Mechanochemical synthesis and characterization of potentially bioactive Isonicotinic acid and its Co (II), Cu(II) & Zn(II) complexes

Abstract

Liquid assisted grinding of Isonicotinic acid with Co (II), Cu(II), and Zn(II) resulted in coloured metal (II) complexes with the formula [M(INA)₂(OH)₂(H2O)₂] (M = Co (II), Cu(II), and Zn(II), INA = Isonicotinic acid). Elemental analysis, infrared spectroscopy,
magnetic measurement, single crystal, and Powder x-ray diffraction were used to characterize the coordination compounds. The Infrared spectra of the ligand showed a strong band at 1695cm^-1 and 1289cm^-1 which corresponds to C=O and C-O stretching vibrations. A shift of the C=N stretching vibration from 1580 cm^-1 which was observed in
the IR spectrum of the ligand to lower values in the spectra of the coordination compounds provides evidence of coordination to the central metal ion. This was further confirmed by the appearance of new bands in the spectra of the coordination compounds in the range (550-500cm^-1) which corresponds to (M-N) stretching vibrations. For all of the complexes, the effective magnetic moment values (5.11 and 1.71 for Co and Cu complexes
respectively) suggest octahedral geometry. The CHN Elemental analysis agreed well with the calculated value, indicating a ligand-metal ratio of 2:1. The crystal is triclinic with a P- 1 space group a = 6.307 Å, b = 6.798 Å, c = 9.181Å, and a distorted octahedral geometry. The experimental PXRD patterns of the coordination compounds matched those simulated from single-crystal data, indicating the phase purity of bulk samples. The antimicrobial
activity of the ligand and its metal (II) complexes was tested against six pathogenic microorganisms (Staphylococcus aureus, Escherichia coli, Salmonella typhi, Aspergillus flavus, and Aspergillus fumigatus). Gentamycin and Ketoconazole were used as reference drugs for bacteria and fungi respectively. All the compounds demonstrated moderate
antimicrobial activity.