Investigation of the corrosion inhibition potentials of some 2-(4-(substituted) arylidene)-1H-indene-1,3-dione derivatives: density functional theory and molecular dynamics simulation

Background: Corrosion is a threat to material strength and durability. Electron-rich organic inhibitor may offer good corrosion mitigation potentials. In this work, anti-corrosion potentials of nine derivatives of 1H-indene-1,3-dione have been investigated using density functional theory (DFT) approach and molecular dynamics (MD) simulation. Chemical reactivity descriptors like energies of lowest unoccupied molecular orbital (E-LUMO), highest occupied molecular orbital (E-HOMO), electron affinity (A), ionization potential (I), energy gap (Delta E-gap), global hardness (eta), global softness (sigma), electronegativity (X), electrophilicity (omega), number of transferred electrons (Delta N) and back-donation (Delta Eback-donation) were computed at DFT/B3LYP/6-31G(d) theoretical level. The local reactive sites and the charge partitioning on the compounds were studied using Fukui indices and molecular electrostatic potential (MEP) surface analysis. The adsorption behavior and the binding energy of the inhibitors on Fe (110) surface in hydrochloric acid solution were investigated using MD simulation. Results: The high chemical reactivity, kinetic instability and good corrosion inhibition potentials demonstrated by the inhibitors are rationalized based on their high E-HOMO, A, sigma, Delta N, Delta Eback-donation and low Delta E-gap, E-LUMO, l and eta. A wide difference of approximately 2.4-3.2 eV between the electronegativities of iron and the 1H-inden-1,3-diones suggests good charge transfer tendency from the latter to the low-lying vacant d-orbitals of iron. The heteroatoms (O and N) and the aromatic moieties are the nucleophilic sites on the inhibitors for effective adsorption on the metal surface as shown by condensed Fukui dual functions and MEP analysis. The MD simulation shows good interaction and strong binding energy between the inhibitor and Fe (110) surface. Conclusions: Effective surface coverage and displacement of H3O+, Cl- and water molecules from Fe (110) surface by the inhibitors indicate good corrosion inhibition properties of the inden-1,3-diones. 2((4,7-dimethylnaphthalen-1-yl)methylene)-1H-indene-1,3(2H)-dione display low energy gap, strongest binding interaction and most stabilized iron-inhibitor configuration, hence, the best anti-corrosion potential.