were dissolved DMSO, and Ar–H, J ¼ 7.4 Hz), 7.36–7.40 (m, 3H, Ar–H) 7.48–7.54 (m,
chemical shifts were referenced to TMS (1H and 13C-NMR). 2H, Ar–H), 14.24 (s, 1H, SH); 13C-NMR (100 MHz, DMSO-
Chemicals were purchased from Aldrich or Merck. The d6, d, ppm): 114.4, 116.2, 125.2, 128.3, 129.3, 129.6, 132.5,
1
Supplemental Material contains FT-IR, H-, and 13C-NMR 134.8, 147.1 (N–C–N), 158.9 (C–F), 168.7 (C¼S). Elemental
spectra for compounds 4a–d and 6a–d (Figures S1–S24).
analysis: Calculated: C, 61.98; H, 3.72; N, 15.49; S, 11.82.
Found: C, 61.70; H, 3.60; N, 15.55; S, 11.90.
General procedure for the synthesis of 4a–d
Synthesis of 4-benzyl-5-(2-fluorophenyl)-2,4-dihydro-3H-1,
2,4-triazole-3-thione (4d) (C15H12FN3S)
A mixture of 2-fluorobenzo hydrazide (1) (0.01 mol), ethyl
alcohol (50 mL), and substituted isothiocyanate (2a–e) were
refluxed for 3 h and after about 4 h, solid thiosemicarbazide White solid, yield 75%, m.p. 223–224 ꢁC; FT-IR (KBr, cmꢀ1
,
began to form in the reaction flask. KOH (0.15 mol) was V): 3035–3103 (Ar–H), 2922–2998 (C–H), 1626 (C¼N),
added to the solid, and dissolution was started. After 6 h, 1241 (C–F) 1574, 1268, 1074, 990 (N–C¼S, I, II, III ve IV
1
the reaction was stopped and brought to pH 3–4 with HCl. amide bands); H-NMR (400 MHz, DMSO-d6, d, ppm): 5.16
The residue was poured onto crushed ice while stirring. The (s, 2H, N–CH2–C6H5), 6.88–6.90 (m, 2H, Ar–H), 7.15–7.17
resulting solid was collected by filtration, dried, and recrys- (m, 3H, Ar–H) 7.27 (t, 2H, Ar–H, J ¼ 7.6 Hz), 7.31 (t, 1H,
tallized from ethyl alcohol.
Ar–H, J ¼ 9.2 Hz), 7.44 (t, 1H, Ar–H, J ¼ 7.3 Hz), 7.59 (dd,
1H, Ar–H, J ¼ 14.1 Hz, J ¼ 7.0 Hz), 14.21 (s, 1H, SH); 13C-
NMR (100 MHz, DMSO-d6, d, ppm): 47.0, 114.4, 116.5,
125.4, 127.3, 128.0, 128.8, 132.0, 134.1, 135.7, 146.9
(N–C–N), 159.2 (C–F), 168.3 (C¼S). Elemental analysis:
Calculated: C, 63.14; H, 4.24; N, 14.73; S, 11.24. Found: C,
63.25; H, 4.20; N, 14.80; S, 11.40.
Synthesis of 4-ethyl-5-(2-fluorophenyl)-2,4-dihydro-3H-
1,2,4-triazole-3-thione (4a) (C10H10FN3S)
White solid, yield 68%, m.p. 193–194 ꢁC; FT-IR (KBr, cmꢀ1
,
V): 3050–3100 (Ar–H), 2860–2984 (C–H), 1623 (C¼N),
1227 (C–F), 1563, 1263, 1031, 964 (N–C¼S, I, II, III ve IV
1
amide bands); H-NMR (400 MHz, DMSO-d6, d, ppm): 1.09
General procedure for the synthesis of 6a–d
(t, 3H, N–CH2–CH3, J ¼ 7.1 Hz), 3.86 (q, 2H, –N–CH2–CH3,
J ¼ 7.1 Hz), 7.43 (t, 1H, Ar–H, J ¼ 7.5 Hz), 7.49 (t, 1H, K2CO3 (0.02 mol) was dissolved in dry acetone (30 mL). 2-
Ar–H, J ¼ 7.5 Hz), 7.70 (dt, 2H, Ar–H, J ¼ 7.3 Hz, chloro-1-(3-methyl-3-mesityl cyclobutyl) ethanone (0.02 mol)
J ¼ 19.7 Hz), 14.10 (s, 1H, SH); 13C-NMR (100 MHz, was added to this solution. A solution of appropriate triazoles
DMSO-d6, d, ppm): 13.6, 39.6, 114.4, 116.7, 125.7, 132.5, (4a–d) (0.02 mol) was then added dropwise to this solution for
134.3, 146.7 (N–C–N), 161.4 (C–F), 167.2 (C¼S). Elemental 6 h at room temperature. The resulting solid was collected by
analysis: Calculated: C, 53.79; H, 4.51; N, 18.82; S, 14.36. filtration, dried, and recrystallized from ethyl alcohol.
Found: C, 53.70; H, 4.45; N, 18.85; S, 14.40.
Synthesis of 1-(3-methyl-3-mesityl)-cyclobutyl-2-{[5-(2-fluo-
Synthesis of 4-allyl-5-(2-fluorophenyl)-2,4-dihydro-3H-1,2,
4-triazole-3-thione (4 b) (C11H10FN3S)
rophenyl)-4-ethyl-4H-1,2,4-triazol-3-yl] sulfanyl}-ethanone
(6a) (C26H30FN3OS)
White solid, yield 65%, m.p. 202–204 ꢁC; FT-IR (KBr, cmꢀ1, V): Shining white solid, yield 62%, m.p. 150–152 ꢁC; FT-IR
3053–3098 (Ar–H), 2852–2992 (C–H), 1630 (C¼N), 1226 (KBr, cmꢀ1, V): 2980–3083 (Ar–H), 2861–2942 (C–H), 1720
(C–F), 1562, 1264, 1035, 979 (N–C¼S, I, II, III ve IV amide (C¼O), 1454 (C¼C), 1372 (C¼N), 1224 (C–F), 1024 (N–N),
1
1
bands); H-NMR (400 MHz, DMSO-d6, d, ppm): 4.52 (d, 2H, 720 (C–S); H-NMR (400 MHz, DMSO-d6, d, ppm): 1.26 (t,
–N–CH2–CH–CH2, J¼ 5.0 Hz), 4.73 (d, 1H, –N–CH2–CH–CH2 3H, N–CH2–CH3, J ¼ 7.1 Hz), 1.50 (s, 3H, –CH3 (cyclobu-
(trans) J¼ 17.2 Hz), 5.00 (d, 1H, N–CH2–CH–CH2, Jcis¼9.7 Hz), tane)), 2.14 (s, 9H, –CH3 (mesitylene)), 2.42–2.54 (m, 4H,
5.64–5.70 (ddt, 1H, N–CH2–CH–CH2, Jtrans¼17.2 Hz, –CH2– (cyclobutane)), 3.58 (p, 1H, –CH– (cyclobutane),
Jcis¼9.7 Hz J CH2 ¼ 5.0Hz), 7.36 (t, 1H, Ar–H, J¼ 7.6 Hz), 7.41 J ¼ 8.80 Hz), 4.09 (q, 2H, N–CH2–CH3, J ¼ 6.9 Hz), 4.35 (s,
(t, 1H, Ar–H, J¼ 9.3 Hz), 7.61 (t, 1H, Ar–H, J¼ 7.3 Hz), 7.65 2H, S–CH2–), 6.70 (s, 2H, Ar–H (mesitylene)), 7.36–7.45
(d, 1H, Ar–H, J¼ 13.3 Hz, J¼ 6.6 Hz) 14.11 (s, 1 H, SH); 13C- (m, 2H, Ar–H), 7.51–7.54 (m, 1H, Ar–H), 7.62–7.68 (m, 2H,
NMR (100 MHz, DMSO-d6, d, ppm): 46.2, 114.4, 116.8, 117.9, Ar–H). 13C-NMR (100 MHz, DMSO-d6, d, ppm): 15.4, 20.5,
125.5, 131.5 132.2, 134.1, 146.9 (N–C–N), 160.9 (C–F), 167.8 21.4, 25.2, 39.1, 40.3, 41.2, 115.4, 116.5, 127.1, 130.2, 130.3,
(C¼S). Elemental analysis: Calculated: C, 56.15; H, 4.28; N, 130.5, 132.5, 143.7, 150.9 (N–C–N), 151.8 (N–C–S), 160.8
17.86; S, 13.63. Found: C, 56.23; H, 4.25; N, 17.82; S, 13.70.
(C–F), 205.3 (C¼O). Elemental analysis: Calculated: C,
69.15; H, 6.70; N, 9.30; S, 7.10. Found: C, 69.01; H, 6.90; N,
9.42; S, 7.25.
Synthesis of 4-phenyl-5-(2-fluorophenyl)-2,4-dihydro-3H-1,
2,4-triazole-3-thione (4c) (C14H10FN3S)
White solid, yield 72%, m.p. 111–112 ꢁC; FT-IR (KBr, cmꢀ1
,
Synthesis of 1-(3-methyl-3-mesityl)-cyclobutyl-2-{[5-(2-fluo-
rophenyl)-4-allyl-4H-1,2,4-triazol-3-yl] sulfanyl}-ethanone
(6b) (C27H30FN3OS)
V): 2987–3088 (Ar–H), 1623 (C¼N), 1226 (C–F), 1548,
1
1278, 1076, 971 (N–C¼S, I, II, III ve IV amide bands); H-
NMR (400 MHz, DMSO-d6, d, ppm): 7.18 (t, 1H, Ar–H, White solid, yield 64%, m.p. 91.3 ꢁC; FT-IR (KBr, cmꢀ1, V):
J ¼ 9.2 Hz), 7.23 (t, 1H, Ar–H, J ¼ 7.6 Hz), 7.27 (d, 2H, 2975–3080 (Ar–H), 2855–2945 (C–H), 1715 (C¼O), 1440

6
K. SARAC¸ ET AL.
(C¼C), 1380 (C¼N), 1217 (C–F), 1012 (N–N), 732 (C–S); synthesized (6a–d) substances.[30] To examine the antibac-
1H-NMR (400 MHz, DMSO-d6, d, ppm): 1.50 (s, 3H, –CH3 terial activities, the synthesized compounds 6a–d and the
(cyclobutane)), 2.14 (s, 9H, –CH3 (mesitylene)), 2.46–2.54 control group were dissolved in DMSO (dimethyl sulfoxide).
(m, 4H, –CH2– (cyclobutane)), 3.58 (p, 1H, –CH– (cyclobu-
tane), J ¼ 9.00 Hz), 4.31 (s, 2H, S–CH2–), 4.44–4.52 (m, 2H,
–N–CH2–CH–CH2), 4.81 (d, 1H, –N–CH2–CH–CH2(trans)
J ¼ 17.2 Hz), 5.25 (d, 1H, N–CH2–CH–CH2, Jcis¼10.4 Hz),
5.74–5.83 (m, 1H, N–CH2–CH–CH2), 6.70 (s, 2H, Ar–H
(mesitylene)), 7.36–7.45 (m, 2H, Ar–H), 7.53 (t, 1H, Ar–H,
J ¼ 7.3 Hz), 7.65 (dd, 2H, Ar–H, J1¼13.7 Hz, J2¼7.2 Hz).
13C-NMR (100 MHz, DMSO-d6, d, ppm): 20.5, 21.4, 25.2,
39.1, 41.3, 46.8, 115.3, 116.6, 118.0, 125.6, 130.5, 132.1,
132.4, 133.5, 134.4, 134.9, 143.8, 150.5 (N–C–N), 151.1
(N–C–S), 161.1 (C–F), 205.3 (C¼O). Elemental analysis:
Calculated: C, 69.95; H, 6.52; N, 9.06; S, 6.92. Found: C,
69.81; H, 6.44; N, 9.15; S, 6.83.
Furthermore, dilution series of decreasing concentrations of
1024, 512, 256, 128, 64, 32, 16, 8, 4 mg mLꢀ1 were prepared
for microorganisms at the indicated concentrations. Stock
solutions were prepared in DMSO, and it was determined
that DMSO did not have an effect on the microorganisms in
the concentration. The microorganisms used were two
Gram-positive bacteria and two Gram-negative bacteria. B.
subtilis ATCC 6633, L. monocytogenes Scott A strains as
Gram-positive bacteria, P. vulgaris FMC 1, and S. typhimu-
rium NRRL B 4420 strains as Gram-negative bacteria were
used. Ampicillin as a standard antibiotic was used for bac-
terial strains. Each bacterial strain in the stock was seeded in
nutrient broth (pH 7.4) liquid under sterile conditions and
allowed to incubate at 37 ꢁC for 24 h. Thus, the concentra-
tion of bacterial strains on the media was adjusted to
105 CFU mLꢀ1. Test compounds dissolved in DMSO were
first prepared at a concentration of 1024 mg mL–1 and then
diluted up to 4 mg mL–1 by adding the medium. Besides this,
a series of control groups were prepared. Bacterial cultures
prepared one day in advance were inoculated in dilution
tubes and allowed to incubate for 24 h at 37 ꢁC. After incu-
bation, MIC values were calculated using the turbidity deter-
mination method. Experiments were performed in two
parallel runs.
Synthesis of 1-(3-methyl-3-mesityl)-cyclobutyl-2-{[5-(2-fluo-
rophenyl)-4-phenyl-4H-1,2,4-triazol-3-yl] sulfanyl}-etha-
none (6c) (C30H30FN3OS)
White solid, yield 68%, m.p. 101–103 ꢁC; FT-IR (KBr, cmꢀ1
,
V): 2951–3059 (Ar–H), 2861–2920 (C–H), 1705 (C¼O), 1426
1
(C¼C), 1329 (C¼N), 1224 (C–F), 1009 (N–N), 759 (C–S); H-
NMR (400 MHz, DMSO-d6, d, ppm): 1.50 (s, 3H, –CH3 (cyclo-
butane)), 2.14 (s, 9H, –CH3 (mesitylene)), 2.42–2.58 (m, 4H,
–CH2– (cyclobutane)), 3.58 (p, 1H, –CH– (cyclobutane),
J¼ 8.90 Hz) , 4.30 (s, 2H, S–CH2–), 6.71 (s, 2H, Ar–H (mesity-
lene), 7.17–7.34 (m, 4H, Ar–H), 7.47–7.58 (m, 5H, Ar–H).
13C-NMR (100 MHz, DMSO-d6, d, ppm): 20.5, 21.4, 25.2, 39.1,
40.8, 115.4, 116.5, 127.1, 130.2, 130.3, 130.5, 132.5, 143.7, 150.9
(N–C–N), 151.8 (N–C–S), 160.8 (C–F), 205.3 (C¼O).
Elemental analysis: Calculated: C, 72.12; H, 6.05; N, 8.41; S,
6.42. Found: C, 72.25; H, 6.21; N, 8.32; S, 6.50.
Free radical clearing activity
The free radical scavenging activity of the compounds was
determined with a small modification according to the Blois
method using 1,1-diphenyl 2-picryl hydrazyl (DPPH).[32]
The principle of the method is based on the reduction of
1,1-diphenyl 2-picrylhydrazyl radical (DPPH.), which is the
colored free radical of free radical scavenger. DPPH is a sta-
ble red free radical. When free radicals are eliminated by
antioxidant compounds, the color turns from red to yellow.
The decrease in the absorbance at 517 nm of the reaction
mixture indicates increased antioxidant activity in the free
radical scavenging.
Synthesis of 1-(3-methyl-3-mesityl)-cyclobutyl-2-{[5-
(2-fluorophenyl)-4-benzyl-4H-1,2,4-triazol-3-yl] sulfanyl}-
ethanone (6d) (C31H32FN3OS)
White solid, yield 65%, m.p. 85–87 ꢁC; FT-IR (KBr, cmꢀ1
,
V): 2950–3065 (Ar–H), 2866–2925 (C–H), 1715 (C¼O),
1434 (C¼C), 1321 (C¼N), 1220 (C–F), 1018 (N–N), 761
1
(C–S); H-NMR (400 MHz, DMSO-d6, d, ppm): 1.49 (s, 3H,
–CH3 (cyclobutane)), 2.14 (s, 9H, –CH3 (mesitylene)),
2.51–2.57 (m, 4H, –CH2– (cyclobutane)), 3.55 (p, 1H, –CH–
(cyclobutane), J ¼ 8.70 Hz), 4.32 (s, 2H, S–CH2–), 5.38 (s,
2H, N–CH2–C6H5), 6.71 (s, 2H, Ar–H (mesitylene)),
7.17–7.34 (m, 4H, Ar–H), 7.47–7.58 (m, 5H, Ar–H). 13C-
NMR (100 MHz, DMSO-d6, d, ppm): 20.5, 21.4, 25.2, 39.1,
40.0, 40.8, 48.1 115.4, 116.5, 125.2, 126.9, 130.5, 130.9, 132.5,
134.4, 134.9, 140.0, 143.7 (N–C–N), 151.9 (N–C–S), 160.8
(C–F), 205.3 (C¼O). Elemental analysis: C, 72.48; H, 6.28;
N, 8.18; S, 6.24. Found: C, 72.52; H, 6.35; N, 8.15; S, 6.30.
Reagents used
0.1 mM DPPH (prepared in ethanol); a-tocopherol
1 mg mL–1; Butyl hydroxy anisole 1 mg/mL; DPPH (1,1-
diphenyl-2-picrylhydrazyl) free radical scavenging activity,
butylhydroxytoluene (BHT), a-tocopherol, and ethyl alcohol
were obtained from Merck or Aldrich. In the study, the syn-
thesized compound was dissolved in ethyl alcohol as
1 mg mL–1. The standard was dissolved in ethanol again to
be 1 mg mL–1. The test compound and standards were
placed in test tubes at 50, 100, 250 mg mL–1, respectively,
and completed with pure ethanol to be at a total volume of
3 mL. 1 mL of the stock DPPH solution was then added to
each sample tube. It was incubated in the dark at room tem-
perature. After incubation, the absorbances at 517 nm
Biological assays
Antibacterial assays
The standard broth dilution method was used to measure (UV–Vis Spectrophotometry: Shimadzu UV-1700) were
the MIC values of the in vitro antimicrobial activities of our measured. As a control, 3 mL of ethanol and 1 mL of DPPH

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
7
[4] Sztanke, K.; Tuzimski, T.; Rzymowska, J.; Pasternak, K.;
solution were used. Reduced absorbance gives the free rad-
ical scavenging activity of the remaining amount of DPPH
solution. The calculations for DPPH radical scavenging
activity in the reaction medium were calculated according to
the following formula.
ꢁ
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%Free radical scavenging activity ¼ ðA0 ꢀ A1=A0Þ ꢂ 100,
Arylideneamino-3-Mercapto-1,2,4-Triazoles
and
Related
where A0 is an absorbance of the control reaction and A1 is
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thesis compounds were confirmed by FT-IR, H-, and 13C
1
ꢀ
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bacterial activities. Among various sulfanyl compound deriv-
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activity than the other derivatives and the standard BHT
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