Synthesis and characterization of bimetallic post transition complexes for antimicrobial activity

Article abstract of DOI:10.1080/15533174.2013.841218

Antimicrobial and antibacterial activities of bimetallic complexes are very important in variety of biological mechanisms. In this research work, a Schiff base ligand 2-(bis-2-hydroxylphenylidene)-1,2-iminoethane was prepared by condensation reaction betw

Full text of DOI:10.1080/15533174.2013.841218

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Synthesis and Characterization of Bimetallic Post
Transition Complexes for Antimicrobial Activity
M. Pervaiza, M. Yousafa, M. Sagirb, M. Mushtaqb, M. Y. Nazc, S. Ullahb & R. Mushtaqd
a Department of Chemistry, Government College University, Faisalabad, Pakistan
b Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar,
Tronoh, Perak, Malaysia
c Department of Physics, University of Agriculture, Faisalabad, Pakistan
d Royal Medical College, Ipoh, Perak, Malaysia
Accepted author version posted online: 26 Sep 2014.Published online: 24 Oct 2014.
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To cite this article: M. Pervaiz, M. Yousaf, M. Sagir, M. Mushtaq, M. Y. Naz, S. Ullah & R. Mushtaq (2015) Synthesis and
Characterization of Bimetallic Post Transition Complexes for Antimicrobial Activity, Synthesis and Reactivity in Inorganic,
Metal-Organic, and Nano-Metal Chemistry, 45:4, 546-552, DOI: 10.1080/15533174.2013.841218
To link to this article: http://dx.doi.org/10.1080/15533174.2013.841218
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry (2015) 45, 546–552
Copyright © Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2013.841218
Synthesis and Characterization of Bimetallic Post Transition
Complexes for Antimicrobial Activity
M. PERVAIZ1, M. YOUSAF1, M. SAGIR2, M. MUSHTAQ2, M. Y. NAZ3, S. ULLAH2, and R. MUSHTAQ4
1Department of Chemistry, Government College University, Faisalabad, Pakistan
2Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Tronoh, Perak, Malaysia
3Department of Physics, University of Agriculture, Faisalabad, Pakistan
4Royal Medical College, Ipoh, Perak, Malaysia
Received 24 June 2013; accepted 1 September 2013
Antimicrobial and antibacterial activities of bimetallic complexes are very important in variety of biological mechanisms. In this
research work, a Schiff base ligand 2-(bis-2-hydroxylphenylidene)-1,2-iminoethane was prepared by condensation reaction between the
reactants. Using this ligand, the derivatives of post transition bimetallic complexes were also synthesized by condensation reaction
between salicylaldehyde and ethylenediamine followed by transition metals (Cu, Co, Mn, Zn). The synthesized ligand was characterized
1
by FT-IR, H NMR, 13C NMR, and MS techniques, whereas the bimetallic complexes were characterized by FT-IR and X-ray
crystallographic techniques. In a later stage, the ligand and bimetallic complexes were screened in vitro for antibacterial and antifungal
activities by using disc diffusion method. Different bacterial strains such as Escherichia coli, Staphylococcus aureus, and Bacillus subtilis
were used to check the antibacterial activities of ligand and bimetallic complexes. Similarly, the used fungal strains were Aspergillus
flavus, Alternaria alternata, and Aspergillus niger. The biological activity data showed that the bimetallic complexes exhibit higher
values of antibacterial and antifungal activities as compared with ligand.
Keywords: Schiff base, transition metals, salicylaldehyde, ethylenediamine, bacterial strains, fungal strains
Introduction
A number of biological components such as glucose, vita-
mins, drugs, nitrogenous bases, and some heterocyclic com-
The Schiff bases and their complexes are very important due pounds containing nitrogen atom act as bioligands. These
to their uses in a variety of biological mechanisms.[1] Many bioligands exhibit average antimicrobial activities, which can
transition metal complexes have been found exhibiting be enhanced by coordination with transition metals. Com-
greater stability and are very active against many different plex formation enhancing dissolving power of different drugs
kinds of diseases. Depending on the stability and functional- in lipid containing organisms and ultimately enhances the
ity, the transition metals and their complexes are commonly drugs effect against different diseases. The activities of anti-
used in tumor and cancer treatment.[2] The stability of these cancer, antitumor, antianalgesic, and antibiotic drugs can
complexes mainly depends on chelating and donating power also be increased by making their complexes with transition
of the ligand, which ultimately facilitates oxidizing and elec- metals.[5] Metallo-elements specially zinc and copper play sig-
trophilic reactions. The less stability of metal complexes nificant role in the viral growth and restrict virus to enter into
restricts their applications in some biological processes.[3] the host cell. For example, the sulfur and zinc are found in
Ligands made from salicylaldehyde exhibit higher values of viruses and bacterium respectively. Zinc quickly coordinates
antibacterial activities against different species including with sulfur present at the outer layer of virus and can transfer
S. aureus, P. mirabilis, H. influenza, and Salmonella spp.[4] virus into the host cell. In order to break this coordination,
Apart from ligands and metal complexes, the salicylaldehyde the transition metals are considered to be very important
is also very important and used frequently as larvicide and because they arrest the sulfur. So, the viral growth becomes
fungicide.
more dependent on these metals and can be controlled by
varying concentrations of metallo-elements.[6]
Therefore, in this detailed note, a Schiff base ligand 2-(bis-
2-hydroxylphenylidene)-1,2-iminoethane was prepared by
condensation reaction between the reactants. Using this
ligand, the derivatives of post transition bimetallic complexes
were also synthesized by condensation reaction between
salicylaldehyde and ethylenediamine followed by transition
metals (Cu, Co, Mn, Zn). The ligand was characterized by
Address correspondence to M. Sagir, Department of Chemical
Engineering, Universiti Teknologi PETRONAS, Bandar Seri
Iskandar, 31750 Tronoh, Perak, Malaysia. E-mail: sagir.utp@
gmail.com.
Color versions of one or more of the figures in the article can be
found online at www.tandfonline.com/lsrt.

Synthesis of Bimetallic Complexes
547
1
FT-IR, H NMR, 13C NMR, MS, and the bimetallic com- crystals of bimetallic complexes were characterized by FT-IR
plexes were characterized by FT-IR and X-ray crystallo- and X-ray crystallographic techniques.
graphic techniques. The ligand and bimetallic complexes
were screened in vitro for antibacterial and antifungal activi-
ties by using disc diffusion method. Different bacterial strains
Characterization of Compounds
such as Escherichia coli, Staphylococcus aureus, and Bacillus
subtilis were used to check the antibacterial activities of
ligand and bimetallic complexes.
Different spectroscopic techniques were used to obtain the
spectroscopic data of synthesized compounds. The mass spec-
tra of ligand were taken at 70 eV by means of electron ioniza-
tion technique on Perkin Elmer Clarus 680 GC-MS
instrument in the Rand D section of Zeta Chemical Com-
pany (PVT) Ltd, Lahore, Pakistan. FT-IR spectra were taken
on a Perkin Elmer FT-IR and Thermo FT-IR Nicolet IS 10.
1H NMR and 13C NMR data were recorded via 60 MHz
JNM-ECX60 FT-NMR System. Crystallographic data
(X-ray crystallography) of bimetallic complexes was taken on
the single crystal Apex–II Bruker X-ray diffractometer.
Experimental
For the synthesis of ligand and bimetallic complexes, all the
solvents and regents (chemicals) including ethylenediamine,
cobalt acetate, copper acetate, manganese acetate, zinc ace-
tate, ethanol, salicylaldehyde, acetic acid, toluene, and ethyl
acetate of AR grade were imported from Sigma-Aldrich
(Germany).
Antimicrobial Activity
Disc diffusion method was used to test the antibacterial and
anti fungal activity. Different strains (bacterial and fungal
strains) were engaged to check the antibacterial and antifun-
gal activities.
Synthesis of Ligand (L)
The ligand was synthesized by condensation reaction of equi-
molar quantities of salicylaldehyde (23.4 g, 0.1 mol) and eth-
ylenediamine (6 g, 0.1 mol). The reactants along with glacial
acetic acid (1 mL) were refluxed in 40 mL of ethanol.[7] After
refluxing for 7 h, the progress of the reaction was checked by
Antibacterial activity
TLC test in a pet. ether-ethylacetate (1:1) solvent system. The Different strains were used to test the antibacterial activity.
flask was then put in the refrigerator overnight but no crystal The selected strains were Escherichia coli, Staphylococcus
formation was observed. The crude product was then sub- aureus, and Bacillus subtilis.[8] The ligand and bimetallic com-
jected to column chromatography after removing the solvent plexes were employed for antibacterial activity by using disc
by rotary evaporator. Silica gel and pet. ether-ethylacetate diffusion method.[9] Nutrient agar was mixed and dispersed
(1:1) solvent system were used in column chromatography. homogenously in distilled water. Sterilization of the medium
The eluent of the column chromatography was then concen- was carried out by means of autoclave at 121ꢀC for 20 min.
trated up to dryness by rotary evaporator. After drying well Medium was treated with inoculums before it is transferred
the productivity was calculated to be 72%.
to Petri plates. Hereafter, filter paper discs were placed par-
allel on growth medium, which contains 100 mL of bimetal-
lic complexes and ligand. The incubation of Petri plates was
carried out for 24 h at 37ꢀC for bacterial growth. The com-
plexes and ligand having antibacterial activities inhibited the
growth of bacteria and formed clear zones. The zone reader
was employed to measure the inhibition zones in the milli-
meter range where rifamipicin was used as a standard
drug.[10]
Synthesis of Bimetallic Complexes
Four bimetallic complexes of Schiff base ligand (L) were pre-
pared by reacting one by one equimolar quantities of etha-
nol/toluene dissolved metal acetates (Co, Cu, Mn, Zn) with
ligand dissolved in toluene. Ligand and metal acetates were
heated and stirred separately in order to dissolve the com-
pounds completely. Then metal acetates were mixed with
ligand in separate flasks and were stirred with adjustable stir-
Antifungal activity
ring system. The final solutions were refluxed for 4–5 h to The fungal strains were used to test the antifungal activity.
complete the reaction. The success of each reaction was The selected strains were A. flavus, A. alternata, and A.
checked by TLC test. On completion of the reaction, the sol- niger.[11] The growth medium was synthesized, sterilized and
vent was removed by the rotary evaporator and washed with then transferred to the Petri plates. Petri dishes were incu-
pet-ether. Then the concentrated solution was put in the bated for 48 h at 28ꢀC for fungus growth. Filter paper discs
refrigerator at low temperature in order to get the crystals. were cited on growth medium for the growth of fungus. The
After cooling, the microcrystalline material was obtained bimetallic complexes and ligand were applied up to 100 mL
instead of pure crystals. Then the solvent was removed up to on each disc. Petri plates were then incubated where the com-
dryness and redissolved in combination of three solvents; eth- plexes and ligand exhibited the antifungal activities. They
anol, toluene, and ethyl acetate (TCS by volume 50%, 10%, inhibited the growth of fungus and clear zones were pro-
and 40% respectively). Thereafter, fine crystals were obtained duced. Fluconazole was used as a standard drug for antifun-
by maintaining the low temperature for 3–4 days. The final gal activity of complexes and ligand.[12]

548
Pervaiz et al.
OH
Results and Discussion
N
N
+
M(O2CCH3)2
Synthesis of 2-(bis-2-hydroxylphenylidene)-1,2-iminoethanne (L)
HO
This ligand was synthesized by condensation reaction of equi-
molar quantities of salicylaldehyde (23.4 g, 0.1 mol) and eth-
ylenediamine (6 g, 0.1 mol) as expressed in scheme 1. The
reactants along with glacial acetic acid (1 mL) were refluxed
in 40 mL of ethanol for 7 h.[13] After refluxing the reactants,
the progress of the reaction was checked by TLC test in a pet.
ether-ethylacetate (1:1) solvent system. The flask was then
put in the refrigerator overnight but no crystal formation was
observed. The crude product was then subjected to column
chromatography after removing the solvent by rotary evapo-
rator. Silica gel and pet. ether-ethylacetate (1:1) solvent sys-
tem was used in column chromatography. The eluent of the
column chromatography was then concentrated up to dryness
by rotary evaporator. After drying well the productivity was
calculated to be 72%.
N
N
O
M
N
O
O
O
M
Synthesis and XRD Studies of 2-(bis-2 hydroxylphenylidene)-
1,2-iminoethanne (L) Derivatives of Bimetallic Complexes by
Using Triple Component Solvent System
N
With the ligand (L), total four bimetallic complexes were pre- Sch. 2. Synthesis route for bimetallic copper complex with L,
where M D Co, Cu, Mn, Zn.
pared by mixing equimolar quantities of ligand and the metal
acetate (Cu, Mn, Zn, Co) in prepurified ethyl alcohol and tol-
uene as expressed in Scheme 2.
combination of three solvents (i.e., ethanol, toluene, and
ethyl acetate; TCS by volume 50%, 10%, and 40%,
respectively).
Synthesis of bimetallic copper complex
The titled complex of copper was prepared by mixing equi-
molar quantities of copper acetate monohydrate (3.98 g,
0.02 mol) and ligand (5.36 g, 0.02 mol) dissolved in ethanol
and toluene, respectively. Before mixing, the ligand and cop-
per acetate were heated and stirred separately in order to dis-
solve them completely. Both the solutions were mixed and
stirred in a 250 mL flask adjusted with stirring system and
then refluxed for 4–5 h to complete the reaction. The success
of the reaction was checked by TLC test. After the reaction,
the solvent was removed by the rotary evaporator and
washed with pet-ether. The crude product was recrystallized
from toluene/pet-ether system. The product after filtration
was dried well under vacuum. The product was redissolved in
small quantity of the toluene and was put in the refrigerator
at low temperature in order to get the crystals. Nevertheless,
microcrystalline material was obtained instead of pure crys-
tals. The productivity was calculated up to 72%. Finally, the
solvent was removed up to dryness and redissolved in
Synthesis of bimetallic manganese complex
The bimetallic manganese complex was synthesized by mix-
ing equimolar quantities of manganese acetate (3.54 g,
0.02 mol) dissolved in ethanol and ligand (5.36 g, 0.02 mol)
dissolved in toluene. The solution was randomly stirred and
heated. After mixing the manganese and ligand solutions, the
resultant product was continuously refluxed and stirred for
4–5 h. The success of the reaction was checked by TLC test.
Once the reaction was complete, the solvent was removed by
the rotary evaporator and washed with pet-ether. The crude
product was recrystallized using toluene/pet-ether system.
The purified product after filtration was dried well under vac-
uum and yield was calculated up to 65%.
Synthesis of bimetallic zinc complex
The bimetallic zinc complex was prepared by reacting equi-
molar quantities of zinc acetate dihydrate (2.19 g, 0.01 mol)
dissolved in ethanol and ligand (2.68 g, 0.01 mol) dissolved
in toluene. Both the solutions were mixed in a 250 mL flask
and refluxed for 5–6 h along with continuous stirring. The
success of the reaction was checked by TLC test. Once the
reaction was complete, the solvent was removed by the rotary
evaporator and washed with pet-ether. The crude product
was recrystallized from the toluene/pet-ether system. After
filtration, the purified product was dried well under vacuum
and yield was calculated up to 70%.
Sch. 1. Synthesis route for 2-(bis-2-hydroxylphenylidene)-1, 2-
iminoethane.

Synthesis of Bimetallic Complexes
549
Table 1. Physical properties of ligand and its complexes.
Table 3. Characteristic IR absorption frequencies of ligand and
bimetallic complexes in cm¡1: bending vibrations for imine
group.
Mol.
Mol.
Melting
point
Sr. #
Compound
weight
formula
Compound
Observed value
Standard value
1
2
3
4
5
L
268
658
650
642
662
C16H16O2N2
116ꢀC
Cu(L)
Co(L)
Mn(L)
Zn(L)
Cu2(C16H16O2N)2
Co2(C16H16O2N)2
Mn2(C16H16O2N)2
Zn2 (C16H16O2N)2
>350ꢀC
L
1625–1609 cm¡1
1625–1597 cm¡1
1629–1594 cm¡1
1623–1595 cm¡1
1633–1597 cm¡1
1575–1630 cm¡1
1575–1630 cm¡1
1575–1630 cm¡1
1575–1630 cm¡1
1575–1630 cm¡1
>350ꢀC Cu(L)
>350ꢀC Co(L)
>350ꢀC Mn(L)
Zn(L)
Synthesis of bimetallic cobalt complex
Characterization of Ligand and Bimetallic Complexes
The bimetallic cobalt complex was prepared by mixing equi-
molar quantities of ligand (2.68 g 0.01 mol) dissolved in tolu-
ene and cobalt acetate tetrahydrate (2.49 g 0.01 mol)
dissolved in ethanol. Both of the solutions were mixed and
refluxed in a 250 mL flask for 5–6 hours along with continu-
ous stirring. The success of the reaction was checked by TLC
test. At the end of the reaction, the solvent was removed by
the rotary evaporator and washed with pet-ether. The crude
product was recrystallized from pet-ether/toluene system.
After filtration, the product was dried well under vacuum
and yield was calculated up to 68%.
FT-IR was used to confirm the bimetallic complexes and
ligand’s functional groups. The range used for the FT-IR
spectra was 4000–400 cm¡1 as KBr pallets on the basis of
previously works.[14] NMR spectra (1H NMR and 13C
NMR) of the ligand were recorded by using ECX60 FT
NMR (60 MHz) and solvent used was CDCl3. Tetramethyl-
silane (TMS) was used a reference standard. The ligand was
analyzed for molecular mass on the basis of previous reported
results and the data was elucidated and confirmed.[15] Apex–
II Bruker X-Ray diffractometer was used to establish the
structure, bond angles and lengths of bimetallic complexes.
Physical Properties of Ligand and the Bimetallic Complexes
IR spectra of ligand and complexes
The ligand and corresponding bimetallic complexes showed
sharp melting points and were soluble in most of the organic
solvents as expressed in Table 1.
In the IR spectra of ligand L1, the bending vibrations for the
CHHN group were observed at 1625–1609 cm¡1. The bend-
ing vibrations of cobalt (L), copper (L), manganese (L), a¡n1d
zinc (L) for CHHN group were found at 1629–1594 cm
1625–1597 cm¡1, 1623–1595 cm¡1, and 1633–1597 cm¡1
,
,
Crystallization of Bimetallic Complexes With Ligand in
Tri-Component Solvent System
respectively. Similarly the bending vibrations for phenolic
OH group were observed at 1370 and 1198.8 cm¡1, 1387.7
and 1190 cm¡1
, , 1384.7 and
1386 and 1190.19 cm¡1
We successfully adopted a combination of three solvents in
order to get excellent crystals of the bimetallic complexes. Ini-
tially, three different individual solvents were employed for
the crystallization of the said bimetallic complexes but none
of them was good enough to dissolve the compounds and ulti-
mately weigh down the crystallization of the complexes.
Therefore, a three component solvent system (ethanol, tolu-
ene, ethyl acetate: 50%, 10%, and 40%, respectively) was
1200 cm¡1, and 1389.7 and 1190.3 cm¡1 for ligand (L),
cobalt (L), copper (L), manganese (L), and zinc (L), respec-
tively. The characteristic IR absorption frequencies of ligand
and bimetallic complexes in cm¡1 units are expressed in
Tables 3 and 4.
Mass spectrometric analysis of ligand
tested and it was noticed that the solubility had been Molecular ion peak of ligand was observed at 268, which is
enhanced significantly.[13] The final results were inspiring also the base peak. The molecular ion fragment was disinte-
because of strong intermolecular interactions between the sol- grated by the cleavage of OH group and corresponding frag-
vent and the solute particles as expressed in Table 2.
ment peak was noticed at 251. The fragment pattern of the
Table 2. Solubility of ligand and complexes.
Solubility
Mixed solvent system
DMSO
Chloroform
Ethyl alcohol
(ethanol-toluene-ethyl acetate)
Sr. #
Compound
1
2
3
4
5
L
C
C
C
C
C
C
C
C
Cu(L)
Co(L)
Mn(L)
Zn(L)
Slightly soluble
Slightly soluble
Slightly soluble
Slightly soluble
Slightly soluble
Slightly soluble
Slightly soluble
Slightly soluble
Slightly soluble
Slightly soluble
Slightly soluble
Slightly soluble

550
Pervaiz et al.
molecules was observed by the cleavage of the nitrogen-
Table 4. Characteristic IR absorption frequencies of ligand and
bimetallic complexes in cm¡1: Bending vibrations of phenolic ethylene bond. Two fragments were observed in the spec-
OH group.
Compound
L
trum. The molecular mass of the first fragment was 148,
whereas, the molecular mass of the second fragment was
120. The second fragment with mass 120 gave a spectral
peak at 134 when combined with nitrogen. The second
fragment after eliminating nitrogen resulted in fragment
that was observed at 106. Isotopic peak for the molecule
was observed at 269 with intensity of about 1% of the
molecular ion peak.
Observed value
Standard value
1370 and 1198.8 cm¡1
Sharp at 1410–1310 and
»1200 cm¡1
Cu(L)
Co(L)
Mn(L)
Zn(L)
1386 and 1190.19 cm¡1 Sharp at 1410–1310 and
»1200 cm¡1
1387.7 and 1190 cm¡1
1384.7 and 1200 cm¡1
Sharp at 1410–1310 and
»1200 cm¡1
Sharp at 1410–1310 and
»1200 cm¡1
Nuclear magnetic resonance spectroscopic analysis
1389.7 and 1190.3 cm¡1 Sharp at 1410–1310 and
»1200 cm¡1
(a) 1H NMR analyses of ligand
The singlet peak at 3.95 ppm was exhibited by protons of eth-
ylene. Each aryl group has four protons in the molecule.
Different environment for these protons was found as
shown in Table 5. Labeled with C1, C2, C3, and C4, these
protons showed doublet, triplet, triplet, and doublet at
7.02, 7.52, 7.08, and 7.66 ppm, respectively. Imines pro-
tons showed singlet at 8.54 ppm. Imine group has p elec-
trons that were deshielded and showed high value. A
singlet at 11.26 ppm was exhibited by phenolic protons
that was probably due to the strong effect of deshielded
oxygen atom.
Table 5. 1H NMR data of ligand.
Position
of protons
Type of peak
Value in ppm
C1
C2
C3
C4
Doublet
Triplet
Triplet
7.02
7.08
7.52
7.66
(b) 13C NMR analyses of ligand
Doublet
13C NMR spectrum of L1 is shown in Table 6. Two carbon
atoms correspond to each peak in the molecule. First
peak at 61.9 ppm was due to the CH2–CH2 group.
The signals of sp3 hybridized carbon atom present in
the middle of the molecule mostly appears at about
30 ppm but due to the presence of electronegative
atom (N) and p bonds adjacent to CH2–CH2 group,
the signals were noticed at downfield (61.9 ppm). The
CH carbon exhibits sp2 hybridization, which is not ter-
minal and is found generally at 140 ppm. The presence
of electronegative nitrogen (N) is correlated with the
observed value of carbon, which showed some devia-
tion. Also the aryl group contains carbon atoms,
which are observed from 120–130 ppm whereas the
phenolic carbons of the molecule showed peak at
161.1 ppm. This was perhaps due to the presence of
more electronegative oxygen atom (O), which was
bonded to carbon and described the downfield shift.
Table 6. 13C NMR data of ligand.
Position
of carbon
Observed value
in ppm
Peak area equivalent
to no. of carbon
1, 1/
2, 2/
3, 3/
4, 4/
5, 5/
6, 6/
7, 7/
8, 8/
61.9
157.5
124.6
161.1
117.8
132.4
121.4
132.1
Two
Two
Two
Two
Two
Two
Two
Two
Table 7. Antibacterial activity data of ligands and complexes.
Tested microorganism diameter of inhibition zone
E. coli
S. aureus
B. subtilis
Sr. #
Compound
1
2
3
4
5
6
(L)
4 § 0.816
9 § 0.816
6 § 0.816
5.25 § 0.957
6.25 § 0.957
10.5 § 0.577
5.75 § 0.5
4.25 § 0.957
8 § 0.816
Co (L)
Cu (L)
Mn (L)
Zn (L)
Standard
5.25 § 0.957
8.75 § 0.5
6 § 1.154
9.75 § 0.5
6.5 § 0.577
23 § 0.816
6.5 § 0.577
23.25 § 2.061
24.5 § 0.577

Synthesis of Bimetallic Complexes
551
30
25
20
15
10
5
E. coli
S. aureus
B. subtilus
0
L
Co (L)
Cu (L)
Mn (L)
Zn(L)
Standard
Fig. 1. Antibacterial activity data of ligand and complexes.
On the contrary, oxygen atoms also contain lone pair, gave the zone 24.5 § 0.577 mm as expressed in Table 7 and
which is correlated with the ortho and para carbons of Figure 1.
the phenols, which exhibit up field shift by mesomeric
effect. The meta carbon of phenol was remained
unchanged.
Antifungal activity
The synthesized ligand and bimetallic complexes were tested
for their activity against various fungus (A. alternata, A.
niger, and A. flavis) by using disc diffusion method. Flucona-
zole was used as standard drug. The highest activity was
shown by bimetallic complexes. The activity against A. alter-
nata and A. niger was highest with zone 12.25 § 0.062 mm
Biological Activities
Antimicrobial and antibacterial activity analyses
The antimicrobial activity was observed by using disc diffu- and 7.75 § 0.957 mm, respectively. A. flavus with zones
sion method against different species of fungus and bacteria. 10.25 § 0.5 showed the average activity. All of these results
The results confirmed that the activity of bimetallic com- are in comparison with standard drug (fluconazole), which
plexes is considerably higher against bacteria and fungus as gave the zone 24.0 § 0.577 mm as shown in Table 8 and
compared to ligand as given in Tables 3 and 4. The synthe- Figure 2.
sized ligand and complexes were also tested for their activity
It is anticipated that the antimicrobial activity of the com-
against B. subtilis, S. aureus, and E. coli using Rifamipicin as plexes was either due to decease of microbes or inhabitation
positive control. The ligand showed less activity as compared of their development by jamming their active sites. The values
to bimetallic complexes. The highest activity was shown designated that most complexes have higher antimicrobial
against S. aureus with zone 10.5 § 0.577 mm. The activity activity than the free ligands. The enhanced activity of metal
against B. subtilis and E. coli were average with zones 9.75 § complexes can be explained on the basis of chelation. On che-
0.5 mm and 9.00 § 0.816 mm, respectively. All results were lation, the polarity of the metal ion decreases to a greater
given in comparison with standard drug (rifamipicin), which extent due to the ligand overlapping.[11]
Table 8. Antifungal activity data of ligands and complexes.
Tested microorganism diameter of inhibition zone
A. flavus
A. flavus
A. alternata
Sr. #
Compound
1
2
3
4
5
C16H16O2N2
Nil
4.25 § 0.577
7.75 § 0.957
10.25 § 0.5
5.75 § 0.5
4 § 1.825
12.25 § 0.062
8.5 § 0.577
Nil
Cu2(C16H16O2N)2
Mn2(C16H16O2N)2
Zn2(C16H16O2N)2
Standard
4 § 1.825
6 § 0.816
6.5 § 0.577
24.5 § 0.577
23.25 § 2.061
23 § 0.816

552
Pervaiz et al.
30
25
20
15
10
5
A.niger
A.flavous
A. alternata
0
(L)
Co (L)
Cu (L)
Mn (L)
Zn(L)
Standard
Fig. 2. Antifungal activity data of ligand and complexes.
Conclusion
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The authors would like to acknowledge the technical support
of Dr M. Wakeel Ahsan, Chief Executive of Bhatti Scientifics
Lahore, Pakistan, and Mr. Faisal Hameed from Biochemika
International Lahore, Pakistan, throughout the conducted
research work.