Full Length Research Paper
Synthesis and
Antimicrobial Evaluation of Schiff base of 3 (4-Nitrophenyl) Ethylidene Amino Phenyl
Ethanone.
Dr.
Rakesh D. Talele[1] and Dr. Jayant P. Nehete2
1-Department of Chemistry, Dhanaji Nana Mahavidyalaya,
Faizpur, Dist.- Jalgaon (M.S) - 425503, India
2-Department of Chemistry, SVP Arts and Science College, Ainpur,
Dist.- Jalgaon (M.S) - 425507, India
ARTICLE DETAILS ABSTRACT
- Introduction
Schiff base compounds are formed by
the condensation of a primary amine with an aldehyde or ketone, resulting in
the formation of an imine linkage (-C=N-).1-3 These compounds
exhibit a wide range of biological properties, including antimicrobial,
anti-inflammatory, anticancer, and antioxidant activities.4-6 Schiff bases find wide applications in various
fields such as the food industry, dye industry, analytical chemistry,
catalysis, fungicidal and agrochemical industries, as well as in biological
activities.7 A Schiff base synthesized from indoline-2,3-dione and
2-aminobenzoic acid, along with its Tin complex, exhibited antibacterial
activity against Staphylococcus aureus.8 The Schiff bases derived
from 2,6-diacetylpyridine and 2-pyridine carboxaldehyde with
4-amino-2,3-dimethyl-1-phenyl-3-pyrozolin-5-one form complexes with Co(II),
Cu(II), Ni(II), Mn(II), and Cr(III) which exhibit antibacterial and antifungal
activity against various bacteria. The antibacterial effect of the complexes is
greater than that of the free ligand.9 The enhanced activity in the
organotin complexes can be attributed to the coordination and polarity of a
tin(IV) atom with oxygen in the ligand.10
Antifungal activities were studied for
N-(2-hydroxy-1-naphthalidene) phenyl glycine and its transition metal
complexes. The results showed that complexation enhanced the activity of the
ligand against fungi. Cu(II), Ni(II) and Co(II) complexes were found to have
better antifungal activity compared to the ligand and corresponding metal
salts.11 The fungicidal effect of salicylaldimine containing
formaldehyde and piperazine moiety and its metal polychelates were determined
against Candida albicans and Aspergillus.12 In summary, this work
focuses on the synthesis, characterization, and evaluation of amino-based
Schiff bases derived from various amines. The determination of melting points,
solubility, Rf values, analysis of functional groups via infrared spectroscopy,
and assessment of antimicrobial activities contribute to a comprehensive
understanding of these compounds. The results obtained from this study hold
promise for the development of novel antimicrobial agents and their potential
applications in the field of medicinal chemistry.
2.
Material and methods
All chemicals used in the experiments
were of analytical grade and were purified using established methods. Melting
points of the synthesized compounds were determined using open capillaries and
were corrected accordingly. Infrared (IR) spectra of the compounds were
recorded using Shimadzu FTIR 8400 (Model SI 118675 A) using KBr pellets. to analyse
and identify the presence of specific functional groups. Thin-layer
chromatography plates were prepared using silica gel slurry in chloroform or
silica-coated aluminium foil TLC plates. The TLC was performed using a mobile
phase of diethyl ether/petroleum ether, and detection was achieved using an
iodine vapour chamber.
For evaluating the antimicrobial
activity of the compounds, the synthesized Schiff base and standard antibiotics
were tested against the antifungal strain Aspergillus Niger (A. Niger) and the
antibacterial strain Escherichia coli (E. coli) Gram-negative microbial
cultures were grown for testing. Sterile Petri dishes containing nutrient agar
and potato dextrose agar were used. 70% ethanol was used for sterilisation
purposes. Whatman filter paper discs with a diameter of 5mm were utilized.
Sterile spreaders were employed for spreading the microbial cultures.
2.1 Experimental
Synthesis of [UA01] Schiff base: 3
(4-Nitrophenyl) ethylidene amino phenyl ethanone prepared by a known method.13
Synthesis of [UA02 to UA06] Schiff base: Schiff base [UA02 to UA06] has
been prepared from synthesised Schiff base [UA01] and was mixed in a 1:1 ratio
with different amines in ethanol solvent. The resulting mixture is stirred for 2
to 2.5 hours at a temperature of 60°C. The antibacterial activity of a specific
compound concentration is (100 μg/ml), as determined by the disc diffusion
method. The compound diffuses out of the disc into the agar, creating a
concentration gradient that inhibits the growth of the microorganism. The
inhibition zone, characterized by a lack of visible growth around the disc, is
measured to assess the compound's effectiveness. In the case of antibacterial
activity, bacterial strains such as Escherichia coli (E. coli) or
Staphylococcus aureus and in the case of antifungal activity, fungal strains
such as Aspergillus niger or Candida albicans are commonly employed.
3.
Result and discussion
This study explored the synthesis, characterization, and
antimicrobial activity of Schiff bases derived from various amines. The results
obtained provide valuable insights into the potential applications of these
compounds in the field of medicinal chemistry. The infrared spectrum assignments of the ligand were made by simple
inspection and by reference to generalized charts of characteristic group
frequencies and based on analogous structures, known earlier. A notable
absorption band at 1673 cm⁻¹ was attributed to the stretching vibration
of the C=N bond, confirming the presence of an imine group. Another band at
1749 cm⁻¹ corresponded to the stretching vibration of the >C=O bond,
indicating the presence of a ketone group. The in-plane bending vibrations of aromatic
C-H bonds were observed within the 1250–950 cm⁻¹ range, while
characteristic frequencies for the out-of-plane bending vibrations of aromatic
C-H bonds were detected between 600–900 cm⁻¹. This IR spectral analysis
provides valuable information about the molecular structure and functional
groups, including imine (>C=N), ketone (>C=O), and aromatic amine (C-N in
an aromatic ring), with the aromatic C-H bond vibrations further confirming the
presence of aromatic groups.
The infrared analysis of ligands UA02 to UA06 revealed important findings regarding the presence of
functional groups. Specifically, the stretching frequencies associated with the
C=N bond were observed in the typical range of 1650-1673 cm-1. This
confirms the presence of an imine group in these compounds. Furthermore, the
stretching frequencies corresponding to the C-N bond in an imine group were
found within the range of 1180-1350 cm-1. This supports the
identification of an additional imine linkage in the compounds, as evidenced by
the presence of a second >C=N stretching frequency. Interestingly, the
disappearance of keto frequencies suggests a transformation of the carbonyl
group to an imine group. This indicates that the compounds underwent a chemical
reaction involving the conversion of the carbonyl group (C=O) to an imine group
(>C=N), contributing to the formation of the observed functional groups.
Overall, the infrared spectroscopic analysis
provided evidence of the presence of multiple imine groups in ligands B, C, D,
E, and F. The disappearance of keto frequencies further supports the structural
transformation from a carbonyl group to an imine group. These findings
contribute to a better understanding of the molecular composition and
functional groups in the synthesized compounds. Furthermore,
the antimicrobial activity of the Schiff bases was evaluated against both
bacterial and fungal strains. These results suggest the potential of the
synthesized Schiff bases as antimicrobial agents. The antimicrobial activity
can be attributed to the presence of certain functional groups in the Schiff
bases, which may interact with the microbial cells, disrupting their growth and
viability. The differences in antimicrobial activity among the compounds can be
attributed to variations in their chemical structures and functional groups,
highlighting the structure-activity relationship in antimicrobial properties.
Table 1: Physical Parameter of Synthesized
Schiff base
Table 2: Antimicrobial activity of Synthesized
Schiff base
- Conclusion
Synthesis of Schiff Base derived [UA01
to UA06] was synthesised and characterized by IR. In the synthesis, the HC=N
bond formed between the amine group of various amines including
3-aminoacetophenone, 2-aminobenzothiazole, 2-amino-3-hydroxypyridine,
2-amino-5-bromopyridine, 4-amino antipyrine, and isoniazid and the carbonyl
group which IR Band confirmed in the 1650-1673 cm-1 range. Nearly all
synthesised compounds [UA01 to UA06] are more active towards the antibacterial
and antifungal strains which are shown in the results and discussion section.
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