Synthesis, spectral, biological activity, and crystal structure evaluation of novel pyrazoline derivatives having sulfonamide moiety

Article abstract of DOI:10.1007/s00044-017-1838-5

In the present study, synthesis and characterization of pyrazoline derivatives integrated with sulfonamide scaffold have been performed. The characterization of the molecules was done by elemental analysis, ultraviolet–visible, infrared, nuclear magnetic

Full text of DOI:10.1007/s00044-017-1838-5

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-017-1838-5
ORIGINAL RESEARCH
Synthesis, spectral, biological activity, and crystal structure
evaluation of novel pyrazoline derivatives having sulfonamide
moiety
Rajitha Sadashiva1 Damodara Naral2 Jyothi Kudva3 Naveen Shivalingegowda4
●
●
●
●
Neratur Krishnappagowda Lokanath5 Kudigana Jayaprakash Pampa6
●
Received: 2 February 2016 / Accepted: 1 March 2017
© Springer Science+Business Media New York 2017
Abstract In the present study, synthesis and characteriza-
tion of pyrazoline derivatives integrated with sulfonamide
scaffold have been performed. The characterization of
the molecules was done by elemental analysis,
ultraviolet–visible, infrared, nuclear magnetic resonance
(NMR), and mass spectra. Crystal structure of compounds
2e and 2g were determined by single crystal X-ray dif-
fraction. In the compounds 2e and 2g, the intra molecular
hydrogen bonds N15--H15…O13 and N14--H14…N1 were
closed to form a S(6) ring motif, whereas the N14--H14…
O17 hydrogen bond links, pairs of molecules related by
high potent against M. tuberculosis and most of the mole-
cules have shown good potential against different bacteria
and fungi.
●
●
Keywords Mycobacterium tuberculosis Antimicrobial
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Pyrazolines Sulfonamides X-ray diffraction analysis
Introduction
inversion, forming the familiar R2 (10) ring motif. The
2
Hirshfeld surface analysis comprising of the dnorm surface
plots, electrostatic potentials and two-dimensional finger-
print plots were generated in order to give visual con-
firmation of the intermolecular interactions. The molecules
were screened for their in vitro antitubercular and anti-
microbial activity. The molecules 2n and 2m have shown
Tuberculosis (TB) is a widespread infectious disease caused
by various strains of mycobacterial, which is usually M.
tuberculosis. It remains one of the world’s deadliest com-
municable diseases. TB was slowly declining each year and
it was estimated that 37 million lives were saved between
the year 2000 and 2013 through effective diagnosis and
treatment (WHO Global Tuberculosis Report 2014). There
were very few antimicrobial agents available that can be
used for life-threatening microbial infections. So the
development of an effective antimycobacterial drug is an
emerging opportunity in the field of drug discovery.
* Jyothi Kudva
jyothikudva@gmail.com
1
Pyrazolines are well known nitrogen containing five-
membered heterocyclic compounds, which possesses a wide
range of biological activity. Pyrazoline derivatives are
known for their prominent property as drugs like, pyr-
azofurin (antibiotic), sulfinpyrazone (uricosurgic), and
metamizole (antipyretic). Numerous studies demonstrated
that, the pyrazoline derivatives exhibit antibacterial (Sha-
haryar et al. 2006; Ali et al. 2007; Siddiqui et al. 2011),
antidepressant (Prasad et al. 2005), anticonvulsant (Batulin
1968; Parmar et al. 1974; Soni et al. 1987), antihypertensive
(Turan-Zitouni et al. 2000), antitumor (Bano et al. 2011)
activity. Some of the pyrazoline derivatives are reported to
Sigma-Aldrich Chemical Pvt. Ltd., Bommasandra-Jigani link
Road, Bengaluru 560100, India
2
Department of Chemistry, Canara Engineering College,
Benjanapadavu, Mangaluru 574219, India
3
Department of Chemistry, St. Joseph Engineering College,
Vamanjoor, Mangaluru 575005, India
4
Institution of Excellence, Vijnana Bhavana, University of Mysore,
Manasagangotri, Mysuru 570006, India
5
Department of Studies in Physics, University of Mysore,
Manasagangotri, Mysuru 570006, India
6
Department of Studies in Microbiology, University of Mysore,
Manasagangotri, Mysuru 570006, India

Med Chem Res
Scheme 1 Synthetic pathway
for pyrazoline derivatives
integrated with sulfonamide
scaffold. Reagents and
conditions: (i) Ethanol, KOH,
RT, 10 h; (ii) CH3OCONHNH2,
methanol, 70 °C, 5 h; (iii) N2H4.
H2O, methanol, 80 °C, 8 h; (iv)
Fluorosubstituted benzene
sulfonyl chloride, CH2Cl2,
pyridine, 5 °C, 2 h
O
CHO
COCH3
i
+
R
R1
R
iv
R1
A
B
1a-n
ii
iii
R
O
O
H
S
N
N
R1
N
N
H
O
R3
R2
2a-n
Compounds 2a 2b 2c 2d 2e
2f
2g
2h 2i 2j
2k 2l
2m 2n
R
H
H
H
F
F
Br Cl OCH3 CH3 OCH3
F
F
H
F
H
H
F
CH3 Br SCH3
Cl
H
H
H
H
H
H
H
R1
R2
R3
H
H
F
H
F
F
H
H
F
H
H
F
H
H
F
H
F
F
H
F
F
H
H
H
H
H
H
F
possess anti-inflammatory (Bansal et al. 2001) and anti-
diabetic activity (Ahn et al. 2004).
tuberculosis H37Rv and antimicrobial property was studied
against Staphylococcus aureus MTCC 96, Bacillus subtilis
MTCC 441, Pseudomonas aeruginosa MTCC 1688,
Escherichia coli MTCC 443, Aspergillus fumigatus
ATCC1028, Aspergillus niger MTCC 282, Candida albi-
cans MTCC 227, and Aspergillus flavus ATCC 9643.
The detailed single crystal X-ray diffraction study and
Hirshfeld surface analysis were carried out for the com-
pounds 2e and 2g.
Sulfa drug was the first drug largely employed and sys-
tematically used as preventive and chemotherapeutic agent
against various diseases (Sammes 1990). The sulfonamide
derivatives were reported as orally active endothalins
selective antagonists (Kanda et al. 2001), antibacterial
(Stokes et al. 2012), antiprotozoal (Chibale et al. 2001),
antifungal (Ezabadi et al. 2008), anti-inflammatory (Ken-
nedy and Thorley 1999), nonpeptidic vasopressin receptor
antagonists (Gal 2001) and translation initiation inhibitors
(Natarajan et al. 2004).
Pyrazoline derivatives integrated with sulfonamide
scaffold have the capacity of inhibiting the human carbonic
anhydrase isoenzymes in a noncompetitive manner and the
inhibition effects of some molecules for isozymes were
almost in nanomolar concentration range (Balseven et al.
2013). The pyrazoline and sulfonamide integrated mole-
cules have shown the anticancer and anti-inflammatory
(Bashir et al. 2011) capacity and some of the pyrazoline
derivatives were discovered as fluorescent probe for
detecting glutathione among biological thiols in aqueous
media (Wang et al. 2013).
Results and discussion
Chemistry
The synthetic route for target pyrazoline derivatives inte-
grated with sulfonamide scaffold 2a–n was carried out as
outlined in Scheme 1. The substituted chalcones 1a–n were
prepared as per well-known Claisen-Schmidt reaction using
para substituted arylaldehydes (A) and para substituted
acetophenones (B). The N-methyl ester substituted pyrazo-
line ring was constructed by the reaction of suitable chal-
cone with methyl hydrazine carboxylate in methanol. The
corresponding carbohydrazide derivatives of pyrazoline
were synthesized by the reaction of N-methyl ester sub-
stituted pyrazoline derivatives with hydrazine hydrate. The
required pyrazoline derivatives integrated with sulfonamide
scaffold was obtained by the reaction of fluorosubstituted
benzene sulfonyl chloride with pyrazoline carbohydrazide
derivatives in the presence of pyridine.
In view of the potential application of pyrazoline and
sulfonamide derivatives, synthesis of new series of pyr-
azolines integrated with sulfonamide scaffold (2a–n) was
undertaken. The molecules were structurally characterized
by elemental analysis, ultraviolet (UV)– visible (Vis),
infrared (IR), nuclear magnetic resonance (NMR), and mass
spectra. The antitubercular property was studied against M.

Med Chem Res
Fig. 1 Labeling of atoms and
rings of pyrazoline derivatives
integrated with sulfonamide
scaffold (2a–n)
R2
O
S
N
R3
O
D
H1N
N
H2N
R1
C
N
O
N
B
Ha
A
Hc
Hb
R
Spectral analysis
spectra, methylene carbon atom of pyrazoline ring was
resonated from δ, 40.3 to 48.5 ppm. The methine and azo-
methine carbon atom of pyrazoline ring were resonated
from δ, 62.3 to 67.9 ppm and δ, 150.1 to 154.0 ppm,
respectively. The aromatic carbons were resonated between
δ, 105.38 and 166.14 ppm. The mass spectra of all syn-
thesized pyrazoline derivatives 2a–n were recorded and m/z
value of all the compounds has the correlation with the
theoretical molecular weight of the compounds. The purity
of the compounds was analyzed by elemental analysis.
The synthesized molecules 2a–n exhibit intense absorption
band in UV–Vis spectra, which was attributed to the π–π*
transition of the conjugated backbone (Sverdlova et al.
1968). The absorption maximum (λmax) was found in the
range of 293–298 and 217–223 nm, which was due to
absorption of –SO2–NH– and Ar–N–N=C–Ar groups,
respectively (Bhat et al. 2009; Sheat et al. 2011).
Infrared spectra of the synthesized compounds were
recorded in the region 4000–400 cm−1
. The strong
stretching bands in the region 3400–3100 cm−1 indicate the
presence of N–H group. The asymmetric and symmetric
stretching bands of SO2 group were observed in the region
1340–1150 cm−1, respectively (Stuart 2004). The C=O
stretching frequency was obtained in the region of 1650
cm−1. The absorption bands in the region 1583–1618 cm−1
indicate the C=N stretching frequency (Stuart 2004).
The NMR spectra of the compounds were recorded in
DMSO-d6. The pyrazoline nucleus has two geminal protons
Ha and Hb, which were magnetically non-equivalent due to
the presence of chiral proton Hc in the adjacent carbon
(Fig. 1). These three pyrazoline protons displayed three
doublet of doublets as ABX pattern with varying coupling
constant (J) values. The protons Ha and Hb were resonated
at δ, 3.00 and 3.60 ppm, respectively. The chiral proton
Hc was resonated in the region δ, 5.50–6.00 ppm, which
was due to vicinal coupling with adjacent two protons
Ha and Hb. This confirms the presence of pyrazoline ring in
the compound (Hassner and Michelson 1962). All the aro-
matic protons were resonated in the region between δ, 7.00
and 8.00 ppm. The two amine protons, H2N and H1N were
resonated in the region δ, 9.00–9.90 ppm. In 13C NMR
Biology
Antitubercular studies
The antitubercular potency of the synthesized molecules
2a–n was screened by micro plate alamar blue assay
(MABA). The alamar blue oxidation-reduction dye is a
general indicator of cellular growth and/or viability; the
blue, non-fluorescent, oxidized form becomes pink and
fluorescent upon reduction. The activity was expressed as
the minimum inhibitory concentration (MIC) in μg/mL
(Table 1).
The MIC value of each compound was depended on the
nature of the group present at R, R1, R2, and R3 (Fig. 1).
The compound 2n, which has the neat phenyl ring A, C, and
D have shown an excellent potency, which was 7.81-fold
more potent than the streptomycin and 3.9-fold more potent
than the pyrazinamide and ciprofloxacin. The compound
2m (R=Cl) has shown MIC 1.6 μg/mL, which was 3.90-
fold more potent than the standard drug streptomycin and
1.9-fold more active than the pyrazinamide and cipro-
floxacin. The derivatives with neat phenyl ring D, such as

Med Chem Res
Table 1 Antitubercular and
antimicrobial activity data of
compound 2a–n in terms of
MIC (µg/mL)
Compounds
MIC (µg/mL)
M. tuberculosis
Gram-positive
bacteria
Gram-
negative
bacteria
Fungi
S. aa
B. sb
E. cc
P. ad
A. fe
A. nf
A. fg
C. ah
2a
25.0
50.0
100.0
12.5
12.5
50.0
6.25
100.0
12.5
50.0
3.12
3.12
1.6
75.0
100.0
150.0
125.0
75.0
75.0
75.0
75.0
75.0
100.0
–
50.0
50.0
50.0
100.0
50.0
75.0
75.0
50.0
50.0
75.0
50.0
50.0
75.0
–
75.0
25.0
75.0
100.0
50.0
75.0
50.0
100.0
75.0
75.0
–
50.0
50.0
75.0
50.0
50.0
50.0
50.0
75.0
50.0
75.0
50.0
50.0
50.0
–
–
–
75.0
75.0
25.0
50.0
25.0
50.0
–
50.0
–
–
50.0
50.0
50.0
75.0
75.0
–
2b
2c
75.0
150.0
100.0
–
50.0
100.0
100.0
75.0
25.0
–
2d
2e
2f
2g
–
2h
–
50.0
50.0
–
–
2i
75.0
–
10.0
50.0
50.0
75.0
50.0
50.0
–
25.0
50.0
–
2j
2k
50.0
–
50.0
50.0
–
2l
–
–
50.0
75.0
50.0
–
2m
75.0
75.0
–
–
–
2n
0.8
–
50.0
–
50.0
–
Pyrazinamide
Streptomycin
Ciprofloxacin
Fluconazole
3.125
6.25
3.125
–
–
–
–
–
–
–
–
–
–
–
–
10.0
–
10.0
–
10.0
–
10.0
–
10.0
30.0
10.0
30.0
10.0
30.0
10.0
30.0
‘–‘Indicates bacteria were resistant to the compound >100 μg/mL
a
S. aureus
b
B. subtilis
c
E. coli
d
P. aeruginosa
e
A. fumigatus
f
A. niger
g
A. flavus
h
C. Albicans
compounds 2k, 2l, 2m, and 2n were found to be more
active compared to the activity of the compounds with
fluoro atom on phenyl ring D (2a, 2c, 2d, and 2e). Cer-
tainly, the potency of the molecules was decreased on
substitution of fluoro atom on phenyl ring ‘D’. The com-
pounds 2f (R2 = H, R3 = F) and 2j (R2, R3 = F) have shown
the similar MIC (μg/mL) values. It indicates that, the
activity of the molecules was not based on the number of
fluoro atoms on phenyl ring ‘D’ and it was only due to the
substitution on phenyl ring ‘A’. Among the compounds with
fluoro atom on phenyl ring D, the compound 2g has shown
the comparable activity as that of the streptomycin. It was
concluded from the above facts that, the activity of mole-
cules mainly depended on substitution on phenyl ring ‘A’
and phenyl ring ‘C’. The reactivity of electron withdrawing
and electron donating groups has been found in the order,
Cl > H > F > Br and CH3 < H < Cl.
Antimicrobial studies
Most of the synthesized compounds were active against the
Gram-positive bacteria Bacillus subtilis and Gram-negative
bacteria Pseudomonas aeruginosa (Table 1). The com-
pounds with fluoro atom on phenyl ring D (2a, 2b, 2c, 2h,
and 2i), have shown the higher potency compared to the
compounds with neat phenyl ring D (2m and 2n). The
compound 2a (R3 = F) has exhibited a good potency com-
pared to compound 2n (R3 = H). None of the molecules
have shown the MIC value equal to that of ciprofloxacin.
Some of the for pyrazoline derivatives integrated with
sulfonamide scaffold were active against the Aspergillus
niger and Aspergillus flavus (Table 1). The compounds 2c,
2e, and 2i have shown the good activity over all fungi.
When the activity was compared with the standard drug, the
compound 2i (R2, R3 = F) has shown the threefold more

Med Chem Res
Table 2 Crystal and structure
refinement data for compounds
2e and 2g
Parameter
Value
Value
Compound 2e
Compound 2g
CCDC deposit no.
Empirical formula
Formula weight
1,054,672
1,056,212
C23H21FN4O4S
468.50
C23H20F2N4O4S
486.49
Temperature
293(2) K
293(2) K
Wavelength
1.54178 Å
1.54178 Å
Crystal system, space group
Unit cell dimensions
Monoclinic, C2/c
a = 10.293(2) Å
b = 23.397(5) Å
c = 19.150(4) Å
β = 102.424(11)°
4503.7(16) Å3
Monoclinic, P21/n
a = 7.6673(14) Å
b = 22.900(4) Å
c = 12.874(2) Å
β = 95.122(6)°
2251.3(7) Å3
Volume
Z, Calculated density
Absorption correction
Absorption coefficient
F(000)
8, 1.382 Mg/m3
4, 1.435 Mg/m3
Multi-scan
1.680 mm−1
Multi-scan
1.769 mm−1
1952
1008
Crystal size
0.25 × 0.25 × 0.25 mm
3.78° to 64.21°
−10 ≤ h ≤ 11
0.25 × 0.25 × 0.25 mm
6.11° to 64.48°
−8 ≤ h ≤ 8
ø range for data collection
Limiting indices
−23 ≤ k ≤ 26
−26 ≤ k ≤ 26
−20 ≤ l ≤ 21
−14 ≤ l ≤ 15
Reflections collected/unique
Refinement method
11,312/3654 [R(int) = 0.0430]
Full-matrix least-squares on F2
3654/0/300
21,534/3693 [R(int) = 0.0384]
Full-matrix least-squares on F2
3693/0/308
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2σ(I)]
R indices (all data)
1.034
1.043
R1 = 0.0497, wR2 = 0.1405
R1 = 0.0575, wR2 = 0.1481
0.390 and −0.431 e Å−3
R1 = 0.0431, wR2 = 0.1213
R1 = 0.0451, wR2 = 0.1236
0.321 and −0.461 e Å−3
Largest diff. peak and hole
Table 3 Bond length (Å) of some selected bonds of compounds 2e
and 2g
potency against the Aspergillus flavus and 1.2-fold more
potency against the Candida albicans, also the compounds
2c and 2e have shown 1.2-fold more potency against
Aspergillus niger. It was concluded that, the potency of
molecules increases with the increase in fluoro atoms on
phenyl ring ‘D’. On substitution of bromo (2c) and chloro
(2d) atom at R position, a noticeable increase in the potency
was observed.
Atoms
2e
2g
N1–C2
1.283(3)
1.396(3)
1.508(3)
1.471(3)
1.349(3)
1.226(3)
1.373(3)
1.406(3)
1.657(19)
1.756(3)
1.357(2)
1.389(2)
1.539(2)
1.287(2)
1.484(2)
1.218(2)
1.373(2)
1.402(2)
1.643(18)
1.761(2)
N1–N5
C2–C3
C4–N5
N5–C12
C12–O13
C12–N14
N14–N15
N15–S16
S16–C19
Crystal structure analysis of compounds 2e and 2g
The details of the crystal structure and data refinement were
given in Table 2. The list of bond lengths and bond angles
of the non-hydrogen atoms were given in Tables 3 and 4,
respectively. Figs 2 and 3 represent the ORTEP diagram of
the molecules 2e and 2g with thermal ellipsoids drawn at
50% probability, respectively.
In the compound 2e, the central pyrazoline ring adopts a
twisted conformation on the C3–C4 bond and its mean
plane makes dihedral angles of 7.80(13)°, 71.14(15)°, and
75.48(12)° with the phenyl, 4-fluorophenyl, and 4-
methoxyphenyl rings, respectively. In the compound 2g, a
study of torsion angles, asymmetric parameters and least-
squares calculations reveals that, the pyrazoline ring adopts

Med Chem Res
Table 4 Bond angle (°) of some selected bonds of compounds 2e and
2g
In the compounds 2e and 2g, the structures exhibit both
inter and intramolecular hydrogen bonds of the type N--
H···N, C--H…O, C--H…N and N--H…N, N--H…O, C--
H…F, C—H…O respectively, which play a vital role in
stabilizing the crystal structure. In both the structures, the
intra molecular hydrogen bonds N15--H15…O13 and
N14--H14…N1 were closed to form a S(6) ring motif,
whereas the N14--H14…O17 hydrogen bond links pairs of
Atoms
2e
Atoms
2g
C2–N1–N5
107.72(16)
123.46(19)
112.7(2)
C2-N1-N5
107.2(2)
N1–C2–C6
N1-C2-C6
122.3(2)
N1–C2–C3
N1-C2-C3
114.0(2)
C6–C2–C3
123.84(19)
103.24(16)
113.48(17)
99.48(16)
111.96(19)
122.80(17)
123.78(18)
113.37(16)
120.1(2)
C6-C2-C3
123.6(2)
C2–C3–C4
C2-C3-C4
104.2(2)
molecules related by inversion, forming the familiar R2 (10)
2
N5–C4–C26
N5–C4–C3
N5-C4-C27
N5-C4-C3
113.16(19)
100.33(18)
115.5(2)
ring motif. In the compound 2e, the packing of the mole-
cule, when viewed along the c axis indicates that the
molecules were interlinked by the intermolecular hydrogen
bonds to form a chain like structure (Fig. 4), whereas, for
the compound 2g, the packing of the molecule indicates that
they were interconnected by these hydrogen bonds to form a
zig-zag structure (Figs 5 and 6).
C26–C4–C3
C12–N5–N1
C12–N5–C4
N1–N5–C4
C27-C4-C3
C12-N5-N1
C12-N5-C4
N1-N5-C4
122.1(2)
121.16(19)
113.96(18)
120.3(3)
C11–C6–C2
O13–C12–N5
O13–C12–N14
N5–C12–N14
C12–N14–N15
N14–N15–S16
O18–S16–O17
O18–S16–N15
O17–S16–N15
O18–S16–C19
O17–S16–C19
N15–S16–C19
F25–C22–C21
F25–C22–C23
C11-C6-C2
O13-C12-N5
O13-C12-N14
N5-C12-N14
C12-N14-N15
N14-N15-S16
O18-S16-O17
O18-S16-N15
O17-S16-N15
O18-S16-C19
O17-S16-C19
N15-S16-C19
F25-C22-C21
F25-C22-C23
122.46(19)
122.0(2)
120.7(2)
122.7(2)
115.51(19)
114.17(18)
112.19(14)
120.15(11)
104.02(10)
106.72(11)
108.99(12)
107.85(11)
108.61(10)
119.0(3)
116.6(2)
Hirshfeld surface analysis
117.00(18)
114.58(15)
120.23(11)
104.73(11)
104.66(10)
110.22(12)
106.82(12)
107.98(8)
119.1(3)
The Hirshfeld surface analysis comprising of the dnorm
surface plots, electrostatic potentials and the two-
dimensional fingerprint plots (FPs) were generated in
order to quantify and give visual confirmation of the
intermolecular interactions and to explain the observed
crystal structures (Tables 5 and 6). The quantitative analysis
of the intermolecular interactions can be made by compar-
ing the FPs of the compounds 2e and 2g (Fig. 7). The full
FP of each compound was different in both size and shape,
thus indicating that, the nature and separation of the various
interatomic contacts in the two compounds were very dif-
ferent. The FP for different atom…atom contacts in com-
pounds 2e and 2g and the percentage contribution of each
contacts to the Hirshfeld surfaces of compounds (Fig. 8)
showed that, the greatest contribution was due to H…H
contacts (i.e., dispersive forces), followed by H…C, H…O,
and H…F contacts in each structure. The FP plot for the
compound 2e features a pair of long sharp spikes char-
acteristic of a strong hydrogen bond at di + de≈2.2 Å,
whereas in compound 2g similar sharp spikes occur at a
relatively shorter contact distance di + de≈2.0 Å, indicating
that the hydrogen bonds in compound 2g were shorter and
stronger than those in compound 2e. The crystal structure
118.1(3)
117.2(3)
an envelope conformation on C4 and its mean plane makes
dihedral angles of 15.34(10)°, 65.65(10)°, and 88.73(11)°
with the phenyl, 2,4-difluorophenyl and 2-methoxyphenyl
rings, respectively. The geometry around the S atom was
distorted from regular tetrahedron, with the largest deviation
observed for the O-S-O [O17-S16-O18 = 120.15(11)° and
120.23(11)° for compounds 2e and 2g, respectively] and O-
S-N angle [O17-S16-N15 = 106.72(11)° and 104.66(10)°
for compounds 2e and 2g, respectively]. This widening of
the angles was due to the repulsive interactions between the
S=O bonds and the non-bonded interactions involving the
two S–O bonds and the varied steric hindrance of the
substituent’s. The value of bond angles N15-S16-C19 was
108.61(10)° and 107.98(8)°for the compounds 2e and 2g,
respectively, which was comparable with the ideal tetra-
hedral value of 109.47°and was attributed to the Thorpe-
Ingold effect (Bassindale 1984). Both the structures possess
a chiral center at C4 with R conformation. Since the
molecules have crystallized in a centrosymmetric space
group, we can summarize that the compounds crystallize as
a recemate.
of compound 2e features H…H contacts, with demini
=
dimini≅1.1 Å, while in compound 2g, these contacts appear
at demini = dimini≅1 Å. Also, noteworthy was that the FP for
the H…H contact of compound 2g was slightly broader
than that of compound 2e. This illustrates that, the H…H
contacts in compound 2e were the result of a head-on
approach, while in compound 2g, it is more or less due to
the side-ways approach. Further, the presence of C–H…π
and π…π interactions in both the structures was established
by investigating the FP for both compounds.

Med Chem Res
Fig. 2 ORTEP diagram of the
compound 2e with thermal
ellipsoids drawn at 50%
probability
Fig. 3 ORTEP diagram of the
compound 2g with thermal
ellipsoids drawn at 50%
probability
Conclusions
ray diffraction study of the compounds 2e and 2g was
revealed that, the molecules exhibit both inter and intra-
molecular hydrogen bonds of the type N--H···N, C--H…O,
C--H…N, and N--H…N, N--H…O, C--H…F, C--H…O
respectively, which play a vital role in stabilizing the crystal
structure. The FP for different atom…atom contacts in
In the present study, fourteen pyrazoline derivatives inte-
grated with sulfonamide scaffold were synthesized and
structurally characterized by elemental analysis, UV–Vis,
IR, NMR, and mass spectra. The results of single crystal X-

Med Chem Res
Fig. 4 Packing of the compound
2e, when viewed down along the
c axis. The dotted lines indicate
hydrogen bonds
contacts followed by H…C, H…O and H…F contacts. The
compounds 2m and 2n have shown the best effect over the
growth of M. tuberculosis. The SAR of the compounds
revealed that the antitubercular activity of the synthesized
compounds decreased with the introduction of fluoro atoms
on phenyl ring ‘D’. Majority of the compounds have shown
remarkable high potential antimicrobial activity. The anti-
microbial activity of the pyrazoline derivatives integrated
with sulfonamide scaffold was enhanced with the intro-
duction of fluoro atom on phenyl ring ‘D’. This research
work has an influence on further exploration of the title
compound in the field of drug discovery.
Materials and methods
Chemistry
All the reactions were carried out in oven dried glassware
and under nitrogen atmosphere. Melting point was deter-
mined by an open capillary method and was uncorrected.
The chemicals used for the reaction were from Sigma-
Aldrich Chemical Pvt. Ltd. Bengaluru, India. The reactions
were monitored by thin-layer chromatography (TLC) using
recoated silica gel 60F254 plates (Merck) and 40% ethyl
acetate in petroleum ether was used as mobile phase. Purity
of the synthesized compounds was confirmed by TLC.
Fig. 5 Packing of the compound 2g, when viewed down along the c
axis. The dotted lines indicate hydrogen bonds
compounds 2e and 2g and the percentage contribution of
each contacts to the Hirshfeld surfaces of compounds
showed that the greatest contribution was due to H…H

Med Chem Res
Fig. 6 dnorm and electrostatic potential mapped on Hirshfeld surface for visualizing the intermolecular contacts in compounds 2e (molecule 1) and
2g (molecule 2)
Table 5 Hydrogen bond geometry for compound 2e (Å, °)
Table 6 Hydrogen bond geometry for compound 2g (Å, °)
D—H···A
d (D—H) d (H···A) d (D···A) <(DHA)
D—H···A
d (D—H) d (H···A) d (D···A) <(DHA)
N14--H14···N1
0.86
0.86
1.01
0.97
0.93
0.93
2.39
2.53
2.00
2.59
2.59
2.53
2.35
2.53
2.698 (3) 101
3.113 (3) 126
2.617 (3) 117
3.397 (3) 140
3.262 (4) 130
2.900 (3) 104
3.212 (3) 154
2.877 (3) 103
N14--H14···N1
0.86
0.86
0.97
2.37
2.26
2.45
2.43
2.50
2.49
2.685 (2) 102
2.870 (2) 128
3.345 (3) 153
3.242 (2) 145
3.358 (3) 154
2.869 (3) 105
N14--H14···O17(i)
N15--H15···O13
C3—H3A…O18(ii)
N15--H15···O13(i)
C3—H3A…F25(ii)
C11—H11…O17(iii) 0.93
C21—H21…O18(iv) 0.93
(iii)
C8—H8…O18
C20—H20…O17
C24—H24…O13(iv) 0.93
C24—H24…O18
0.93
Symmetry codes: (i) 1 − x, −y, 2 − z; (ii) 1/2 + x, 1/2 − y, 1/2 + z;
(iii) 2 − x, −y, 2 − z; (iv) −1 + x, y, z
C31—H31···N5 0.82
Symmetry codes: (i) 3/2 − x, 3/2 − y, 1 − z; (ii) −1 + x, y, z; (iii) −1/2
+ x, 3/2 − y, 1/2 + z; (iv) 1 − x, y, 1/2 − z
(FTIR) 100 series spectrometer. Samples were dried at
100 °C, under vacuum for 24 h and 16 scans were averaged
across the spectral range of 400–4000 cm−1. The IR
stretching frequency of the important functional groups was
reported in cm−1. The NMR spectra of the compounds were
recorded on a Bruker amx 400 spectrometer operating at
Spots were detected by their absorption under UV light. The
elemental analysis and spectra were recorded in analytical
lab, Sigma-Aldrich Chemical Pvt. Ltd. Bengaluru, India.
Elemental analysis was performed on Leco-932 CHNS
analyzer. The UV–Vis spectra of the compounds were
determined using Perkin-Elemer lambda spectrometer and
methanol was used as solvent. IR spectra were recorded in
Perkin Elmer Fourier transform infrared spectroscopy
1
400 and 100 MHz for H and 13C nuclei, respectively. The
chemical shifts were given in ppm, coupling constant (J)
values were presented in hertz (Hz) and the abbreviations
were as follows: s (singlet), d (doublet), t (triplet), and

Med Chem Res
Fig. 7 Comparison of the FP for each of compounds 2e and 2g. di was the closest internal distance from a given point on the Hirshfeld surface and
de was the closest external contacts
Fig. 8 Percentage contributions
of the various intermolecular
contacts contributing to the
Hirshfeld surfaces of
compounds 2e and 2g
m (multiplets). The mass spectra of compounds were
recorded on Agilent LC/MVD XCT plus mass
spectrometer.
added. The reaction mass was allowed to stir for 2 h at 5 °C.
The progress of the reaction was monitored using TLC. The
product was extracted with ethyl acetate. The solvent
removed under vacuum and the final product was recrys-
tallized using ethanol. The physical properties, overall
yields, spectral data of synthesized compounds were listed
below.
Synthesis of the pyrazoline derivatives integrated with
sulfonamide scaffold (2a–n)
The N-methyl ester pyrazolines were synthesized from the
corresponding chalcones 1a–n by utilizing the process
mentioned in the literature (Raghav and Singh 2014). These
pyrazoline derivatives was converted into corresponding
carbohydrazide derivatives by the reaction with hydrazine
hydrate at reflux temperature in methanol as mentioned in
the literature (Wu et al. 2013).
The mixture of appropriate pyrazoline derivative (1.00
mmol) and pyridine (2.00 mmol) was dissolved in dichlor-
omethane. The reaction mass was cooled to 5 °C and fluoro
substituted benene sulfonyl chloride (1.02 mmol) was
N’-(4-fluorobenzenesulfonyl)-3,5-diphenyl-4,5-dihydro-1H-
pyrazole-1-carbohydrazide (2a)
Light-yellow crystals. Yield: 65%; m.p. 186–187 °C;
UV–Vis λmax (nm): 296.30, 217.58; FTIR stretching fre-
quencies (cm−1): 1154.72 and 1342.12 (S=O), 1430.91
(C=N), 1673.18 (C=O), 3343.95 (N–H), 3677.16 (N–H);
1H NMR (400 MHz, DMSO-d6) δ (ppm): 3.02–3.07 (dd,
1H, pyrazoline CHaH, J = 5.0 Hz, 18.2 Hz), 3.74–3.82 (dd,
1H, pyrazoline CHHb, J = 12.0 Hz, 18.0 Hz), 5.25–5.29 (dd,

Med Chem Res
1H, pyrazoline CHc, J = 5.2 Hz, 12.0 Hz), 7.02–7.05 (m,
2H, CH arom), 7.21–7.31 (m, 5H, CH arom), 7.43–7.44 (m,
3H, CH arom), 7.79–7.84 (m, 4H, CH arom), 9.39 (s, 1H,
NH2N), 9.68 (s, 1H, NH1N); 13C NMR (100 MHz, DMSO-
d6) δ (ppm): 41.39, 60.28, 115.76, 125.28, 126.77, 127.01,
128.42, 128.53, 129.97, 130.55, 130.64, 131.12, 135.64,
142.41, 152.50, 163.12; Anal. Calcd for C22H19FN4O3S: C,
60.26; H, 4.37; N, 12.78; S, 7.37. Found: C, 60.27; H, 4.38;
N, 12.76; S, 6.09; ESI MS: m/z = 439.2 [M + H]+.
5-(4-chlorophenyl)-N’-(4-fluorobenzenesulfonyl)-3-phenyl-
4,5-dihydro-1H-pyrazole-1-carbohydrazide (2d)
White crystalline solid. Yield: 72%; m.p. 231–232 °C;
UV–Vis λmax (nm): 294.96, 220.24; FTIR stretching fre-
quencies (cm−1): 1167.78 and 1342.30 (S=O), 1468.89
(C=N), 1677.03 (C=O), 2879.78 (CH arom), 3117.98
1
(N–H), 3414.10 (N–H); H NMR (400 MHz, DMSO-d6) δ
(ppm): 3.09–3.15 (dd, 1H, pyrazoline CHaH, J = 5.6 Hz,
18.0 Hz), 3.80–3.87 (dd, 1H, pyrazoline CHHb, J = 12.2
Hz, 17.8 Hz), 5.31–5.35 (dd, 1H, pyrazoline CHc, J = 5.4
Hz, 11.8 Hz), 7.10–7.13 (dd, 2H, CH arom, J = 2.2 Hz, 8.6
Hz), 7.31–7.36 (m, 2H, CH arom), 7.40–7.42 (dd, 2H, CH
arom, J = 2.2 Hz, 8.2 Hz), 7.50–7.51 (t, 3H, CH arom, J =
3.2 Hz), 7.85–7.91 (m, 4H, CH arom), 9.45 (s, 1H, NH2N),
9.71 (s, 1H, NH1N); 13C NMR (100 MHz, DMSO-d6)
δ (ppm): 41.47, 59.70, 115.71, 126.79, 127.36, 128.38,
128.54, 130.04, 130.63, 131.03, 131.62, 135.51, 141.32,
152.35, 152.66, 163.08; Anal. Calcd for C22H18ClFN4O3S:
C, 55.87; H, 3.84; N, 11.85; S, 6.78. Found: C, 55.85; H,
3.86; N, 11.82; S, 6.45; ESI MS: m/z = 471.0 [M + H]+.
N’-(4-fluorobenzenesulfonyl)-5-(4-fluorophenyl)-3-phenyl-
4,5-dihydro-1H-pyrazole-1-carbohydrazide (2b)
Light-yellow crystalline solid. Yield: 82%; m.p. 228–229 °C;
UV–Vis λmax (nm): 296.74, 219.80; FTIR stretching fre-
quencies (cm−1): 1154.80 and 1342.32 (S=O), 1486.73
(C=N), 1675.52 (C=O), 2882.09 (CH arom), 3108.96
1
(N–H), 3414.14 (N–H); H NMR (400 MHz, DMSO-d6) δ
(ppm): 2.85–2.90 (dd, 1H, pyrazoline CHaH, J = 5.6 Hz,
18.0 Hz), 3.54–3.62 (dd, 1H, pyrazoline CHHb, J = 12.0
Hz, 18.4 Hz), 5.07–5.11 (dd, 1H, pyrazoline CH, J = 5.2
Hz, 12.8 Hz), 6.87–6.95 (m, 4H, CH arom), 7.07–7.12 (m,
2H, CH arom), 7.25–7.27 (m, 3H, CH arom), 7.61–7.67 (m,
N’-(4-fluorobenzenesulfonyl)-5-(4-methoxyphenyl)-3-
phenyl-4,5-dihydro-1H-pyrazole-1-carbohydrazide (2e)
4H, CH arom), 9.19 (s, 1H, NH2N), 9.47 (s, 1H, NH1N); 13
C
NMR (100 MHz, DMSO-d6) δ (ppm): 41.61, 59.68, 115.13,
115.70, 126.80, 127.46, 128.54, 130.01, 130.64, 131.08,
135.52, 138.58, 152.33, 152.69, 159.99, 163.03; Anal.
Calcd for C22H18F2N4O3S: C, 57.89; H, 3.97; N, 12.27; S,
7.02. Found: C, 57.90; H, 3.94; N, 12.29; S, 7.12; ESI MS:
m/z = 457.2 [M + H]+.
Light-pink color powder. Yield: 62%; m.p. 196–197 °C;
UV–Vis λmax (nm): 298.08, 223.36; FTIR stretching fre-
quencies (cm−1): 1169.56 and 1423.93 (S = O), 1482.60
(C = N), 1667.86 (C = O), 2967.77 (CH3), 3063.02 (CH
arom), 3100.90 (CH arom), 3176.75 (N–H), 3354.01
(N–H);1H NMR (400 MHz, DMSO-d6) δ (ppm): 3.07–3.12
(dd, 1H, pyrazoline CHaH, J = 5.2 Hz, 17.6 Hz), 3.76–3.84
(dd, 1H, pyrazoline CHHb, J = 11.8 Hz, 17.8 Hz), 3.79 (s,
3H, CH3), 5.26–5.30 (dd, 1H, pyrazoline CHc, J = 5.2 Hz,
12.2 Hz), 6.89–6.91 (d, 2H, CH arom, J = 8.4 Hz),
7.01–7.03 (d, 2H, CH arom, J = 8.8 Hz), 7.32–7.36 (m, 2H,
CH arom), 7.49–7.51 (t, 3H, CH arom, J = 3.2 Hz),
7.85–7.91 (m, 4H, CH arom), 9.37 (s, 1H, NH2N), 9.69 (s,
1H, NH1N); 13C NMR (100 MHz, DMSO-d6) δ (ppm):
41.66, 55.07, 59.83, 113.78, 115.71, 126.61, 126.76,
128.54, 129.94, 130.60, 131.20, 134.45, 135.58, 152.26,
152.63, 158.34, 163.07; Anal. Calcd for C23H21FN4O4S: C,
58.96; H, 4.52; N, 11.96; S, 6.84. Found: C, 58.92; H, 4.50;
N, 11.94; S, 6.73; ESI MS: m/z = 469.2 [M + H]+.
5-(4-bromophenyl)-N’-(2,4-difluorobenzenesulfonyl)-3-
phenyl-4,5-dihydro-1H-pyrazole-1-carbohydrazide (2c)
Light-brown powder. Yield: 72%; m.p. 224–225 °C;
UV–Vis λmax (nm): 298.52, 219.80; FTIR stretching fre-
quencies (cm−1): 1162.85 and 1348.97 (S=O), 1471.76
(C=N), 1675.41 (C=O), 2883.29 (CH arom), 3101.19
1
(N–H), 3404.71 (N–H); H NMR (400 MHz, DMSO-d6) δ
(ppm): 3.01–3.07 (dd, 1H, pyrazoline CHaH, J = 5.4 Hz,
18.2 Hz), 3.73–3.80 (dd, 1H, pyrazoline CHHb, J = 12.0
Hz, 18.0 Hz), 5.22–5.27 (dd, 1H, pyrazoline CHc, J = 5.6
Hz, 12.0 Hz), 6.94–6.97 (m, 2H, CH arom), 7.08–7.13 (m,
1H, CH arom), 7.27–7.33 (m, 1H, CH arom), 7.42–7.49 (m,
5H, CH arom), 7.75–7.84 (m, 3H, CH arom), 9.48 (s, 1H,
NH2N), 9.93(s, 1H, NH1N); 13C NMR (100 MHz, DMSO-
d6) δ (ppm):41.38, 59.79, 105.38, 111.32, 120.07, 124.02,
126.80, 127.60, 128.54, 130.04, 130.99, 131.30, 132.37,
141.71, 152.38, 152.67, 158.80, 163.95; Anal. Calcd. for
C22H17BrF2N4O3S: C, 49.36; H, 3.20; N, 10.47; S, 5.99.
Found: C, 49.34; H, 3.21; N, 10.45; S, 6.10; ESI MS: m/z =
534.9 [M + H]+.
N’-(4-fluorobenzenesulfonyl)-5-(4-methylphenyl)-3-phenyl-
4,5-dihydro-1H-pyrazole-1-carbohydrazide (2f)
White powder. Yield: 75%; m.p. 212–213 °C; UV–Vis λmax
(nm): 297.19, 219.35; FTIR stretching frequencies (cm−1):
1169.16 and 1342.68 (S=O), 1492.56 (C=N), 1672.52 (C=O),
1
3059.06 (CH3), 3241.77 (N–H), 3416.03 (N–H); H NMR
(400 MHz, DMSO-d6) δ (ppm): 2.33 (s, 3H, CH3) 3.05–3.11

Med Chem Res
(dd, 1H, pyrazoline CHaH, J = 5.4 Hz, 17.8 Hz), 3.78–3.85 (dd,
1H, pyrazoline CHHb, J = 11.8 Hz, 17.8 Hz), 5.27–5.31 (dd,
1H, pyrazoline CHc, J = 5.2 Hz, 12.0 Hz), 6.97–6.99 (d, 2H,
CH arom, J = 8.4 Hz), 7.14–7.16 (d, 2H, CH arom, J = 8.8
Hz), 7.35–7.35 (t, 2H, CH arom, J = 9.2 Hz), 7.49–7.51 (m,
3H, CH arom), 7.85–7.90 (m, 4H, CH arom), 9.38 (s, 1H,
NH2N), 9.67 (s, 1H, NH1N); 13C NMR (100 MHz, DMSO-d6) δ
(ppm): 20.58, 41.66, 60.09, 115.72, 125.26, 126.74, 128.55,
128.93, 129.94, 130.58, 131.16, 135.58, 136.18, 139.53,
152.27, 152.64, 163.20; Anal. Calcd for C23H21FN4O3S: C,
61.05; H, 4.68; N, 12.38; S, 7.09. Found: C, 61.07; H, 4.70; N,
12.35; S, 7.10; ESI MS: m/z = 453.2 [M + H]+.
C, 53.66; H, 3.28; N, 11.38; S, 6.76. Found: C, 53.67; H,
3.29; N, 11.34; S, 6.78; ESI MS: m/z = 475.2 [M + H]+.
N’-(2,4-difluorobenzenesulfonyl)-3,5-diphenyl-4,5-dihydro-
1H-pyrazole-1-carbohydrazide (2i)
Light-yellow powder. Yield: 70%; m.p. 189–190 °C;
UV–Vis λmax (nm): 297.19, 218.46; FTIR stretching fre-
quencies (cm−1): 1170.23 and 1348.77 (S=O), 1509.35
(C=N), 1653.77 (C=O), 3114.57 (N–H), 3356.97 (N–H);
1H NMR (400 MHz, DMSO-d6) δ (ppm): 3.07–3.13 (dd,
1H, pyrazoline CHaH, J = 5.2 Hz, 18.0 Hz), 3.80–3.88 (dd,
1H, pyrazoline CHHb, J = 11.8 Hz, 18.2 Hz), 5.31–5.35
(dd, 1H, pyrazoline CHc, J = 6.0 Hz, 12.2 Hz), 7.06–7.08
(m, 2H, CH arom), 7.15–7.20 (m, 1H, CH arom), 7.26–7.40
(m, 4H, CH arom), 7.48–7.51 (m, 3H, CH arom), 7.83–7.91
(m, 3H, CH arom), 9.52 (s, 1H, NH2N) 10.0 (s, 1H, NH1N);
13C NMR (100 MHz, DMSO-d6) δ (ppm): 40.29, 58.79,
104.11, 109.94, 122.66, 123.80, 125.36, 125.56, 126.97,
127.10, 128.55, 129.69, 130.84, 140.88, 150.91, 151.35,
157.35, 162.44; Anal. Calcd for C22H18F2N4O3S: C, 57.89;
H, 3.97; N, 12.27; S, 7.02. Found: C, 57.87; H, 3.96; N,
12.28; S, 7.05; ESI MS: m/z = 457.2 [M + H]+.
N’-(2,4-difluorobenzenesulfonyl)-5-(4-methoxyphenyl)-3-
phenyl-4,5-dihydro-1H-pyrazole-1-carbohydrazide (2g)
Light-brown crystalline solid. Yield: 68%; m.p. 197–198 °
C; UV–Vis λmax (nm): 295.41, 222.91; FTIR stretching
frequencies (cm−1): 1163.23 and 1351.6 (S=O), 1473.77
(C=N), 1672.81 (C=O), 2882.25 (CH3), 3102.02 (N–H),
1
3405.91 (N–H); H NMR (400 MHz, DMSO-d6) δ (ppm):
3.00–3.05 (dd, 1H, pyrazoline CHaH, J = 5.2 Hz, 18.0 Hz),
3.70–3.77 (dd, 1H, pyrazoline CHHb, J = 12.4 Hz, 17.6
Hz), 3.73 (s, 3H, CH3), 5.19–5.24 (dd, 1H, pyrazoline CHc,
J = 5.2 Hz, 12.0 Hz), 6.82–6.94 (dd, 4H, CH arom, J = 8.8
Hz, 39.2 Hz), 7.09–7.14 (m, 1H, CH arom), 7.30–7.36 (m,
1H, CH arom), 7.43–7.44 (m, 3H, CH arom), 7.76–7.84 (m,
N’-(2,4-difluorobenzenesulfonyl)-5-(4-methylphenyl)-3-
phenyl-4,5-dihydro-1H-pyrazole-1-carbohydrazide (2J)
Light-yellow crystals. Yield: 55%; m.p. 184–185 °C;
UV–Vis λmax (nm): 296.74, 217.13. FTIR stretching fre-
quencies (cm−1): 1169.70 and 1347.30 (S=O), 1506.00
(C=N), 1668.32 (C=O), 2884.30 (CH3), 3104.00 (CH
arom), 3404.61 (N–H), 3343.90 (N–H); 1H NMR (400
MHz, DMSO-d6) δ (ppm): 2.32 (s, 3H, CH3), 3.01–3.09 (dd,
1H, pyrazoline CHaH, J = 5.2 Hz, 12.8 Hz), 3.76–3.84 (dd,
1H, pyrazoline CHHb, J = 12.0 Hz, 18.0 Hz), 5.25–5.30 (dd,
1H, pyrazoline CHc, J = 5.2 Hz, 12.0 Hz), 6.93–6.95 (d, 2H,
CH arom), 7.12–7.19 (m, 3H, CH arom), 7.34–7.39 (m, 1H,
CH arom), 7.48–7.49 (m, 3H, CH arom), 7.81–7.89 (m, 3H,
CH arom), 9.48 (s, 1H, NH2N), 9.97 (s, 1H, NH1N); 13C
NMR (100 MHz, DMSO-d6) δ (ppm): 20.57, 41.65, 60.00,
105.48, 111.27, 124.02, 125.20, 126.74, 128.53, 128.90,
129.92, 131.15, 132.26, 136.09, 139.36, 152.25, 152.68,
161.32; Anal. Calcd for C23H20F2N4O3S: C, 58.72; H, 4.28;
N, 11.91; S, 6.81. Found: C, 58.70; H, 4.25; N, 11.92; S,
6.89; ESI MS: m/z = 471.2 [M + H]+.
3H, CH arom), 9.41 (s, 1H, NH2N), 9.91 (s, 1H, NH1N); 13
C
NMR (100 MHz, DMSO-d6) δ (ppm): 41.61, 55.02, 59.72,
105.51, 111.42, 113.73, 124.14, 126.52, 126.74, 128.53,
129.94, 131.17, 132.35, 134.34, 152.29, 152.64, 158.30,
161.34, 166.50; Anal. Calcd for C23H20F2N4O4S: C, 56.78;
H, 4.14; N, 11.52; S, 6.59. Found: C, 56.76; H, 4.16; N,
11.54; S, 6.65; ESI MS: m/z = 487.2 [M + H]+.
N’-(4-fluorobenzenesulfonyl)-3,5-bis(4-fluorophenyl)-4,5-
dihydro-1H-pyrazole-1-carbohydrazide (2h)
Brown solid. Yield: 80%; m.p. 227–228 °C; UV–Vis λmax
(nm): 293.19, 221.13; FTIR stretching frequencies (cm−1):
1156.34 and 1339.85 (S=O), 1494.86 (C=N), 1689.74
1
(C=O), 3247.15 (N–H), 3440.55 (N–H); H NMR (400
MHz, DMSO-d6) δ (ppm): 2.94–3.00 (dd, 1H, pyrazoline
CHaH, J = 5.6 Hz, 18.0 Hz), 3.63–3.70 (dd, 1H, pyrazoline
CHHb, J = 12.0 Hz, 18.0 Hz), 5.16–5.20 (dd, 1H, pyrazo-
line CHc, J = 5.2 Hz, 12.0 Hz), 6.96–7.05 (m, 4H, CH
arom), 7.16–7.23 (m, 4H, CH arom), 7.70–7.73 (m, 2H, CH
arom), 7.79–7.83 (m, 2H, CH arom),9.32 (s, 1H, NH2N),
9.56 (s, 1H, NH1N); 13C NMR (100 MHz, DMSO-d6) δ
(ppm): 41.72, 59.80, 115.00, 115.22, 115.65, 127.46,
127.75, 129.13, 130.61, 135.49, 138.50, 151.44, 152.73,
160.02, 161.86, 163.12; Anal. Calcd for C22H16F4N4O3S:
N’-(benzenesulfonyl)-5-(4-bromophenyl)-3-phenyl-4,5-
dihydro-1H-pyrazole-1-carbohydrazide (2k)
White powder. Yield: 68%; m.p. 227–228 °C; UV–Vis λmax
(nm): 296.30, 220.24; FTIR stretching frequencies (cm−1):
1165.90 and 1338.25 (S=O), 1505.92 (C=N), 1676.48
1
(C=O), 3211.46 (N–H), 3345.36 (N–H). H NMR (400

Med Chem Res
MHz, DMSO-d6) δ (ppm): 3.09–3.15 (dd, 1H, pyrazoline
CHaH, J = 5.6 Hz, 18.0 Hz), 3.80–3.87 (dd, 1H, pyrazoline
CHHb, J = 12.0 Hz, 16.6 Hz), 5.30–5.34 (dd, 1H, pyrazo-
line CHc, J = 5.2 Hz, 12.0 Hz), 7.06–7.08 (dd, 2H, CH
arom, J = 2.0 Hz, 6.4 Hz), 7.49–7.51 (m, 3H, CH arom),
7.53–7.54 (m, 2H, CH arom), 7.55–7.56 (m, 2H, CH arom),
7.61–7.65 (m, 1H, CH arom), 7.82–7.84 (d, 2H, CH arom,
J = 7.6 Hz), 7.87–7.90 (m, 2H, CH arom), 9.37 (s, 1H,
NH2N), 9.66 (s, 1H, NH1N); 13C NMR (100 MHz, DMSO-
d6) δ (ppm): 41.46, 59.79, 120.09, 126.79, 127.50, 127.78,
128.54, 128.60, 130.02, 131.04, 131.33, 132.51,
139.38, 141.86, 152.31, 152.75; Anal. Calcd for
C22H19BrN4O3S: C, 52.91; H, 3.84; N, 11.22; S, 6.42.
Found: C, 52.95; H, 3.88; N, 11.25; S, 6.49; ESI MS: m/z =
499.38 [M + H]+.
Hz), 7.60–7.64 (m, 1H, CH arom), 7.83–7.85 (d, 2H, CH
arom, J = 7.6 Hz), 7.88–7.90 (m, 2H, CH arom), 9.40 (s,
1H, NH2N), 9.70 (s, 1H, NH1N); 13C NMR (100 MHz,
DMSO-d6) δ (ppm): 41.61, 59.75, 124.12, 125.33, 126.80,
127.42, 128.62, 130.07, 130.50, 131.01, 132.61, 133.07,
139.44, 144.88, 152.35, 152.84; Anal. Calcd for
C22H19ClN4O3S: C, 58.08; H, 4.21; N, 12.32; S, 7.05.
Found: C, 58.10; H, 4.25; N, 12.33; S, 7.10; ESI MS: m/z =
454.93 [M + H]+.
N’-(benzenesulfonyl)-3,5-diphenyl-4,5-dihydro-1H-
pyrazole-1-carbohydrazide (2n)
Light-yellow colored crystals. Yield: 69%; m.p. 230–231 °
C; UV–Vis λmax (nm): 295.41, 216.69; FTIR stretching
frequencies (cm−1): 1166.85 and 1331.97 (S=O), 1474.15
(C=N), 1690.43 (C=O), 3069.55 (Ar–H), 3211.68 (N–H),
N’-(benzenesulfonyl)-5-[4-(methylsulfanyl)phenyl]-3-
phenyl-4,5-dihydro-1H-pyrazole-1-carbohydrazide (2l)
1
3418.56 (N–H); H NMR (400 MHz, DMSO-d6) δ (ppm):
3.13–3.19 (dd, 1H, pyrazoline CHaH, J = 5.6 Hz, 17.6 Hz),
3.83–3.91 (dd, 1H, pyrazoline CHHb, J = 12.0 Hz, 18.0
Hz), 5.40–5.44 (dd, 1H, pyrazoline CHc, J = 5.6 Hz, 12.0
Hz), 7.34–7.34 (d, 2H, CH arom, J = 8.4 Hz), 7.49–7.53
(m, 5H, CH arom), 7.56–7.60 (m, 1H, CH arom),
7.71–7.73 (d, 2H, CH arom, J = 8.4 Hz), 7.81–7.84 (d, 2H,
CH arom, 7.2 Hz), 7.88–7.90 (m, 2H, CH arom), 9.43 (s,
1H, NH2N), 9.60 (s, 1H, NH1N); 13C NMR (100 MHz,
DMSO-d6) δ (ppm): 41.43, 59.98, 125.46, 125.58, 126.31,
126.81, 127.51, 127.86, 128.59, 130.09, 130.97, 132.48,
139.31, 147.02, 152.31, 152.78; Anal. Calcd for
C22H20N4O3S: C, 62.84; H, 4.75; N, 13.32; S, 7.62. Found:
C, 62.80; H, 4.75; N, 13.30; S, 7.68; ESI MS: m/z = 420.49
[M + H]+.
Light-yellow crystals. Yield: 60%; m.p. 175–176 °C;
UV–Vis λmax (nm): 294.07, 260.27, 217.58; FTIR stretch-
ing frequencies (cm−1): 1166.51 and 1338.96 (S=O),
1505.83 (C=N), 1690.87 (C=O), 3059.10 (CH arom),
3248.35 (N–H), 3416.00 (N–H); 1H NMR (400 MHz,
DMSO-d6) δ (ppm): 2.45 (s, 3H, CH3), 3.01–3.07 (dd, 1H,
pyrazoline CHaH, J = 5.2 Hz, 18.0 Hz), 3.72–3.80 (dd, 1H,
pyrazoline CHHb, J = 12.0 Hz, 18.0 Hz), 5.22–5.26 (dd,
1H, pyrazoline CHc, J = 4.8 Hz, 11.6 Hz), 6.98–7.00 (d,
2H, CH arom, J = 8.4 Hz), 7.17–7.19 (d, 2H, CH arom, J =
8.4 Hz), 7.43–7.46 (m, 3H, CH arom), 7.48–7.50 (d, 2H,
CH arom, J = 7.6 Hz), 7.56–7.59(m, 1H, CH arom),
7.76–7.78 (d, 2H, CH arom, J = 7.6 Hz), 7.81–7.83 (m, 2H,
CH arom), 9.26 (s, 1H, NH2N), 9.59 (s, 1H, NH1N); 13C
NMR (100 MHz, DMSO-d6) δ (ppm): 14.58, 41.54, 59.89,
126.09, 126.21, 126.76, 127.50, 128.55, 128.62, 129.96,
131.12, 132.54, 136.72, 139.72, 139.39, 152.24, 152.78;
Anal. Calcd for C23H22N4O3S2: C, 59.21; H, 4.75; N,
12.01. S, 13.74. Found: C, 59.25; H, 4.71; N, 12.04; S,
13.67; ESI MS: m/z = 466.57 [M + H]+.
Biological assay
Antitubercular studies
Antitubercular activity was carried out against strain M.
tuberculosis by MABA method (Franzblau et al. 1998).The
outer perimeter wells of sterile 96-wells plate (falcon, 3072:
Becton Dickinson, Lincoln Park NJ) was covered with 200
μL of sterile deionized water to minimize evaporation of the
medium. The 96-wells plate received 100 µl of the Mid-
dlebrook 7H9 broth (Difco laboratories, Detroit, MI, USA)
and serial dilutions of compounds were made directly on the
plate. The final drug concentrations tested were 100 to 0.8
µg/mL. Plates were covered and sealed with parafilm and
incubated at 37 °C for 5 days. After 5 days 25 µl of freshly
prepared 1:1 mixture of almar blue reagent (Accumed
International, Westlake Ohio) and 10% tween 80 was added
to the plate and incubated for 24 h. A blue color in the well
was interpreted as no bacterial growth and pink color was
scored as growth. The results were compared with the MIC
N’-(benzenesulfonyl)-5-(4-chlorophenyl)-3-phenyl-4,5-
dihydro-1H-pyrazole-1-carbohydrazide (2m)
Colorless crystals. Yield: 59%; m.p. 201–202 °C; UV–Vis
λmax (nm): 295.85, 220.24; FTIR stretching frequencies
(cm−1): 1163.76 and 1331.61 (S=O), 1504.44 (C=N),
1671.36 (C=O), 3232.89 (N–H), 3338.66 (N–H); 1H NMR
(400 MHz, DMSO-d6) δ (ppm):3.13–3.19 (dd, 1H, pyr-
azoline CHaH, J = 5.6 Hz, 18.0 Hz), 3.80–3.88 (dd, 1H,
pyrazoline CHHb, J = 12.0 Hz, 18.0 Hz), 5.34–5.38 (dd,
1H, pyrazoline CHc, J = 5.6 Hz, 12.4 Hz), 7.08–7.20
(m, 2H, CH arom), 7.35–7.42 (m, 2H, CH arom), 7.50–7.51
(m, 3H, CH arom), 7.53–7.55 (d, 2H, CH arom, J = 8.0

Med Chem Res
of standard drug pyrazinamide, ciprofloxacin, and
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