Benzotrithiophene Derivative as a Corrosion Inhibitor: Insights from Density Functional Theory and Monte Carlo Simulation Studies

Abstract

This study presents a comprehensive theoretical investigation into the corrosion inhibition efficiency of benzo[1,2-b:3,4-b':5,6 b'']trithiophene (BTH) on iron surfaces using density functional theory (DFT) and Monte Carlo (MC) simulations. The molecular geometry, electronic structure, and reactivity descriptors of BTH were explored in both gas and solvent environments (DMSO, H2O, ethanol) at the wB97XD/6-311++G(2d,2p) level of theory. Geometry optimization and vibrational frequency analyses indicated that BTH maintains a stable molecular structure regardless of the solvent. Natural Bond Orbital (NBO) analysis revealed significant donor–acceptor interactions, especially in polar solvents, suggesting enhanced electron delocalization and stabilization. Molecular electrostatic potential (MESP) maps and electrophilicity indices confirmed BTH's increased electron-accepting capacity in polar media. Quantum chemical descriptors such as HOMO-LUMO gap, ionization potential, and softness affirmed BTH's suitability as an efficient electron donor and moderate electrophile. Monte Carlo simulations of BTH adsorption on the Fe(110) surface showed strong and stable interactions in both gas (adsorption energy = –121.88 kcal/mol) and solution phases (adsorption energy = –2819.34 kcal/mol), with stronger binding and larger deformation in the solvated environment. These findings confirm that BTH exhibits significant promise as a corrosion inhibitor in both dry and acidic media.