Synthesis, characterization, DFT calculation, and biological activity of pyrazole-based azo-metal(II) complexes

Abstract

An azo dye ligand, [HL, (Z)-1-((5-amino-3-methyl-1-phenyl-1H-pyrazol-4-yl)diazenyl)naphthalene-2,7-diol], and its Cu(II), Co(II), and Fe(II) complexes were synthesized in a 1:1 metal to ligand ratio. The prepared compounds were characterized by FT-IR and UV–vis spectroscopy, thermogravimetric and elemental analysis, X-ray powder diffraction, magnetic susceptibility measurements, scanning electron microscopy, and density functional theory (DFT) calculations. The electronic spectra and magnetic moments indicated that all complexes are paramagnetic and have an octahedral geometry. The antimicrobial activity was tested against the gram-positive bacteria B. subtilis and S. aureus and gram-negative bacteria E. coli and N. gonorrhoeae, whereas the antifungal activity was tested against C. albicans using the disk diffusion method. The Fe(II) complex showed strong antimicrobial activity against all the tested strains. Treatment of HepG2 liver cancer cells with different concentrations of the free ligand and its metal complexes in vitro using the MTT assay revealed that the free ligand and Co(II) complex demonstrated greater cytotoxicity (IC50 43.24 and 62.45 µg/mL, respectively) compared to the other metal complexes.