BackgroundThe purpose of this research is to illustrate the synthesis, characterization, and reactivity of three new mononuclear complexes (NiSniL, CuSniL, and VOSniL) from the direct coordination of sodium sulfonate pyridylhydrazone (H2SniL) to Ni2+, Cu2+, and VO2+ ions, respectively. The reactivity was studied catalytically and biologically considering the type and nature of the central metal ion. MethodsThe spectral analysis of IR, NMR, and mass spectra, in addition, other essential tools (e.g., elemental and thermogravimetric analyses) were used as the main methods in the characterization of all studied compounds. All M2+-complexes showed high catalytic efficiency towards the 1,2-cyclooctene epoxidation with H2O2, in which the central metal ion presented an effective action in its complex catalyst for such catalytic processes. The significant findingsThe significant findings of the catalytic studies are summarized that VO-complex catalyst (95% after 2 h at 70 °C), with the high valence of VO2+ ion (V4+ ion), exhibited a little more efficiency than that of NiSniL and CuSniL (90 and 94% after 4 h at 70 °C) within low valence of Ni2+ and Cu2+ ion, respectively. The valid oxidation state (V4+/V5+) interchangeable behavior of V4+ ion, the high electrochemical reversibility, and the strong Lewis acid feature gave additional catalytic activity to VOSinL over the other studied complex catalysts. Catalytically, VOSniL catalyst could be assigned as a candidate for further industrial catalytic application, homogeneously. The effect of M2+ ion in their complexes was also biologically investigated. The reactivity of H2SniL, NiSniL, CuSniL, and VOSniL towards ctDNA was investigated spectrophotometrically and evaluated with viscosity which assigned valuable interaction. The interaction of the current compounds was estimated with the binding constant (4.11, 6.01, 6.15, and 6.22 × 108 mol−1 dm3, respectively), which referred to their high reactivity towards ctDNA. Also, the Gibbs’ free energy values for such interaction supported their high potential against ctNDA (-32.03, -32.96, -33.02, and -33.06 kJ mol−1, respectively). The investigated compounds were enhanced bioaction with ctDNA over their free ligand, which was observed with various potentials based on the M2+ type and displayed significant antimicrobial, antioxidant, and anticancer activities, and that were also supported within the molecular docking assessment. Therefore, from the obtained results, it could be suggested that our M-complexes with their effective antimicrobial, antioxidant, and cytotoxicity activity would be probably nominated for treatment of bacterial and fungal infections and could be also appraised clinically for further applications.