scholarly journals Quantum Chemical Analysis of the Corrosion Inhibition Potential by Aliphatic Amines

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6197
Author(s):  
Szymon Malinowski ◽  
Michał Wróbel ◽  
Agnieszka Woszuk
Keyword(s):  
Molecular Orbital ◽  
Corrosion Inhibition ◽  
Quantum Chemical ◽  
Electrostatic Interactions ◽  
Inhibition Efficiency ◽  
Energy Gap ◽  
Aliphatic Amines ◽  
Chemical Structures ◽  
Protonation Reaction ◽  
Corrosion Inhibition Efficiency

Destructive corrosion processes lead to the loss of primary mechanical properties of metal construction materials, which generates additional costs during their maintenance connected with repairs and protection. The effectiveness of corrosion inhibitors can be determined by using many methods, in particular quantum chemical modeling. The subject of the theoretical analyses presented in this work involves the anticorrosion properties of amines with various chemical structures. Evaluation of the corrosion inhibition properties of selected amines was performed on the basis of the HOMO–LUMO energy gap, dipole moment (µ), electronegativity (χ) determined as a result of the energy of the highest occupied molecular orbital (HOMO) and the energy of the lowest unoccupied molecular orbital (LUMO). Moreover, the HSAB (Hard and Soft Acids and Bases) theory was used to explain the reactivity of the analyzed amines, while the Mulliken population analysis was used to determine their electrostatic interactions with the surface of protected metal. The obtained results indicate that the protonation reaction of aliphatic amines leads to a change in the nature of the formation of a coordination bond with the surface of the protected metal. In turn, the quantum chemical calculations showed that the protonation reaction of aliphatic amines leads to a decrease in their corrosion inhibition efficiency. Most of the analyzed parameters indicated that tertiary amines are characterized by the highest corrosion inhibition efficiency.

scholarly journals Quantum Chemical Study on the Corrosion Inhibition of Some Oxadiazoles

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Hong Ju ◽  
Li Ding ◽  
Can Sun ◽  
Jie-jing Chen
Keyword(s):  
Mild Steel ◽  
Molecular Orbital ◽  
Quantum Chemical ◽  
Inhibition Efficiency ◽  
Energy Gap ◽  
Structural Parameters ◽  
Quantum Chemical Study ◽  
Dft Method ◽  
Frontier Molecular Orbital ◽  
Acid Media

Quantum chemical calculations based on DFT method were performed on three nitrogen-bearing heterocyclic compounds used as corrosion inhibitors for the mild steel in acid media to determine the relationship between the molecular structure of inhibitors and inhibition efficiency. The structural parameters, such as energy and distribution of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), the charge distribution of the studied inhibitors, the absolute electronegativity (χ) values, and the fraction of electrons (ΔN) transfer from inhibitors to mild steel were also calculated and correlated with inhibition efficiencies. The results showed that the inhibition efficiency of inhibitors increased with the increase in energy of HOMO and decrease in energy gap of frontier molecular orbital, and the areas containing N and O atoms are most possible sites for bonding the steel surface by donating electrons to the mild steel.

scholarly journals DFT, Monte Carlo and molecular dynamics simulations for the prediction of corrosion inhibition efficiency of novel pyrazolylnucleosides on Cu(111) surface in acidic media

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rachid Oukhrib ◽  
Youness Abdellaoui ◽  
Avni Berisha ◽  
Hicham Abou Oualid ◽  
Jeton Halili ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo ◽  
Molecular Dynamics Simulations ◽  
Corrosion Inhibition ◽  
Inhibition Efficiency ◽  
Energy Gap ◽  
Chemical Hardness ◽  
Acidic Media ◽  
Corrosion Inhibition Efficiency ◽  
Dynamics Simulations

AbstractFive novel pyrazolylnucleosides have been evaluated theoretically for their corrosion inhibition efficiency on the Cu(111) surface in acidic media. DFT calculations were carried out to exhibit the intrinsic properties such as lowest unoccupied (ELUMO) and highest occupied (EHOMO) molecular orbital energies, as well as energy gap (∆E), chemical hardness (η), chemical softness (σ), electronegativity (χ), electrophilicity (ω) and nucleophilicity (ε). The theoretical FT-IR spectra were recorded to indicate the presence of the specific bonds in the studied molecules. The surface interactions between the inhibitor molecules and the metal surface were investigated using molecular dynamics simulations and Monte Carlo (MC) simulations. As a result, we have found that the inhibitor pyrazolylnucleosides 5a–e have strong interactions with Cu(111) surface, and therefore have excellent predictive inhibition power against copper corrosion.

scholarly journals Computational Methods and Molecular Modelling for Some Predicted Tautomers of Pyrimidine compounds

2021 ◽  
Vol 01 ◽  
Author(s):  
Mamdouh S. Masoud ◽  
Marwa Y. Abd El-Kaway
Keyword(s):  
Molecular Orbital ◽  
Molecular Modelling ◽  
Quantum Chemical ◽  
Chemical Potential ◽  
Energy Gap ◽  
Thiobarbituric Acid ◽  
Orbital Energy ◽  
Chemical Structures ◽  
Molecular Orbital Energy ◽  
Modelling Techniques

Introduction: Several molecular modelling techniques and quantum chemical methods have been performed to correlate the chemical structures of the compounds with their physical molecular properties. Methods: Using theoretical parameters help to characterize the molecular structure of the investigated ligands and to study their equlibria mechanism. Molecular modelling data such as the bond length, bond order, bond angles and dihedral angles values were estimated for some pyrimidine compounds, where the data suggested the presence of tautomerism and a dynamic equilibria are deduced between all the detected tautomers in the solid state. Results: Four main tautomers are predicted for barbital and thiobarbituric acid while three tautomers are for thiouracil. Quantum chemical parameters such as the highest occupied molecular orbital energy (EHOMO), the lowest unoccupied molecular orbital energy (ELUMO), energy gap (ΔE), dipole moment (µ ), sum of the total negative charge (STNC), electronegativity (Χ), chemical potential (Pi), global hardness (η) and softness (σ ) were calculated.

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