Mixed ligand octahedral Zn(II) complex of N^N^O donor tridentate Schiff base ligand and N^N donor bidentate bipyridine ligand: Synthesis, characterization, biological activity and cytotoxicity

Tridentate NNO donor Schiff base ligand and its mixed ligand zinc(II) complex were synthesized stoichiometrically and characterized by electronic, infrared, mass spectral techniques and elemental analysis. To understand the DNA binding ability, the complex was investigated by various analytical and spectroscopic techniques in presence of calf thymus DNA (CT-DNA). The binding studies showed that the zinc complex interacts with DNA by groove binding mode with intrinsic binding strength of 2.11 × 10⁵ M⁻¹ and with bovine serum albumin the complex showed dynamic quenching attributed for changes in the secondary structure of BSA with efficient interaction. The MCF-7 cell line studies of the zinc(II) complex with 90.8 μM IC₅₀ value revealed that the complex is effective for the breast cancer cell line and has a potential as anticancer drug. Furthermore, the tridentate ligand and its mixed ligand zinc complex were screened for antibacterial and antifungal activities, which showed better antimicrobial activity for complex.