Synthesis, characterization and theoretical determination of corrosion inhibitor activities of some new 4,5-dihydro-1H-1,2,4-Triazol-5-one derivatives

Nine novel {bis-4-[(3-alkyl-5-oxo-1H-1,2,4-triazol-4(5H)-yl)-iminomethyl]-phenyl} [1,1′-biphenyl]-4,4′-disulfonates were synthesized and their structures were determined with spectral methods. Corrosion inhibitor activities of the title compounds were investigated using quantum mechanical methods. The parameters such as the Energy of the Highest Occupied Molecular Orbital (E(HOMO)), Energy of the Lowest Unoccupied Molecular Orbital (E(LUMO)), energy gap (ΔE = E(LUMO) - E(HOMO)) and dipole moment (μ) which are related to the corrosion effectivity of the organic compounds whose the molecular geometry and electronic properties are especially studied, were determined by using the density function theory method. Using these calculation results, properties such as hardness (ɳ), softness (σ), electronegativity (χ) values were calculated. Also quantum chemical parameters such as the fraction of transferred electrons (ΔN) between the iron surface and the 4,5-dihydro-1H-1,2,4-triazole-5-one derivative compounds were calculated. It has been discussed that which parameters have a good linear relationship with inhibition efficiency. The results of the calculations show that there is a close relationship between the activity of organic-based corrosion inhibitors showing good corrosion inhibitor activity and the calculated quantum chemical parameters of the process. Thus, corrosion inhibitor activity can be predicted without conducting an experimental study.