Investigation of mono-nuclear cobalt(II) complexes with a tri-dentate quinoxalyl-hydrazone ligand for their potential in biological research and interaction with ct-DNA

The condensing reaction of 2-hydroxy-1-naphthaldehyde with quinoxalyl-2-carbohydrazide resulted in synthesizing of a novel derivative of hydrazone quinoxalyl ligand (H₂dpq). The bonding behavior between H₂dpq and Co(II) ion was investigated in molar ratios of 1: 1 and 2: 1 to produce two different complexes, Codpq and Co(dpq)₂, respectively. Their chemical structure was verified using several spectroscopic approaches. The characterization envolved micro-C, H, and N-elemental analyses, thermogravimetric investigations, as well as the examination of their magnetic and conductance properties. The inhibitory effects of H₂dpq (the free ligand) and its Co(II)-chelates on the growing up of three specific bacterial series, three specific fungal series, and three famous human cancer cell lines were evaluated based on their structure features. The study referred to the pivotal function of Co(II) and its ratio in the two complexes. The antioxidant activity was determined for all current compounds within DPPH and SOD assays, reporting respectable antioxidant reactivity. The interaction of H₂dpq, Codpq, and Co(dpq)₂ with calf thymus DNA (ct-DNA) was assessed by analyzing through the alterations in the viscometric and spectrophotometric properties. Determination of binding constant (K_b, 13.12, 16.02, and 16.82 × 10⁷ mol^-1 dm³), Gibb's free energy (∆G_b^≠, were -40.21, -46.13, and -46.67 kJ mol^-1), and the chromism mode (hypo-character) were employed for H₂dpq, Codpq, and Co(dpq)₂ to assess the interactive modes, respectively. Rewardingly, the monometallic-chelates Co(II)-complexes displayed modified binding action more than that of H₂dpq against ct-DNA.