Synthesis, characterizations, crystal structure, inhibition effects and theoretical study of novel Schiff base on the corrosion of carbon steel in 1 M HCl

•Synthesis and characterizations of new Schiff base ligand the 2,4- Bis (2‑hydroxy naphthaldehyde) diiminotholuene by 1HNMR, 13CNMR, IR, UV–Vis.•The structure of ligand was determined by X-ray diffraction method.•The system carbone steel/HCl was studied using chemical (weight loss) and electrochemical (impedance spectroscopy and potentiodynamic) measurements.•SEM studies of metal surfaces confirmed the formation of the adsorbed layer of inhibitor.•Theoretical studies using DFT calculations. A novel Schiff base 2, 4- Bis (2‑hydroxy naphthaldehyde) diiminotholuene (L), was prepared and characterized by the analysis techniques: FT-IR, UV-Vis,1H and 13C NMR. X-Ray Diffraction (XRD), showing that the L was crystallized in phenol-imine form. The corrosion inhibition of carbon steel in 1 M hydrochloric acid solutions of ligand L was studied using chemical (weight loss) and electrochemical (potentiodynamic and electrochemical impedance spectroscopy (EIS)) measurements, these measurements show that the inhibition efficiency obtained by this compound increased by increasing the concentration of L. The polarization studies show that this L acts as mixed type inhibitor. This inhibitor functions through adsorption following Langmuir isotherm. The UV–Vis absorption spectroscopy was used to investigate the forming of complex between inhibitor L and Fe. The scanning electron microscopy (SEM) studies the metal surfaces confirming the formation of the adsorbed layer of inhibitor, which slows down the corrosion process in the corrosive solution. The Density functional theory (DFT) and Simulations of the Molecular Dynamics (SMD) were used to determine the relationship between quantum chemical parameters and their inhibition efficiencies, and the correlation between theoretical and experimental results was discussed. [Display omitted]