Characterization and biological studies on Co(II), Ni(II) and Cu(II) complexes of carbohydrazones ending by pyridyl ring

The chelating behavior of ligands based on carbohydrazone core modified with pyridine end towards Co(II), Ni(II) and Cu(II) ions have been examined. The ligands derived from the condensation of carbohydrazide with 2-acetylpyridine (H2APC) and 4-acetylpyridine (H2APEC). The 1H NMR, IR data and the binding energy calculations of H2APC revealed the presence of two stereoisomers syn and anti in the solid state and in the solution. The 1H NMR, IR data and the binding energy calculations confirmed the presence of H2APEC in one keto form only in the solid state and in the solution. The spectroscopic data confirmed that H2APC behaves as a monobasic pentadentate in Co(II) and Cu(II) complexes and as mononegative tetradentate in Ni(II) complex. On the other hand, H2APEC acts as a mononegative tridentate in Co(II) complex, neutral tridentate in Ni(II) complex and neutral bidentate in Cu(II) complex. The electronic spectra and the magnetic measurements of complexes as well as the ESR of the copper complexes suggested the octahedral geometry. The bond length and bond angles were evaluated by DFT method using material studio program. The thermal behavior and the kinetic parameters of degradation were determined using Coats–Redfern and Horowitz–Metzger methods. The antioxidant (DDPH and ABTS methods), anti-hemolytic and in vitro Ehrlich ascites of the compounds have been screened.

Figure optionsDownload as PowerPoint slideHighlights
► Preparation of Co2+, Ni2+ and Cu2+ complexes of carbohydrazones.
► Elemental analysis, spectral characterization of the ligands and their complexes.
► Thermal behavior of the solid metal complexes was studied using TGA technique.
► The compounds were screened for erythrocyte hemolysis, antioxidant activity and cytotoxicity.