Biological Potency of New Benzimidazole Derived Imine Based Ligand and its Co(III), Ni(II), Cu(II) and Pt(II) Complexes: Synthesis, Structure, Antimicrobial, Antioxidant and BSA Interaction Studies

In this study, we report the synthesis and characterization of transition metal complexes (MC1, MC2, MC3, MC4) where M= Co(III), Ni(II), Cu(II) and Pt(II), respectively, using a new imine-based ligand, 2-{(E)-[(1H-benzimidazol-2-ylmethyl)imino]methyl}-4-bromophenol (HBMB). The molecular structure of the HBMB ligand and its complexes were confirmed by various analytical techniques such as UV-Vis, FT-IR, 1H, 13C-NMR, ESR, TGA/DTA, LC-MS, molar conductance, and magnetic moment measurements. The spectral data of complexes recommended tridentate binding modes of HBMB ligand and suggested an octahedral geometry for MC1 and MC2 complexes while square planar geometry for MC3 and MC4 complexes. Further, the biological activities viz., antimicrobial, antioxidant, and BSA interaction studies were performed using the prepared compounds. The antimicrobial activity results suggested that all the synthesized transition metal complexes showed significant antimicrobial activity against several bacterial and fungal species compared with standard drug and the parent ligand, HBMB. The interaction of metal complexes with BSA (Bovine serum albumin) was performed. The results strongly recommended among the synthesized complexes, platinum complex (MC4) showed marked interaction with the BSA protein. It also indicates that the probable quenching mechanism of BSA fluorescence by complexes is a static quenching procedure, and the spontaneous binding interaction is mainly entropy driven with either van der Waals force or hydrogen binding reaction. The free radical scavenging ability of test samples was assessed using an in vitro assay viz., DPPH.