ABSTRACT A novel family of binuclear transition metal complexes was synthesized with M = Zinc (II), Cobalt (II), Nickel (II), Copper (II), and Manganese (II). These complexes, formulated as M₂(L)Cl₂(H₂O)₆ and M′₂(L)Cl₂(H₂O)₂, were prepared using (E)‐2,4‐dihydroxy‐5‐((3‐hydroxyphenyl)diazenyl)benzoic acid (LH₂), a newly synthesized pentadentate/hexadentate azo dye ligand. Their coordination patterns and structural features were systematically investigated using a wide range of spectroscopic and analytical techniques, including Fourier Transform Infrared (FTIR) spectroscopy, UV–Vis spectroscopy, magnetic susceptibility measurements, elemental analysis, thermal studies (TGA/DTA), powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), and energy‐dispersive X‐ray (EDX) analysis. An octahedral geometry surrounding the metal centers was confirmed by magnetic and spectroscopic evidence. XRD patterns indicated a hexagonal structure for the ligand and a cubic structure for the Cobalt (II) complex, with nanocrystalline sizes of ~20–29 nm. The complexes' electronic structures, frontier molecular orbitals (HOMO–LUMO gap), molecular electrostatic potential (MEP), optical responses, and ideal geometries were all investigated using Density Functional Theory (DFT) and Time‐Dependent DFT (TD‐DFT) computations. Both metal‐to‐ligand (MLCT) and ligand‐to‐metal (LMCT) charge‐transfer transitions were visible in the simulated TD‐DFT spectra. While HOMO‐LUMO gaps ranged from 1.76 to 3.12 eV, suggesting varied reactivity across complexes. ESR spectroscopy of the Copper (II) complex indicated strong metal–ligand covalency and confirmed a binuclear configuration. Biological screening showed enhanced antibacterial activity for all complexes, especially against Pseudomonas aeruginosa . Antioxidant studies revealed the Ni (II) complex as the most potent (IC₅₀ ≈ 26.9 μM). Cytotoxicity assays (SRB) on MCF‐7 cells showed that the Ni (II) complex exhibited the highest activity (IC₅₀ = 6.33 μM ), comparable to doxorubicin (5.15 μM), followed by LH₂ (22.97 μM) C,o (II) (44.28 μM), Zn (II) (59.41 μM), and Cu (II) (78.87 μM). Molecular docking with EGFR, HER2, and 1MBB confirmed strong binding, supported by QSAR and ADMET profiles suggesting drug‐likeness and low toxicity. These results highlight their therapeutic and optoelectronic potential.
Tripathy et al. (Mon,) studied this question.