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.

The Schiff base was synthesized by condensation of 2-hydroxy-1-naphthaldehyde with 3- aminobenzoic acid in 1:1 molar ratio. The Schiff base ligand formed complexes with Co (II), Ni (II), Cu (II) and Zn (II) acetate via mechanochemical synthesis. The synthesized compounds were characterized by solubility test, thermal analysis, FT-IR, powder x-ray diffraction, molar conductance measurement, magnetic susceptibility and elemental analysis. The Schiff base has a melting point of 190 oC. The decomposition temperature of complexes was found to be in the range 289 – 302 oC. The Schiff base and its metal (II) complexes were soluble in DMF, DMSO and sparingly soluble in acetonitrile, chloroform, diethyl ether and insoluble in n-hexane which indicate the polar nature of the synthesized compounds. The IR spectral analysis of the free Schiff base shows a band at 1622 cm-1, assigned to v(C=N) stretching vibrations. This band was shifted in the spectra of complexes (1607 – 1633 cm-1), indicating coordination of the Schiff base to the metal ion through the azomethine group. The molar conductance of complexes determined are in the range 9.51 – 14.87 Ohm-1cm2mol-1 which indicate the non-electrolytic nature in DMF. Magnetic susceptibility measurements of Co (II), Ni (II) and Cu (II) complexes exhibit a magnetic moment in the range 1.25 – 3.08 BM. The values correspond to square-planar geometry. The magnetic moment value of Zn (II) complex indicates a diamagnetic behaviour. The elemental analysis of the complexes for C, H and N determined showed that the observed and the calculated percentages of the elements are in good agreement.