Integrated Density Functional Theory and QSAR Modelling of Selected Imidazole Derivatives for Corrosion Inhibition of Mild Steel in Acidic Medium
Jegede Alexander
Department of Chemistry, Faculty of Science, Federal University Lokoja, Kogi State, Nigeria.
Tenimu Adogah Abubakar
Department of Chemistry, Faculty of Science, Federal University Lokoja, Kogi State, Nigeria.
Semire Banjo *
Department of Chemistry, Faculty of Science, Federal University Lokoja, Kogi State, Nigeria and Computational Chemistry Research Group, Department of Pure and Applied Chemistry, Ladoke Akintola University of Technology, PMB 4000, Ogbomoso, Oyo State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Organic nitrogen-containing heterocycles can inhibit corrosion through their interactions with metal surfaces, but computational descriptors alone do not establish the performance of proposed inhibitors.
Aim: This study integrated density functional theory (DFT) and quantitative structure–activity relationship (QSAR) modelling to examine the corrosion-inhibition behaviour of selected imidazole derivatives for mild steel in an acidic medium.
Methods: A literature-derived dataset of 21 compounds was assembled. Molecular geometries and electronic descriptors were calculated using Spartan at the B3LYP/6-31G** level in an aqueous computational environment. Molecular descriptors generated using PaDEL were screened through a genetic-algorithm procedure, and a three-descriptor multiple linear regression model was developed using AATSC0p, TDB10s and E1m. Seventeen compounds were used for model development and four for external validation.
Results: Compound 11 had the highest reported inhibition efficiency (98.5%), a HOMO–LUMO energy gap of 3.70 eV and a softness of 0.54 eV⁻¹. The QSAR model yielded R² = 0.9161, adjusted R² = 0.8968, Q²LOO = 0.8685, Q²F1 = 0.8199, Q²F2 = 0.8195 and a concordance correlation coefficient of 0.8803. Compound 17 was identified as a response outlier. Four analogues of compound 15 were proposed and assessed computationally within the stated applicability domain.
Conclusion: This combined approach offers a framework for molecular prioritisation, but predictions for the designed analogues require numerical reconciliation, followed by experimental assessment.
Keywords: Corrosion inhibition, imidazole derivatives, DFT, QSAR, mild steel, molecular design