Synthesis, spectral analysis, physicochemical investigation and biomedical potential of some novel Cu(II), Ru(III) and VO(II) complexes with anthraquinone-based Schiff base supported by DFT and molecular docking insights

Four novel Cu(II), Ru(III) and VO(II) complexes of tetra-dentate Schiff base ligand 2-[(5-Bromo-2-hydroxy-benzylidene)-amino]-1-(2-oxo-1,2-dihydro-indol-3-ylideneamino) anthraquinone(BOA) were synthesized. Elemental analyses, magnetic measurements, FT-IR, electronic spectra, molar conductivity measurements were used to measure the stoichiometric ratios and physiochemical properties of these complexes. Utilizing the nitrogen and oxygen atoms from the azomethine group, the spectroscopic study demonstrated that the synthesized Schiff base ligand, referred to as BOA, established coordination complexes with copper(II), ruthenium(III), and vanadium(IV) oxide metal centers. BOA-Cu and BOA-Ru complexes have octahedral geometry while BOA-VO complex has square pyramidal geometry. The M:L ratio was validated through the outcomes of both continuous variation and molar ratio analyses, revealing an optimal composition of 1:1. The pH profile revealed that the wide range of pH stability of the tested complexes (pH = 4-10). To complement the experimental findings, Density Functional Theory (DFT) analyses were employed to explore the electronic structure and chemical reactivity of the synthesized complexes. The theoretical investigations provided insights into the optimized molecular geometries, energy levels of the frontier orbitals (HOMO and LUMO), energy gaps, and key reactivity parameters. These computational outcomes supported the proposed coordination modes and structural stability of the complexes. In parallel, molecular docking studies were carried out to predict the interaction potential of the ligand and its metal complexes with specific biological targets relevant to antimicrobial and anticancer activities. The BOA-Ru complex, in particular, demonstrated strong binding affinities and stable interactions within the active sites of selected target proteins, aligning with its superior biological performance. These computational insights reinforce the experimental results, indicating promising therapeutic potential for the BOA-derived metal complexes. An innovative study evaluated the in vitro efficacy of a recently synthesized Schiff base ligand and its corresponding metal compounds in suppressing the proliferation of various bacterial pathogens and fungi aiming to contribute to the development of advanced therapeutic agents against these harmful microbes. The results indicated that, in contrast to the benchmark medications Ofloxacin and Fluconazole, the BOA-Ru complex emerged as the most prevalent inhibitor, exhibiting superior antimicrobial efficacy. Moreover, an investigation assessed the cell-killing properties of an innovative molecule and its subsequent compounds in a controlled environment, targeting Hep-G2, MCF-7, and HCT-116 cancerous cell lines to ascertain their efficacy in combating malignancy. The comparison of complexes clearly indicated that BOA-Ru exhibits greater efficacy as an active component in contrast to Doxorubicin. Furthermore, the antioxidant potential of the ligand and its metal complexes was evaluated using standard radical scavenging assays. The results revealed that the BOA-Ru complex exhibited the highest antioxidant activity, likely due to its enhanced electron-donating ability and stable coordination framework.