Synthesis, spectroscopic characterization, DFT, oxygen binding, antioxidant activity on Fe(III), Co(II) and Ni(II) complexes with a tetradentate ONNO donor Schiff base ligand

Abstract

The Schiff base ligand, namely (7E)-N-benzylidene-2-styrylbenzena-mine1,2-diamine-2,4-dihydroxy-phenol, (L), was synthesized from condensation of 2,4-dihydroxybenzaldehyde with o-phenylenediamine. The reaction of the ligand with Fe(III), Co(II) and Ni(II) salts in a 1: 1 ratio yielded three complexes 1-3. Different analytical tools like elemental analysis, ESI-mass spectra, FT-IR, conductivity, electronic spectra, magnetic susceptibility, NMR and EPR mea-surements are used to elucidate the structure of the ligand and complexes. Density Functional Theory (DFT) calculation at the B3LYP/3-211G++/LANL2DZ level of the theory has been carried out to optimize the geometry of the ligand and complexes. The tetradentate ligand has coordinated to metals through ONNO donors affording octahedral geometry. Complexes were studied for their oxygen-binding activity and free radical scavenging activities. Complex 1 and 2, which contain Fe(IIl) and Co(II), displayed reversible oxygen binding activity. On the other hand, complex 3 fails to show oxygen binding. The order of antioxidant activity is 3 > 1 > 2 > L.

Synthesis, Characterization and Antimicrobial Activity of Complexes Metal Ions Ni(II), Zn(ΙΙ), Pd(II) and Pt(IV) with Polydentate 1,2,4-Triazole Ligand

“…As well as the free ligand solution in blank DMSO exhibits medium inhibition zones (10-17) mm toward Staphylococcus aureus and Escherichia coli bacteria, whereas no remarkable antifungal, which may be reasonable in high polarity of the triazole structure [22]. Furthermore, the solutions of Ni(II) and Zn(II) displayed the lowest activity toward the E. coli and S. aureus bacteria compared with the control drug of azithromycin (10 ppm), which mainly resulted from the ionic character of chloride ions in the outer sphere of their chemical structures [10,21]. It is observed that the solutions of Pt(IV) and Pd(II) showed greater activity against Candida albicans and Aspergillums favus which are close to the activity of control Miconazole antifungal drug of 10 ppm concentration.…”