This work describes
the syntheses, structural characterization,
and biological profile of Mn(II)- and Zn(II)-based complexes 1 and 2 derived from the aroyl-hydrazone Schiff
base ligand (L1). The synthesized compounds were thoroughly
characterized by elemental analysis, Fourier transform infrared spectroscopy
(FTIR), UV–vis, electron paramagnetic resonance (EPR), nuclear
magnetic resonance (NMR), and single-crystal X-ray diffraction (s-XRD).
Density functional theory (DFT) studies of complexes 1 and 2 were performed to ascertain the structural and
electronic properties. Hirshfeld surface analysis was used to investigate
different intermolecular interactions that define the stability of
crystal lattice structures. To ascertain the therapeutic potential
of complexes 1 and 2, in vitro interaction studies were carried out with ct-DNA and bovine serum
albumin (BSA) using analytical and multispectroscopic techniques,
and the results showed more avid binding of complex 2 than complex 1 and L1. The antioxidant
potential of complexes 1 and 2 was examined
against the 2,2-diphenyl picrylhydrazyl (DPPH) free radical, which
revealed better antioxidant ability of the Mn(II) complex. Moreover,
the antibacterial activity of synthesized complexes 1 and 2 was tested against Gram-positive and Gram-negative
bacteria in which complex 2 demonstrated more effective
bactericidal activity than L1 and complex 1 toward Gram-positive bacteria. Furthermore, the in vitro cytotoxicity assessment of L1 and complexes 1 and 2 was carried out against MDA-MB-231 (triple negative
breast cancer) and A549 (lung) cancer cell lines. The cytotoxic results
revealed that the polymeric Zn(II) complex exhibited better and selective
cytotoxicity against the A549 cancer cell line as was evidenced by
its low IC50 value.