DNA Binding and Electrochemical Characterization of Oxidative Products of the Cobalt(II) Complex

The synthesis of meso-tetrakis(3,4,5-trimethoxyphenyl)porphyrin [H₂T(3,4,5-OCH₃)PP] and cobalt(II) meso-tetrakis(3,4,5-trimethoxyphenyl)porphyrin [Co(T(3,4,5-OCH₃)PP)] has been successfully accomplished. The oxidation properties of [Co(T(3,4,5-OCH₃)PP)] have been assessed through UV-vis, NMR, and EPR techniques. It can be seen in the UV-vis spectrum that adding SbCl₅ caused extra peaks to appear at 674 nm, which means that a π-cation radical was formed. The voltammogram shows how the ligand system helps the Co(II) electrochemical oxidation process to become Co(III). As shown by the EPR spectrum, the cobalt(II) changes its oxidation state to Co(III) due to the introduction of SbCl₅. NMR data can also support this conclusion. The interaction of DNA with [Co(T(3,4,5-OCH₃)PP)] has been evaluated. The decrease in current and the favorable alteration in the E_1/2 value highlight the substantial intercalative interaction between DNA and [Co(T(3,4,5-OCH₃)PP)]. Hirshfeld surface analysis has been performed to recognize the many intermolecular interactions. In vitro cytotoxicity activity results suggest that the incorporation of a metal center enhances cytotoxic activity, as the metalloporphyrin derivative consistently showed greater potency than that of the corresponding free-base porphyrin. This enhancement may be attributed to the intrinsic π-conjugated structure of the porphyrin framework, which facilitates cellular uptake and interactions with biological targets.