Antimicrobial potentials of N,N’-(4-bromo-1,2-phenylene)bis(1-(pyridin-2-yl)methanimine) and its Mn(II), Fe(II), Co(II) and Ni(II) complexes

A salophen ligand (L = N,N'-(4-bromo-1,2-phenylene)bis(1-(pyridin-2-yl)methanimine)) was synthesized by refluxing 4-bromobenzene-1,2-diamine with 2-pyridinecarboxaldehyde (1:2 mole ratio, respectively) in ethanol.M(II) complexes (M = Mn, Fe, Co and Ni) of the ligand were synthesized by refluxing the ligand solution with the corresponding M(II) salt solution (1:1 mole ratio) in ethanol.The synthesized compounds were characterized using Fourier transform infrared (FTIR) spectroscopy, CHN elemental analysis, magnetic moments, and molar conductivity.FTIR spectra of the ligand showed a strong band at 1588 cm -1 for the C=N stretching vibrations.The band shifted to higher frequency (1596-1603 cm -1 ) in the M(II) complexes signifying complexation.CHN elemental analysis showed strong agreement with theoretical values for the ligand and the M(II) complexes, supporting the proposed formula of the compounds.All the samples were non-electrolyte due to the low molar conductance values (17.12-55.40 -1 cm 2 mol -1 ).Effective magnetic moments (3.23-5.97BM) of the complexes indicated their paramagnetic nature and octahedral geometry.The samples were tested for antimicrobial activity against four bacterial and two fungal isolates.Generally, the complexes were more potent than the free ligand against all the tested isolates.The increasing order of antimicrobial potential of the compounds follows: L < [Ni(II) (L)2] < [Mn(II) (L)2] < [Fe(II) (L)2] < [Co(II) (L)2].