Schiff base derived from the reaction of 2-amino phenol and 2-hydroxy-1-naphthaldehyde and its Co (II), and Mn (II) complexes have been synthesized and characterized by solubility test, melting point/ decomposition temperatures, molar conductance, IR and magnetic susceptibility. The number of ligands coordinated to the metal ion was determined using Job’s method of continuous variation. Their molar conductance values indicate that all the complexes are non-electrolytes. Magnetic moment values of the complexes showed that both Mn (II) and Co (II) are paramagnetic. The spectroscopic data of metal complexes indicated that the metal ions are complexed with azomethine nitrogen and deprotonated oxygen atom. Corrosion inhibition of the schiff base and Mn (II) and Co (II) complexes were evaluated using the weight loss method in a 0.1MHCl solution for copper metal. The inhibition efficiency increased with increasing inhibitors concentration. The negative values of Gibb’s free energy of adsorption (ΔGads) confirmed the spontaneity and physical adsorption of the inhibition process which is inconsistent with Langmuir adsorption isotherm.

Transition Metal Complexes of Mn(II),Co(II) and Ni(II) with Schiff base derived from 4- chloroaniline and Salicylaldehyde were synthesized and characterized by conductivity measurement, magnetic susceptibility, infrared spectra, metal-ligand ratio determination and solubility test. The Schiff base and its metal complexes were tested for antibacterial activity against Staphylococcus aureus and Escherichia coli and fungal activity against Aspergillus flavus and Mucor species. The low molar conductance values range (16-28.1Ohm- cm2 mol-1) indicated that all the complexes are non electrolytes. The magnetic susceptibility revealed that all the complexes are paramagnetic in nature. The metal-ligand ratio was found to be 1:2 in all the complexes. The infrared spectra suggested that the Schiff base behaves as a bidentate ligand. The antimicrobial studies revealed moderate activity against the tested organism when compared with the standards (Ciprofloxacin and Ketoconazole), and this activity increases by increasing concentration. And also the Metal Complexes showed higher activity than free Ligand due to chelation.Keywords: Salicyldehyde, 4-chloroaniline, Mn(II), Co(II), Zn(II) complexes, antimicrobial activity

Schiff base derived from condensation of 2-hydroxy-1-naphthaldehyde and 4-iodoaniline was synthesized and used for the preparation of Co(II) and Ni(II) complexes. The complexes were characterized by IR, Powder-XRD, Solubility test, thermal analysis, conductivity measurement, magnetic susceptibility and elemental micro analysis. IR study indicated a strong band in the spectra of the Schiff base at 1603 cm-1 assigned to azomethine v(C=N) stretching vibration. It shifted to new frequency regions (1618 - 1622 cm-1) in the spectra of the complexes indicating the formation of the desired complexes. The decomposition temperatures of the complexes are in the range of (260-265) oC , molar conductance values are in the range of (4.51 -11.31) Ohm-1cm2 mol-1, indicating non electrolytic nature of the synthesized complexes in DMF. Magnetic susceptibility measurement indicated that Co(II) and Ni(II)  complexes are  paramagnetic and exhibit magnetic moment in the range of 2.92-3.24 BM, the values correspond to the square planar geometry. The Powder x-ray diffraction analysis showed the patterns of the metal(II) complexes were different from the reactants, signifying that reactants were changed to product. The CHN analysis results show the formation of 1:2 metal to ligand ratio. The synthesized compounds have been studied for antimicrobial activity using pathogenic bacteria and fungal pathogens by disc diffusion method. The results indicated that metal complexes (10 – 15 mm inhibition zone) are more active compared to Schiff base (8 – 12 mm inhibition zone) against the test organisms.