The adsorption and corrosion inhibition properties of two imidazole derivatives namely, 2-(4-chlorophenyl)-1,4,5-triphenyl-1H-imidazole (IM-Cl) and 1,4,5-triphenyl-2-(p-tolyl)-1H-imidazole (IM-CH3) for mild steel in 0.5 M H2SO4 solution are studiedby electrochemical and computational calculations. The results obtained from the electrochemical methods show that IM-Cl and IM-CH3imparted high resistance and behave as mixed type inhibitors. Inhibition efficiency (IE %) increases with the increase of inhibitors concentration to attain 96 % and 91% at 10-3 M of IM-Cl and IM-CH3 respectively. EISdatais analyzed to model the inhibition process through appropriate equivalent circuit model. Thermodynamic and kinetic parameters controlling the adsorption process are calculated and discussed. DFT calculations are carried out at the B3LYP levels of theory with 6-31G (d,p) basis stein gas and aqueous phase for neutral and protonated forms. Quantum chemical calculations section of the study provides enough calculation and discussion on the relationship between corrosion inhibition and global reactivity descriptors.

Corrosion inhibition studies of carbon steel (CS) in 1 M HCl by newly synthesized bichalcophene compounds namely; 4-(2,2′-bifuran-5-yl)benzamidine (MA-0947) and 6-(2,2′-bifuran-5-yl)nicotinamidine (MA-0941) and 6-[5-(thiophen-2-yl)furan-2-yl]nicotinamidine (MA-0940) have been conducted using chemical and electrochemical methods. MA-0940 exhibited the highest inhibition efficiency % η = 95% at 18 × 10⁻⁶ M. The adsorption and thermodynamic activation parameters were calculated and discussed. Potentiodynamic polarization (PP) studies showed that the investigated compounds act as mixed-type inhibitors and chemically adsorbed on CS surface following the Langmuir adsorption isotherm. The surface morphology was analyzed using Atomic Force Microscopy (AFM). The effect of molecular structure on the inhibition efficiency has been explored by quantum chemical computations. The relation between the inhibition efficiency and some quantum parameters has been discussed and obvious correlations were observed. The binding energies of tested bichalcophene derivatives on Fe (110) surfaces were calculated using molecular dynamics simulation. The adsorption energies between metal surface and investigated bichalcophenes followed the order: MA-0940 > MA-0941 > MA-0947 and this order is in good agreement with the experimental data.