Cell Cycle Arrest, Apoptosis Assay, Cytotoxicity, Molecular Docking, DNA Binding/Cleavage, and Biological Evaluation of Pt(II), Ni(II), Pd(II), and Cu(II) Nano-Sized Complexes of 2-(6-Fluorobenzo[d]thiazol-2-yl)phenol: Design, Synthesis, and Spectral Approach

Abstract

A new novel bidentate benzothiazole ligand, 2-(6-fluorobenzo[d]thiazol-2-yl)phenol (HFBTP), is synthesized through condensing 2-mercaptoaniline and 2-hydroxybenzoic acid in 1:1 ratio. Nano-sized bivalent metal complexes are created and subsequently characterized using various physical methods. Based on the elemental analysis results, the complexes are inferred to follow the overall formula [M (FBTBT)₂] (as M = Cu(II) (S1), Ni(II) (S2), Pd(II) (S3), and Pt(II) (S4) and FBTP = Ligand). Quantum chemical calculations, along with electronic spectra, electron paramagnetic resonance (EPR), cyclic voltammetry (CV), and magnetic susceptibility findings, indicate that all complexes exhibit a square planar configuration. The SEM, EDX, and AFM analyses of the studied complex unveils distinct and strong diffraction peaks, indicating its crystalline nature and providing evidence of its nano-sized particle sizes. The in vitro antimicrobial efficacy of the ligand and metal complexes was inspected against various bacterial and fungal pathogens. Viscosity measurements and UV–visible absorption were used to study the binding interactions of S1–S4 with calf thymus DNA. The DNA cleavage ability of S1–S4 with pUC19 DNA indicates that the complexes can cleave DNA without the use of any external agents. The complexes showed significantly high cytotoxicity against PC3 (prostate cancer cells). Moreover, M(II) complexes exhibited the capability for triggering DNA damage in HePG2 cells, resulting in dose-dependent cell apoptosis. Subsequent investigations revealed that complex triggered cell cycle arrest during the S and G2 phases.