Ab Initio Study on Electronic Structure of Some Imidazole Derivatives and Its Correlation with Corrosion Inhibition Properties

Imidazole and some of its derivatives have been known as a good candidate for corrosion inhibition application. In this study, ab initio calculation was carried out for several imidazole derivatives i.e. 2-phenylimidazole[1,2-α]pyridine, 6-methyl-2-phenylimidazole[1,2-α]pyridine, 6-methyl-2-(4-metoxyplenylimidazole)[1,2-α]pyridine, and 6-methyl-2-(4-chlorophenylimidazole)[1,2α]pyridine, in order to investigate their electronic properties as well as its correlation with their corrosion inhibition properties. Calculations were performed using Firefly software package with RHF method and 6-31G(d,p) basis set. Based on calculation results and analysis, it was found that 6-methyl-2-(4-metoxyphenylimidazole) [1,2α]pyridine compound has better potential as corrosion inhibitor than the rest of the compounds due to its small HOMO-LUMO energy gap, low ionization potential, low electron affinity, low electronegativity, and low global hardness i.e. 10.184 eV, 7.199 eV, -2.985 eV, 2.107 eV and 5.092 eV respectively. This compound also has the highest global softness (0.098 eV), while the greatest value of the dipole moment was owned by 6-methyl-2-(4-chlorophenylimidazole)[1,2α]pyridine with value of 6.125 Debye due to the existence of Cl atom that has larger polarity than the other substituents.