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Meso-tetra-4-actophenyl-porphyrin (TAcPPH2) was synthesised by reacting 4-acetyl-benzaldehyde with pyrrole in proprionic acid, and used as ligand for the synthesis of palladium (II) complex (PdTAcPP). The structure of the ligand and the complex was characterized by NMR and electronic spectroscopy. The antioxidant activity and the binding parameters of both the ligand and its complex with superoxide anion radical were measured using cyclic voltammetry based assay. The assays were based on the measurement of the anodic peak current density of electrochemically generated by reduction of molecular oxygen in DMF. The complex PdTAcPP shows highest antioxidant activity (0.73 ± 0.01 mg/mL) which is four times higher than that of standard antioxidant α-tocopherol (3.04 ± 0.03 mg/mL). Binding parameters like binding constants, ratio of binding constants and binding free energies were also measured. The value of the binding free energy ranging from -7.89 KJ.mol-1 for TAcPPH2 to -17.59 KJ.mol-1 for PdTAcPP suggests an electrostatic interaction of with TAcPPH2 and PdTAcPP which has been found to be the dominant interaction mode. The kinetics of the interaction reaction of the ligand and complex was quantitated having second-order rate constant values equal to 0.2 and 1.3 M-1 s-1 respectively.
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