Synthesis, spectral characterization and antimicrobial, antioxidant properties of Au(III), Pd(II), Cu(II), Fe(II) and Mn(II) metal complexes of 1-Hydroxy-2-acetonaphthone Schiff base

Novel metal complexes of Au(III), Pd(II), Cu(II), Fe(II) and Mn(II) metals with unique asymmetrical bidentate Schiff base, obtained by condensation reaction between 1-Hydroxy-2-acetonaphthone and 4-Methoxyphenyl ethylamine, 2-(1-((4-methoxyphenethyl)imino)ethyl)naphthalen-1-ol (HL1). Synthesized Schiff base ligand and their metal complexes are well characterized by UV-Vis, FT-IR, NMR, LCMS, ESR, TGA-DSC, XRD and SC-XRD. Analytically proved the structure of metal complexes and ligand. Herein, our reports for the molar ratio of metal to ligand are1:2 in metal complexes with optimization. Interestingly, proved and analysed the interactions between the metal ions and ligand occurring deprotonated oxygen and Schiff base imine nitrogen using FT-IR, NMR, TGA-DSC and XRD. Also the geometries for the metal complexes such as square planar geometries for Au(III), Pd(II), Cu(II) complexes and octahedral geometries for Fe(II) and Mn(II) complexes. Synthesized metal complexes were examined for their in vitro anti-bacterial activity against the gram-negative bacteria E. coli, P. aeruginosa, and gram-positive S. aureus, B. subtilis, as well as their in vitro antifungal activity against the two fungus C. albicans, A. niger. According to the biological investigations, metal complexes are more effective against species of bacteria and fungi than non-complexed ligand. Interestingly, Pd(II) complexes have outstanding antioxidant activity, while Au(III) and Mn(II) complexes exhibit moderate to good antioxidant activity.