Molecular structure and electronic characteristics study of imidazole and dioxol derivatives as corrosion inhibitors : a quantum methodology investigation

Abstract EN

The quantum chemical calculations were performed for four organic molecules differ in the number and type of hetero atoms namely1,2-di(1H-benzo[d]imidazol-2-yl)ethane(DBIE); 1,2- di(benzo[d][1,3]dithiol-2-yl)ethane(DBTE);1,2-di(benzo[d][1,3]dioxol-2-yl)ethane(DBOE);and(E)- Nꞌ-(benzo[d][1,3]dioxol-2-ylmethyl)-N-(benzo[d][1,3]dithiol-2-yl) formimidamide (BDBF).

Their efficiency as inhibitors for iron corrosion were evaluated in two phases, the first is a studying of molecular structure effect and its physic-chemical properties which included the molar refractivity, lipophilicity coefficient(logP),molecular electrostatic potential(MEP), molecular volume, molecule surface area and molecular polarizability(pol).

Either second phase comprised studying electronic characteristics of molecules such as energy of the highest occupied molecular orbital EHOMO, the energy of the lowest unoccupied molecular orbital ELUMO, ∆EBack−donation , dipole moment (μ), ∆Egap, global softness (σ), global hardness(η), number of transferred electrons(ΔN), global electrophilicity(ω), chemical potential (?), electronegativity (x), ionization potential(E), electron affinity(A), the energy each of electronic, hydration, total, solvation, potential, kinetic, binding and adsorption energy.

The local reactive was studied through Fukui functions where appropriate sites for electrophilic and nucleophilic attacks have been identify and are necessary for adsorption processes on iron surface.

Electronic characteristics of the molecules depends orbital analysis of HOMO and LUMO.

Where it was noted there is satisfactory agreement on that these characteristics clearly affect on inhibition process.

Finally, it was noted that molecules efficiency increases as the following: DBOE˂DBIE˂BDBF˂ DBTE .