Theoretical Studies on the Copper Corrosion Inhibition by Vitamins B1, B2 and B6 in 1 M HNO3 Using DFT and QSPR Methods

The study of the inhibition properties of Thiamine Hydrochloride (THC), Riboflavin (RF) and Pyridoxine Hydrochloride (PHC) as copper corrosion inhibitor in nitric acid solution has been carried out by Density Functional Theory (DFT) and Quantitative Structure Property Relationships (QSPR) methods. DFT calculations showed that there is a correlation between inhibition efficiencies and quantum chemical parameters such as EHOMO (Highest Occupied Molecular Orbital Energy), ELUMO (Lowest Unoccupied Molecular Orbital Energy), energy gap (ΔE), dipole moment (μ), electronegativity (Χ), hardness (η), softness (S), electrophylicity index (ω), electron affinity (A), ionization energy (I) and the fraction of electron transferred (ΔN). The Quantitative Structure Property Relationships (QSPR) approach has been used to determine the relationship between molecular structure and the compounds inhibition efficiencies. In addition, UV visible was used to show the adsorptive nature of the compounds studied. It was found that theoretical results and experimental data agree.