Experimental and Theoretical Studies of New Schiff Base as a Corrosion Inhibitor in Acidic Media and Study Antioxidant Activity

In the present study, the Schiff base was synthesized [1,1'-((1E,1'E)-((4,5-dimethyl-1,2-phenylene)bis(azanylylidene))bis(methanylylidene))bis(naphthalen-2-ol) ] derived from the reaction of 2-hydroxy-1-naphtha-aldehyde with, 4,5-Dimetyl-1,2-penylenediamine for 4hr. and yield was 90.09%. The prepared compound was identified by C.H.N, UV-Vis, FT-IR 1H–NMR, and mass spectroscopy and was studied also theoretically using Gaussian 09 software based on the DFT method at B3LYP/6-31G (d,p). Quantum chemical calculations were performed to provide further insight into the inhibition efficiencies that were conducted experimentally. The weight loss method was used to measure the efficiency of the prepared compound as a corrosion inhibitor in an acid medium. It was found that the inhibition efficiency was increased with decreasing temperature and the concentration increase of synthesized Schiff base and the highest inhibition efficiency was obtained at an optimum concentration of (1×10-3 M) for inhibitor at 298 K. Moreover, it was found that the adsorption process of the inhibitor on the surface of the brass is obeyed by the Langmuir isotherm of adsorption. The value of the free energy change was found to be -28.28 kJ/mol, which indicates that the prepared compound adsorbed on the surface of the metal. The antioxidant activity of the prepared Schiff base was investigated on the basis of the radical scavenging effect of 1,1-diphenyl-2-picryl-hydrazyl (DPPH)-free radical activity was also studied. The ligand (S1) exhibited excellent activity.