DFT and QSAR study of corrosion inhibition on 3,5-di-substituted pyrazole derivatives with heteroatom on position one

Abstract

MTHT) were investigated at density functional theory (DFT) B3LYP/6-31G** (d,p) level. The calculated molecular descriptors such as the HOMO, LUMO, the dipole moment, chemical potential (μ), chemical hardness (ղ), softness (s), global nucleophilicity (N) and average Mulliken charges on nitrogen atoms are discussed in relation to the observed inhibitory efficiency for the compounds. The developed qualitative structural activity relationship (QSAR) models relate the calculated molecular descriptors to the corrosion efficiency; thus QSAR model predicted the experimental corrosion efficiencies. The possible sites for nucleophilic and electrophilic attacks on the compounds were analyzed through the Fukui functions.

A New Insight into Non‐Steroidal Anti‐Inflammatory Drugs (NSAIDs) as Modulated Green Inhibitory Agent on Mild Steel Corrosion

“…While few studies have shown that low μ value do favour the adsorption of inhibitor molecules on the MS surface, thus increasing the inhibition effectiveness. Hitherto others have proposed an opposite correlation where high μ value enhances the NSAIDs adsorption on the MS surface, which in turns favor higher %IE …”

“…ΔE (energy gap) between the LUMO and HOMO energy levels determine %IE. [15,[36][37][38][39] Studies have shown that the lower ΔE values indicate higher inhibitory effectiveness because the excitation energy gap is more favorable and is associated with chemical reactivity. [40] In our case, Aspirin has least ΔE value and highest E HOMO value thereby indicating it to exhibit greater inhibition efficiency which pronouns to be in good agreement with the experimental results ( Figure 12).…”

“…Hitherto others have proposed an opposite correlation where high μ value enhances the NSAIDs adsorption on the MS surface, which in turns favor higher %IE. [36] In addition to this, 3D-molecular electrostatic potential (MEP) descriptor show the Mulliken charges of corresponding atoms which predict the involved electrophilic and nucleophilic sites of the inhibitors considering the electron charge density distribution around oxygen, nitrogen, chlorine and neighboring carbon atoms. [41,42] Here 3D-MEP in red for more negative potential (nucleophilic centers) and in blue for more positive potential (electrophilic sites).…”

“…Thus, the NSAIDs adsorption on the MS surface is attributed to the interaction between 3 d , and 4 s orbitals of Fe atom with the front molecular orbitals of the inhibitor. ΔE (energy gap) between the LUMO and HOMO energy levels determine %IE ,. Studies have shown that the lower ΔE values indicate higher inhibitory effectiveness because the excitation energy gap is more favorable and is associated with chemical reactivity .…”

Theoretical Evaluation of the Corrosion Inhibition Performance of an Organic Heterocyclic Compound

“…The optimized molecular structures of TZ CDI are shown in Figure 3. In general, the inhibition efficiency of an inhibitor is associated with its electronic structure [32], especially some calculated quantum chemical descriptors such as the E HOMO , the E LUMO , the ∆E gap , η, χ, and Fukui function. Table 3 shows the obtained values of these parameters for the studied inhibitor.…”