Synthesis, Antioxidant Activity, and Determination of Binding Parameters of Meso-Tetra-4-Actophenyl-Porphyrin and its Palladium (II) Complex with Superoxide Anion Radicals

Abstract

: 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.

Experimental and theoretical study on corrosion inhibition of mild steel by meso-tetraphenyl-porphyrin derivatives in acid solution

“…The synthesis of meso-tetraphenyl-porphyrin derivatives (TPPH2, TPPH2(p-Me), and TAcPPH2) used in this work as potential inhibitors of corrosion of XC52 mild steel in aqueous sulfuric acid solution, was performed following our previously reported procedure [10]. Molecular structures of three synthesized porphyrin derivatives are shown in Figure 1.…”

“…In order to obtain more information about the frontier molecular orbitals and consequent inhibitory action of the investigated compounds, theoretical study based on molecular orbital analysis was performed. The EHOMO and ELUMO of the investigated compounds were obtained using density functional theory (DFT) without imposing any symmetry constraints, and calculations were realized with the Gaussian 09 package [10]. The exchange functional of Becke and the correlation functional of Lee, Yang and Parr (B3LYP) were employed with 6-311++G(d,p) basis sets.…”

“…The presence of four nitrogen atoms in their skeletons qualifies them to be potential corrosion inhibitors. Additionally, the fully aromatic character of meso-tetraphenyl-porphyrin derivatives facilitates the mobility of electrons in the rings, which makes possible their application in many fields such as electrochemistry and catalysis [9], photomedicine [10] and photosynthesis [11].…”

Solvent extraction effects on phytochemical profiles, antioxidant activities and superoxide anion radical interactions of whole fruit, pulp and skin of Cucurbita pepo L.

“…Tetrabutylammonium tetrafluoroborate (Bu4NBF4) was used as supporting electrolyte and its concentration was kept 0.1 M. Superoxide anion radical was generated in DMF, the scan rate was kept at 100 mV/s, and potential window was from −1.6 to 0.0 V, the extract solutions were added incrementally to the in situ generated radical. The ability of the test sample to quench (% inhibition of ) was calculated using the following equation 3 [16][17][18]:…”

“…) [16][17][18]. It was selected because of its presence in human body it has longer half life and is capable of generating other harmful radicals such as hydroxyl radical [19].…”