Synthesis, characterization, and biological applications of pyrazole moiety bearing osmium(IV) complexes

Article abstract of DOI:10.1080/15257770.2021.1921795

Osmium (IV) complexes with pyrazole nucleus containing ligands were synthesized. Os(IV) compounds were characterized using ESI-MS, ICP-OES, IR spectroscopy, electronic spectroscopy, conductance, and magnetic measurements. Whereas, ligands were characterized by heteronuclear spectroscopy, (¹H and ¹³C), IR spectroscopy, and elemental analysis. All the compounds were tested for their potential to interact with HS-DNA by absorption titration, fluorescence spectroscopy, viscosity measurement, and docking study. The quenching constant and Stern Volmer constant values were calculated using fluorescence study. The synthesized compounds were studied for in-vitro bacteriostatic and cytotoxic activities. The cancer cell line studies of all the synthesized complexes were carried out on human lung cancer cells (A549). Supplemental data for this article is available online at https://doi.org/10.1080/15257770.2021.1921795.

Full text of DOI:10.1080/15257770.2021.1921795

Nucleosides, Nucleotides & Nucleic Acids
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/lncn20
Synthesis, characterization, and biological
applications of pyrazole moiety bearing
osmium(IV) complexes
Bharat H. Pursuwani, Bhupesh S. Bhatt, Dilip B. Raval, Vasudev R. Thakkar,
Jyoti Sharma, Chandramani Pathak & Mohan N. Patel
To cite this article: Bharat H. Pursuwani, Bhupesh S. Bhatt, Dilip B. Raval, Vasudev R. Thakkar,
Jyoti Sharma, Chandramani Pathak & Mohan N. Patel (2021) Synthesis, characterization, and
biological applications of pyrazole moiety bearing osmium(IV) complexes, Nucleosides, Nucleotides
&
Nucleic Acids, 40:6, 593-618, DOI: 10.1080/15257770.2021.1921795
To link to this article: https://doi.org/10.1080/15257770.2021.1921795
View supplementary material
Published online: 28 May 2021.
Submit your article to this journal
Article views: 78
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
https://www.tandfonline.com/action/journalInformation?journalCode=lncn20

Nucleosides, Nucleotides aNd Nucleic acids
021, Vol. 40, No. 6, 593–618
2
hꢂꢂpꢆ://ꢁꢇꢅ.ꢇrg/10.1080/15257770.2021.1921795
Synthesis, characterization, and biological applications
of pyrazole moiety bearing osmium(IV) complexes
a
a
b
Bharat H. Pursuwani , Bhupesh S. Bhatt
, Dilip B. Raval , Vasudev R.
b
c
c
Thakkar
, Jyoti Sharma , Chandramani Pathak
, and Mohan N.
a
Patel
ꢀ
b
sꢀrꢁꢀr Pꢀꢂꢃꢄ unꢅvꢃrꢆꢅꢂy, chꢃmꢅꢆꢂry, Vꢀꢄꢄꢀbh Vꢅꢁyꢀnꢀgꢀr, inꢁꢅꢀ; sꢀrꢁꢀr Pꢀꢂꢃꢄ unꢅvꢃrꢆꢅꢂy, Bꢅꢇꢆꢈꢅꢃnꢈꢃ,
ꢈ
Vꢀꢄꢄꢀbh Vꢅꢁyꢀnꢀgꢀr, inꢁꢅꢀ; amꢅꢂy inꢆꢂꢅꢂꢉꢂꢃ ꢇf Bꢅꢇꢂꢃꢈhnꢇꢄꢇgy, amꢅꢂy unꢅvꢃrꢆꢅꢂy, Hꢀryꢀnꢀ, Gꢉrgꢀꢇn,
inꢁꢅꢀ
ARTICLE HISTORY
Received 4 July 2019
Accepted 21 April 2021
ABSTRACT
Osmium (IV) complexes with pyrazole nucleus containing
ligands were synthesized. Os(IV) compounds were characterized
using ESI-MS, ICP-OES, IR spectroscopy, electronic spectroscopy,
conductance, and magnetic measurements. Whereas, ligands
were characterized by heteronuclear spectroscopy, ( H and C),
IR spectroscopy, and elemental analysis. All the compounds
were tested for their potential to interact with HS-DNA by
absorption titration, fluorescence spectroscopy, viscosity mea-
surement, and docking study. The quenching constant and
Stern Volmer constant values were calculated using fluores-
cence study. The synthesized compounds were studied for
in-vitro bacteriostatic and cytotoxic activities. The cancer cell
line studies of all the synthesized complexes were carried out
on human lung cancer cells (A549).
KEYWORDS
Pyrazole nucleus;
absorption titration;
docking;
1
13
Os(IV) complexes
GRAPHICAL ABSTRACT
CONTACT Mꢇhꢀn N. Pꢀꢂꢃꢄ
jꢃꢃnꢃn@gmꢀꢅꢄ.ꢈꢇm
sꢀrꢁꢀr Pꢀꢂꢃꢄ unꢅvꢃrꢆꢅꢂy, chꢃmꢅꢆꢂry, Vꢀꢄꢄꢀbh Vꢅꢁyꢀnꢀgꢀr
3
88120 inꢁꢅꢀ
sꢉppꢄꢃmꢃnꢂꢀꢄ ꢁꢀꢂꢀ fꢇr ꢂhꢅꢆ ꢀrꢂꢅꢈꢄꢃ ꢅꢆ ꢀvꢀꢅꢄꢀbꢄꢃ ꢇnꢄꢅnꢃ ꢀꢂ hꢂꢂpꢆ://ꢁꢇꢅ.ꢇrg/10.1080/15257770.2021.1921795.
2021 tꢀyꢄꢇr & Frꢀnꢈꢅꢆ Grꢇꢉp, llc
©

5
94
B. H. PURSUWANI ET AL.
Introduction
After the success of cisplatin in chemotherapy, there has been an eye over
the diverse fields of inorganic medicinal chemistry to explore applications
of metal complexes in chemotherapy.[ There is a continuous investigation
going on medicinal chemistry field to discover transition metal ion-based
complexes that could serve as more effective chemotherapeutic agents
1]
[
2]
with fewer side effects compared to reported drugs. Metal complexes
have been proved to be important in inorganic medicinal chemistry in
curing diseases and treating cancer. Human lung cancer cell line A549 is
commonly used for in vivo cytotoxicity of human carcinoma against epi-
[
3]
thelial cells.
DNA has been a primary target for any drug to cure diseases.[4] Metal
complexes could readily interact with DNA and are used in curing dis-
eases. Interaction of metal-based compounds with DNA to alter biological
[
5]
mechanisms could help in finding different cisplatin analogs. Metal
complexes bind with DNA via different selective modes such as interca-
lative, partial intercalative, groove, noncovalent, and electrostatic modes
of interactions.[ The binding affinities of metal complexes vary according
to the environment around the central metal ion. Metal complexes having
greater binding affinity could interact more effectively with DNA sequences
by one of the above modes.[7]
6]
Coordination compounds with sulfur and nitrogen atoms have been
[
8]
developed because of their significant roles in biological applications.
The pyrazole ring has been an effective bioactive motif in medicinal
organic chemistry. Heterocycles with pyrazole in the nucleus possess effec-
[
9]
tive antibacterial, antifungal and antimalarial activities. Pyrazole nucle-
[
10]
us-based metal complexes have proven to be effective as anticancer drugs.
Metal ions coordinated with sulfur and nitrogen atoms possess anti-in-
flammatory activities.[ Osmium is present in small amounts in nature
11]
[
12]
and has been explored as anticancer drugs.
Synthetic chemistry of
ruthenium, osmium, and iridium metal ions has been explored widely.[
These metal ions are of great interest since they possess different oxidation
states. Osmium(IV) complexes with nitrogen atom donating imidazolenu-
cleus-based heterocyclic ligands have been evaluated for their cytotoxicity
effect as antitumor drugs.[ Osmium metal ion complexes with pyridyl
nucleus ligands have been explored for their luminescence properties.[
Various approaches have been developed to study modes of action of
bioactive molecules. Amongst them, fluorescence has been proved to be
successful in monitoring the mode of interaction of bioactive molecules
with a DNA sequence. Fluorescent inducing probes have been used to
examine anticancer mechanisms. Tumor penetration can be mapped with
13]
14]
15]
[
16]
the help of fluorescence quenching studies.

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
595
This report presents the synthesis, characterization, and biological appli-
cation of nine heterocyclic ligands containing a pyrazole nucleus forming
bidentate and tridentate coordination complexes with Os(IV) metal. The
synthesized compounds were screened for biological studies such as in-vivo
and in-vitro cytotoxicity. DNA binding behavior was studied via absorption
titration, viscosity measurements, molecular docking, and fluorescence
quenching studies.
Materials and methods
Material and reagents
The chemicals were purchased and used without further purification.
Osmium tetroxide, 3-acetyl thiophene, 5-bromo-3-acetyl thiophene,
5
-chloro-3-acetyl thiophene, 3-bromo-3-acetyl thiophene, 5-iodo-3-acetyl
thiophene, potassium tert-butoxide, benzhydrazide have been obtained
from Sigma- Aldrich. Ethidium bromide and Schizosaccharomyces pombe
cells were purchased from IMTECH, Chandigarh, India. Various bacteria
used for the study were obtained from the Institute of microbial technol-
ogy, Chandigarh, India. All the studies were carried out using double
distilled water. Infrared spectra were taken from FT-IR spectrophotometer,
ABB Bomen Inc, Canada.
Physical measurements
Elemental percentages were determined using 240 Perkin Elmer instrument
(
MA, USA). Infrared spectra were taken using a Shimadzu spectropho-
−
1
tometer in the spectral range of 400–4000 cm . UV spectroscopy data
were taken using a UC-160A instrument (Kyoto, Japan). Heteronuclear
spectra were taken using a Bruker Avance (400 MHz) instrument. LC-MS
were taken using a thermo scientific mass spectrometer. Magnetic mea-
surements were taken using a Guoy’s balance. A laminar airflow cabinet
(
Toshiba) was used for carrying out bacteriostatic activity measurements.
A fluoroMax-4 spectrofluorometer was used to do fluorescence quenching
TM
studies. AlphaDigiDoc software was used to observe photolytic cleaved
images (CA, USA).
General method for synthesis of ligands
2
-Chloro-3-formyl-quinoline was synthesized using a Vilsmeier–Haack reac-
[
17]
tion.
Different quinoline-based thiophene and acetophenone derivatives
[
18]
were synthesized using the Claisen Smith condensation.

5
96
B. H. PURSUWANI ET AL.
1
4
Scheme 1. Gꢃnꢃrꢀꢄ rꢃꢀꢈꢂꢅꢇn ꢆꢈhꢃmꢃ fꢇr ꢂhꢃ ꢆynꢂhꢃꢆꢅꢆ ꢇf N, o-ꢁꢇnꢇr bꢅꢁꢃnꢂꢀꢂꢃ ꢄꢅgꢀnꢁꢆ (l -l ),
1
4
ꢀ
nꢁ oꢆ(iV) ꢈꢇmpꢄꢃxꢃꢆ (c -c )
Synthesis and characterization of (5-(2-chloroquinolin-3-yl)-3-(p-tolyl)-4,5-
[
1]
dihydro-1H-pyrazol-1-yl)(phenyl)methanone (L, C H ClN O)
2
6
20
3
Ligand was synthesized using benzhydrazide and p-tolyl acetophenone deriv-
ative of quinoline moieties in presence of ethanol as solvent. Color: Yellow,
yield: 92%, mol. Wt: 425gm/mol, m.p.: 265°C; anal. Cal. (%) for: C, 73.32;
H, 4.73, N, 9.87; Found (%),C, 73.16; H, 4.55, N, 9.75; Mass m/z(%):
+
1
4
25[M] . H-NMR (400MHz, DMSO-d ) δ/ppm: 2.404(S, 3H, CH ), 3.248
6
3
4
2
3
4
3
(
dd,1H, H a, J =5.2 Hz, J =5.2 Hz, 4.005 (dd, 1H, H b, J =11.6 Hz,
1
2
1
3
5
J =11.6Hz), 4.551 (t, 1H, H ), 7.222–8.175 (m, 14H, H
2
2 ’, 3 ’, 5 ’, 6 ’, 3 ’, 4’ ’, 5’ ’, 6’ ’, 7’ ’, 8’ ’, 2’’ ’,
1
3
,
Ar-H). C-NMR (100MHz, DMSO-d ) δ/ppm: 189.10 (C=O, Cquat),
3
’’ ’, 5’’ ’, 6’’’
6
1
1
51.30 (C5, Cquat), 150.61 (C1 ’, C ), 146.04 (C4 ’, C ), 144.62 (C2’ ’, Cquat),
quat quat
42.04 (C3’ ’, Cquat), 132.08 (C4a, Cquat), 131.26 (C2 ’, C6 ’, CH), 131.23 (C3 ’,

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
597
Scheme 2. Gꢃnꢃrꢀꢄ rꢃꢀꢈꢂꢅꢇn ꢆꢈhꢃmꢃ fꢇr ꢂhꢃ ꢆynꢂhꢃꢆꢅꢆ ꢇf s, N, o-ꢁꢇnꢇr ꢂrꢅꢁꢃnꢂꢀꢂꢃ ꢄꢅgꢀnꢁꢆ
5
9
5
9
(
l -l ), ꢀnꢁ oꢆ(iV) ꢈꢇmpꢄꢃxꢃꢆ (c -c )
C5 ’, CH), 131.12 (C4’ ’, CH), 130.45 (C5’ ’, CH), 130.37 (C6’ ’, CH), 130.31
C8a, Cquat), 129.03 (C7’ ’, CH), 128.06 (C8’ ’, CH), 126.37 (C1’’ ’, Cquat),
26.17 (C2’’ ’, C6’’ ’, CH), 124.45 (C3’’ ’, C5’’ ’, CH), 124.40 (C4’’ ’, CH), 1, 41.07
C4, CH ), 33.35 (C3, CH), 24.40 (CH , Methyl). (No. of signals observed:
(
1
(
2
3
2
2: Signal of C and CH = 10 (pyrazole= 2, phenyl ring = 3, quinoline
2
=
4, carbonyl = 1), signal of CH and CH = 12 (pyrazole= 1, phenyl ring=
3
−
4
−3
6
, quinoline= 5). UV–Vis (DMSO, c = 10 mol dm ): λ (e) = 267.50 nm
max
-
1
−1
−1
(
29,350) mol dm3 cm ). IR (KBr, cm ): 3063 ν(=C-H); 1550 ν(C–N);
390 ν(C–H); 1618 ν(C = C); 1614 ν(C = O).
1

5
98
B. H. PURSUWANI ET AL.
Synthesis and characterization of (3-(4-chlorophenyl)-5-(2-chloroquinolin-3-
yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone (L2, C25H17Cl2N3O)
It was synthesized using 4-chloro acetophenone by the above procedure
1
mentioned in synthesis and characterization of ligand L . Color: Yellow,
yield: 90%, mol. Wt: 490 gm/mol, m.p.: 260 °C; anal. Cal. (%) for: C,
6
7.28; H, 3.84, N, 9.41; Found (%),C, 67.46; H, 3.70, N, 9.56; Mass
+
1
m/z(%): 447[M] H-NMR (400 MHz, DMSO-d ) δ/ppm: 3.244(dd, 1H,
.
6
4
2
3
4
2
3
H a, J ,=6.0 Hz, J =7.6 Hz), 4.005(dd, 1H, H b, J =10.8 Hz, J =11.2 Hz),
1
2
1
2
5
4
.551 (t, 1H, H ), 7.393–8.142 (m, 14H, H
C-NMR (100 MHz, DMSO-d ) δ/ppm: 189.46 (C = O, Cquat), 152.16 (C5,
Ar-H).
2
’, 3 ’, 5 ’, 6 ’, 3 ’, 4’ ’, 5’ ’, 6’ ’, 7’ ’, 8’ ’, 2’’ ’, 3’’ ’, 5’’ ’, 6’’ ’,
1
3
6
Cquat), 146.16(C1 ’, C ), 144.87 (C4 ’, Cquat), 142.13 (C2’ ’, Cquat), 132.17
quat
(
C3’ ’, Cquat), 131.60 (C2 ’, C6 ’, CH), 131.59 (C3 ’, C5 ’, CH), 131.29 (C4’ ’,
CH), 130.67 (C5’ ’, CH), 130.62 (C6’ ’, CH), 130.61 (C4a, Cquat), 129.13
C8a, Cquat), 128.89 (C7’ ’, CH), 126.68 (C8’’ CH), 126.28 (C2’’ ’, C6’’ ’, CH),
(
1
24.77 (C3’’ ’, C5’’ ’, CH), 124.60 (C1’’ ’, Cquat), 124.46 (C4’’ ’, CH),42.60 (C4,
CH ), 34.47 (C3, CH). (No. of signals observed: 21: Signal of C and
2
CH = 9 (pyrazole= 2, phenyl ring = 2, quinoline = 4, carbonyl = 1),
signal of CH = 12 (pyrazole= 1, phenyl ring= 6, quinoline= 5). UV–Vis
2
−
4
−3
−1
−1
(
DMSO, c = 10 mol dm ): λ
(e) = 244.50 nm (5,270 mol dm3 cm ),
max
−
1
IR (KBr, cm ): 3063 ν(=C–H); 1589 ν(C–N); 1119 ν(C–H); 1422 ν(C = C);
713 ν(C = O).
1
Synthesis and characterization of (3-(4-bromophenyl)-5-(2-chloroquinolin-3-
yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone (L3, C25H17BrClN3O)
It was synthesized using 4-bromo acetophenone by the above procedure
mentioned in 2.3.1. Color: Yellow, yield: 85%, mol. Wt: 490 gm/mol, m.p.:
2
70 °C; anal. Cal. (%) for: C, 61.18; H, 3.49, N, 8.56; Found (%),C, 61.32;
+
1
H, 3.35, N, 8.64; Mass m/z(%): 490[M] . H-NMR (400 MHz, DMSO-d )
6
4
2
3
4
δ/ppm: 3.221(dd, 1H, H a, J ,=6.4 Hz, J =6.8 Hz), 3.570(dd, 1H, H b,
1
2
2
3
5
J =7.2Hz, J =6.8Hz), 4.561 (t, 1H, H ), 7.303–8.160 (m, 14H, H
1
2
2 ’, 3 ’, 5 ’, 6 ’, 3 ’, 4’ ’, 5’ ’, 6’ ’,
1
3
Ar-H). C-NMR (100 MHz, DMSO-d ) δ/ppm: 189.43 (C = O,
7
’ ’, 8’ ’, 2’’ ’, 3’’ ’, 5’’ ’, 6’’ ’,
6
Cquat),152.04 (C5, Cquat), 146.14 (C1 ’, C ), 144.85 (C4 ’, C ), 142.11 (C2’ ’,
Cquat), 132.15 (C3’ ’, Cquat), 131.58 (C2 ’, C6 ’, CH), 131.57 (C3 ’, C5 ’, CH),
quat
quat
1
1
31.27 (C4’ ’, CH), 130.65 (C5’ ’, CH), 130.60 (C6’ ’, CH), 130.58 (C4a, Cquat),
29.11 (C8a, Cquat), 128.86 (C7’ ’, CH), 126.66 (C8’’ CH), 126.26 (C2’’ ’, C6’’ ’,
CH), 124.73 (C3’’ ’, C5’’ ’, CH), 124.58 (C1’’ ’, Cquat), 124.44 (C4’’ ’, CH),
4
2.57(C4, CH ), 34.45 (C3, CH). (No. of signals observed: 21: Signal of
2
C and CH = 9 (pyrazole= 2, phenyl ring = 2, quinoline = 4, carbonyl =
2
1
), signal of CH = 12 (pyrazole= 1, phenyl ring= 6, quinoline= 5). (No.
of signals observed: 21: Signal of C and CH = 9 (pyrazole= 2, phenyl
2
ring = 2, quinoline = 4, carbonyl = 1), signal of CH = 12 (pyrazole= 1,
phenyl ring= 6, quinoline= 5). UV-Vis (DMSO, c = 10 mol dm ): λ
−
4
−3
max

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
599
-
1
−1
−1
(
1
e) = 251.50 nm (22,170 mol dm3 cm ), IR (KBr, cm ): 3013 ν(=C–H);
591 ν(C–N); 1396 ν(C–H); 1432 ν(C = C); 1643 ν(C = O).
Synthesis and characterization of (5-(2-chloroquinolin-3-yl)-3-(4-fluorophenyl)-
,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone (L4, C25H17ClFN3O)
4
It was synthesized using 4-fluoro acetophenone by the above procedure
1
mentioned in synthesis and characterization of ligand L . Color: Yellow,
+
yield: 90%, mol. Wt: 429 gm/mol, m.p.: 260 °C; Mass m/z(%): 429[M] .
1
3
4
2
H-NMR (400 MHz, DMSO-d ) δ/ppm: 3.246 (dd, 1H, H a, J =6.0 Hz,
6
1
4
2
3
5
J =6.8 Hz), 3.998 (dd, 1H, H b, J =9.6 Hz, J =11.2 Hz), 4.540 (t, 1H, H ),
.398–8.148 (m, 14H, H2 ’, 3 ’, 5 ’, 6 ’, 3 ’, 4’ ’, 5’ ’, 6’ ’, 7’ ’, 8’ ’, 2’’ ’, 3’’ ’, 5’’ ’, 6’’ ’, Ar-H). C-NMR (100MHz,
2
1
2
1
3
7
DMSO-d ) δ/ppm: 189.58 (C = O, Cquat), 152.19 (C5, Cquat), 146.18 (C1’,
6
C
(
), 144.91 (C4 ’, Cquat), 142.17 (C2’ ’, Cquat), 132.19 (C3’ ’, Cquat), 131.62
C2 ’, C6 ’, CH), 131.59 (C3 ’, C5 ’, CH), 131.32 (C4’ ’, CH), 130.69 (C5’ ’,
quat
CH),130.62 (C6’ ’, CH), 130.61 (C4a, Cquat), 129.16 (C8a, Cquat), 128.92 (C7’ ’,
CH), 126.71 (C8’’ CH), 126.31 (C2’’ ’, C6’’ ’, CH), 124.79 (C3’’ ’, C5’’ ’, CH),
1
(
24.62 (C1’’ ’, Cquat), 124.49 (C4’’ ’, CH), 42.64 (C4, CH ), 34.50 (C3, CH).
No. of signals observed: 21: Signal of C and CH = 9 (pyrazole= 2, phenyl
2
2
ring = 2, quinoline = 4, carbonyl = 1), signal of CH = 12 (pyrazole= 1,
phenyl ring= 6, quinoline= 5). (No. of signals observed: 21: Signal of C
and CH = 9 (pyrazole= 2, phenyl ring = 2, quinoline = 4, carbonyl =
2
1
), signal of CH = 12 (pyrazole= 1, phenyl ring= 6, quinoline= 5). UV–Vis
−
4
−3
−4
−3
(
DMSO, c = 10 mol dm ): UV-Vis (DMSO, c = 10 mol dm ): λ
(e) =
max
-
1
−1
−1
2
48.50 nm (12.510 mol dm3 cm ). IR (KBr, cm ): 3009 ν(=C–H); 1512
ν(C–N); 1227 ν(C–H); 1656 ν(C = C); 1643 ν(C = O).
Synthesis and characterization of (5-(2-chloroquinolin-3-yl)-3-(thiophen-2-yl)-
4
,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone (L5, C23H15ClN3OS)
It was synthesized using 3-acetyl thiophene by the above procedure men-
1
tioned in synthesis and characterization of ligand L . Color: Yellow, yield:
8
3
8%, mol. Wt: 417 gm/mol, m.p.: 275 °C; anal. Cal. (%) for: C, 66.10; H,
.86, N, 10.06; S, 7.67; Found (%),C, 66.22; H, 3.70, N, 10.14; S, 7.82;
+
1
Mass m/z(%): 417[M] . H-NMR (400 MHz, DMSO-d ) δ/ppm: 3.339(dd,
6
4
2
3
4
2
3
1
4
H, H a, J ,=2.8 Hz, J =7.6Hz), 3.402(dd, 1H, H b, J =6.4Hz, J =2.4Hz),
1 2 1 2
5
.316 (t, 1H, H ), 7.652-8.108 (m, 13H, H2 ’, 3 ’, 5 ’, 3 ’, 4’ ’, 5’ ’, 6’ ’, 7’ ’, 8’ ’, 2’’ ’, 3’’ ’, 5’’ ’, 6’’’, Ar-H).
1
3
C-NMR (100 MHz, DMSO-d ) δ/ppm: 189.73 (C = O, Cquat), 150.31 (C5,
6
Cquat), 146.55 (C5 ’, C ), 145.27 (C2’ ’, Cquat), 137.35 (C3’ ’, Cquat), 133.79
quat
(
(
(
C4a, Cquat), 132.54 (C2 ’, CH), 131.43 (C3 ’, CH), 130.38 (C4 ’, CH), 130.16
C8a, Cquat), 130.03 (C4’ ’, CH), 127.29 (C1’’ ’, CH), 127.16 (C5’ ’, CH), 123.42
C6’ ’, CH), 122.42 (C7’ ’, CH), 122.32 (C8’ ’, CH), 122.13 (C2’’ ’, C6’’ ’, CH),
1
21.92 (C3’’ ’, C5’’ ’, CH), 121.52 (C4’’ ’, CH), 41.97 (C4, CH ), 34.55 (C3,
2
CH).(No. of signals observed: 23: Signal of C and CH = 9 (pyrazole= 2,
2

6
00
B. H. PURSUWANI ET AL.
phenyl ring = 1, quinoline = 4, thiophene = 1, carbonyl = 1), signal of
CH= 12 (pyrazole= 1, phenyl ring= 3, quinoline= 5, thiophene= 3). UV–
−
4
−3
−1
3
Vis (DMSO, c = 10 mol dm ): λ
(ε) = 232 nm (9,800 mol dm
max
−
1
−1
cm ), IR (KBr, cm ): 3086 ν(=C–H); 1490 ν(C–N); 1322 ν(C–H); 1430
ν(C = C); 1690 ν(C = O); 1160 ν(C–S).
Synthesis and characterization of (3-(5-bromothiophen-2-yl)-5-(2-
chloroquinolin-3-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone (L6,
C23H15ClBrN3OS)
It was synthesized using 5-bromo-3-acetyl thiophene by the above procedure
1
mentioned in synthesis and characterization of ligand L . Color: Yellow, yield:
9
5%, mol. Wt: 496gm/mol, m.p.: 280°C; anal. Cal. (%) for: C, 55.61; H, 3.04,
N, 8.46, S, 6.45; Found (%),C, 55.78; H, 3.24, N, 8.62, S, 6.53; Mass m/z(%):
+
1
4
4
96[M] . H-NMR (400 MHz, DMSO-d ) δ/ppm: 3.464 (dd, 1H, H a,
6
2
3
4
2
3
J =5.2Hz, J =7.6Hz), 3.572 (dd, 1H, H b, J =6.8Hz, J =7.2Hz), 4.582 (t,
1
2
1
2
5
13
1
H, H ), 7.106–8.164 (m, 12H, H2
Ar-H). C-NMR
’, 3′,5′,4′ ’, 5 ′ ’, 6 ′ ’, 7 ′ ’, 8 ′ ’, 2 ′’ ’, 3 ′’ ’, 5 ′’ ’, 6 ′’ ’,
(
(
(
(
(
1
2
4
100MHz, DMSO-d ) δ/ppm: 189.98 (C=O, Cquat), 150.64 (C5, Cquat), 146.89
6
C5 ’, C ), 145.48 (C2 ’, C ), 137.62 (C2’ ’, Cquat), 133.96 (C3 ’, Cquat), 132.76
quat
quat
C3’ ’, Cquat), 131.62 (C4 ’, CH), 130.64 (C4a, Cquat), 130.39 (C8a, Cquat), 130.22
C4’ ’, CH), 127.46 (C5’ ’, CH), 127.32 (C1’’ ’, Cquat), 123.72 (C6’ ’, CH), 122.50
C7’ ’, CH), 122.40 (C8’ ’, CH), 122.23 (C2’’ ’, C6’’ ’, CH), 121.98 (C3’’ ’, C5’’ ’, CH),
21.60 (C4’’ ’, CH), 42.08 (C4, CH ), 34.64 (C3, CH).(No. of signals observed:
3: Signal of C and CH = 10 (pyrazole= 2, phenyl ring = 1, quinoline =
2
2
, thiophene = 2, carbonyl = 1), signal of CH= 11 (pyrazole= 1, phenyl
−4
−3
ring= 3, quinoline= 5, thiophene= 2). UV–Vis (DMSO, c=10 mol dm ):
-
1
3
−1
−1
λ
(ε) = 287.50nm (10,270mol dm cm ), IR (KBr, cm ): 3032 ν(=C–H);
max
1510 ν(C–N); 1456 ν(C–H); 1522 ν(C=C); 1705 ν(C=O); 1163 ν(C–S).
Synthesis and characterization of (5-(2-chloroquinolin-3-yl)-3-(5-
chlorothiophen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone (L7,
C23HCl2N3OS)
It was synthesized using 5-chloro-3-acetyl thiophene by the above pro-
1
cedure mentioned in synthesis and characterization of ligand L . Color:
Yellow, yield: 80%, mol. Wt: 452 gm/mol, m.p.: 278 °C; anal. Cal. (%)
for: C, 61.7; H, 3.34, N, 9.29, S, 7.09; Found (%),C, 61.55; H, 3.41, N,
+
1
9
.36; S,7.23; Mass m/z(%): 452[M] . H-NMR (400 MHz, DMSO-d ) δ/
6
4
2
3
4
ppm: 3.461 (dd, 1H, H a, J =6.8 Hz, J =7.2 Hz), 3.562 (dd, 1H, H b,
1
2
2
3
5
J =6.8 Hz, J =7.6 Hz), 4.535 (t, 1H, H ), 6.158–8.162 (m, 12H, H
1
2
2 ’, 3′,
1
3
Ar-H). C-NMR (100 MHz, DMSO-d ) δ/ppm:
5
′,4′ ’, 5 ′ ’, 6 ′ ’, 7 ′ ’, 8 ′ ’, 2 ′’ ’, 3 ′’ ’, 5 ′’ ’, 6 ′’ ’,
6
1
89.92 (C = O, Cquat), 150.51 (C5, Cquat), 146.81 (C5 ’, C ), 145.41 (C2 ’,
quat
Cquat), 137.52 (C2’ ’, Cquat), 133.91 (C3 ’, Cquat), 132.71 (C3’ ’, Cquat), 131.55
(
C4 ’, CH), 130.59 (C4a, Cquat), 130.33 (C8a, Cquat), 130.17 (C4’ ’, CH),

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
601
1
27.40 (C5’ ’, CH), 127.29 (C1’’ ’, Cquat), 123.68 (C6’ ’, CH), 122.48 (C7’ ’,
CH), 122.38 (C8’ ’, CH), 122.21 (C2’’ ’, C6’’ ’, CH), 121.96 (C3’’ ’, C5’’ ’, CH),
21.58 (C4’’ ’, CH), 42.06 (C4, CH ), 34.61 (C3, CH). (No. of signals
1
2
observed: 23: Signal of C and CH = 10 (pyrazole= 2, phenyl ring =
2
1
, quinoline = 4, thiophene = 2, carbonyl = 1), signal of CH= 11
(
(
pyrazole= 1, phenyl ring= 3, quinoline= 5, thiophene= 2).UV-Vis
−
4
−3
−1
−1
DMSO, c = 10 mol dm ): λ
IR (KBr, cm ): 3032 ν(=C–H); 1411 ν(C–N); 1396 ν(C–H); 1412
ν(C = C); 1651 ν(C = O); 1158 ν(C–S).
(ε) = 251 nm (3,750 mol dm3 cm ).
max
−
1
Synthesis and characterization of (3-(3-bromothiophen-2-yl)-5-(2-
chloroquinolin-3-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone (L8,
C23H15BrClN3OS)
It was synthesized using 3-bromo-3-acetyl thiophene by the above proce-
1
dure mentioned in synthesis and characterization of ligand L . Color:
Yellow, yield: 87%, mol. Wt: 496 gm/mol, m.p.: 280 °C; anal. Cal. (%) for:
C, 55.61; H, 3.04, N, 8.46, S, 6.45; Found (%),C, 55.81; H, 3.24, N, 8.62;
1
4
S, 6.52; H-NMR (400 MHz, DMSO-d ) δ/ppm: 3.463 (dd, 1H, H a,
6
2
3
4
2
3
J =7.6 Hz, J =6.0 Hz), 3.562 (dd, 1H, H b, J =5.4 Hz, J =6.8 Hz), 4.535
1
2
1
2
5
13
(
t, 1H, H ), 7.104–8.168 (m, 12H, H
Ar-H). C-
2
’, 3′,5′,4′ ’, 5 ′ ’, 6 ′ ’, 7 ′ ’, 8 ′ ’, 2 ′’ ’, 3 ′’ ’, 5 ′’ ’, 6 ′’ ’,
NMR (100MHz, DMSO-d ) δ/ppm: 189.86 (C=O, Cquat), 150.44 (C5, Cquat),
6
1
1
46.77 (C5 ’, C ), 145.36 (C4 ’, C ), 137.46 (C2’ ’, Cquat), 133.88 (C2 ’, CH),
quat quat
32.66 (C3’ ’, Cquat), 131.51 (C3 ’, CH), 130.52 (C4a, Cquat), 130.26 (C8a,
Cquat), 130.13 (C4’ ’, CH), 127.36 (C5’ ’, CH), 127.25 (C1’’ ’, Cquat), 123.52
(
C6’ ’, CH) 122.42 (C7’ ’, CH), 122.36 (C8’ ’, CH), 122.18 (C2’’ ’, C6’’ ’, CH),
21.95 (C3’’ ’, C5’’ ’, CH), 121.56 (C4’’ ’, CH), 41.02 (C4, CH ), 34.58 (C3,
1
2
CH). (No. of signals observed: 23: Signal of C and CH = 10 (pyrazole=
2
2
, phenyl ring = 1, quinoline = 4, thiophene = 2, carbonyl = 1), signal
of CH= 11 (pyrazole= 1, phenyl ring= 3, quinoline= 5, thiophene= 2).
−
4
−3
-
UV–Vis (DMSO, c = 10 mol dm ): λ
(ε) = 275.50 nm (40,000 mol
max
1
−1
+
−1
dm3 cm ). Mass m/z(%): 496[M] . IR (KBr, cm ): 3032 ν(=C–H); 1490
ν(C–N); 1410 ν(C–H); 1142 ν(C = C); 1624 ν(C = O); 1152 ν(C–S).
Synthesis and characterization of (5-(2-chloroquinolin-3-yl)-3-(5-iodothiophen-
2
-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone (L9, C23H15ClIN3OS)
It was synthesized using 5-iodo-3-acetyl thiophene by the above procedure
1
mentioned in synthesis and characterization of ligand L . Color: Yellow, yield:
9
2%, mol. Wt: 544gm/mol, m.p.: 275°C; anal. Cal. (%) for: C, 50.80; H,
.78, N, 7.73, S, 5.90; Found (%),C, 50.92; H, 2.60, N, 7.90, S, 5.76; Mass
2
+
1
m/z(%): 544[M] . H-NMR (400MHz, DMSO-d ) δ/ppm: 3.226 (dd, 1H,
H a, J =7.6Hz, J =6.0Hz), 3.296 (dd, 1H, H b, J =7.2Hz, J =6.8Hz), 4.306
6
4
2
3
4
2
3
1
2
1
2

6
02
B. H. PURSUWANI ET AL.
5
13
(
(
(
(
(
(
1
2
4
t, 1H, H ), 6.890–8.110 (m, 12H, H 2
Ar-H). C-NMR
′,3′,5′,4′ ’, 5 ′ ’, 6 ′ ’, 7 ′ ’, 8 ′ ’, 2 ′’ ’, 3 ′’ ’, 5 ′’ ’, 6 ′’ ’,
100MHz, DMSO-d ) δ/ppm: 189.82 (C=O, Cquat), 150.36 (C5, Cquat), 146.67
6
C5 ’, C ), 145.32 (C2 ’, C ), 137.42 (C2’ ’, Cquat), 133.84 (C3 ’, Cquat), 132.61
quat
quat
C3’ ’, Cquat), 131.47 (C4 ’, CH), 130.44 (C4a, Cquat), 130.21 (C8a, Cquat), 130.08
C4’ ’, CH), 127.33 (C5’ ’, CH), 127.21 (C1’’ ’, Cquat), 123.46 (C6’ ’, CH), 122.44
C7’ ’, CH), 122.34 (C8’ ’, CH), 122.15 (C2’’ ’, C6’’ ’, CH), 121.94 (C3’’ ’, C5’’ ’, CH),
21.53 (C4’’ ’, CH), 41.98 (C4, CH ), 34.56 (C3, CH). (No. of signals observed:
2
3: Signal of C and CH = 10 (pyrazole= 2, phenyl ring = 1, quinoline =
2
, thiophene = 2, carbonyl = 1), signal of CH= 11 (pyrazole= 1, phenyl
−4
−3
ring= 3, quinoline= 5, thiophene= 2). UV–Vis (DMSO, c=10 mol dm ):
-
1
−1
−1
λ
1
(ε) = 261.50nm (35,720mol dm3cm ). IR (KBr, cm ): 3063 ν(=C–H);
max
512 ν(C–N); 1396 ν(C–H); 1227 ν(C=C); 1683 ν(C=O); 1155 ν(C–S).
Synthesis and characterization of metal salt and complexes: synthesis
of ammonium hexabromoosmate(IV)
Ammonium hexabromoosmate(IV) was synthesized using osmium tetroxide
as starting material.[
19,20]
Synthesis and characterization of tetrabromido(5-(2-chloroquinolin-3-yl)-3-(p-
tolyl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone)osmium(IV)
1
(
C , C H Br Cl N OOs)
2
5
17
4
2
3
1
It was synthesized using (NH ) OsBr (0.60 g, 0.085 mmol) and ligand L
4
2
6
(
0.36g, 0.085mmol) in methanol solvent. The reaction mixture was refluxed
at 80 °C for 2 h. The solution was allowed to evaporate. To the resultant
solid mass obtained, ethyl acetate was added. The complex gets readily
soluble in the solvent which was evaporated to obtain brownish solid
metal complex. Color: Yellow, yield: 65%, mol. Wt: 935.76 gm/mol, m.p.:
>
300°, Cal. (%) for: Os, 20.33; Found (%), Os, 20.01 (ICP-OES), ESI-MS
+
(
70 eV): m/z: 935.30(M ), 855.80, 777.80, 696.30, 616.10, 425.90 (base
−
4
−3
-
peak). UV–Vis (DMSO, c = 10 mol dm ): λ
(ε) = 273 nm (36,663 mol
max
1
−1
−1
2
dm3 cm ). Magnetic Moment: 2.74 B.M; Conductance: 36 ℧ mol cm .
−
1
IR (KBr, cm ): 3163 ν(=C–H); 1570 ν(C–N); 1430 ν(C–H); 1496 ν(C= C);
713 ν(C = O); 538 ν(N–Os); 545 ν(N–Os–Br).
1
Synthesis and characterization of tetrabromido (3-(4-chlorophenyl)-5-(2-
chloroquinolin-3-yl)-4, 5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone)
osmium(IV) (C2, C25H17Br5ClN3OOs)
2
It was synthesized using ligand L (0.38 g, 0.085 mmol) by above method
described in synthesis of complex 1. Color: Brownish black, yield: 60%,
mol. Wt: 956.18 gm/mol, m.p.: >300 °C . Cal. (%) for: Os, 19.89; Found

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
−3
603
−
4
(
%), Os, 19.51 (ICP-OES). UV–Vis (DMSO, c = 10 mol dm ): λ
(ε) =
max
−1
−1
2
72nm (25,800mol dm3cm ). Magnetic Moment: 2.70 B.M; Conductance:
−
1
2
−1
2
8 ℧ mol cm . IR (KBr, cm ): 3171 ν(=C–H); 1651 ν(C–N); 1219
ν(C–H); 1496 ν(C = C); 1651 ν(C = O); 542 ν(N–Os); 560 ν(N–Os–Br).
Synthesis and characterization of tetrabromido(3-(4-bromophenyl)-5-(2-
chloroquinolin-3-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone)
osmium(IV) (C3, C25H17Br4ClFN3OOs)
3
It was synthesized using ligand L (0.38 g, 0.085 mmol) by above method
described in synthesis of complex 1. Color: Brownish black, yield: 60%,
mol. Wt: 1000.63 gm/mol, m.p.: >300 °C. Cal. (%) for: Os, 19.01; Found
−
4
−3
(
%), Os, 18.91 (ICP-OES). UV–Vis (DMSO, c = 10 mol dm ): λ
(ε) =
max
−1
−1
2
86nm (38,200mol dm3cm ). Magnetic Moment: 2.65 B.M; Conductance:
−
1
2
−1
3
6 ℧ mol cm . IR (KBr, cm ): 3022 ν(=C-H); 1610 ν(C–N); 1422 ν(C–
H); 1512 ν(C = C); 1713 ν(C = O); 586 ν(N–Os); 595 ν(N–Os–Br).
Synthesis and characterization of tetrabromido(5-(2-chloroquinolin-3-yl)-3-(4-
fluorophenyl)-4, 5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone)osmium(IV) (C4,
C23H15Br4ClN3OSOs)
4
It was synthesized using ligand L (0.36 g, 0.085 mmol) by above method
described in synthesis of complex 1. Color: Brownish black, yield: 65%,
mol. Wt: 939.73 gm/mol, m.p.: >300 °C. Cal. (%) for: Os, 20.24; Found
−
4
−3
(
2
2
%), Os, 20.21 (ICP-OES). UV–Vis (DMSO, c = 10 mol dm ): λ
(ε) =
max
-
1
−1
77nm (4,680mol dm3cm ). Magnetic Moment: 2.75 B.M; Conductance:
−
1
2
−1
4 ℧ mol cm . IR (KBr, cm ): 3022 ν(=C–H); 1530 ν(C–N); 1396
ν(C–H); 1509 ν(C = C); 1705 ν(C = O); 518 ν(N–Os); 528 ν(N–Os–Br).
Synthesis and characterization of tetrabromido(5-(2-chloroquinolin-3-yl)-3-
(
(
thiophen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone)osmium(IV)
C5, C23H15Br5ClN3OSOs)
5
It was synthesized using ligand L (0.35 g, 0.085 mmol) by above method
described in synthesis of complex 1. Color: Brownish black, yield: 58%,
mol. Wt: 847.85 gm/mol, m.p.: >300 °C. Cal. (%) for: Os, 22.44; Found
+
(
%), Os, 22.28 (ICP-OES). LCMS (70eV): m/z: 847.50(M ), 767.90, 688.03,
−
4
−3
6
08.13, 417.90 (base peak). UV–Vis (DMSO, c = 10 mol dm ): λ
(ε)
max
1
−1
=
296 nm (3,250 mol− dm3 cm ). Magnetic Moment: 2.72 B.M;
−
1
2
−1
Conductance: 140 ℧ mol cm . IR (KBr, cm ): 3032 ν(=C–H); 1510
ν(C–N); 1456 ν(C–H); 1522 ν(C = C); 1705 ν(C = O); 1172 ν(C–S); 518
ν(N–Os); 534 ν(N–Os–Br).

6
04
B. H. PURSUWANI ET AL.
Synthesis and characterization of tetrabromido(3-(5-bromothiophen-2-yl)-5-(2-
chloroquinolin-3-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone)
osmium(IV) (C6, C23H15Br4Cl2N3OSOs)
6
It was synthesized using ligand L (0.42 g, 0.085 mmol) by above method
described in synthesis of complex 1. Color: Brownish black, yield: 55%,
mol. Wt: 926.75 gm/mol, m.p.: >300 °C. Cal. (%) for: Os, 20.53; Found
−
4
−3
(
%), Os, 20.44 (ICP-OES). UV–Vis (DMSO, c = 10 mol dm ): λ
(ε) =
max
−1
−1
2
72nm (25,800mol dm3cm ). Magnetic Moment: 2.68 B.M; Conductance:
35 ℧ mol−1 cm . IR (KBr, cm ): 3101 ν(=C–H); 1489 ν(C–N); 1396
2
−1
1
ν(C–H); 1412 ν(C = C); 1718 ν(C = O); 1168 ν(C–S); 586 ν(N–Os); 598
ν(N–Os–Br);
Synthesis and characterization of tetrabromido(5-(2-chloroquinolin-3-yl)-3-(5-
chlorothiophen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone)
osmium(IV) (C7, C23H15Br5ClN3OSOs)
7
It was synthesized using ligand L (0.38 g, 0.085 mmol) by above method
described in synthesis of complex 1. Color: Brownish black, yield: 60%,
mol. Wt: 882.30 gm/mol, m.p.: >300 °C. Cal. (%) for: Os, 21.56; Found
−
4
−3
(
2
1
%), Os, 21.47 (ICP-OES). UV–Vis (DMSO, c = 10 mol dm ): λ
(ε) =
max
-
1
−1
51nm (6,500mol dm3cm ). Magnetic Moment: 2.66 B.M; Conductance:
45 ℧ mol−1 cm . IR (KBr, cm ): 3086 ν(=C–H); 1520 ν(C–N); 1456
2
−1
ν(C–H); 1382 ν(C = C); 1701 ν(C = O); 1165 ν(C–S); 561 ν(N–Os); 575
ν(N–Os–Br).
Synthesis and characterization of tetrabromido(3-(3-bromothiophen-2-yl)-5-(2-
chloroquinolin-3-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone)
osmium(IV) (C8,C23H15Br4ClIN3OSOs)
8
It was synthesized using ligand L (0.42 g, 0.085 mmol) by above method
described in synthesis of complex 1. Color: Brownish black, yield: 65%,
mol. Wt: 926.75 gm/mol, m.p.: >300 °C. Cal. (%) for: Os, 20.53; Found
−
4
−3
(
%), Os, 20.40 (ICP-OES). UV–Vis (DMSO, c = 10 mol dm ): λ
(ε) =
max
−1
−1
2
58nm (40,000mol dm3cm ). Magnetic Moment: 2.80 B.M; Conductance:
50 ℧ mol−1 cm . IR (KBr, cm ): 3042 ν(=C-H); 1520 ν(C–N); 1456
2
−1
1
ν(C–H); 1382 ν(C = C); 1701 ν(C = O); 1165 ν(C–S); 561 ν(N–Os); 582
ν(N–Os–Br).
Synthesis and characterization of tetrabromido(5-(2-chloroquinolin-3-yl)-3-(5-
iodothiophen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)(phenyl)methanone)osmium(IV)
(
C9,C23H15Br4ClIN3OSOs)
9
It was synthesized using ligand L (0.46 g, 0.085 mmol) by above method
described in synthesis of complex 1. Color: Brownish black, yield: 65%,

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
605
mol. Wt: 973.75 gm/mol, m.p.: >300 °C. Cal. (%) for: Os, 19.54; Found
−
4
−3
(
2
%), Os, 19.48 (ICP-OES). UV–Vis (DMSO, c = 10 mol dm ): λ
(ε) =
max
−
1
−1
86.50 nm (5,240 mol dm3 cm ). Magnetic Moment: 2.71 B.M;
−
1
2
−1
Conductance: 135 ℧ mol cm . IR (KBr, cm ): 3063 ν(=C–H); 1512
ν(C–N); 1456 ν(C–H); 1382 ν(C = C); 1711 ν(C = O); 1161 ν(C–S); 570
ν(N–Os); 583 ν(N–Os–Br).
Experimental section
Biological studies
Absorption titration study of complex to HS- DNA
The mode of the interaction of compounds with herring sperm DNA was
estimated using a UV–visible spectrophotometer. The baseline corrections
were made by taking DMSO in both reference and test compound cuvette.
After refinement of the baseline, varying concentrations of DNA solution
made in phosphate buffer were added to the test compound simultaneously
in increasing order of titrimetric analysis. The incubation time for each
reading to be taken was 10 min. DNA concentration was measured at
−
1
−1
2
60 nm (absorbance coefficient = 12858 M cm ). The binding constant
was calculated using the equation given below.
[
DNA]/(ε −ε ) =[DNA]/(ε −ε )+1/ K (ε −ε )
a
f
a
f
b
a
f
[
DNA] represents the concentration of DNA taken, K represents binding
b
constant, ε is the ratio of absorbance to the concentration of compound
a
taken, ε and ε are coefficients defining extinction of free and bound
DNA, respectively.
f
b
[
21]
Fluorescence quenching study
The experiment was performed with EtBr (ethidium bromide) as a probe
for fluorescence. The probe was reacted with macromolecule forming the
complex bonding between former and guest. The resultant change in
emission intensity was observed. Os(IV) complexes cannot show fluores-
cence, as a result when they bind with macromolecule it is difficult to
predict the binding. EtBr plays the role of intercalator in enhancing
intensity. Hence, when an Os(IV) compound displaces the probe in titra-
tion, a decrease in intensity was observed. The experiment was performed
in a spectrofluorometer (Fluoromax-4) using a quartz cuvette having a
width of 1 cm. The experiment was performed at emission and excitation
wavelength of 610 and 410 respectively. The pH of the solution was
maintained at 7.0 in buffer (phosphate). Varying concentrations of test

6
06
B. H. PURSUWANI ET AL.
compounds were used keeping EtBr and DNA at 33.3 and 10 μM, respec-
tively[ . The data is evaluated using the following Equations (1) and (2)
known as Stern Volmer and Scatchard equations.
22]
I /I =1+ K [Q]
(1)
0
sv
log((I -I)/I) = logK + nlog[Q]
(2)
0
f
I0 and I are emission intensity in the absence and presence of a quencher;
[
Q] represents quencher concentration.; Ksv represents constant defined
by Equation (1); n represent binding sites; K is a constant derived using
f
Equation (2).
Molecular docking with B-DNA
Docking software Hex 8.0.0 was used for calculating docking energy
acquired by compounds while interacting with the macromolecule, that
is, B-DNA (PDB: 432D). The structures of compounds were drawn in
chem-bio draw software. The files were saved in PDB format. The com-
pound and B-DNA PDB files were allowed to load in the software. Solvent
interactions were omitted before the docking process to get precise dock-
ing energy. The compounds were allowed to be placed in the ball and
stick models before interaction. The entire process was activated and
upon orientation and best possible conformational arrangement acquired
by compounds and interacting guest molecule, docking energy was
counted.[
23]
Hydrodynamic volume measurement for complex to HS-DNA interaction
The viscosity of varying concentrations of compounds and a fixed con-
centration of HS-DNA was measured. The flow time was calculated in a
triplicated manner to get the precise judgment about the binding mode.
The viscometer used is Ubbelohde suspended in a homogenous static
environment at constant temperature, that is, 27 ± 0.1 °C. The flow time
1
/3
was calculated. The plot of (η/η ) v/s [compound]/[DNA] represents the
0
[
24]
relative viscosity of test compounds.
Gel electrophoresis
The 0.5% and 3.0% solutions of yeast extract and anhydrous dextrose were
taken in 30 mL volume to prepare the culture. The medium was incubated
for one-day duration at 30 °C. Five sets of test compound concentrations
in multiples of two along with DMSO were used for the study. After
treatment of compounds with culture, the medium was allowed to stand

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
607
for 17 h at the same temperature. The medium was then transferred in
00mL volume capacity tubes to spin the solution at 5000rpm. As a result,
1
the cells get suspended. The solution was washed with buffer (phosphate).
Further, the 20 μL volume was mixed with 0.4% dye (trypan blue). The
resultant mixture was incubated and the sector of the area was selected
to evaluate percentage viability under the microscope by counting the
number of live and dead cells.[25]
Brine shrimp toxicity screening
This experiment was performed using Artemia eggs, which were allowed
to hatch in artificial seawater prepared in laboratory conditions. The media
was placed overnight in the presence of light. The grown nauplii after egg
hatching were used for the experiment. Varying concentrations of com-
pounds were mixed with a counted number of nauplii and kept overnight
to note the cytotoxic effect. From the ratio of dead and live nauplii, per-
centage mortality was evaluated. From the percentage mortality against the
[
26]
concentration of test compounds, a plot was used to evaluate the LC .
5
0
In-vivo cytotoxicity
This activity was performed using S. pombe cell’s DNA, taking 30 mL yeast
extract and incubating for 18 h at 160 rpm in a shaker. The resultant cul-
ture was exposed with test compounds (20–100 μM range) taking DMSO
as the reference control and kept for 24 h. The formed culture and trypan
blue were taken in 80 and 20 mL volumes, respectively, and rotated at
1
0,000 rpm after transferring to 2 mL vials. The centrifugated culture from
each vial was taken and mixed with dye before observation under a
microscope. The dead cells easily penetrate dye. From the selected section
of area % viability was calculated.[
27]
In-vitro bacteriostatic activity
A solution of Luria broth was prepared in double-distilled water. The
solution was autoclaved under high pressure and temperature conditions
to avoid contamination and then placed in laminar airflow to resist con-
tamination. The entire cabinet was cleaned with an ethanol solvent to
+
ve
−ve
avoid contamination. The series of bacteria, that is, gram and gram
bacteria were allowed to grow in culture media for 18 h and allowed to
rotate at optimum 160 rpm speed in an orbital shaker at 37 °C. Different
concentrations of test compounds were implemented in the solution of
bacterial culture repeating the same procedure. The appearance of turbidity
shows that bacteria were growing whereas, the absence of turbidity defines
the relative MIC of test compounds.[
28]

6
08
B. H. PURSUWANI ET AL.
Cell line study
The study was done on lung cancer cell line A549. A549 cells were treated
with varying concentrations of Os(IV) complexes for 24 h. Dulbecco’s
Phosphate Buffered Saline dry powder was used to clean the cells. The
solutions were poured in 0.5 mg/ml MTT solution for the time-period of
4
h at biological human temperature. Further, the solutions have been
incubated for 20 min in the presence of 0.1 ml SDS-hydrochloric acid
solution. A multimode microplate reader (Spectra Max M2e, Molecular
Devices, USA) was used for calculating IC values. Concentrations of 10,
5
0
2
5, 50, 100, 250, 500, and 1000µg/mL were taken about the unit percentage
of DMSO as vehicle control. From the plot of percentage cell proliferation
vs. varying concentrations of test compounds, an IC
was
5
0
determined.[
29]
Results and discussion
1
4
4
In H-NMR spectra of synthesized ligands protons, H a and H b show
chemical shifts in the range of 3.221–3.572 and 3.296–4.512 δ ppm, respec-
5
tively, whereas the H protons of the ligands fall in the range of 4.306–
1
+
4
4
.561 δppm. LC-MS spectrum of ligand L shows a mass peak at [M] at
1
25 m/z, whereas the ESI-MS fragmentation pattern of complex C shows
a molecular ion peak at 933.30 M/z and a base peak is observed at
4
23.90 M/z. In the 13C-NMR spectra of synthesized ligands, the carbonyl
peak is observed at 189.10 δ ppm, whereas aliphatic peaks are observed
at 41.70 and 33.35 δ ppm values, respectively. There is a shift in relative
values with other synthesized ligands depending upon the inductive behav-
1
1
ior of substituents. In the IR spectra of ligand L and complex C , respec-
tive ν(–C–H), ν(C–N), ν(–C–H), ν(C = C) and ν(C = O) peaks show shifts
of 100, 20, 40, 86, and 101 cm−1 providing proof for formation of com-
−
1
plexes. The ν(N–Os) band is observed at 538 cm . The shift in values
could be attributed to the presence of the osmium metal ion and the
inductive bromine atoms, which deshield the frequency values relative to
the free ligand.[
30,31]
Magnetic behavior of synthesized complexes shows
the value of 2.74 Bohr Magneton accounting for the octahedral behavior
[
32]
of the synthesized complexes exhibiting paramagnetic character. Further,
1
in the electronic spectrum of complex C , the d–d transition at 452.00 nm
accounts for (t )4(e.g.,)0 configuration justifying the octahedral geometry.
2
g
A conductivity study shows that complexes V–IX have electrolytic behavior
−
1
2 [33]
having values in the range of 135–150 ℧ mol cm ,
whereas, neutral
−
1
complexes I–IV show conductivity values in the range of 24–36 ℧ mol
2
1
13
cm . H-NMR, C-NMR, LC-MS, ESI-MS, ICP-OES, IR spectra, and CHNS
data have been given in supplementary material no. 1-6.

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
609
Biological activities of synthesized compounds
Absorption titration study of ligands and complexes to HS DNA interaction
Effective strength and mode of binding were determined by an absorption
titration study. Upon subsequent addition of HS-DNA concentration, vari-
ation in the relative viscosity of test compounds was observed. Based on
shifts in the values of wavelength observed, percentage hypochromic shifts
were calculated. It could be concluded that complexes show effective
binding constant values compared to ligands. In the case of N, O- donor
ligands and their respective complexes, the K values are considerably
b
different, whereas in the case of S, N, O- donor atom ligands the values
vary slightly. Table 1 shows the K values and the percentage hypochromic
b
1
shift. Figure 1 shows the absorption titration curve of complex C . DNA
binding constants of Os(IV) complexes fall at about 4.13–12.44 × 10 M .
Complexes C , C , and C show greater binding as compared to reported
Co(III) complexes of 2-oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde
thiosemicarbazones.[
4
−1
1
2
3
34]
Fluorescence quenching study
This activity leads to a conclusion about the binding behavior of complex
to DNA. An intense emission band appears at 610 nm when excited at a
wavelength of 470 nm due to the binding of osmium(IV) compounds with
Figure 1. abꢆꢇrpꢂꢅꢇn ꢆpꢃꢈꢂrꢀꢄ ꢈhꢀngꢃꢆ ꢇn ꢂhꢃ ꢀꢁꢁꢅꢂꢅꢇn ꢇf Hs dNa ꢂꢇ ꢂhꢃ ꢆꢇꢄꢉꢂꢅꢇn ꢇf ꢈꢇmpꢄꢃx
i (ꢀfꢂꢃr ꢅnꢈꢉbꢀꢂꢅng ꢅꢂ fꢇr 10 mꢅn. ꢀꢂ rꢇꢇm ꢂꢃmpꢃrꢀꢂꢉrꢃ ꢅn phꢇꢆphꢀꢂꢃ bꢉffꢃr. Grꢀph: pꢄꢇꢂ ꢇf
[
dNa]/(ε –ε ) vꢃrꢆꢉꢆ [dNa]. (arrꢇw ꢆhꢇwꢆ ꢂhꢃ ꢈhꢀngꢃ ꢅn ꢀbꢆꢇrpꢂꢅꢇn wꢅꢂh ꢀn ꢅnꢈrꢃꢀꢆꢃ ꢅn ꢂhꢃ
ꢀ f
ꢈꢇnꢈꢃnꢂrꢀꢂꢅꢇn ꢇf dNa) ꢀmꢇꢉnꢂ ꢇf ꢈꢇmpꢄꢃxꢃꢆ ꢀnꢁ eꢂBr ꢀꢂ 27 ± 0.1 °c ꢅn phꢇꢆphꢀꢂꢃ bꢉffꢃr (pH
.2).
7

6
10
B. H. PURSUWANI ET AL.
Table 1. inꢂrꢅnꢆꢅꢈ bꢅnꢁꢅng ꢈꢇnꢆꢂꢀnꢂ (K ) vꢀꢄꢉꢃꢆ ꢀnꢁ pꢃrꢈꢃnꢂꢀgꢃ hypꢇꢈhrꢇmꢅꢈ ꢆhꢅfꢂ vꢀꢄꢉꢃꢆ ꢇf ꢀꢄꢄ
b
ꢂhꢃ ꢆynꢂhꢃꢆꢅzꢃꢁ ꢈꢇmpꢇꢉnꢁꢆ.
%
%
cꢇmpꢇꢉnꢁ
Kb Vꢀꢄꢉꢃꢆ
Hypꢇꢈhrꢇmꢅꢆm
cꢇmpꢇꢉnꢁ
Kb vꢀꢄꢉꢃꢆ
Hypꢇꢈhrꢇmꢅꢆm
1
4
1
4
c
12.44 × 10
11.42 × 10
8.86 × 10
7.51 × 10
40.24
21.07
17.67
86.95
14.79
22.49
58.89
29.21
14.21
l
1.46 × 10
25.23
54.62
21.58
10.33
21.51
34.72
35.76
42.36
55.73
2
4
2
4
c
l
1.01 × 10
3
4
4
3
4
c
l
1.42 × 10
4
4
4
c
l
1.21 × 10
5
5
4
c
4.56 × 104
l
3.47 × 10
6
4
6
4
c
4.17 × 10
l
3.81 × 10
7
4
7
4
c
4.29 × 10
l
3.07 × 10
8
4
8
4
c
4.98 × 10
l
3.88 × 10
9
4
9
4
c
4.13 × 10
l
3.65 × 10
base pairs of the DNA helix. The concentrations increased from r = 0.33
to 3.33. The corresponding plots are given in Figure 2. The relative change
in intensities of compounds was related to the blank EB-DNA system as
a reference. The decrease in relative intensity at different concentrations
of compounds shows the interaction of compounds with DNA. Quenching
and binding constants have been calculated and are given in Table 2. The
quenching phenomenon suggests how osmium(IV) complexes replace ethid-
ium bromide from the EB-DNA system.
1
Figure 2. Fꢄꢉꢇrꢃꢆꢈꢃnꢈꢃ ꢃmꢅꢆꢆꢅꢇn ꢇf eB bꢇꢉnꢁ ꢂꢇ Hs-dNa ꢅn ꢂhꢃ prꢃꢆꢃnꢈꢃ ꢇf ꢈꢇmpꢄꢃx c . Pꢄꢇꢂꢆ:
i /i vꢃrꢆꢉꢆ [Qꢉꢃnꢈhꢃr] ꢀnꢁ pꢄꢇꢂ ꢇf ꢄꢇg[i −i] vꢃrꢆꢉꢆ ꢄꢇg[Q] fꢇr ꢂhꢃ ꢂꢅꢂrꢀꢂꢅꢇn ꢇf Hs-dNa eB ꢆyꢆꢂꢃm
0
0
1
wꢅꢂh oꢆ(iV) ꢈꢇmpꢄꢃx c ꢅn 1 M phꢇꢆphꢀꢂꢃ bꢉffꢃr (pH 7.2) mꢃꢁꢅꢉm.
Table 2. sꢂꢃrn–Vꢇꢄmꢃr qꢉꢃnꢈhꢅng ꢈꢇnꢆꢂꢀnꢂ (K ), bꢅnꢁꢅng ꢆꢅꢂꢃꢆ (n),
ꢆv
ꢀ
nꢁ bꢅnꢁꢅng ꢈꢇnꢆꢂꢀnꢂ (K ) vꢀꢄꢉꢃꢆ.
f
−
1
Kf M−1
cꢇmpꢄꢃxꢃꢆ
Kꢆv
M
Bꢅnꢁꢅng sꢅꢂꢃꢆ (n)
1
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
c
5.24 × 10
4.01 × 10
7.31 × 10
8.82 × 10
9.41 × 10
1.28 × 10
9.31 × 10
8.31 × 10
1.50 × 10
1.7643
1.5598
1.0710
1.1048
0.9807
1.3336
1.0357
1.0477
1.1559
2.58 × 10
1.78 × 10
1.60 × 10
2.81 × 10
7.90 × 10
4.28 × 10
1.36 × 10
1.39 × 10
7.55 × 10
2
c
3
c
4
c
5
c
6
c
7
c
8
c
9
c

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
611
Molecular docking with B-DNA
A molecular docking study provides information on the interaction of
non-planar heterocyclic moieties or their respective complexes with a DNA
sequence. The structures are presented in chem-bio draw 3D software for
optimizing structure to possible effective conformational arrangements. The
resultant optimized structures are converted into a PDB file format. Specifically
formatted files of compounds are interacted with a B-DNA sequence by
activating the docking process. Molecules automatically find specific sites
and interact with the sequence via stacking interactions at the periphery of
the DNA- sequence. The docking process suggests effective plausible energy
values of interaction. More negative values of docking energy suggest more
effectiveness of binding with the DNA sequence. Docking energy values of
synthesized ligands and complexes are given in Table 3. Docking images of
synthesized ligands and complexes are given in Supplementary material 8.
Hydrodynamic volume measurements
1
9
All the synthesized ligands L –L and complexes 1–9 show a partial interca-
lative mode of binding. Figures 3 and 4 show an increase in viscosity upon
the addition of increasing concentrations of DNA. The mode of binding of
the synthesized compounds with HS-DNA could be determined by hydro-
dynamic volume measurements. With increasing concentrations of compounds,
the viscosity increases, suggesting a partial intercalative mode of binding for
synthesized compounds. Both ligands with N, O- and S, N, O- donor atoms
and their respective complexes show a partial intercalative mode of binding.[
35]
Photolytic cleavage study
Photolytic cleavage study, that is, gel electrophoresis has been done to
determine the toxic effect of the compounds. The smearing of DNA from
the nucleus suggests the effective toxicity of synthesized compounds. Figure
5
shows the photolytic cleaved images of different compounds.
Table 3. dꢇꢈkꢅng ꢃnꢃrgy vꢀꢄꢉꢃꢆ ꢇf ꢂhꢃ ꢆynꢂhꢃꢆꢅzꢃꢁ ꢈꢇmpꢇꢉnꢁꢆ.
dꢇꢈkꢅng ꢃnꢃrgy
cꢇmpꢇꢉnꢁꢆ
dꢇꢈkꢅng ꢃnꢃrgy (kJ/mꢇꢄ)
cꢇmpꢇꢉnꢁꢆ
(kJ/mꢇꢄ)
1
1
l
−301.28
−303.88
−303.88
−304.94
−288.37
−298.45
−302.39
−302.24
−297.13
c
−303.86
−318.61
−292.66
−287.87
−287.13
−286.28
−282.47
−282.35
−284.14
2
2
l
c
3
3
l
c
4
4
l
c
5
5
l
c
6
6
l
c
7
7
l
c
8
8
l
c
9
9
l
c

6
12
B. H. PURSUWANI ET AL.
Figure 3. thꢃ pꢄꢇꢂ ꢇf ꢃffꢃꢈꢂ ꢇn rꢃꢄꢀꢂꢅvꢃ vꢅꢆꢈꢇꢆꢅꢂy ꢇf Hs- dNa ꢉnꢁꢃr ꢂhꢃ ꢅnflꢉꢃnꢈꢃ ꢇf ꢅnꢈrꢃꢀꢆꢅng
1
9
ꢀ
mꢇꢉnꢂꢆ ꢇf ꢈꢇmpꢄꢃxꢃꢆ c –c ꢀꢂ 27 ± 0.1 °c ꢅn phꢇꢆphꢀꢂꢃ bꢉffꢃr (pH 7.2).
Figure 4. thꢃ pꢄꢇꢂ ꢇf ꢃffꢃꢈꢂ ꢇn rꢃꢄꢀꢂꢅvꢃ vꢅꢆꢈꢇꢆꢅꢂy ꢇf Hs- dNa ꢉnꢁꢃr ꢂhꢃ ꢅnflꢉꢃnꢈꢃ ꢇf ꢅnꢈrꢃꢀꢆꢅng
1
9
ꢀ
mꢇꢉnꢂꢆ ꢇf l –l ꢀꢂ 27 ± 0.1 °c ꢅn phꢇꢆphꢀꢂꢃ bꢉffꢃr (pH 7.2).
Bacteriostatic activity
The MIC values of ligands are in the range of 117.5–160 μM, whereas
MIC values of complexes are in the range of 65–107.50 μM. Amongst N,
O- donor ligands and their complexes, the ligands and their complexes
bearing fluorine atom have better MIC values attributed due to a more
pronounced inductive effect. The inductive groups delocalize the

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
613
−
1
Figure 5. Phꢇꢂꢇgꢃnꢅꢈ vꢅꢃw ꢇf ꢈꢄꢃꢀvꢀgꢃ ꢇf S. pombe dNa (1 μgl ) wꢅꢂh ꢆꢃrꢅꢃꢆ ꢇf ꢈꢇmpꢇꢉnꢁꢆ
−
1
ꢉꢆꢅng 1% ꢀgꢀrꢇꢆꢃ gꢃꢄ ꢈꢇnꢂꢀꢅnꢅng 0.5 (μgl ) eꢂBr.
heterocyclic ring hence lipophilicity of moieties increases and they can
pass easily into the cell membranes. The same can be concluded amongst
S, N, O donor ligands and their respective complexes. Table 4 shows MIC
values of synthesized ligands and complexes. MIC of complexes are effec-
[
36]
tive compared to reported quinoline derived compounds.
Cytotoxicity assay with S. pombe cells
The assay was carried out using S. pombe cells. It was found that moieties
with inductive groups showed improved percentage viability when
Table 4. Mic vꢀꢄꢉꢃꢆ ꢅn ꢂꢃrmꢆ ꢇf μM.
Grꢀm(+vꢃ)
Grꢀm(−vꢃ)
Staphylococcus
Bacillus
subtilis
Serratia
marcescens
Pseudomonas
aeruginosa
Escherichia
coli
cꢇmpꢇꢉnꢁꢆ
aureus
1
c
85
70
105
65
90
65
110
60
85
75
110
65
90
65
105
60
85
70
105
65
2
c
3
c
4
c
5
c
110
70
115
80
110
75
115
70
110
75
6
c
7
c
60
65
60
65
90
8
c
75
80
80
75
75
9
c
80
75
85
75
80
1
l
140
125
150
120
160
135
140
130
145
145
120
155
115
155
130
145
135
150
140
125
155
120
160
130
145
130
145
145
120
150
115
160
140
140
135
150
140
125
155
120
160
132.5
145
130
145
2
l
3
l
4
l
5
l
6
l
7
l
8
l
9
l

6
14
B. H. PURSUWANI ET AL.
Table 5. Pꢃrꢈꢃnꢂꢀgꢃ vꢅꢀbꢅꢄꢅꢂy ꢇn S. pombe ꢈꢃꢄꢄꢆ prꢃꢆꢃnꢂꢃꢁ wꢅꢂh ꢆꢂꢀnꢁꢀrꢁ ꢁꢃvꢅꢀꢂꢅꢇn fꢇr ꢂhrꢃꢃ
ꢅnꢁꢃpꢃnꢁꢃnꢂ ꢃxpꢃrꢅmꢃnꢂꢆ.
cꢇmpꢄꢃxꢃꢆ
Pꢃrꢈꢃnꢂꢀgꢃ vꢅꢀbꢅꢄꢅꢂy pꢃr
ꢈꢇnꢈꢃnꢂrꢀꢂꢅꢇn (µg/ml)
c1
c2
c3
c4
c5
c6
c7
c8
c9
2
4
6
8
46
42
38
34
30
55
51
47
44
40
49
45
42
39
35
66
62
56
51
45
44
41
37
33
28
56
52
48
44
42
63
58
54
48
44
54
50
47
43
41
46
44
42
39
35
1
0
lꢅgꢀnꢁꢆ
Pꢃrꢈꢃnꢂꢀgꢃ vꢅꢀbꢅꢄꢅꢂy pꢃr
ꢈꢇnꢈꢃnꢂrꢀꢂꢅꢇn (µg/ml)
l1
l2
l3
l4
l5
l6
l7
l8
l9
2
4
6
8
63
59
54
52
48
66
62
58
54
50
64
59
55
51
47
71
67
63
58
54
55
51
47
44
41
75
69
64
58
54
77
70
64
58
56
72
66
62
57
53
64
60
58
54
50
1
0
compared with other compounds. All the complexes showed relatively
good cytotoxicity values compared to their respective ligands. Table 5
depicts the cytotoxicity of synthesized compounds upon increasing the
concentrations (µg/mL).
In-vivo cytotoxicity
A brine shrimp cytotoxicity assay is useful to calculate LC50 values of
synthesized compounds. The percentage variation of mortality rate upon
varying concentrations of compounds helps in predicting lethal concen-
tration upon the fatality of 50% nauplii. LC values of synthesized ligands
5
0
and complexes fall in the range of 12.12–17.65 and 5.55–8.49µg/mL respec-
tively, which shows that complexes have effective LC values compared
5
0
[
37]
to ligands and reported N-aryl quinolone derivatives.
Cell line study
1
2
3
4
6
Complexes C , C , C , C , and C show moderate IC values. The presence
5
0
of the thiophene ring has a dramatic effect on the IC50 values. Amongst
synthesized ligands, the ligands with tridentate hetero donating atoms
show better effect in biological studies based on the bacteriostatic study.
7
8
9
5
The IC50 values of complexes C , C , C , and C are <10, 50.15, 109.45,
7
8
and 152.57 μg/mL respectively. Complexes C and C have greater IC
5
0
[
38]
compare to palladium(II) complexes of 8-aminoquinoline derivatives.
IC50 values of all the synthesized complexes are represented in Figure 6.
Results show the relative IC values of synthesized complexes in the order
5
0
7
8
9
5
1
2
3
4
6
C > C > C > C > C =C =C =C =C .

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
615
1
9
Figure 6. ic50 vꢀꢄꢉꢃꢆ ꢇf ꢆynꢂhꢃꢆꢅzꢃꢁ ꢈꢇmpꢄꢃxꢃꢆ c –c .
Conclusion
Series of –N, O and –S, N, O donor atom ligands and their complexes
were synthesized and well characterized. Conductance measurements show
the electrolytic behavior of tridentate ligand-based osmium(IV) complexes.
All the synthesized compounds show a partial intercalative mode of bind-
ing. The synthesized complexes show good bacteriostatic activity and
comparatively higher binding constant values than synthesized pyrazolone
moiety-based ligands. DNA binding constants of Os(IV) complexes are in
4
−1
1
2
3
the range of 4.13–12.44 × 10 M . Complexes C , C , and C show com-
paratively higher binding affinity. The MIC values of ligands are observed
in the range of 117.5–160 μM, whereas MIC values of complexes are
observed in the range of 65–107.50 μM. LC values of synthesized ligands
5
0
and complexes are in the range of 12.12–17.65 and 5.55–8.49 µg/mL,
respectively. Complexes have effective LC50 values comparable to hetero-
cyclic ligands. IC values of tridentate ligands and their complexes dom-
5
0
inate over bidentate ligands and their respective complexes.
Acknowledgments
The authors are thankful to the Head, Department of Chemistry, Sardar Patel University,
Vallabh Vidyanagar, Gujarat, India, for providing the laboratory facilities, U. G. C., New
Delhi for providing financial assistance of UGC BSR grant No. C/2015/BSR/Chemistry/1579
and University Grant Commission under the scheme of “BSR UGC One Time Grant”,
vide UGC letter No. F.25-1/2014-15 (BSR)5-100/2007(BSR)Date13/March, 2015.
ORCID
Bhupesh S. Bhatt
Chandramani Pathak
http://orcid.org/0000-0003-0693-3226
http://orcid.org/0000-0002-9389-8096

6
16
B. H. PURSUWANI ET AL.
Vasudev R. akkar
Mohan N. Patel
http://orcid.org/0000-0003-3864-6926
http://orcid.org/0000-0001-9016-9245
References
[
[
[
1] Sun, C.-Y.; Zhang, Q.-Y.; Zheng, G.-J.; Feng, B. Phytochemicals: Current Strategy to
Sensitize Cancer Cells to Cisplatin. Biomed. Pharmacother. 2019, 110, 518–527. DOI:
0.1016/j.biopha.2018.12.010.
2] Goettel, J. T.; Braunschweig, H. Recent Advances in Boron-Centered Ligands and
eir Transition Metal Complexes. Coord. Chem. Rev. 2019, 380, 184–200. DOI:
0.1016/j.ccr.2018.09.013.
3] Kuthyala, S.; Nagaraja, G. K.; Sheik, S.; Hanumanthappa, M.; Kumar S, M. Synthesis
of Imidazo [1, 2-a]Pyridine-Chalcones as Potent Inhibitors against A549 Cell Line
and eir Crystal Studies. J. Mol. Struct. 2019, 1177, 381–390. DOI: 10.1016/j.mol-
struc.2018.09.087.
1

1
[
[
4] Jastrząb, R.; Nowak, M.; Skrobańska, M.; Tolińska, A.; Zabiszak, M.; Gabryel, M.;
Marciniak, Ł.; Kaczmarek, M. T. DNA as a Target for Lanthanide(III) Complexes
Influence. Coord. Chem. Rev. 2019, 382, 145–159. DOI: 10.1016/j.ccr.2018.12.018.
5] Nath, A. K.; Shi, X.; Harrison, D. L.; Morningstar, J. E.; Mahon, S.; Chan, A.; Sips,
P.; Lee, J.; MacRae, C. A.; Boss, G. R.; et al. Cisplatin Analogs Confer Protection
against Cyanide Poisoning. Cell Chem. Biol. 2017, 24, 565–575.e4. DOI: 10.1016/j.
chembiol.2017.03.013.
[
[
[
[
6] Inamdar, P. R.; Sheela, A. Spectroscopic Investigations on Partial Intercalative Binding
Behaviour of Terpyridine Based Copper(II) Complexes with DNA. J. Photochem.
Photobiol, B. 2016, 159, 133–141. DOI: 10.1016/j.jphotobiol.2016.03.007.
7] Gamov, G. A.; Zavalishin, M. N.; Sharnin, V. A. Comment on the Frequently Used
Method of the Metal complex-DNA Binding Constant Determination from UV–Vis
Data. Spectrochim. Acta, Part A. 2019, 206, 160–164. DOI: 10.1016/j.saa.2018.08.009.
8] dos Santos Chagas, C.; Fonseca, F. L. A.; Bagatin, I. A. Quinoline-Derivative
Coordination Compounds as Potential Applications to Antibacterial and Antineoplasic
Drugs. Mater. Sci. Eng. C 2019, 98, 1043–1052. DOI: 10.1016/j.msec.2019.01.058.
9] Takate, S. J.; Shinde, A. D.; Karale, B. K.; Akolkar, H.; Nawale, L.; Sarkar, D.; Mhaske,
P. C. iazolyl-Pyrazole Derivatives as Potential Antimycobacterial Agents. Bioorg.
Med. Chem. Lett. 2019, 29, 1199–1202. DOI: 10.1016/j.bmcl.2019.03.020.
[
[
[
[
10] Lunagariya, M. V.; akor, K. P.; Pursuwani, B. H.; Patel, M. N. Evolution of 1, 3,
-Trisubstituted Bipyrazole Scaffold Based Platinum(II) Complexes as a Biological
Active Agent. Nucleosides Nucleotides Nucleic Acids 2018, 37, 455–483. DOI:
0.1080/15257770.2018.1498510.
11] Wang, Z.; Sun, X.; Fu, W.; Xu, C.; Ji, B. Four-Coordinate Cu(I) complexes Supported
by N-Heterocyclic Carbene Ligands Bearing Electron-Donating/Withdrawing Groups:
Synthesis, Structures and Photophysical Properties. J. Lumin. 2018, 204, 618–625.
DOI: 10.1016/j.jlumin.2018.08.064.
12] Berger, G.; Grauwet, K.; Zhang, H.; Hussey, A. M.; Nowicki, M. O.; Wang, D. I.;
Chiocca, E. A.; Lawler, S. E.; Lippard, S. J. Anticancer Activity of Osmium(VI)
Nitrido Complexes in Patient-Derived Glioblastoma Initiating Cells and in Vivo
Mouse Models. Cancer Lett. 2018, 416, 138–148. DOI: 10.1016/j.canlet.2017.11.041.
13] Gichumbi, J. M.; Friedrich, H. B. Half-Sandwich Complexes of Platinum Group
Metals (Ir, Rh, Ru and Os) and Some Recent Biological and Catalytic Applications.
J. Organomet. Chem. 2018, 866, 123–143. DOI: 10.1016/j.jorganchem.2018.04.021.
5
1

NUCLEOSIDES, NUCLEOTIDES AND NUCLEIC ACIDS
617
[
14] Büchel, G. E.; Kossatz, S.; Sadique, A.; Rapta, P.; Zalibera, M.; Bucinsky, L.;
Komorovsky, S.; Telser, J.; Eppinger, J.; Reiner, T.; Arion, V. B. Cis-Tetrachlorido-
Bis(Indazole)Osmium(IV) and Its Osmium(III) Analogues: paving the Way towards
the Cis-Isomer of the Ruthenium Anticancer Drugs KP1019 and/or NKP1339. Dalton
Trans. 2017, 46, 11925–11941. DOI: 10.1039/C7DT02194A.
[
[
15] Kamecka, A.; Kapturkiewicz, A.; Suwińska, K. Luminescent Osmium(II) Complexes
with 2-(2-Pyridyl)-Benzimidazolate Anion. Inorg. Chem. Commun. 2018, 89, 27–31.
DOI: 10.1016/j.inoche.2018.01.002.
16] Dong, W.-K.; Zhang, J.; Zhang, Y.; Li, N. Novel Multinuclear Transition Metal(II)
Complexes Based on an Asymmetric Salamo-Type Ligand: Syntheses, Structure
Characterizations and Fluorescent Properties. Inorg. Chim. Acta 2016, 444, 95–102.
DOI: 10.1016/j.ica.2016.01.034.
[
[
17] El-Gamal, K. M.; Hagrs, M. S.; Abulkhair, H. S. Synthesis, Characterization and
Antimicrobial Evaluation of Some Novel Quinoline Derivatives Bearing Different
Heterocyclic Moieties. Bull. Facul. Pharm. Cairo Univ. 2016, 54, 263–273. DOI:
1
0.1016/j.bfopcu.2016.08.002.
18] Michelini, L. J.; Castro, M. R. C.; Custodio, J. M. F.; Naves, L. F. N.; Vaz, W. F.;
Lobón, G. S.; Martins, F. T.; Perez, C. N.; Napolitano, H. B. A Novel Potential
Anticancer Chalcone: Synthesis, Crystal Structure and Cytotoxic Assay. J. Mol. Struct.
2
018, 1168, 309–315. DOI: 10.1016/j.molstruc.2018.05.010.
[
[
[
19] Lay, P. A.; Sargeson, A. M. Tris(1,2-Ethanediamine) Complexes of Osmium(IV),
Osmium(III) and Osmium(II): Oxidative Dehydrogenation Reactions. Inorg. Chim.
Acta 1992, 198-200, 449–460. DOI: 10.1016/S0020-1693(00)92389-2.
20] Maruyama, K.; Mishima, Y.; Minagawa, K.; Motonaka, J. Electrochemical and DNA-
Binding Properties of Dipyridophenazine Complexes of Osmium(II). J. Electroanal.
Chem. 2001, 510, 96–102.
21] Gilewska, A.; Masternak, J.; Kazimierczuk, K.; Trynda, J.; Wietrzyk, J.; Barszcz, B.
Synthesis, Structure, DNA Binding and Anticancer Activity of Mixed Ligand
Ruthenium(II) Complex. J. Mol. Struct. 2018, 1155, 288–296. DOI: 10.1016/j.mol-
struc.2017.10.105.
[
22] Lunagariya, M. V.; akor, K. P.; Varma, R. R.; Waghela, B. N.; Pathak, C.; Patel,
M. N. Synthesis, Characterization and Biological Application of 5-Quinoline
1,3,5-Trisubstituted Pyrazole Based Platinum(ii) Complexes. Med. Chem. Commun.
2018, 9, 282–298. DOI: 10.1039/C7MD00472A.
[
[
23] Mirzaei-Kalar, Z. In Vitro Binding Interaction of Atorvastatin with Calf ymus
DNA: multispectroscopic, Gel Electrophoresis and Molecular Docking Studies. J.
Pharm. Biomed. Anal. 2018, 161, 101–109. DOI: 10.1016/j.jpba.2018.08.033.
24] Raman, N.; Pothiraj, K.; Baskaran, T. DNA Interaction, Antimicrobial, Electrochemical
and Spectroscopic Studies of Metal(II) Complexes with Tridentate Heterocyclic Schiff
Base Derived from 2′-Methylacetoacetanilide. J. Mol. Struct. 2011, 1000, 135–144.
DOI: 10.1016/j.molstruc.2011.06.006.
[
[
[
25] Kou, Y.-Y.; Li, M.-L.; Ren, X.-H. Synthesis, Structure, and DNA Binding/Cleavage
of Two Novel Binuclear Co(II) Complexes. Spectrochim. Acta, Part A. 2018, 205,
4
35–441. DOI: 10.1016/j.saa.2018.07.050.
26] Patel, M. N.; Joshi, H. N.; Patel, C. R. Copper(II) Complexes with Norfloxacin and
Neutral Terpyridines: Cytotoxic, Antibacterial, Superoxide Dismutase and DNA-
Interaction Approach. Polyhedron 2012, 40, 159–167. DOI: 10.1016/j.poly.2012.03.050.
27] Mehta, J. V.; Gajera, S. B.; Patel, M. N. Biological Applications of Pyrazoline-Based
Half-Sandwich Ruthenium(III) Coordination Compounds. J. Biomol. Struct. Dyn.
2
017, 35, 1599–1607. DOI: 10.1080/07391102.2016.1189360.

6
18
B. H. PURSUWANI ET AL.
[
[
[
28] Patra, M.; Wenzel, M.; Prochnow, P.; Pierroz, V.; Gasser, G.; Bandow, J. E.; Metzler-
Nolte, N. An Organometallic Structure-Activity Relationship Study Reveals the
Essential Role of a Re(CO)3 Moiety in the Activity against Gram-Positive Pathogens
Including MRSA. Chem. Sci. 2015, 6, 214. DOI: 10.1039/c4sc02709d.
29] Daryanavard, M.; Jannesari, Z.; Javeri, M.; Abyar, F. A New Mononuclear Zinc(II)
Complex: Crystal Structure, DNA- and BSA Binding, and Molecular Modeling; in
Vitro Cytotoxicity of the Zn(II) Complex and Its Nanocomplex. Spectrochim. Acta,
Part A. 2020, 233, 118175. DOI: 10.1016/j.saa.2020.118175.
30] Ekengard, E.; Glans, L.; Cassells, I.; Fogeron, T.; Govender, P.; Stringer, T.; Chellan,
P.; Lisensky, G.; Hersh, W. H.; Doverbratt, I.; et al. Antimalarial Activity of
Ruthenium(II) and Osmium(II) Arene Complexes with Mono- and Bidentate
Chloroquine Analogue Ligands. Dalton Trans. 2015, 44, 19314–19329. DOI: 10.1039/
c5dt02410b.
[
31] Rudnitskaya, O.; V.; Dobrokhotova, E.; V.; Kultyshkina, E.; K.; Dorovatovskii, P.; V.;
Lazarenko, V.; A.; Khrustalev, V. N. A Balance of Redox and Ligand-Exchange
Processes in the Reaction of H [OsCl ] with iourea: isolation and Characterization
2
6
of a Novel Osmium Complex [(NH ) CSSC(NH ) ] [OsIVCl ]Cl •3H O. Inorg. Chim.
2
2
2 2 2
6
2
2
Acta 2019, 484, 352–356. DOI: 10.1016/j.ica.2018.09.071.
[
[
[
32] Mehta, J.; V.; Gajera, S.; B.; akor, P.; akkar, V.; R.; Patel, M.; N. Synthesis of
1
,3,5-Trisubstituted Pyrazoline Derivatives and eir Applications. RSC Adv. 2015,
5
, 85350–85362. DOI: 10.1039/C5RA17185G.
33] Das, A.; Peng, S.-M.; Bhattacharya, S. Chemistry of 2-(Phenylazo)Pyridine Complexes
of Osmium: synthesis, Characterization and Reactivities. Polyhedron 2000, 19, 1227–
1
232. DOI: 10.1016/S0277-5387(00)00378-8.
34] Ramachandran, E.; omas, S.; P.; Poornima, P.; Kalaivani, P.; Prabhakaran, R.; Padma,
V.; V.; Natarajan, K. Evaluation of DNA Binding, Antioxidant and Cytotoxic Activity
of Mononuclear Co(III) Complexes of 2-Oxo-1,2-Dihydrobenzo[h]Quinoline-3-
Carbaldehyde iosemicarbazones. Eur. J. Med. Chem. 2012, 50, 405–415. DOI:
1
0.1016/j.ejmech.2012.02.026
[
[
[
35] Pursuwani, B.; H.; Bhatt, B.; S.; Vaidya, F.; U.; Pathak, C.; Patel, M. N.; Tetrazolo[1,5-a]
Quinoline Moiety-Based Os(IV) Complexes: DNA Binding/Cleavage, Bacteriostatic
and Photocytotoxicity Assay. J. Biomol. Struct. Dyn. 2020, 39, 2894–2903.
36] Yan, I.; Wang, X.; Wang, Y.; Zhang, Y.; Li, Y.; Guo, Z. Cytotoxic Palladium(II)
Complexes of 8-Aminoquinoline Derivatives and the Interaction with Human Serum
Albumin. J. Inorg. Biochem. 2012, 106, 46–51. DOI: 10.1016/j.jinorgbio.2011.09.032
37] Kathrotiya, H.; G.; Patel, M.; P. Synthesis and Identification of b-Aryloxyquinoline
Based Diversely Fluorine Substituted N-Aryl Quinolone Derivatives as a New Class
of Antimicrobial, Antituberculosis and Antioxidant Agents. Eur. J. Med. Chem. 2013,
6
3, 675–684. DOI: 10.1016/j.ejmech.2013.03.017
[
38] Chagasa, C.; D.; S.; Fonseca, F.; L.; A.; Bagatin, I.; A. Quinoline-Derivative Coordination
Compounds as Potential Applications to Antibacterial and Antineoplasic Drugs.
Mater. Sci. Eng. C 2019, 98, 1043–1052. DOI: 10.1016/j.msec.2019.01.058