Design, Synthesis, Physico-Chemical Characterization, Stability Determination, and Biomedical Applications of Some Novel Tetra-Dentate Imine Metal Chelates Supported by Theoretical Approaches: Bridging Coordination Chemistry and Life Sciences

Abstract

The synthesis of 4-Bromo-2-({2-[(5-bromo-2-hydroxy-benzylidene)-amino]-5-nitro-phenylimino}-methyl)-phenol (BSNP ligand), a straightforward, highly adjustable, and efficient BSNP ligand, was demonstrated. Four novel BSNP ligand coordinating compounds were created. The structures of these compounds were clarified by a variety of spectroscopic and analytical techniques, such as elemental analysis (CHN), spectroscopy (IR, NMR, mass spectrometry), conductivity, magnetic susceptibility, UV–Vis spectrum studies, and theoretical investigations. Additional analysis of the compounds showed that they were surrounded by an octahedral-coordinating environment. With conductance values ranging from 0.9.60 to 11.87 Ω⁻¹ cm² mol⁻¹, molar conductance values showed that the Fe (III), Zn (II), Cu (II), and Ru (III) complexes are non-electrolytes in fresh DMSO solutions, with the exception of the BSNPRu complex, which is mono electrolyte. According to IR spectra, the ligand uses the (N and O) donor sites from the (C=N and C-O) groups in the ligand moiety to coordinate through the metal ions in a tetra-dentate form. A 1:1 (metal:ligand) molar ratio was proposed by Job's approach based on analytical data from solution complexation. According to the stability constant (K_f) values, the complexes' stability order was found to be BSNPFe > BSNPRu > BSNPCu > BSNPZn. The pH profile showed that the complexes under study are stable throughout a broad pH range, usually between pH = 4 and pH = 10. The complexes' geometric structures and ligand coordination capabilities were inferred with the use of magnetic and electronic spectrum studies. To gain deeper insights into the reactivity and potential biological activity of the synthesized metal complexes, DFT calculations were performed. The computational analysis was carried out using the DFT/B3LYP/6-311g (d,p)/LANL2DZ level in the gas phase in order to explore the active sites and quantum chemical reactivity of the compounds. Building on the encouraging results from our in-vitro analyses, which demonstrated notable antimicrobial, antifungal, and anticancer properties of the synthesized metal complexes, molecular docking simulations were subsequently performed to further substantiate these promising biological activities. The anti-pathogenic activity of the generated materials was experimentally verified against a subset of gram (+) and gram (−) bacteria as well as some fungi using the agar well diffusion method. Additionally, the BSPN ligand's and its metal compounds' cytotoxic action on liver cells, breast, and colon cancers was investigated. Furthermore, the examined compounds' ability to suppress the DPPH radical was examined. Additionally, simulations of molecular landing were performed to ascertain how the produced compounds attached to the specific protein binding sites. Some novel metal chelates incorporating 4-Bromo-2-({2-[(5-bromo-2-hydroxy-benzylidene)-amino]-5-nitro-phenylimino}-methyl)-phenol ligand were synthesized and their structures were elucidated by different physico-chemical, analytical techniques, and computational. Moreover, all the new investigated metal chelates were tested in vitro against selected microbial strains and cancer cell lines as well as free radicals. Furthermore, biomedical applications of the investigated compounds were confirmed by docking studies.