Synthesis, spectral characterization and antimicrobial activity of some transition metal(II) complexes with acetone p-amino acetophenone benzoylhydrazone

Complexes of the type [M(apabh)Cl] and [M(Hapabh)(H₂O)SO₄], where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); Hapabh = acetone p-amino acetophenone benzoylhydrazone have been synthesized and characterized. Electronic spectra and μ_eff values suggest a square planar geometry for Co(II), Ni(II) and Cu(II) chloride complexes, whereas, octahedral geometry for the sulfato complexes. ESR data show isotropic spectra for [Cu(apabh)Cl] and axial spectra for [Cu(Hapabh)(H₂O)SO₄] and d_x²_−y² as the ground state for both Cu(II) complexes. The ligand acts as tridentate monobasic in all chloro complexes bonding through two >CN and a deprotonated enolate groups, whereas tridentate neutral in all sulfato complexes coordinating through two >CN and a >CO groups. Thermal analysis (TGA & DTA) of [Ni(apabh)Cl] complex shows a multi-step exothermic decomposition pattern. The complexes show a significant antifungal activity against Rizoctonia sp., Aspergillus sp. and Penicillium sp. and a considerably fair antibacterial activity against Pseudomonas sp. and Clostridium sp. The activity increases at higher concentration of the compound.