Synthesis , Characterization Study of Schiff base Complexes derived from Ampicillin and 4-Hydroxy-3-methoxy benzaldehyde

1,2Department of Chemistry and Research, Women’s Christian College, Nagercoil, Tamil Nadu-629001, India. 3Department of Chemistry and Research, Nesamony Memorial Christian College, Marthandam, Tamil Nadu-629165, India. 4Department of Chemistry, Francis Xavier College of Engineering, Vannarpet, Tirunelveli627003, India. 5Department of Chemistry, White memorial of arts and science for women-695505, India. *Corresponding author E-mail: buvana_subi@yahoo.co.in


INTRODUCTION
Schiff bases are compounds that are derived by condensation reaction of primary amines with carbonyl groups (Abbas H Abdulasada et al., 2018). Schiff base ligand are 'privileged ligands' and are able to stabilize different metals in various oxidation states. It are extensively studied due to synthetic flexibility, selectivity and sensitivity towards variety of metal ions. It have application towards, degradation of organic compounds, radiopharmaceuticals and as corrosion inhibitors in especially acidic environments for various alloys and metals like steel, aluminium and copper. Complexes of transition and non-transition metals with Schiff base ligands are promising materials for opto electronic applications due to their outstanding photo and electroluminescent properties and the case of synthesis that readily allows structural modification for optimization of material properties. Various transition and inner transition metals complexes with bi, tri-and tetradentate Schiff bases containing nitrogen and oxygen donor atoms play important role in biological systems and represent interesting models for metalloenzymes, which efficiently catalyze the reduction of dinitrogen and dioxygen (Mohammed Shakir, 2010). The Schiff base derivatives are infer in the field of optical chemistry and biochemistry. It have been utilized as synthons in the preparation of a number of industrial and biologically active compounds like formazans, 4-thiazolidinines, benzoxazines and so forth, via ring closure, cycloaddition and replacement reaction

Literature review
The articles related to the present study were reviewed for more clearance of the study.

Synthesis of Schiffbase ligand (AHMB)
The synthesis of ligand AHMB held as follows. To an ethanolic solution of Ampicillin (0.05 mol) in alkali medium and 4-hydroxy 3-methoxy benzaldehyde (0.05 mol) in 10 mL ethanolic solution was droped with constant mixing and heated under reflux for 2 h on a heating mentle at 60 o C (Isac Sobana Raj, et al., 2015). Then, the reaction mixture was cooled by pouring it into cool water Fine shinning yellow precipitate of (AHMB) formed was filtered off, washed thoroughly with ethanol-water and stored in a vacuum decicator to dry.

Synthesis of [M(AHMB) 2 (NO 3 ) 2 ] complexes
The Schiff base transition metal complexes were synthesized as per the following literature procedure (  Molar conductivity values suggests that those are non-electrolytes Zn(II) in 10 mL water, ratio of 2:1 was added drop by drop with constant stirring under relux for 10-12 h in a heating mantle at 60-70 o C. The product was cooled by pouring it into cool water. A fine precipitate complexes formed was filtered off and dried.

Findings and analysis Molar conductivity of complexes
Molar conductivity of the transition metal complexes synthesised were measured using a systronic conductivity bridge type 305. Ethanol was the solvent, the observed values in the range 47-63 ohm -1 cm 2 mol -1 are tabulated in the table given below. FT-IR spectra FT-IR spectroscopy technique was utilized for find the bonding nature of AHMBL and their transition metal complexes. The FT-IR spectrum of (AHMBL) and their metal complexes are shown in Fig. 1-6. The stretching representation was given in the Table 2.

Table 2 : FT-IR data for ligand (AHMBL) and their transition metal complexes
The FT-IR range at 1666 cm -1 Schiff base ligand indicates the presence of (C-N) group. In following metal complexes this value varies from 15 to 20 cm -1 indicates a strong double bond character of the imine band and the azomethine nitrogen atom has coordination with transition metal ion. This is also confirmed by the intensity band around 462 cm -1 assigned to (M-N) vibration.
The broad band at 3332 cm -1 of FT-IR shows the stretching frequency of hydroxyl compound. The band ranges from 3340 cm -1 -3325 cm -1 exhibit the noncoordination of -H 2 O molecules in metal complexes to the central metal ion. This also proved by the M-O vibrational bands from 598 cm -1 -586 cm -1 .

Electronic spectra
To find information regarding the coordination geometry, electronic spectra of the synthesised complex were determined with DMF at normal temperature notices and compared with magnetic moment values and parameters. The observed data was given in Table 3. Low intensity absorption bands and low molar extinction belongs to d-d-electron transition.
The colour of synthesised ligand (AHMBL) is yellow and the metal complexes synthesised from the schiff base ligand (AHMBL) are different and also it differ from the corresponding metal ions, it seems the properties of the metal complexes are different from its corresponding metal ions.
The Schiff base ligand (AHMBL) showed two different absorption bands at 251nm and 330nm assigned (p-p*) electronic transition and (n-p*) electronic transition.
In the observation ligand has two absorption bands assigned to p-p* and n-p* transitions. The spectra of metal complexes also has the same transitions, but they shifted lower and higher frequencies confirming the coordination of ligand with transition metal ions.  2 ], showed four absorption bands. Two are of low wavelength shows the presence of (p-p*) and (n-p*) transition. The third and fourth are at low intensity and high wavelength region that is 414 nm and 502 nm are attributed to charge transfer which is ( 6 A 1g -4 A 1g , 6 A 1g 4 E g ) electronic transitions assumed the complex is high spin octahedral geometry.
The Cu(II) complex of synthesised ligand has three electronic spectrum, one with low intensity at 771nm to charge transfer 2 E g 2 T 2g electronic transition, suggested octahedral geometry.
Electronic spectrum of Zn(II) complex produced only two bands in UV region and there is no absorption in visible region because of completely filled d-orbitals. The geometry of Zn(II) complex is octahedral.

H NMR spectra studies
1 H NMR spectrum of synthesised ligand (AHMBL) and its Zn(II) metal complex were recorded in chloroform solution (CDCl 3 ). Tetramethyl silane (TMS) calibrate the chemical shits of each analyte proton which act as internal standard.
The Fig. 4.8 and 4.9 showed the recorded signals of 1 H NMR spectrum of ligand and metal complexes. In ligand a singlet at d = 12.12ppm was attributed to hydrogen of Ar(OH) group. A signal at d = 8.127 ppm showed azomethine proton (N = CH). A strong signal appeared between d (3-4ppm, 2H) was due to excess phenyl amine group.
The Zn(II) complex was examined and compared with ligand showed Zn(II) complex was shifted downfield compared ligand.  XRD Analysis X-ray diffraction gives information about crystallographic structure, chemical composition and physical properties of materials. Examined value of powder XRD for the ligand (AHMBL) and its metal complex [Cu(AHMBL) 2 (NO 3 ) 2 ] data are listed in table 5 and 6. The graphical representation showed feeble peaks for ligand which explains the microcrystalline nature of the sample and also the strong peak indicates the complex formation. Scherrer's equation is used to determine the size of crystals in the form of powder.
Where t-particle size, K = 0.9 (shape factor), l -X-ray wavelength, b -line broadening at half the maximum intensity, q -Bragg angle.

CONCLUSION
The Schiff base ligand AHMB synthesised from Ampicillin and 4-hydroxy, 3-methoxy benzaldehyde. And Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) metal complexes were derived from AHMBL. They were characterized by following physic-chemical methods. FTIR, UV-Vis, 1 HNMR spectroscopy, molar conductivity, magnetic moment data. The XRD and SEM analysis support to find the size and morphology of ligand and metal complexes. They were also recommended to study their biological activity for the pharmacological appliances.