Theoretical investigastion of the relation between quantum chemical parameters and corrosion inhibition of some schiff base compounds

In this thesis, the electronic and molecular structure of some Schiff base inhibitors were investigated theoretically by using Density Functional Theory (DFT). In this study, 7 Schiff bases, which were investigated experimentally, were used, and they were divided into 2 groups according to their molecular weight and structure. While there are 5 low molecular weight Schiff bases in the first group, there are 2 high molecular weight Schiff bases in the second group. The corrosion efficiency and molecular orbitals (MO) of the inhibitors were investigated using the 6-31G(d,p) base set with the DFT/B3LYP method. Quantum chemical properties such as the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies of the compounds, dipole moment (μ), ionization energy (I), electron affinity (A), electronegativity (Ӽ), hardness (η), softness (σ), ΔEBackdonation, transferred electron fraction (ΔN), electrophilic index (ꞷ) were investigated. In addition, the inhibition efficiency of the compounds was evaluated as a result of Mulliken Population Analysis. As a result of these studies, it was determined that the SB4 molecule had the best inhibitory potential among the first group inhibitors, and the DF1 molecule had the best inhibitory potential among the second group inhibitors. It has been found that especially protonated molecules show a better potential for inhibition efficiency. In addition, when the results were compared according to the molecular structure, it was concluded that the DF1 inhibitor with the larger molecular weight was the best potential as a inhibitor.