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.

Quantum chemical studies on some new bipyrazole derivatives as corrosion inhibitors for steel materials

2016 ◽  
Vol 63 (3) ◽  
pp. 231-235
Author(s):  
Hong Ju ◽  
Jiejing Chen ◽  
Can Sun ◽  
Yan Li
Keyword(s):  
Molecular Orbital ◽  
Quantum Chemical ◽  
Corrosion Inhibitors ◽  
Inhibition Efficiency ◽  
Molecular Design ◽  
Dft Method ◽  
Acid Media ◽  
Content Type ◽  
Electronic Parameters ◽  
Distribution Energy

Purpose The purpose of this study is to perform quantum chemical calculations based on the DFT method on four bipyrazoles used as corrosion inhibitors for the plain carbon (“mild”) steel in acid media to determine the relationship between inhibition efficiency and the molecular structure of inhibitors. Design/methodology/approach Several quantum chemical parameters, such as the charge distribution, energy and distribution of highest occupied molecular orbital and lowest unoccupied molecular orbital, the absolute electronegativity (χ) values and the fraction of electrons (△N) transferring from inhibitors to the steel surface, were calculated and correlated with inhibition efficiencies. Findings The results showed that the inhibition efficiency of bipyrazole increased with the increasing in EHOMO, and the areas containing N atoms were the most probable sites to donate electrons for adsorbing the inhibitor molecules onto the metal surface. Originality/value It is a useful method to investigate the mechanisms of reaction by calculating the structure and electronic parameters, which can be obtained by means of theoretical quantum theory. Thus, the behavior and mechanism of the organic inhibitors can be obtained. Quantum chemical method can also be used to guide the selection and molecular design of inhibitors.

Quantum Chemical and Electrochemical Studies on the Inhibitive Effect of Carboxymenthylchitosan for Mild Steel in Different PHs

2008 ◽  
Vol 47-50 ◽  
pp. 205-208
Author(s):  
Shou Gang Chen ◽  
Sha Cheng ◽  
Kin Tak Lau ◽  
Yan Sheng Yin
Keyword(s):  
Mild Steel ◽  
Quantum Chemical ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Dft Method ◽  
Atomic Charges ◽  
Chemical Calculation ◽  
Electrochemical Studies ◽  
Acid Media ◽  
Hcl Solution

The influence of carboxymenthylchitosan(CM-chitosan) on the corrosion of mild steel in different pHs was studied by the quantum chemical calculation and electrochemical measurements. Mulliken atomic charges and LUMO energies calculated by DFT method for CM-chitosan and protonated CM-chitosan show that the protonated CM-chitosan adsorbs easier on the surface of mild steel. The expeimental results of polarization curves and electrochemical impedance spectroscopy (EIS) also indicate that the acid media has the best inhibition efficiency for CM-chitosan. Furthermore, the inhibitive effect of CM-chitosan for mild steel in 1 M HCl solution was studied by weight loss measurements, and the inhibition efficiency increases with the concentration of CM-chitosan to attain 93 % at 200mg/l.

scholarly journals Insights into Corrosion Inhibition Behavior of a 5-Mercapto-1, 2, 4-Triazole Derivative for Mild Steel in Hydrochloric Acid Solution: Experimental and DFT Studies

Lubricants ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 122
Author(s):  
Israa Abd Alkadir Aziz ◽  
Iman Adnan Annon ◽  
Makarim H. Abdulkareem ◽  
Mahdi M. Hanoon ◽  
Mohammed H. Alkaabi ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Acid Solution ◽  
Mild Steel ◽  
Molecular Orbital ◽  
Corrosion Protection ◽  
Hydrochloric Acid Solution ◽  
Steel Surface ◽  
Energy Gap ◽  
Frontier Molecular Orbital ◽  
Mild Steel Surface

A triazole heterocyclic compound namely 3-(4-ethyl-5-mercapto-1, 2, 4-triazol-3-yl)-1-phenylpropanone (EMTP) was examined for its corrosion protection of mild steel (MS) against 1 M hydrochloric acid medium using gravimetric techniques. EMTP exhibited excellent corrosion protection performance at low and high concentrations towards MS in HCl solution. Comparison of corrosion protection performance of EMTP and its parent triazole and temperature effects of on inhibition efficacy were also studied. EMTP has potential corrosion inhibitor for mild steel in 1.0 M hydrochloric acid solution with the highest protection efficacy of 97% at 303 K. The weight loss findings implied that EMTP protects the metal surface corrosion through the creation of a protective layer at the surface mild steel–corrosive solution interface. The inhibitive efficacy increases with the increase of inhibitor concentration and decreases with increased temperature. The adsorption of EMTP on the surface of MS follows Langmuir’s adsorption isotherm process. DFT method was conducted on EMTP molecule to calculate the quantum chemical parameters and to determine the relationship between the molecular structure of EMTP and protection performance. The molecular parameters, such as energy gap and frontier molecular orbital (highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO)), and the absolute electronegativity (χ) value from inhibitor molecules to unoccupied d-orbital of iron atoms on the mild steel surface were also determined and correlated with protection efficiency. The theoretical findings revealed that the protection performance of EMTP increased with the increase in HOMO energy, and the nitrogen, oxygen and sulfur atoms are most probable positions for bonding through giving electrons to the d-orbital of iron atoms on the mild steel surface.

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 Insight into Anticorrosion Mechanism of Ampicillin on Mild Steel in Acidic Environment: A Combined Experimental and Theoretical Approach

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Tuan Dinh ◽  
Nguyen Minh Thong ◽  
Dinh Quy Huong ◽  
Trinh Le Huyen ◽  
Tran Duc Manh ◽  
...  
Keyword(s):  
Mild Steel ◽  
Molecular Orbital ◽  
Corrosion Inhibition ◽  
Inhibition Efficiency ◽  
Energy Gap ◽  
Electrochemical Impedance ◽  
Carbon Steels ◽  
Orbital Energy ◽  
Acidic Environment ◽  
Molecular Orbital Energy

The corrosion inhibition of mild carbon steels in an acidic environment by using ampicillin (AMP) has been evaluated based on experimental and quantum chemistry techniques. The experimental results indicate that the inhibition efficiency goes up at higher AMP concentration. The highest inhibition efficiency reaches 84.9% for polarization measurement and 90.1% for electrochemical impedance spectroscopy with the inhibitor of concentration 100 ppm at 298 K. The surface characteristics (SEM) also reconfirm the steel corrosion inhibition ability of AMP. Some important chemical factors such as EHOMO (highest occupied molecular orbital energy), ELUMO (lowest unoccupied molecular orbital energy), ΔEL−H (energy gap), and Fukui functions were calculated based on the optimized configuration of AMP at the theoretical level of B3LYP/6-31+G(d,p). Moreover, Monte Carlo and molecular dynamics simulations were used to analyze the absorption behavior of inhibitor on the surface of Fe(110), which supplies the mechanism of inhibition corrosion processes. The obtained results showed that AMP is considered to be a potential corrosion inhibitor for mild steel in 1M HCl medium. Moreover, the protonated state of AMP plays an important role in the protection of Fe surface against the corrosive process.

Synthesis, spectroscopic investigation, crystal structure analysis, quantum chemical study, biological activity and molecular docking of three isatin derivatives

2021 ◽  
Vol 77 (6) ◽  
Author(s):  
Srinivasan Bargavi ◽  
Siddan Gouthaman ◽  
Madurai Sugunalakshmi ◽  
Srinivasakannan Lakshmi
Keyword(s):  
Molecular Docking ◽  
Molecular Orbital ◽  
Quantum Chemical ◽  
Chemical Potential ◽  
Energy Gap ◽  
Quantum Chemical Study ◽  
Assay Method ◽  
Orbital Energy ◽  
Molecular Orbital Energy ◽  
Isatin Derivatives

Three isatin derivatives, namely, 1-allyl-3-hydroxy-3-(6-oxocyclohex-1-en-1-yl)indolin-2-one, C17H17NO3, 1-ethyl-3-hydroxy-3-(6-oxocyclohex-1-en-1-yl)indolin-2-one, C16H17NO3, and 5-bromo-3-hydroxy-1-methyl-3-(6-oxocyclohex-1-en-1-yl)indolin-2-one, C15H14BrNO3, were synthesized, crystallized by the slow-evaporation technique, characterized by 1H and 13C NMR spectroscopy, and analysed by the single-crystal X-ray diffraction (XRD) method. Quantum chemical parameters, such as the energy of the highest occupied molecular orbital, energy of the lowest unoccupied molecular orbital, energy gap, electronic energy, ionization potential, chemical potential, global hardness, global softness and electrophilicity index, were calculated. The druglikeness and bioactivity scores of the compounds were calculated. The activities of these isatin derivatives against bacterial strains, such as Eschericia coli, Proteus vulgaris, Shigella flexneri, Staphylococcus aureus and Micrococcus luteus, and the fungal strain Aspergillus niger, were determined using the well-diffusion assay method. Molecular docking studies were carried out to predict the binding mode of the isatin compounds with the penicillin binding protein enzyme and to identify the interactions between the enzyme and the ligands under study.

Copper macrocyclic complex with trans-di[benzo]-porphyrazine and two oxo ligands: DFT quantum-chemical design

2021 ◽  
pp. A-F
Author(s):  
Oleg V. Mikhailov ◽  
Denis V. Chachkov
Keyword(s):  
Quantum Chemical ◽  
Structural Parameters ◽  
Dft Method ◽  
Nbo Analysis ◽  
Macrocyclic Complex ◽  
Chemical Calculation ◽  
Entropy Formula ◽  
Energy Formula ◽  
Thermodynamic Parameters Of Formation ◽  
Benzo Derivative

Based on the results of a quantum chemical calculation using the DFT method in the OPBE/TZVP and B3PW91/TZVP, the possibility of the existence of a copper heteroligand complex with trans-di[benzo]derivative of 3,7,11,15-tetraazaporphine (trans-di[benzo]porphyrazine) and two oxygen (O[Formula: see text] ions that is still unknown for this element was shown. In addition, the data on the structural parameters, the multiplicity of the ground state, NBO analysis and standard thermodynamic parameters of formation (standard enthalpy [Formula: see text], entropy [Formula: see text] and Gibbs’s energy [Formula: see text] for this complex are presented.

scholarly journals QTAIM investigation of bis(pyrazol-1-yl)methane derivative and its Zn(II) complexes (ZnLX2, X=Cl, Br or I)

2015 ◽  
Vol 80 (8) ◽  
pp. 997-1008 ◽  
Author(s):  
Maryam Dehestani ◽  
Leila Zeidabadinejad
Keyword(s):  
Molecular Orbital ◽  
Critical Points ◽  
Structural Parameters ◽  
Frontier Molecular Orbital ◽  
Orbital Energy ◽  
Theory Approach ◽  
Topological Parameters ◽  
Molecular Orbital Energy ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Topological analyses of the electron density using the quantum theory of atoms in molecules (QTAIM) have been carried out at the B3PW91/6-31g (d) theoretical level, on bis(pyrazol-1-yl)methanes derivatives 9-(4-(di (1H-pyrazol-1-yl)-methyl)phenyl)-9H-carbazole (L) and its zinc(II) complexes: ZnLCl2 (1), ZnLBr2 (2) and ZnLI2 (3). The topological parameters derived from Bader theory were also analyzed; these are characteristics of Zn-bond critical points and also of ring critical points. The calculated structural parameters are the frontier molecular orbital energies highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), hardness (?), softness (S), the absolute electronegativity (?), the electrophilicity index (?) and the fractions of electrons transferred (?N) from ZnLX2 complexes to L. The numerous correlations and dependencies between energy terms of the Symmetry Adapted Perturbation Theory approach (SAPT), geometrical, topological and energetic parameters were detected and described.

Electrochemical and quantum-chemical study on newly synthesized triazoles as corrosion inhibitors of mild steel in 1 M HCl

2016 ◽  
Vol 43 (5) ◽  
pp. 3145-3162 ◽  
Author(s):  
Ying Yan ◽  
Xiaoxiao Lin ◽  
Lehua Zhang ◽  
Hao Zhou ◽  
Laiming Wu ◽  
...  
Keyword(s):  
Mild Steel ◽  
Quantum Chemical ◽  
Corrosion Inhibitors ◽  
Quantum Chemical Study ◽  
Chemical Study

scholarly journals Corrosion Inhibition of Mild Steel in Acidic Media by N-[(3,4-Dimethoxyphenyl)Methyleneamino]-4-Hydroxy-Benzamide

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Kashmitha Muthamma ◽  
Preethi Kumari ◽  
M. Lavanya ◽  
Suma A. Rao
Keyword(s):  
Dft Calculations ◽  
Mild Steel ◽  
Corrosion Inhibition ◽  
Density Functional ◽  
Surface Characterization ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Low Carbon ◽  
Acid Media

Abstract Mild steel (a low carbon steel) is an affordable engineering material used for many purposes in various environments including mild acidic environment with some precautions. The corrosion behaviour of mild steel (MS) in 0.5 M H2SO4 and 0.5 M HCl, in the temperature range (303–323 K) without and with the inhibitor N-[(3,4-dimethoxyphenyl) methyleneamino]-4-hydroxy-benzamide (DMHB), was investigated using Potentiodynamic polarization and Electrochemical impedance spectroscopy (EIS) techniques supplementing with surface characterization study using scanning electron microscope (SEM) and atomic force spectroscopy (AFM). Experimental observations were found to be in agreement with Density functional theory (DFT) calculations. The inhibition efficiency increases with increase in DMHB concentration and showed maximum inhibition efficiency of 86% in 0.5 M H2SO4 and 81% in 0.5 M HCl, respectively, at concentration of 3 × 10─3 M at 303 K. The inhibition efficiency of DMHB obtained relatively at its lower concentration (3 × 10─3 M) compared to other reported related compounds confirms its potential towards corrosion inhibition. The variation in the kinetic and thermodynamic parameters indicated physisorption of DMHB on MS and its mixed type inhibitive action followed Langmuir’s isotherm model. DFT calculations go along with the experimental results, signifying the potential corrosion inhibition behaviour of DMHB for MS in both the acid media.

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