Synthesis, characterization, and determination antioxidant activities for new Schiff base complexes derived from 2-(1H-indol-3-yl)-ethylamine and metal ion complexes

•Tetradentate bidentate Schiff base was prepared using a green method.•Characterization using 1H and 13CNMR, FT-IR and UV–visible spectroscopies.•Antioxidant evaluation of prepared compounds.•DPPH scavenging capacities (IC50 in mg/ml) of the compounds has been determined. Tetradentate bidentate Schiff base (L1) from 4-amino-1.5-dimethyl-2-phenyl-1.2-dihydro-pyrazol-3-one and 2-(1H-indol-3-yl)-ethylamine and benzene-1.4-dicarbaldehyde was synthesized and characterized as novel antioxidants. The Schiff base and its metal complexes Mn(II), Co(II),Cu(II), Zn(II), Cd(II) and Re(V) have been characterized by elemental microanalysis, metal content, chloride-containing, molar conductance, FT-IR, 1H NMR, UV–Vis spectroscopy, magnetic susceptibility, mass spectra (MS), and thermal analysis (TGA). The structures of the prepared compounds were observed by antioxidant activities of the Schiff bases derivatives were investigated due to the imine group (-C=N-) and promising results were obtained. The results confirmed that complexes can act as free radical scavengers.