Synthesis, Characterization, and Bioactivity Evaluation of V(IV), Fe(III), Cr(III), Mn(II), Mo(VI), and Ru(III) Complexes with a New Azo Dye Ligand

The new azo dye ligand 1-(2,4,6-trihydroxy-3-(2-hydroxy-phenylazo)phenyl)ethanone (H2L) was produced by reacting the diazonium salt derived from 2-aminophenol, with 2,4,6-trihydroxyacetophenone. This ligand was used to create several azo dye-metal complexes through reactions with salts of V(IV), Fe(III), Cr(III), Mn(II), Mo(VI), and Ru(III). The ligand was characterized using 1H- and 13C-NMR spectroscopy. The metal complexes were analyzed via UV-vis, FTIR, MS, thermal analysis (TGA, DSC), conductivity measurements, magnetic susceptibility, metal/chlorine content, and melting point determination. The results showed that the ligand acts as a tetradentate ligand with Ru, Mo, and VO, and as a tridentate ligand with Cr, Mn, and Fe. All complexes were octahedral in shape, except for the vanadium complex, which exhibited a square pyramidal structure. All complexes exhibited non-electrolytic properties. The compounds' capacity to act as antioxidants was assessed by measuring their ability to inhibit the DPPH free radical, with ascorbic acid serving as a standard reference. The half-maximal inhibitory concentration (IC50) values were determined, revealing the following order of activity: H2L > Ru-complex > Fe-complex > ascorbic acid = VO-complex = Mo-complex > Mn-complex > Cr-complex. The compounds were also tested for antibacterial and antifungal activity at two concentrations.