Synthesis And Antimicrobial Study of Fe (Ii) Complex of Schiff Base Derived From 4- Acyl Antipyrine and Substituted Aniline

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Synthesis And Antimicrobial Study of Fe (Ii) Complex of Schiff Base
Derived From 4- Acyl Antipyrine and Substituted Aniline

1*Okolo Azubuike Jeremiah, 1Ezenweke Linus Obi, 1Ojiako Eugenia Nonye, 1Oragwu Ifeoma Perpetual,
1Okwuego Peter Obinna, 2Ogbuagu Obiaku Efuru, 3Silas Canice Uchechukwu, 4Chukwuemeka

Nwachukwu Udeogu

1Department of Pure and Industrial Chemistry Chukwuemeka Odumegwu Ojukwu University, Uli
Campus, Anambra State, Nigeria.

2Department of Science Education, Alvan Ikoku Federal University of Education, Owerri, Imo State,
Nigeria.

3Department of Chemistry, Kingsley Ozumba Mbadiwe University, Ogboko, Imo State, Nigeria.

4Department of Chemistry, Alvan Ikoku Federal University of Education, Owerri, Imo State, Nigeria

*Corresponding Author

DOI: https://doi.org/10.51584/IJRIAS.2025.1010000031

Received: 07 Oct 2025; Accepted: 15 Oct 2025; Published: 30 October 2025

ABSTRACT

The incidence of drug- resistant microbial infections is a growing concern worldwide, necessitating the
development of novel antimicrobial agents that would break barrier of resistance, guarantee safety and potency
of pharmaceutical products. The chemical synthesis and antimicrobial studies of Iron (II) complexes of Schiff
base derived from acetyl chloride antipyrine (4-acyl antipyrine) were carried out using substituted aniline (2-
hydroxylaniline) was one such attempts of development of new molecular compounds capable of breaking
barrier of resistance. The primary ligand, Schiff base ligand and their metal complex was characterized using
spectroscopic techniques ranging from IR, UV-Vis, GCMS. The melting point, molar conductivity, elemental
composition was determined. Interestingly, all the synthesized compounds were obtained in good yield (76%-
86%). The molecular ion peaks (M+) indicating the molecular weight of the synthesized ligand and metal
complex were detected using the various fragments produced by the ligands and metal complexes based on
their mass to charge ratio obtained from GC-MS Spectra. Octahedral geometry was observed for Fe (II)
complex. The IR absorption showed characteristic behaviour in the sense that the v(C=N) found in SLOA and
the metal complexes with frequency range of (1,582.90cm-1) indicate that imine group/Schiff base is formed.
The absorption band assigned to C=O in the ligand and metal complexes are as follow 1,700.65cm-1 and
1,623.00cm-1 respectively. The Schiff base ligands SLOA (I,700.65cm-1) showed a notable shift to higher
wavenumbers indicating increase C=O bond strength due to coordination with metal through its oxygen or
electron withdrawal in the Schiff base framework. Metal complexes show C=O stretching shifted back to
lower frequency value (1.633.54cm-1) suggesting co-ordination of oxygen to metal. The metal complexes
demonstrated great antimicrobial efficiency on test organisms of both bacteria (Salmonella typhi, Escherichia
coli, Staphylococcus aureus and Streptococcus pyogenes) and fungi (Candida albicans) more than the ligand
due to lipophilicity of the chelated complexes which retarded their growth process. This study showed that
synthesis and complexation have taken place and the knowledge gained will help to advance the course of
bioinorganic and inorganic chemistry as well as incorporating ligands and metal complexes into antibiotic
drugs production.

Keywords: Schiff base, Antimicrobial, Metal complex, 4-acyl antipyrine, Fe(II)Complex, Coordination.

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INTRODUCTION

The coordination chemistry of metal complexes plays a vital role in biological system of organisms. Transition
metal complexes are important in catalysis, material synthesis, photochemistry and biological systems. The
synthesis of ternary complexes mainly involves the interaction of metal ion with two or more different ligands.
Recently there has been considerable interest in mixed chelation because it occurs commonly in biological
fluids, which contain millions of potential ligands which are likely to compete in vivo for metal ions. It is well
known that the ternary coordination complexes play an important role in biological processes as exemplified
by many instances in which enzymes are known to be activated by metal ions [1]. Ternary complexes have
also been implicated in the storage and transport of active substances through membranes [2] and these
phenomena are strongly dependent on the formation of these species and the electronic configuration of metal
ion concerned. The stability constant and complexation behaviour of Fe (II) complexes with various ligand
have been studied extensively [3].

The coordination number is the number of ligand-binding sites on the metal ion. The bond between the metal
ion and the ligand, where the ligand supplies both electrons, is known as a co-ordinate covalent bond. A co-
ordinate bond, also known as a dative covalent bond is a covalent bond, a shared pair of electrons in which
both electrons to be shared originate from the same atom. Transition metals are up to all sorts of unusual
activities in the chemical world. Like giving colour to compounds or performing vital functions in living
things. Many of their unique abilities have to do with their electron configurations. Because they are so special,
we often find transition metals as the center of attention, literally. In coordinated compounds the transition
metal is in the middle of the complex ion [4].

Transition metals involved in the complex ion have two sets of valence electrons participating in bonding. The
first set of bonding electrons is called primary valence, and it is the oxidation number of the metal. The
oxidation number can be determined by looking at the charge on the transition metal ion. Iron (Fe), for
example, has an oxidation number of 2. Sometimes this number must be inferred based on the overall charge
of the complex ion. The primary valence electrons are involved in typical ionic bonds [5]. The second set of
transition metal valence electrons are called secondary valence, usually referred to as the coordination number.
The secondary valence electrons are involved with bonding with the ligands. The coordination number
indicates the number of ligands that a metal ion is bonded to [6]. Ligands bond to transition metals by sharing
a lone pair of electrons. This type of interaction is a Lewis acid-base reaction, where the metal ion is the Lewis
acid and the ligand is the Lewis base. The resulting bond in which one species donates both bonding electrons
is called a coordinate covalent bond [7].

Pyrazolone derivatives are also used in preparing dyes and pigments [8]. 2,3-dimethyl-1-phenyl-5-pyrazolone
(antipyrine) has been discovered as antipyretics of the quinoline type [9]. This discovery initiated the
beginning of the German Drug Industry that dominated the field for approximately 40 years.

5- pyrazolone as a widely used precursor to variety of compounds, documented well for their numerous
applications such as products and intermediates in analytical, agricultural, biological and pharmaceutical
chemistry [10,11,12]. Some of them also serve as important pharmaceutical agents including antipyrine and its
congeners. With continuous evaluation for their pharmacological properties like analgesic [13], potential
antipyretic, anti-nociceptive and antioxidant activities [14]. Recently, acylpyrazolone have been reported to
have a multidrug resistance modulating activity [11]. Benzoyl pyrazolone particularly, is potential antiprion
agents [15]. An antiprion agent is a compound or drug designed to target and combat prions, which are
abnormally folded proteins responsible for causing fatal neurodegenerative diseases known as prion diseases
[16]. These antiprion agents work by inhibiting the misfolding of normal cellular prion protein into the
infectious, pathogenic form [17]. The presence of fragment azomethine group (-N=CH-R) in Schiff bases is
known for its biological activity [18]. Many reports exist on structure- activity relationship of the class of this
compound, therefore it becomes worthwhile to continue to further investigate in this molecule.

Iron(II) complex, in particular, have become of research interest because several Fe(II)– 4 acyl antipyrine
complex has demonstrated promising antibacterial and antifungal result in vitro, and in some cases, improved
activity against drug-resistant strains.[9] These findings justify exploring Fe(II) chelates of new Schiff base

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ligand as potential antimicrobial agents. This can be attributed to the concept called lipophilicity which is the
ability of the metal complex to penetrate or dissolve the cell membrane of microorganism hence retards the
growth of the microorganism [18].

This research work focuses on Synthesize and characterize Fe (II) complexes of Schiff base ligand derived
from 4- acyl antipyrine using substituted anilines (2-hydroxylaniline) and the determination of the
antimicrobial activities of the synthesized ligand and metal complex.

Experimental

The Apparatus and Reagents

The reagents used in this work are analytical grade and they are as follows; Chloroacetyl Chloride (Sigma –
Aldrich), Acetyl Chloride (Sigma-Aldrich), Antipyrine (Sigma -Aldrich),2- amino aniline (Sigma-Aldrich), 2-
Hydroxyl aniline (Sigma- Aldrich), Cobalt (II) Acetate (J.T. Baker), Nickel (II) Acetate (J.T.Baker), Iron (II)
Acetate (J.T. Baker) and Dioxane (Sigma- Aldrich), HCl(Sigma- Aldrich), Calcium Hydroxide (Sigma-
Aldrich), n-Hexane (Sigma- Aldrich),Carbon tetra chloride(Sigma- Aldrich), Deionized water. The solvents
were ethanol (J.T. Baker), Methanol (J. T. Baker), Acetone (J. T. baker) and Ether (J. T. Baker)

The electronic equipment: Fourier Transform Infrared (FTIR) (Nicolet Is5, Thermo
Fisher Scientific USA), Electronic weighing balance (Ohaus,Adeventurer),Beakers(Pyrex),Conical flasks(Pyre
x),Bunsen burner (Fisherbrand),Waterbath (Grant), Filter paper (Fisherbrand),Stuart MP 3, Agilent 7977 Gas
Chromatograph,5973D Inert Mass Spectrometer (Thermo Scientific USA),Conductivity meter (HACH
HQ40D), Elemental Analyzer CE -440 (Exeter Analytical Inc.UK).

The bacteria Species: Salmonella typhi (Gram negative bacteria) Escherichia coli (Gram negative bacteria),
Staphylococcus aureus (Gram positive bacteria). Streptococcus pyogenes (Gram positive bacteria), Candida
albicans (Fungi, yeast) were obtained from the Reference Laboratory Section of Gomecs-everglad
Laboratories, Owerri, Imo State, Nigeria. The organisms were maintained on Nutrient Broth for 24 hours.

Synthesis of 4- acyl antipyrine:

9g (0.05mol) of antipyrine (2,3-dimethyl-1-phenylpyrazolone-5) was dissolved in hot dioxane (70cm3) placed
in a round bottom flask equipped with a stirrer, separating funnel and reflux condenser. Calcium hydroxide
(7.00g,0.1mol) was added to this solution, followed by acetyl chloride (5ml, 0.07mol) added drop wise. The
reaction mixture became thick paste and was refluxed for 2 hrs. and allowed to cool. The mixture was poured
into hydrochloric acid (200cm3). The cream-coloured crystals obtained were filtered and then recrystallized
from cold ethanol- water acidified with HCl to destroy any undecomposed calcium complex and recrystallized.
The yield was 80%, melting point 1160C and was labelled LOA.

Fig 2.1: Scheme of Reaction for the Synthesis of 4-Acyl Antipyrine.

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KEY:

LOA = Ligand of acetyl chloride antipyrine

LOC = Ligand of monochloroacetyl chloride antipyrine

Synthesis of Schiff base ligand from 4-acyl antipyrine and 2- hydroxyl aniline:

2.18g, 0.02mol of 2-hydroxylaniline was dissolved with 150ml absolute ethanol in 500ml round bottomed
flask, to this solution was added dropwise 2.68g, 0.03mol of LOA in 30cm3 of absolute ethanol over
30minutes while stirring. Stirring continued for another 30minutes and mixture refluxed for 3hrs.The resulting
solution was allowed to cool and filtered to remove the solvent and the solid residue was washed with cold
ethanol and then recrystallized with a mixed solvent of methanol, ethanol and acetone in the ratio of 1:1:1. The
yield was 86% and melting point 2320C. The Schiff base formed was labelled SLOA.

Fig 2.2 Scheme of Reaction for the Synthesis of the Schiff Base

KEY:

LOA = Ligand of acetyl chloride antipyrine

LOC = Ligand of monochloroacetyl chloride antipyrine

SLOA = Schiff base ligand of 2- hydroxylanilne

SLOC = Schiff base ligand of 2- aminoaniline

Synthesis of metal complexes:( M= Fe(II))

1 mmole solution of the metal acetate, M(II) (OAC)2: 0.216g Fe (II) (OAC)2 was placed in boiling ethanol
solvent. I mmol solution of the Schiff base Ligand (SLOA 0.419g) was added then, a few drops of piperidine
were also added as a precursor. The whole mixture was refluxed for 1 hour. It was then allowed to cool to
deposit-coloured metal complexes. The precipitate was washed with the cold methanol and cold ether, allowed
to dry in oven at a temperature of 500C. Metal complexes formed was labelled SLOAFe. The yield and melting
point were SLOAFe 76%, 280-2840C.

Instrumental analysis:

The molar conductivity measurement of the samples was carried out with a 10-3m solution of the sample in
absolute ethanol, at 25±0.50C. The conductivity was determined using conductivity meter (HACH HQ40d).
The FT-IR Spectra of the samples were obtained in the 400-4000 cm-1 range using Fourier Transform Infrared
(FTIR) (Nicolet Is5, Thermo Fisher Scientific USA), equipped with KBr optics and complimentary ATR
diamond accessories. The acquired interferogram was converted into a spectrum by Fourier Transformation. In

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other to achieve good balance ripple size and resolution, the Happ Genzel function was used for Apodization
(used in Hannwindow in fast FT analyzer to smooth the discontinuities at the beginning and end of the
sampled time record). Agilent micro lab Expert FTIR Spectrometer software was used to acquire and process
the data. The C, H, O and M(Metals) Contents of the samples were determined by flash combustion, using
elemental analyzer (CE-440 Elemental Analyzer,Exeter Analytical Inc, UK). Sample weight used for the
determination ranged from 1.0-1.5mg. The combustion and reduction were 975 and 6000C respectively while
the oven temperature was 810C. The chromatographic column Parapak PQS column, while the detector was
thermal conductivity detector. The combustion was calculated from the second stage after pyrolysis and
subsequent formation of Carbon monoxide (CO). The instruments used for the determination of GCMS was
Agilent 7977 Gas Chromatograph, coupled to 5973D Inert Mass Spectrometer (with triple axis detector) with
electron-impact source.

Complexation reaction of Schiff base with metals to form complexes (proposed structures)

Where M= Fe

M = Fe(II) Complex of Schiff base of 2- Hydroxylaniline (SLOAFe)

RESULT AND DISCUSSION

The ligands and metal complexes maintain their characteristic coloration as seen in Table 3.0. Interestingly, the
ligands and metal complexes gave good yield (76-86%) indicating that the method of synthesis was viable.
When compared with the work of [19,37,35,38] it was evidence that the yield of this work is good. The
melting point of the synthesized ligand was high and that of the metal complexes was higher which later
melted and decomposed. The increases in melting point are attributed to the increase in mass of the formed
complexes and thus provide evidence for complexation. The elemental composition when compared with that
of [19, 25, 27,29,39] is relatively good.

The solubility test results for the prepared ligands and their metal complexes are presented in Table 3.1. The
Ligand and metal complex are insoluble in Diethyl ether and n-hexane. LOA showed slightly soluble in
methanol, ethanol, carbon tetra chloride. The Schiff base ligand (SLOA) showed strongly soluble in methanol,
ethanol and in acetone and water it showed slightly soluble. Furthermore, the metal complexes showed
moderately soluble, strongly soluble and slightly soluble in methanol, ethanol, acetone, carbon tetra chloride
and water respectively [36].

The Characteristic infrared frequencies of the ligand and metal complexes are listed in Tables 3.2, 3.3 and 3.4
hence presented in Appendix 1 to 3. The IR Spectral data shows the following important bands such as
v(C=O), v(OH), v(C=N), v(C-CH3), v(C6H6), v(C=C), v(C-H), v(M-O) and v(M-N). The absorption band
assigned to C=O in the ligand and metal complexes ranges from 1.700.65cm-1 to 1,613.73cm-1. The Schiff base
ligands SLOA (I,700.65cm-1) showed a notable shift to higher wavenumbers indicating increase C=O bond

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strength due to coordination with metal through its oxygen or electron withdrawal in the Schiff base
framework [37]. Metal complexes show C=O stretching shifted back to lower frequency values (1.623.54cm-1)
suggesting co-ordination of oxygen to metal found in work of [6,22,26,29,33].

However, the Schiff base SLOA has a frequency value (3,500.06cm-1) assigned to v(OH) in the aromatic ring
[6,34.35]. The absorption band assigned to C=N Stretching in the Schiff base ligand as seen in SLOA –
1,582.90cm-1 confirming Schiff base formation. In complexes, C=N band shift downward (e.g., SLOAFe -
1,513.91cm-1) as seen in table 3.4 indicate consistent coordination via azomethine nitrogen to the metal
[28,32]. The frequencies ranging from 2,998.95cm-1 to 2, 510 cm-1 are assigned to v(C-CH3) bonding for the
ligand and the metal complex [34,35,36]. There is strong indication of the formation of aromatic C=C bond in
the ligands and complexes with values ranging from 1,446.38cm-1 to 1,430.10cm-1[37,33]. The variation in
frequency values in the complex can be attributed to subtle π- electron redistribution upon coordination. The
frequency values of the range 2,998.95cm-1 to 2,842.10cm-1 was assigned to stretching C-H bond. The
absorption band assigned to aromatic ring (C6H6) vibration in the ligand (LOA) are 813.54cm-1. The Schiff
base SLOA (800.62cm-1) show slight down shift possible as a result of ring substitution effect. In complexes,
the frequency values range from (881.20cm-1) [6,19,30].

Moreover, there are strong evidence of the formation of v(M-O) and v(M-N) bond in the metal complex with
assigned values as follows 790.33cm-1 and 560.34cm-1 respectively, indicating coordination of both oxygen
and nitrogen donor atoms to the metal [6,20.21,23,25,31].

The UV-Vis spectrum of the Schiff base SLOA and metal complex (SLOAFe) were characterized mainly by
one absorption and thus appear to have virtually identical spectra, and absorb in the near visible region around
λ1=278nm for the Schiff base Ligand and metal complex λ1= 420nm. The absorptions of the Schiff base are
ascribed to n  π*, then the absorption of the metal complex can be ascribed to dd* which are shown in
Table 3.5 and presented in Appendix 7 to 8

The mass spectroscopy of the primary ligands, Schiff bases and metal complexes under study are shown in the
Table 3.6 and presented in Appendix 4 to 6.

The mass spectrum of primary ligands (LOA) showed a molecular ion peak at 230.1m/z. The Schiff base
ligand molecular ion peaks (SLOA) where found at m/z 321.0. The Schiff base ligand SLOA showed a
characteristic peak of 107.0m/z and 214 m/z representing the aniline and acetyl chloride antipyrine fragment
ion indicating the stability of these fragment ions in the Schiff base ligand SLOA. The base peak of SLOA is
216.1 m/z which is the most intense (tallest) peak in the mass spectrum, due to the ion with the greatest relative
abundance [6,24,32,30].

The metal complexes SLOAFe showed a characteristic peak of 106.0 m/z, 214.1 m/z, 320.1 m/z representing
the aniline, acetyl chloride antipyrine and the Schiff base ligand fragment ion respectively. The fragment ion
with peak 640 m/z showed that the co-ordination of the Schiff base ligand (SLOA) with the metal ion is in the
ratio of 2:1. The molecular ion peaks of the SLOAFe 696.0 m/z.

All the molecular ion peaks of the primary ligand, Schiff base ligand and metal complex agreed or equivalent
to their calculated molecular masses.

The antibacterial activity of the test component was evaluated using the paper disc diffusion method against
different species of bacteria; Salmonella typhi (Gram negative), Escherichia coli (Gram negative),
Staphylococcus aureus (Gram positive), Streptococcus pyogenes (Gram positive) [6]. The antimicrobial
activities were presented in the Table 3.8,3.9 and 3.10 as seen below. The test samples showed pronounced
activities against the test bacteria. The streptococcus pyogenes showed resistance in LOA, SLOA. SLOAFe,
SLOA and LOA inhibited the growth of bacteria when compared with others. The metal complex showed
great inhibition against test microorganisms because of lipophilicity which is the ability of metal complex to
dissolve in lipids or soluble in fat, since the cell membrane of microorganisms are made up of lipids [6]. The
lipophilic metal complex can penetrate the cell wall of the test organism and inhibit their growth.

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Antifungal activity was evaluated using the paper disc diffusion method against Candida albicans. Generally,
SLOAFe, SLOA and LOA inhibited the growth of fugal.

The test samples showed pronounced MIC (Minimum Inhibition Concentration) activities against the test
micro-organism as seen in table 3.8. SLOAFe, SLOA, LOA showed MIC at the range of 500mg/ml to
125mg/ml against the test microorganism. Moreover, no MIC was recorded for LOA and SLOA against
Streptococcus pyogenes and SLOAFe against Candida albicans.

Finally, the metal complex showed high inhibition against microorganisms when compared with the ligands.

Table 3.0 showing the physical characteristics of the synthesized compounds

S/N Synthesize
d

compounds

Yield
(%)

Colour Melt
ing

Poin
t(0C)

Mol
ecul
ar

Wei
ght(
m/z)

Molar
Conductivity

Ω-1 cm-2 mol-1

Elemental Compositions (%)

In
aceton

In
ethan

C H N O Cl M

1 LOA

C13H14N2O
2

80 Cream
yellow

1160

C
230.

1
3.2 1.4 68.42

(67.2
3)

4.83

(4.46)

6.40

(6.30
)

12.70

(12.2
0)

- -

3 SLOA

C19H19N3O
2

86 Black 2320

C
321.

0
2.6 1.5 58.42

(58.2
5)

5.74

(5.25)

7.86

(7.17
)

12.88

(12.0
1)

- -

5 SLOAFe

C38H36N6O
4Fe

76 Grayis
h

Brown

280-
2840

696.
0

2.5 2.1 62.34

(61.0
2)

3.48

(3.22)

5.32

(4.89
)

10.25

(10.3
6)

- 10.82

(10.52
)

KEY

LOA= Ligand of acetyl chloride antipyrine

SLOA= Schiff base ligand of 2- hydroxylaniline

SLOAFe = Iron (II) Complex of Schiff base of 2-hydroxylaniline

( ) = Calculated

Table 3.1: Solubility Values of The Ligands and Metal Complex

Methanol Ethanol Acetone Diethyl
Ether

Carbon
Tetra

Chloride

Water n-Hexane

LOA SIS SIS MS Insol SIS SIS Insol

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SLOA SS SS SIS Insol Insol SIS Insol

SLOAFe MS MS SIS Insol SIS SIS Insol

KEY: SS: Strongly Soluble; MS: Moderately Soluble; Insol: Insoluble; SIS: Slightly Soluble

Table 3.2: Showing the FTIR Spectral data of LOA Ligand

Assignment of Bond Frequency range in cm-1 Functional Group

v(C=O) Stretch 1,613.73 Carbonyl group in
Pyrazolone

v(C-CH3) Stretch 2,982.08 Alkyl methyl group in
Pyrazolone

v(C6H6) 813.54 Aromatic ring vibration

v(C=C) Stretch 1,436.36 Aromatic

v(C-H) bending vibration 2,896.42 Aromatic ring

Table 3.3: Showing the FTIR Spectral data of SLOA Ligand

Assignment of Bond Frequency range in (cm-1) Functional Group

v(C=O) Stretch 1,700.65 Carbonyl group in
Pyrazolone

v(O-H) Stretch 3,500.06 Hydroxyl group in Aromatic
ring

v(C-CH3) Stretch 2,998.95 Alkyl methyl group in
Pyrazolone

v(C6H6) 800.62 Aromatic ring vibration

v(C=N) Stretch 1,582.90 Imine group/Schiff base

v(C=C) Stretch 1,446.38 Aromatic C=C

v(C-H) Bending vibration 2,998.95 Aromatic ring

Table 3.4: Showing the FTIR Spectral data of the Metal Complexes (cm-1)

v(C=O)
Stretch

v(C-
CH3)

Stretch

v(C6H6) v(C=N)
Stretch

v(C=C)
Stretch

v(C-H)
Bending

v(M-O) v(M-N)

SLOAFe 1,623.00 2,510.83 881.20 1,513.91 1,430.10 2,842.10 790.33 560.34

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Table 3.5 UV-Visible Spectral for Schiff Base and Metal complex

Compounds Wavelength(nm) Elemental Transition

SLOA 278 n  π*

SLOAFe 420 d  d*

Table 3.6: GCMS Analysis of Ligands and Metal Complex

Compounds Calculated
Molecular

Mass(g/mol)

Observed
Molecular ion

(M+)

Base Peak(m/z) Observed Fragment ions

LOA 230.1 230.1 148.1 54.2,84.1,120.1,185.1

SLOA 321.0 321.0 216.1 98.1,107.0,214.0,223.1

SLOAFe 695.9 696.0 640.1 106.1,212.0,214.1,320.0,640.1

Table 3.7: Summary of some Fragments in GCMS Spectrum

m/z Assignment/formula of compounds Structure fragments

321.0 SLOA C19H19N3O2

214 C13H14N2O

107 C6H5NO

696.0 SLOA(M)

C38H36N6O4(M1)

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214 C13H14N2O

106 C6H4NO

302 C19H18N3O2

Where M = Fe, Ni, Co

M1 = Fe

Formulations/Zone
of Inhibition(mm)

Test Organisms SLOAFe SLOA LOA OFX NY

Salmonella
typhi

20 18 16 12 -

Escherichia coli 16 12 16 30 -

Staphylococcus
aureus

20 18 28 30 -

Streptococcus
pyogenes

14 10 8 26 -

Candida
albicans

10 16 18 - 26

TABLE 3.8: ANTIMICROBIAL SUSCEPTIBILITY TESTING

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Key:mm = Millimeter

SLOAFe, SLOA ETC = Sample codes

OFX = Ofloxacin

NY = Nystatin

Clinical Laboratory Standard Institute guideline for antimicrobial agents

- = Not determined

NI = No inhibition

R = Resistant (0 – 12 mm)

S = Susceptible (16 mm and above)

Formulations/concentrations(mg/ml)

Test organisms SLOAFe SLOA LOA

Salmonella typhi 125 250 500

Escherichia coli 500 500 500

Staphylococcus
aureus

125 250 125

Streptococcus
pyogenes

500 ND ND

Candida albicans ND 500 250

TABLE 3.9: TEST FOR MINIMUM INHIBITORY CONCENTRATIONS

Key: mg/ml = Milligram per millilitre

SLOAFe, SLOA ETC = Sample codes

ND = Not detected

Formulations/concentrations(mg/ml)

Test organisms SLOAFe SLOA LOA

Salmonella typhi 500 ND ND

Escherichia coli ND ND ND

Staphylococcus
aureus

500 ND 500

Streptococcus
pyogenes

ND ND ND

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Candida albicans ND ND ND

TABLE 3.10: TEST FOR MINIMUM BACTERICIDAL/FUNGICIDAL CONCENTRATIONS

Key: mg/ml = Milligram per millilitre

SLOAFe, SLOA ETC = Sample codes

ND = Not detected

CONCLUSION

This study has shown that Schiff base ligand can be synthesize using 2-hydroxyaniline with acetyl chloride
antipyrine (4-acyl antipyrine) as primary ligand. The melting point of the metal complexes was higher than
that of the ligands but later melted and decomposed. The increases in melting point are attributed to the
increase in mass of the formed complexes and thus provide evidence for complexation. Complexation of Fe(II)
complex was successful using the above Schiff base ligands as shown by GCMS, FTIR, UV-VIS
Spectrometric spectra interpretation.

The antimicrobial activities revealed that the complex show greater potency than the Schiff base ligand and
primary ligand on the test organism due to chelation.

However, the interpretation from GCMS, UV-VIS and FTIR deduced that the octahedral geometry was
proposed for the structure of the metal complex.

ACKNOWLEDGEMENT

The authors acknowledged the immense assistance rendered by Dr. Chinyere E. Okafor, Department of Pure
and Industrial Chemistry, Chukwuemeka Odumegwu Ojukwu University Uli Campus, Anambra State,
Nigeria. I wish to appreciate Prof Emmanuel O. Iloh for his input.

Conflicts of Interest:

The authors declare that they have no conflicts of interest.

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