New Cu(II), Co(III) and Ni(II) metal complexes based on ONO donor tridentate hydrazone: Synthesis, structural characterization, and investigation of some biological properties

Abstract

New Cu(II), Co(III) and Ni(II) metal complexes of N'-(3-ethoxy-2-hydroxybenzylidene)acetohydrazide (ehbahH2) ligand derived from 3-ethoxysalicylaldehyde and acethydrazide were obtained. The K[Cu(ehbah)(OAc)]·2H2O (1), K[Co(ehbah)2]·H2O (2) and [Ni(ehbahH)2] (3) complexes were characterized by elemental analysis, LC-MS and magnetic susceptibility measurements, electronic, IR spectra and thermal experiments (TGA and DTA). The molecular structures of 1 and 2 were also established by single-crystal X-ray diffraction. Both complexes had a complex ion unit and a potassium (I) cation leading to a neutral three-dimensional network. The single-crystal X-ray experiments revealed that the complex ions of 1 and 2 exhibited distortion in the square-planar and octahedral geometry, with ligand in enol form. The characterization studies of the complex 3 showed that the ligand was coordinated in the keto tautomeric form, and the ratio of metal ligand was 1:2. All of the compounds were screened for their in vitro antibacterial and antifungal activity. The cleavage activities of the ligand and its complexes were assayed on supercoiled pBR322 DNA by the agarose gel electrophoresis method in the presence and absence of H2O2. The results indicated that only 1 and 2 effectively cleaved pBR322 DNA. Lastly, all compounds obtained in the study were evaluated for their antioxidant (ABTS radical scavenging) properties.