Syntheses, crystallographic, mass-spectroscopic determination and antioxidant studies of Co(II), Ni(II) and Cu(II) complexes of a new imidazol based Schiff base

•Co(II), Ni(II), Cu(II) complexes of imidazolic Schiff base have been synthesized.•The geometries of all complexes have found to be distorted octahedra.•Structural and electronic properties of Cu(II) complex have been further studied.•Radical scavenging behaviors of the complexes have been explored.

A new imidazole-based Schiff base, 2-((1H-imidazol-4-yl)methyleneamino)benzylalcohol (HL) and corresponding analogous bis(2-((1H-imidazol-4-yl)methyleneimino)benzylalcohol)metal(II) perchlorates (M: Co(1), Ni(2), Cu(3)) have prepared and characterized by elemental analyses, ESI-MS, IR, UV–Vis spectroscopies and conductivity measurements. X-ray single crystal structures of 1 and 2 have been also determined. Elemental analyses, spectroscopic and conductance data of 3 demonstrated similar structural features with these of crystallographically characterized complexes and based upon this relevances, HL ligands are neutrally coordinated to metal(II) ions in tridentate mode and all complexes are isostructural, dicathionic, contain perchlorate anions as complementary ions and, are in octahedral geometry with the formulae of [M(HL)2](ClO4)2 (for 3) and [M(HL)2](ClO4)2·H2O (for 1 and 2). Radical scavenging activities of the complexes have been evaluated by using DPPH, DMPD+, and ABTS+ assays. SC50 values (μg/mL) of the complexes and standards on DPPH, DMPD+, ABTS+ follow the sequences, BHA (9.06 ± 0.33) > CMPD3 (15.62 ± 0.52) > CMPD2 (17.43 ± 0.29) > Rutin (21.65 ± 0.60) > CMPD1 (25.67 ± 0.51) > Trolox (28.57 ± 0.37), Rutin > BHA > CMPD3 > CMPD2 > Trolox > CMPD1, and Trolox > BHA > CMPD3 > CMPD2 > Rutin > CMPD1 respectively.

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