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JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Synthesis of Tetradentate Schiff Bases Derivatives
very active against different diseases. Depending upon the
stability, the transition metals and their complexes have
also been used against tumor and cancer treatment.7 The
stability of complexes mainly depends on the chelating and
donating powers of the ligand which ultimately facilitates
oxidizing and electrophilic reactions. The less stability of
metal complexes restricts their applications in some bio-
logical processes.8 Ligands made from salicylaldehyde ex-
hibit higher values of antibacterial activities against differ-
ent species including S.aureus, P.mirabilis, H.influenza and
salmonella spp.9 Apart from ligands and metal complexes
salicylaldehyde is more frequently used as larvicide and
fungicides.
moved by rotary evaporator. The product was dried and 74% pro-
ductivity was found. Finally purified product was characterized
by FT-IR, MS, 1HNMR and 13CNMR techniques.
Synthesis of bimetallic Complexes. All the transition bi-
metallic complexes were synthesized by the following proce-
dures. Equimolar quantities of metal acetates (Co, Cu, Mn, Zn)
and ligand were taken. the metal acetate was dissolved in ethanol/
toluene and continuously stirred and heated on hot plate. Where-
as, the ligand was stirred in binary solution of toluene and ethanol
(1:1). Then both of the solutions were mixed and stirred for 5-6
hours in 250 mL flask. The progress of the reaction was checked
by TLC test and the solvent after the completion of the reaction
was removed by the rotary evaporator and washed with pet-ether.
The crude product was subjected to column chromatography after
removing the solvent by rotary evaporator. Then the concentrated
solution was put in the refrigerator at low temperature in order to
get the crystals but rather cyrstaline, the microcrystalline material
was obtained. Finally, the solvent was removed up to dryness and
the product was redissolved in a combination of three solvents
i.e. ethanol, toluene, and ethyl acetate (TCS by volume 50%,
10% and 40% respectively). The fine crystals were obtained at
low temperatures after 3-4 days. The crystals of the bimetallic
complex were characterized by FT–IR and X-ray crystallogra-
phy.
In the present research work, a series of Co(II), Cu(II),
Mn(II) and Zn(II) bimetallic complexes are synthesized
with the Schiff base ligand 2-(bis-2-hydroxyl phenylidene)
diimine (L) derived from the condensation of hydrazine
and salicylaldehyde. The synthesized ligand and bimetallic
complexes with ligand (L) are characterized by different
spectroscopic techniques. The ligand characterization is
carried out using FT-IR, H1NMR, C13NMR, MS while the
bimetallic complexes are characterized by FT-IR and X-ray
crystallographic techniques. Then these complexes and
ligand are employed in vitro for antifungal and antibacte-
rial activities by using disc diffusion method. Different
fungal strains such as Alternaria alternate, Aspergillus
flavus and Aspergillus niger are used to check antifungal
activities of bimetallic complexes and ligand.
Spectroscipic Analysis. The spectroscopic data of ligand
and bimetallic complexes was calculated by using different spec-
troscopic techniques. FT-IR spectra were taken on a Perkin Elmer
FT-IR. Mass spectra of ligand were taken at 70 eV by Electron
ionization technique using Perkin Elmer Clarus 680 GC-MS in-
strument in the R & D section of Zeta Chemical Company (PVT)
Ltd, Lahore, Pakistan. H1NMR and C13NMR were recorded via
60 MHz JNM-ECX60 FT NMR System. Crystal data (X-Ray
crystallography) of bimetallic complexes were taken on the single
crystal Apex – II Bruker X-Ray diffractometer.
EXPERIMENTAL
All solvents and regents (chemicals) including Salicyl-
aldehyde, Cobalt acetate, Copper acetate, Manganese acetate,
Zinc acetate, Ethanol, Hydrazine, Acetic acid, Toluene and Ethyl
acetate of AR grade were supplied by Sigma-Aldrich (Germany).
Synthesis of Ligand. In order to prepare the ligand (L),
condensation reaction was carried out between equimolar of
hydrazine (0.01 mole) and salicylaldehyde (0.01 mole). Binary
solvent mixture containing toluene and ethanol (1:1) was taken in
a flask and stirred for 3 hours. Then both reactants and glacial ace-
tic acid (1 mL) were stirred in 100 mL flask for 6 hours at room
temperature. TLC test was employed in a pet. ether-ethylacetate
(1:1) solvent system to check the success of the reaction. The re-
action flask was put in the refrigerator for 22 hours and no crystal
formation was observed. The solvent was removed by rotary
evaporator and the product was then subjected to column chroma-
tography by using silica gel and pet. ether-ethylacetate (1:1) sol-
vent system. The final mixture was cooled and solvent was re-
Antimicrobial Activity. The selected strains were Escheria
coli, staphylococcus aureus and Bacillus Subbtilis.10 The ligand
and bimetallic complexes were employed for antibacterial activ-
ity by using disc diffusion method CLSI, 2007. Nutrient agar was
mixed with distilled water and dispersed homogeneously. Steril-
ization of the medium was carried out by means of autoclave at
121 oC for 20 minutes. The medium was treated with inoculums
before it is transferred to petri plates. Hereafter, filter paper discs
were placed parallel on growth medium which contains 100 µL
(micro liters) of bimetallic complexes and ligand. The incubation
of petri plates was carried out for 24 hours at 37 oC for bacterial
growth. The complexes and ligand full of antibacterial activities
inhibited the growth of bacteria and formed clear zones. Zone
J. Chin. Chem. Soc. 2013, 60, 1150-1155
© 2013 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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