A novel synthesis, characterization and biological studies of ferrocenyl substituted pyrazoles

Article abstract of DOI:10.14233/ajchem.2019.22161

It has been discovered that ferrocenyl substituted heterocyclic compounds have wide scope of restorative methodology. The combination of ferrocenyl substituted pyrazole is the new class in these compounds with upgraded natural activity. This work center a

Full text of DOI:10.14233/ajchem.2019.22161

Asian Journal of Chemistry; Vol. 31, No. 12 (2019), 2729-2732
A
SIAN
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OURNAL OF HEMISTRY
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https://doi.org/10.14233/ajchem.2019.22161
A Novel Synthesis, Characterization and Biological Studies of Ferrocenyl Substituted Pyrazoles
1,*
1
2
3
1
MANOJ KUMAR , SHASHI SHARMA , HARDEEP SINGH TULI , RAJSHREE KHARE and VINIT PARKASH
1Department of Chemistry, Maharishi Markandeshwar University, Sadopur-Ambala-134003, India
2Department of Biotechnology, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala-133207, India
3Department of Chemistry, Maharishi Markandeshwar (Deemed to be University), Mullana-Ambala-133207, India
*Corresponding author: E-mail: manojraju27@gmail.com
Received: 28 April 2019;
Accepted: 5 June 2019;
Published online: 16 November 2019;
AJC-19611
It has been discovered that ferrocenyl substituted heterocyclic compounds have wide scope of restorative methodology. The combination
of ferrocenyl substituted pyrazole is the new class in these compounds with upgraded natural activity. This work center around blend of
ferrocenyl substituted pyrazoles through novel course. The combination of 1-phenyl-3-ferrocenyl-pyrazole was examined including
addition-cyclocondensation like response conditions. The response continued through three phases using of expansion cyclo-buildup of
acetyl ferrocene with phenyl hydrazine pursued by cyclizing reagent iodine with NaHCO3. In both syntheses, each time single product
isolated having good yields (87 and 79 %). Ferrocenyl substituted pyrazoles were examined by spectroscopic techniques (1H NMR, IR,
MS) and their biological properties have been screened.
Keywords: Ferrocenyl substituted pyrazoles, Addition cyclo-condensation, Biological activities.
all things considered, added to their novel motivator as standard
key segments of different medications. Starting late, unique
products, catalysts and reagents have been made for the asso-
ciation of heterocyclic compounds. An expansive number of
them encounter the impacts of various drawbacks as usage of
toxic reagents, long reaction times, lesser yields and low selec-
tivity. Along these properties, scientists are continuing sear-
ching for some reagents which can be used to coordinate new
heterocyclic structures with inconceivable identity, higher
reactivity and noticeable viability. Five membered heterocycles
have a group of such compounds however pyrazole is one of
them for research point of view since it is a piece of numerous
medications. Pyrazole ring is the primary substance in the
structure of helpful pesticides and composts in agribusiness
just as in pharmaceutical organizations. Pyrazole and its deriva-
tives have immense natural properties moreover cytotoxic,
against malarial, antitumour, antibacterial, antimicrobial action
and calming, antiproliferatie, hostile to angiogenics narcotic
sleep inducing activities [3-9]. In decades ago, pyrazole com-
pounds are progressively underlined on account of their various
properties. Pyrazole and its related compounds are very
dynamic in medication structuring as a result of their distinctive
INTRODUCTION
The science of heterocyclic compounds is the most mind
blowing parts of natural science. It is similarly fascinating for
its hypothetical ramifications, for the assorted variety of its
engineered techniques, and for the physiological and modern
criticalness of heterocyclic compounds. Specifically, the hetero-
cyclic compounds have been widely contemplated for their
characteristic enthusiasm, as well as on the grounds that numerous
normal items, numerous medications and drugs and numerous
dyestuffs have a place with this gathering. Heterocyclic comp-
ounds are cyclic natural substances which contain in the ring
framework somewhere around one or more carbons are replaced
with other atoms. Numerous alkaloids, nutrients, antitoxins
and numerous manufactured medicines and dyestuffs are hetero-
cyclic, thus likewise are numerous substances (for example,
nucleic acids, vitamins, etc.) which are most associated with
the life processes. Probably any particle which can shape two
covalent bonds is fit for framing a heterocyclic compound [1,2].
Heterocyclic compounds hold a unique place among pharma-
ceutical industries. The excellent limit of heterocyclic centers
to serve both as biomimetics and as open pharmacophores has,
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2730 Kumar et al.
Asian J. Chem.
organic exercises like enemy of angiogenic, anti-inflammatory,
antibacterial activities, etc. Therapeutic scientific experts are
likewise open to the incorporation of ferrocene into their medi-
cation plan systems due to the uniqueness presented by its
essence. Ferrocene is a steady, non-toxic compound and having
great redox properties. Present research is proceeding to plan
new compounds which are dynamic against a wide scope of
malignant growths and have lesser symptoms [10,11]. Ferro-
cenes are likewise known to display a wide scope of natural
movement and furthermore ferrocene has pulled in unique
consideration since it is an impartial artificially steady and
non-poisonous. Numerous ferrocenyl compounds show intri-
guing, cytotoxic, antitumor, antimalarial, hostile to organo-
metallic compounds and DNA separating exercises [12-17].
There are numerous models available in literature to the
utilization of ferrocene in tranquilize structure techniques. In
one examination on some non-steroidal calming operators, the
substitution of fragrant ring by ferrocene did not enhance cells
to joint or platelet aggregatory exercises in the subsequent
compound [18]. Examinations with ferrocene-containing
penicillins, cephalosporins and rifamycins demonstrated that
the consideration of ferrocene did not present any uncommon
favourable position [19,20]. Then again, critical changes in
action profiles had been recorded when ferrocene was brought
into set up medications like tamoxifen and chloroquine. Ferro-
cenyl subordinates are among the most potential mixes which
can be utilized in malignant growth examining. Malignancy
is a class of malady described by uncontrolled cell expansion
and the capacity of these cells to attack different tissues. In
2007, 5-alkyl-2-ferrocenyl-6,7-dihydropyrazolo-[1,5-a]pyrazin-
4[5H]-one complex and its subsidiaries having inhibitory
impact towardsA549 malignancy cell development was disco-
vered [21]. New ferrocenyl subordinates of pyrazole analogs
were set up in 2014. One of them was (2-formyl-1-chlorovinyl)-
ferrocene arranged by utilizing acetylferrocene. These mixes
have anticancer and organic activities [22].
(R)-N,N-dimethyl-1-[(S)-2-{3-(1-phenyl)-1H-pyrazolyl}-
ferrocenyl]ethylamine was combined from 1-(R)-N,N-dimethyl-
ferrocenylethylamine by Burkhardt and Drommi [23]. This
exploration was another methodology in the field of chelating
pyrazole-containing ligands [23]. In 2008, Hasinoff et al. [24]
determined ester coupled bisanthrapyrazole subsidiaries of 7-
chloro-2-[2[-[(2-hydroxyethyl)methyl amino]ethyl]anthrax-
[1,acd]pyrazole-6(2H)-one (APa) have more grounded DNA
official and cytotoxic action. The bisintercalation capability
of the compound and the quality of DNA restricting was acquired
by increment in DNA liquefying temperature [24]. Tan et al.
[25] integrated the subordinates of novel anthrapyrazole from
emodin and found the cytotoxic impact of these towards malig-
nant growth cell. These subsidiaries were gotten by joining
different cationic alkyl amino side chains onto a pyrazole ring.
Emodin has co-planar structure so it has low DNA restricting
partiality and low or inconsequential cytotoxicity against
different malignant growth cells.
IR spectra was made utilizing Perkin Elmer-Spectrum RX-
IFTIR instrument tests were set up as KBr pellets. Mass spectra
(m/z) was made by utilizing Gas Chromatography Mass Spectro-
metry through SAIF LAB, Chandigarh, India. Every single
synthetic compounds utilized of investigative grade procured
from LOBA, MERCK and OTTO.All the solvents were distilled
before use.
Synthesis of cyclopenta-2,4-dien-1-yl(2-(1-phenyl-1H-
pyrazol-4-yl)cyclopenta-2,4-dien-1-yl)iron(III): 1-Phenyl-
3-ferrocenyl pyrazole was synthesized by using vinyl ferrocene.
Vinyl ferrocene was treated with phenyl hydrazine hydro-
chloride by refluxing at 100 ºC using water bath for 3 h. Desired
product was synthesized by treating reaction mixture with iodine
crystals (0.001 mol) and (0.02 mol) of sodium bicarbonate by
refluxing using magnetic stirrer with hot plate at 60 ºC for 2 h
followed by treating hot reaction mixture with ice and a single
product was separated out (Scheme-I). IR (KBr, νmax, cm-1):
1
752 (C-H str.), 1150 (C-N str.), 1666 (C=N str.), H NMR:
(400 MHz, DMSO, in ppm) δ: 6.69-6.79 (m, 5H, Cp), 1.93 (s,
1H, allylic-H), 7.27-7.31 (d, 1H, cis-H), 1.99-2.00 (d, 1H,
allylic-H), 4.30 (s, 1H, vinyl-H), 2.48 (s, 1H, CH-N), 7.00-
7.16 (m, 5H,Ar-H). GC-MS (m/z) calcd. (found): 328 (328.17).
Anal. calcd. (found) % for C19H17N256Fe : C, 69.51 (69.47); H,
5.18 (5.13); N, 9.14 (9.11).
N
N
(i) Phenyl hydrazine hydrochloride
Fe
Fe
(ii) I2/NaHCO3
Scheme-I
Synthesis of cyclopenta-2,4-dien-1-yl(2-(1-(2,4-dinitro)-
phenyl-1H-pyrazol-4-yl)cyclopenta-2,4-dien-1-yl)iron(III):
Nitro derivative of 1-phenyl-3-ferrocenyl pyrazole was synthesized
by using acetyl ferrocene. Acetyl ferrocene was treated with
2,4-dinitrophenyl hydrazine by refluxing at 60 ºC using water
bath for 3 h. Desired product was synthesized by treating
reaction mixture with iodine crystals (0.001 mol) and sodium
bicarbonate (0.02 mol) by refluxing using magnetic stirrer
with hot plate at 100 ºC for 2.5 h followed by treating hot
reaction mixture with ice for quenching the reaction at this
stage and a single product was separated out (Scheme-II). IR
(KBr, νmax, cm-1): 473 (Cp-Fe-Cp str.), 742 (C-H str.), 1140 (C-
N str.), 1661(C=N str.).1H NMR: (400MHz, DMSO, in ppm)
δ: 6.49-6.57(m, 5H, Cp), 0.83 (s, 1H, allylic-H), 7.66-7.68 (d,
1H, cis-H), 0.99-1.00 (d, 1H, allylic-H), 4.30 (s, 1H, vinyl-
H), 4.08(s, 1H, CH-N), 7.10-7.16 (m, 5H, Ar-H). GC-MS
(m/z) calcd. (found): 422 (422.23). Anal. calcd. (found) % for
C19H14N4O456Fe: C, 54.02 (53.99); H, 3.31 (3.31); N, 14.3 (14.21).
Antimicrobial assay: in vitro Antimicrobial activity has
been evaluated for ferrocenyl substituted pyrazoles against
pathogenic strains of bacteria (Staphylococcus aureus, Klebsiella
pneumoniae) and fungi (Aspergillus niger, Trichophyton rubrum)
using disc plate diffusion assay. The stock solutions of both
EXPERIMENTAL
1H NMR spectra was recorded on Bruker Avance II 400
NMR Spectrometer at 400MHz using TMS as internal standard.

Vol. 31, No. 12 (2019)
A Novel Synthesis, Characterization and Biological Studies of Ferrocenyl Substituted Pyrazoles 2731
RESULTS AND DISCUSSION
N
COCH3
Antimicrobial activities: The antimicrobial effect of
N
(i) 2,4-Dinitrophenyl hydrazine
(ii) I2/NaHCO3
synthesized ferrocenyl substituted pyrazoles towards harmful
human pathogenic microorganisms has been studied with
comparison to Neomycin and fluconazole. The antimicrobial
Fe
Fe
NO2
action of ferrocenyl substituted pyrazoles was measured in
term of zone of inhibition (Tables 1 and 2) and MIC values were
found to be in the range of 85-95 µg/mL. Previous evidences
have supported that pyrazole based derivatives possesses broad
NO2
Scheme-II
spectrum of antimicrobial effects. Bekhit and Abdel-Aziem
[26] investigated the antimicrobial effect of novel pyrazole
derivatives against Gram-positive and Gram-negative bacterial
as well as pathogenic fungi. Mandal et al. [27] and Munyaneza
et al. [28] have also reported the promising antimicrobial
activities of metal complexes of pyrazole.
DNA photo-cleavage: The photo-induced DNA cleavage
has been carried out using super coiled plasmid DNA by gel
electrophoresis [29]. The result of DNA photo-cleavage investi-
gations is shown in Fig. 1.As literature revealed that in plasmid
DNA electrophoresis the super coiled DNA (form I) migrate
relatively fast with comparison to nicked DNA (form II) [30].
Super coiled form is relaxed to produce a open-circular form
which is slower moving if one strand of super coiled form is
cleaved. If both strands of super coiled form are cleaved, a
synthesized feroocenyl substituted pyrazoles (1000 ppm) were
prepared in DMSO. The plates of culture medium using nutrient
agar and potato-dextrose agar were prepared for bacterial and
fungal growth respectively under sterilized condition. The
various concentrations of ferrocenyl substituted pyrazoles
(100, 150, 200 and 250 ppm) were loaded on 5 mm sterilized
filter paper discs and placed on agar plates followed by incub-
ation at 30 ºC for 24 h and 72 h to evaluate the effect of compound
on bacterial and fungal growth, respectively. Neomycin and
fluconazole were used as standard antimicrobial agents for
bacterial and fungal study, respectively.
DNA photo-cleavage assay: DNA cleavage activity of
the synthesized ferrocenyl substituted pyrazoles were studied
by agarose gel electrophoresis using supercoiled pUC19 plasmid
DNA. The total volume of reaction mixture was 10 µL cont-
aining 0.5 µg of plasmid DNA in TE (tris 10 mM, EDTA 0.01
mM, pH 8.0) buffer with various concentrations of synthesized
ferrocenyl substituted pyrazoles. The Eppendorfs carrying
reaction mixture were placed directly on the surface of a trans-
illuminator (8000 mW/cm) at 360 nm for 30 min. After irrad-
iation, samples were further incubated at 37 ºC for 1 h. Irradiated
samples were mixed with 6X loading dye containing 0.25 %
bromophenol blue and 30 % glycerol. The samples were then
analyzed by electrophoresis on a 0.8 % agarose horizontal
slab gel in tris-acetate EDTA buffer (40 mM Tris, 20 mM acetic
acid, 1 mM EDTA, pH: 8.0) with comparison to untreated
plasmid DNA as a control. Gel was stained with ethidium bromide
(1 µg/mL) and photographed under UV light.
FSP 1
100 200
FSP 2
200 300 (ppm)
Untreated
300 100
Fig. 1. DNA photo-cleavage activity (FSP = ferrocenyl substituted pyrazoles)
TABLE-1
ANTIMICROBIAL EFFECTS OF SPECTRAL STUDY OF CYCLOPENTA-2,4-DIEN-1-
YL(2-(1-PHENYL-1H-PYRAZOL-4-YL)CYCLOPENTA-2,4-DIEN-1-YL)IRON(III)
Bacterial strains
Fungal strains
Trichophyton rubrum
S. aureus
K. pneumoniaae
A. niger
150 200
Conc. (ppm)
Zone
100
150
200
250
100
150
200
250
100
250
100
150
200
250
of 12
16
17
18
11
13
18
20
10
12
15
18
09
12
14
18
inhibition (mm)
0.5
0.7
0.6
0.6
0.5
0.5
0.5
0.7
0.5
0.5
0.5
0.5
0.7
0.4
0.5
0.6
Standards
21 mm (Neomycin)
23 mm (Neomycin)
24 mm (Fluconazole)
9 mm (Fluconazole)
TABLE-2
ANTIMICROBIAL EFFECTS OF CYCLOPENTA-2,4-DIEN-1-YL(2-(1-(2,4-
DINITRO)PHENYL-1H-PYRAZOL-4-YL)CYCLOPENTA-2,4-DIEN-1-YL)IRON(III)
Bacterial strains Fungal strains
S. aureus
K. pneumoniaae
A. niger
150 200
Trichophyton rubrum
Conc. (ppm)
100
150
200
250
100
150
200
250
100
250
100
150
200
250
Zone of
12
15
17
21
10
14
16
19
10
13
16
18
09
12
15
17
inhibition (mm)
0.5
0.7
0.6
0.6
0.5
0.5
0.5
0.7
0.5
0.5
0.5
0.5
0.7
0.4
0.5
0.6
Standards
21 mm (Neomycin)
23 mm (Neomycin)
24 mm (Fluconazole)
9 mm (Fluconazole)

2732 Kumar et al.
Asian J. Chem.
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In the present study, two ferrocenyl substituted pyrazoles
have been designed and synthesized by means of novel course
and characterized. The IR, 1H NMR and mass data confirmed
the proposed structure and geometry. It is obvious from the
confirmations that such holding is possible. The antimicrobial
study shown that both ferrocenyl substituted pyrazoles are
strong antimicrobial agents and further DNA photocleavage
investigation confirmed that both compounds have good DNA
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CONFLICT OF INTEREST
The authors declare that there is no conflict of interests
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