Synthesis, characterization and theoretical exploration of pyrene based Schiff base molecules as corrosion inhibitor

Abstract Synthesis of highly efficient organic molecules to be used for corrosion inhibition is the prime importance to minimize the degradation of metal substrates from the corrosive solutions. In this regards, the theoretical exploration of the corrosion inhibitor before its application is very important. Herein, pyrene based two novel Schiff bases, viz., 4-((pyren-3-yl)methyleneamino)phenol (PMP) and 2-(2,4-dinitrophenyl)-1-((pyren-3-yl)methylene)hydrazine (DPH) were synthesized and characterized. The incorporation of pyrene unit (fused aromatic rings) and contribution of hydroxyl or nitro functional groups in the Schiff base skeleton might make these molecules work as efficient corrosion inhibitors. The atomic-level insight of the electronic properties, the presence of local reactive sites and the adsorption behaviours of these molecules were investigated meticulously. Subsequently, it's probable use as corrosion inhibiting molecule was predicted based on computational outcomes obtained from density functional theory (DFT), Fukui indices (FIs) analysis and molecular dynamics (MD) simulation approaches, simultaneously. The optimization of the geometries of molecules, analysis of electron density distribution within frontier molecular orbitals obtained from DFT outcomes; and FIs analysis of each atom of these synthesized molecules were carried out to investigate the plausible mode of interactions of these designed molecules with metal's atoms. Furthermore, the crystal morphology study was performed using “Morphology” module in Material Studio software to explore the growth characteristics as well as to find out the exceptionally stable surface present in α-Fe crystal. In doing so, the Wulff construction plot was used to analyse α-Fe crystal morphology. Afterwards, the MD simulation technique was employed to envisage interaction spontaneity and adsorption of the synthesized molecules with equilibrium configuration onto the metal surface atoms imitating the actual corrosion inhibiting processes that occurs in actual corrosive environments.