Synthesis, Characterization and Antibacterial Activity of Mixed Ligands of Schiff Base and It’s Metal(II) Complexes Derived from Ampicilin, 3-Aminophenol and Benzaldehyde

Schiff base ligands were synthesis via a condensation of the ligands in methanol in 1:1:1 molar ratio reactions. The transition metal(II) complexes were formed by the reaction of Co, Cu, Mn, Fe with the Schiff base and ampicillin and they were characterized via FTIR, electronic spectra, melting points, solubility and molar conductance. The invitro antibacterial activities of the complexes were tested using four bacterial strains; gramnegative; (Escherichiacoli, salmonellatyphi) and grampositive; (staphylococcus pyogenes and staphylococcus aureus). The complexes were formed in good yield and they have various shades of colors and sharp melting points. The IR spectrum of the HL (Table4) displays a new at (1651) cm -1 which is due to υ(HC=N) group of the azomethine stretching vibrations of the ligand, on complexation these band has been shifted to lower frequencies (1651), (1621), (1651), and (1627)cm -1 for complexes [Co(Ampi)(3AMPB)Cl], [Cu(Ampi)(3AMPB)], [Mn(Ampi)(3AMP)Cl] and [Fe(Ampi)(3AMPB)] respectively. The overlap band at (1688)cm -1 stretching vibration is due to υ(C=O) for β-Lactam group, these band has been shifted to lower frequency at (1370-1425)cm -1 for complexes showing that the coordination is through the Oxygen atom of β-Lactam group. The band sat (525), (526), (524) and (526)cm -1 were assigned to υ(M–O) for compounds of Co, Cu, Mn, Fe, indicating that to the carbocyclic oxygen, and oxygen of β-Lactam group of the ligand are involved in coordination with metalions. The bands at (659), (669), (660), and (698)cm -1 were assigned to υ(M–N) for compounds Co, Cu, Mn, Fe respectively, indicating that the nitrogen is involved in coordination with metal ions. The electronic spectral data of the complexes suggest an Octahedral and tetrahedral geometry for all the complexes. The molarconductivity indicates that the synthesized complexes are all non-electrolytes and soluble in protic solvent such as methanol and ethanol. The invitro antibacterial screening of Schiff base and its metal complexes showed that they are potential antibacterial agents against the tested microorganisms


Introduction
Schiff bases and their complexes are versatile compounds synthesized from the condensation of an amino compound with carbonyl compounds and widely used for industrial purposes and also exhibit a broad range of biological activities including antifungal, antibacterial, antimalarial, antiproliferative, anti-inflammatory, antiviral, and antipyretic properties [1] Schiff base are the compound containing azomethine group (-HC=N-). The acid/base catalysis or heating is employed for the synthesis of Schiff bases as their reactions are mostly reversible [2].
The aim of the research is to synthesize, characterize and evaluate the antibacterial activity of the synthesized Schiff base and its metal (II) complexes of Fe(II), Co(II), Cu(II) and Mn(II) ions .
While the specific objectives of the study will be to: i. Prepare Schiff base using a mixed ligands of 3aminophenol and Benzaldehyde. ii. Synthesize Schiff base metal complexes of Fe(II), Co(II), Cu(II) and Mn(II) ions. iii. Synthesize Schiff base and ampicillin with its metal Ligands of Schiff Base and It's Metal(II) Complexes Derived from Ampicilin, 3-Aminophenol and Benzaldehyde complexes of Fe(II), Zn (II), Co(II), Cu(II) Ni(II) and Mn(II) ions. iv. Determine the physico-chemical properties of Schiff base and its metal complexes using different analytical technique like melting point, FTIR, conductivity, solubility test and UV/Visible spectrophotometer. v. Study the antibacterial activity of the Schiff base and it's metal(II) complexes.

Materials and Method
All chemicals, reagents and drug that were used in this research are of Analar grade.

Synthesis of Schiff Base 3-aminophenol Benzaldehyde HL 1
The Schiff base was synthesized by a slight modification of literature [3]. This is done by the condensation of methanolic solution of benzaldehyde (0.005mol, 0.53g) with 3-aminophenol (0.005mol, 0.55g) in 20ml of methanol (1:1 molar ratio). The resulting mixture was then refluxed for 1hr. the precipitate was separated by a suction filtration. It was recrystallized from ethanol and dried, and preserve in a desiccator for 24hr over CaCl 2.  The complexes were synthesized using (1:1:1 molar ratio). A solution of the Schiff base (HL) (0.001mol, 0.43g) in 10ml of methanol and a solution of ampicillin (Ampi) ( 0.001mol, 0.35g) in 10ml methanol, were added to a stirred solution of (0.001mol, 0.16g of CuSO 4 .5H 2 0, 0.001mol, 0.24gof CoCl 2 .6H 2 0, 0.001mol, 0.15g of FeSO 4, 0.001mol, 0.20g of MnCl 2 .4H 2 0)in 5ml of methanol. The resulting mixtures were heated under reflux for 3hr. then the mixture was filtered by suction and the precipitate was washed with excess of ethanol and dried at room temperature for 24hr in a desiccator over CaCl 2 [4].

Characterization of Schiff Base and Its Metal (II) Complexes
Characterization involve simple fingerprint of compounds already known, or more extensive investigation designed to establish the formula and structure of a new compound [5]. The Schiff base and its metal complexes was characterized by using different physico-chemical techniques like Melting point, U/Visible spectrophotometer, FTIR, Conductivity, Solubility test.

Antibacterial Activity
The four bacterial species were used two gram-negative (Escherichia coli, Salmonella typhi) and two gram-positive (Staphylococcus aureus, Streptococcus pyrpgens), were obtained from pharmaceutical microbiology Department of the Gombe state University. The antibacterial activity of the ligand and the complexes was determined by the disc diffusion technique. The compounds were screened invitro. A 1mg/ml solution in DMSO was used. Ceftriaxone and subactam were used as standard reference drug. The bacterium was maintained on nutrient agar and the agar media was incubated for different microorganism culture tests. After 24hrs of incubation at 37 0 C for the bacteria, the diameters of zone of inhibition (mm) thus formed around each disc containing the test compound was measured [3].

Physical Characteristics and Analytical Data of Ligands/Complexes
In  [6]. The Schiff base and its metal (II) complexes were prepared in good yield, ranging from 50-80% (7). The molar conductance of the complexes was determined in DMSO. It was found to be 4.1, 6.1, 3.1, 13.2 and 5.7Ω -1 cm -2 mol -1 for the Co, Cu, Mn, Fe complexes respectively. These low values suggested their nonelectrolytic nature [7,8].

Solubility Test of the Complexes
The

Electronic Spectral Data of Ligands and Complexes
The electronic spectrum of the ligandHL was been measured in DMSO solution between 200-1100 nm at room temperature. In the spectrum of the Schiff base ligand HL, the absorption band observed at (212 nm) (47169 cm -1 , which assigned to (π-π transition. The UV-Vis spectrum for the

Major FTIR Spectral Data of Ligands and Complexes
The IR spectrum of the HL (Table 4) displays a new at (1651) cm -1 which is due to υ (HC=N-) group of the azomethine stretching vibrations of the ligand, on complexation these band has been shifted to lower frequencies

Antibacterial Activity of the Ligands/Complexes of (3AMPB)
The antibacterial activity of the Metal complexes of Schiff base derived from (HL) and Co, Cu, Mn Fe showed a good antibacterial activity against Gram-negative (Escherichia coli and Salmonella typhi,). The Co, Cu, Mn Fe complexes caused strong inhibition for E. coli and Salmonella typhi. The importance of these lies in the fact that, these complexes could be applied fairly in the treatment of some common diseases caused by E. coli and Salmollatyphi. However, Co, Cu, Mn Fe complexes were specialized in inhibiting Grampositive bacterial strains (Staphylococcus auerus andStreptococcus pyrogens). The importance of this unique property of the investigated Schiff base complexes lies in the fact that, it could be applied safely in the treatment of infections caused by any of these particular strain [1,14,15].

Conclusion
The complexes are multi-colored, colors, they have good % yields with sharp melting point. The electronic spectral data of the complexes suggest an Octahedral and tetrahedral geometry for the complexes. The Results of the molar conductivity indicate that the synthesized complexes are non-electrolytes and 1:2 electrolytes as compared with the electrolytic value of CaCl 2 . The invitro antibacterial screening of schiff base and its metal complexes showed that they are potential antibacterial agents against the tested