scholarly journals Semiempirical Theoretical Studies of 1,3-Benzodioxole Derivatives as Corrosion Inhibitors

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Omnia A. A. El-Shamy
Keyword(s):  
Molecular Orbital ◽  
Corrosion Inhibitors ◽  
Energy Gap ◽  
Quantitative Structure Activity Relationship ◽  
Mulliken Charge ◽  
Semiempirical Methods ◽  
Log P ◽  
Chemical Calculation ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The efficiency of 1,3-benzodioxole derivatives as corrosion inhibitors is theoretically studied using quantum chemical calculation and Quantitative Structure Activity Relationship (QSAR). Different semiempirical methods (AM1, PM3, MNDO, MINDO/3, and INDO) are applied in order to determine the relationship between molecular structure and their corrosion protection efficiencies. Different quantum parameters are obtained as the energy of highest occupied molecular orbitalEHOMO, the energy of the lowest unoccupied molecular orbitalELUMO, energy gapΔEg, dipole momentμ, and Mulliken charge on the atom. QSAR approach is applied to elucidate some important parameters as the hydrophobicity (Log P), surface area (S.A), polarization(P), and hydration energy (EHyd).

INHIBITORY EFFECT AND ADSORPTION CHARACTERISTICS OF 2,3-DIAMINONAPHTHALENE AT ALUMINUM/HYDROCHLORIC ACID INTERFACE: EXPERIMENTAL AND THEORETICAL STUDY

2008 ◽  
Vol 15 (06) ◽  
pp. 903-910 ◽  
Author(s):  
I. B. OBOT ◽  
N. O. OBI-EGBEDI
Keyword(s):  
Molecular Orbital ◽  
Inhibition Efficiency ◽  
Inhibitory Effect ◽  
Mulliken Charge ◽  
Chemical Calculation ◽  
Active Centers ◽  
Langmuir Adsorption ◽  
Highest Occupied Molecular Orbital ◽  
Calculation Results ◽  
Lowest Unoccupied Molecular Orbital

The inhibitive effect of 2,3-diaminonaphthalene (2,3-DAN) for corrosion of aluminum in 1 M HCl was investigated using hydrogen evolution technique at 30 and 40°C. Quantum chemical calculation results showed that 2,3-DAN molecule possessed planar structure with a number of active centers, which aided the adsorption process. The Mulliken charge density, the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) were found mainly focused around nitrogen atoms and the cyclic of the benzene as well. The presence of 2,3-DAN molecules in the corrosive medium (1 M HCl solution) inhibits the corrosion process of aluminum and as the concentration of 2,3-DAN increases the inhibition efficiency also increases but decreases with rise in temperature. The corrosion inhibition of 2,3-DAN was discussed in terms of blocking of the Al surface by adsorption of the molecules of the inhibitor at the active centers. It was found that the adsorption of 2,3-DAN onto the Al surface followed the Langmuir adsorption isotherm and 2,3-DAN adsorbed on Al surface probably by physisorption. The proposed physisorption mechanism was supported by the calculated values of Ea, Q ads , and ΔG ads .

Computational and Experimental Study onthe Adsorption and Inhibition Effects of 1,3-Benzothiazol-6-ol on the Corrosion ofSteel X80 in Acidic Solution

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Iman Danaee ◽  
Paria Nikparsa ◽  
Mohammad Reza Khosravi-Nikou
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Acidic Solution ◽  
Energy Gap ◽  
Force Microscopy ◽  
Highest Occupied Molecular Orbital ◽  
Low Concentrations ◽  
Noise Data ◽  
Chemical Factors ◽  
Lowest Unoccupied Molecular Orbital

Abstract In this work, the adsorption and inhibition behavior of 1,3-benzothiazol-6-ol were investigated by computational and experimental techniques for steel X80 corrosion in acidic solution. The density functional theory was carried out and quantum chemical factors like the energy gap, energy of highest occupied molecular orbital, the energy of lowest unoccupied molecular orbital, the fraction of electron transferred, and Mulliken charges have been calculated. In addition, according to quantum calculation, S atom in 1,3-benzothiazol-6-ol indicated more tendency for electrophilic attack in adsorption. The main reason for high inhibition efficiencies in very low concentrations is the planar and simplicity of inhibitor structure which leads to increasing the efficiency of adsorption by functional group especially sulfur. Electrochemical frequency modulation and potentiodynamic polarization indicated that this material has excellent inhibiting features in very low concentrations. The influence of DC trend on the explanation of electrochemical noise data was evaluated by polynomial fitting and the optimum polynomial order m = 5 was obtained. Noise resistance and the inhibition efficiency was calculated and compared in different methods. The theory of shot noise in frequency domain was used to obtain the electrochemical event charge. The corroded surface of steel in the absence and existence of thiazole compound was studied by Atomic force microscopy.

The Geometric and Electronic Structures of Fen-1Si(n=2-7) Clusters

2010 ◽  
Vol 150-151 ◽  
pp. 984-987
Author(s):  
Shuai Qin Yu ◽  
Li Hua Dong ◽  
Yan Sheng Yin
Keyword(s):  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Energy Difference ◽  
Ground State Structure ◽  
Magic Numbers ◽  
Highest Occupied Molecular Orbital ◽  
Hybridization Intensity ◽  
Lowest Unoccupied Molecular Orbital ◽  
The Stability

The geometric structures and electronic properties of Si doped Fen (n=2-7) clusters have been systematically studied at the BPW91 level in density-functional theory (DFT). Calculated results show that an Si impurity does not change the ground-state structure of small iron clusters and prefers to occupy surface site bonding with iron atoms as many as possible. The second-order energy difference and the vertical ionization potential show that n=4 and 6 are magic numbers within the size range studied, but the maximum value occurs at n=4 for the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital(LUMO). It is found that the hybridization intensity between Si and Fe atoms is relevant to the stability of clusters.

scholarly journals Density Functional Theory Study of CL-20/Nitroimidazoles Energetic Cocrystal Compounds in an External Electric Field

2021 ◽  
Author(s):  
xiaosong Xu ◽  
Renfa Zhang ◽  
Wenxin Xia ◽  
Peng Ma ◽  
Congming Ma ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electric Field ◽  
Nitro Group ◽  
External Electric Field ◽  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

Abstract The external electric field has a significant influence on the sensitivity of the energetic cocrystal materials. In order to find out the relationship between the external electric field and sensitivity of energetic cocrystal compounds 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/1,4-dinitroimidazole (CL-20/1,4-DNI), 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/1-methyl-2,4-dinitro-1H-imidazole (CL-20/2,4-MDNI) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/1-methyl-4,5-dinitro-1H-imidazole (CL-20/4,5-MDNI). In this work, density functional theory (DFT) at B3LYP-D3/6-311+G(d,p) and M062X-D3/ma-def2 TZVPP levels was employed to calculate the bond dissociation energies (BDEs) of selected N-NO2 trigger bonds, frontier molecular orbitals, electrostatic potentials (ESPs) and nitro group charges (QNO2) under different external electric field. The results show that as the positive electric field intensity increases, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy gap and BDEs become smaller, and the local positive ESPs becomes larger, so that the energetic cocrystals tends to have higher sensitivity. In addition, the linear fitting results show that the trigger bond length and nitro group charge changes are closely related to the external electric field strength.

scholarly journals Photophysical and Electrocatalytic Properties of Rhenium(I) Triazole-Based Complexes

Inorganics ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 22
Author(s):  
Adrian Comia ◽  
Luke Charalambou ◽  
Salem A. E. Omar ◽  
Paul A. Scattergood ◽  
Paul I. P. Elliott ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Energy Gap ◽  
Cyclic Voltammograms ◽  
Reduction Wave ◽  
Peak Potential ◽  
Diimine Ligands ◽  
Highest Occupied Molecular Orbital ◽  
Catalytic Wave ◽  
Ligand Charge Transfer ◽  
Lowest Unoccupied Molecular Orbital

A series of [Re(N^N)(CO)3(Cl)] (N^N = diimine) complexes based on 4-(pyrid-2-yl)-1,2,3-triazole (1), 1-benzyl-4-(pyrimidin-2-yl)-1,2,3-triazole (2), and 1-benzyl-4-(pyrazin-2-yl)-1,2,3-triazole (3) diimine ligands were prepared and their photophysical and electrochemical properties were characterized. The ligand-based reduction wave is shown to be highly sensitive to the nature of the triazole-based ligand, with the peak potential shifting by up to 600 mV toward more positive potential from 1 to 3. All three complexes are phosphorescent in solution at room temperature with λmax ranging from 540 nm (1) to 638 nm (3). Interestingly, the complexes appear to show inverted energy-gap law behaviour (τ = 43 ns for 1 versus 92 ns for 3), which is tentatively interpreted as reduced thermal accessibility of metal-centred (3MC) states from photoexcited metal to ligand charge transfer (3MLCT) states upon stabilisation of the N^N-centred lowest unoccupied molecular orbital (LUMO). The photophysical characterisation, supported by computational data, demonstrated a progressive stabilization of the LUMO from complex 1 to 3, which results in a narrowing of the HOMO–LUMO energy gap (HOMO = highest occupied molecular orbital) across the series and, correspondingly, red-shifted electronic absorption and photoluminescence spectra. The two complexes bearing pyridyl (1) and pyrimidyl (2) moieties, respectively, showed a modest ability to catalyse the electroreduction of CO2, with a peak potential at ca. −2.3 V versus Fc/Fc+. The catalytic wave that is observed in the cyclic voltammograms is slightly enhanced by the addition of water as a proton source.

Theoretical studies on lindqvist polyoxometalates [M6O19]n−(M = Mo, W, n=2; M = V, Nb, Ta, n=8) and derivatives: Electronic structures, stability and bonding

2017 ◽  
Vol 16 (06) ◽  
pp. 1750054 ◽  
Author(s):  
Xiao-Fang Su ◽  
Bo Zhu ◽  
Cai-Xia Wu ◽  
Li-Kai Yan ◽  
Zhong-Min Su
Keyword(s):  
Charge Density ◽  
Molecular Orbital ◽  
Electronic Structures ◽  
Density Functional ◽  
Geometrical Structure ◽  
Energy Gap ◽  
Lumo Energy ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

The geometrical and electronic structures of [M6O[Formula: see text]][Formula: see text] (M [Formula: see text] Mo, W, [Formula: see text]; M [Formula: see text] V, Nb, Ta, [Formula: see text]) and their derivatives were investigated by using density functional theory methods. The results indicate that the geometrical structure of [V6O[Formula: see text]][Formula: see text] is not different from other Lindqvist-type anions. The energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) (HOMO[Formula: see text]LUMO energy gap) of [V6O[Formula: see text]][Formula: see text] is smaller than those of same charge anions, [Nb6O[Formula: see text]][Formula: see text] and [Ta6O[Formula: see text]][Formula: see text]. In addition, the charge density [Formula: see text] of [V6O[Formula: see text]][Formula: see text] is larger when compared with those of other studied clusters. The investigation on the derivatives shows that the valence of V atom (V[Formula: see text] or V[Formula: see text]) and the methoxy ligand influence the HOMO[Formula: see text]LUMO energy gap and the charge density [Formula: see text] of the studied clusters.

Investigation on Stability and Optical Properties of ZnnSen(n=1~13) Nanocluster in CIGS-ZnSe Heterojunction Interface

2014 ◽  
Vol 953-954 ◽  
pp. 991-994
Author(s):  
Liang Yan Chen ◽  
Chao Fang
Keyword(s):  
Optical Properties ◽  
Molecular Orbital ◽  
Energy Gap ◽  
Stable State ◽  
Building Blocks ◽  
Energy Difference ◽  
Generalized Gradient ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital ◽  
The Stability

ZnSe cluster is the main form of growth mechanism in CuInGaSe based solar cells as the buffer layer and the building blocks for larger bulk ZnSe materials as well. With the generalized gradient approximation in first principle all-electron calculations, a number of configurations and structural isomers of ZnnSen(n=1~13) nanoclusters has been geometrically optimized to get the lowest energy constructions of ZnnSen(n=1~13). Second-order energy difference were applied to investigate the stability of small ZnSe nanoclusters. And the nanocage Zn12Se12cluster has been identified to be in rather stable state and can be the building block of larger ZnSe nanoclusters materials. Energy gap between lowest unoccupied molecular orbital and the highest occupied molecular orbital, Infrared Spectroscopy have also been investigated for further study on size and optical properties through testing methods.

QSAR Analyzes for the Predictive Toxicity of Substituted Phenols and Anilines to Fish (carp)

2013 ◽  
Vol 295-298 ◽  
pp. 109-112 ◽  
Author(s):  
Ping Sun ◽  
Shu Mei Gao ◽  
Hiu Liu ◽  
Jian Ting Chen
Keyword(s):  
Molecular Orbital ◽  
Dft Method ◽  
Qsar Model ◽  
Quantitative Structure Activity Relationship ◽  
Substituted Phenols ◽  
Substituted Anilines ◽  
Qsar Study ◽  
Highest Occupied Molecular Orbital ◽  
Main Effect ◽  
Lowest Unoccupied Molecular Orbital

A quantitative structure-activity relationship (QSAR) study for predicting the acute toxicity 96h - LC50 values of substituted anilines and phenols to carp is presented in this work. For this, the descriptors were obtained with DFT method at the B3LYP/6-311G** level using the Gaussian 03 software package. Afterwards the obtained parameters were taken as theoretical descriptors to establish a QSAR model for predicting -lgLC50. The model contains two variables, energy of the highest occupied molecular orbital (EHOMO) and energy of the lowest unoccupied molecular orbital (ELUMO), which suggest that the main effect on biological toxicity of phenols and anilines is the interaction of electrons between the molecules of organic chemicals. Besides, the model was further validated by variance inflation factors (VIF) and t-test, and show fine stabilities and predictive abilities, which can be used to predict -lgLC50 of these kinds of compounds.

scholarly journals Synthesis, Geometry Structure and Properties of N, N’-Carbonic Bis(Piperonylic Acid) Dihydrazide

2020 ◽  
Vol 213 ◽  
pp. 01014
Author(s):  
Yanhua Cai ◽  
Lian Luo ◽  
Jun Qiao ◽  
Lisha Zhao
Keyword(s):  
Molecular Orbital ◽  
Energy Gap ◽  
Geometry Optimization ◽  
Nucleation Site ◽  
Orbital Energy ◽  
Melt Crystallization ◽  
Heating Rates ◽  
Neat Plla ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

In this study, N, N’-carbonic bis(piperonylic acid) dihydrazide (BPACH) was synthesized to broaden the category of piperonylic acid derivative and evaluate its influences on the thermal properties of poly(L-lactic acid) (PLLA). The geometry optimization of BPACH showed that the highest occupied molecular orbital mainly focused on the formed amide group and carbonic dihydrazide, whereas the lowest unoccupied molecular orbital mainly focused on the piperonylic acid, and the orbital energy gap was 0.10418 eV. The differences in melt-crystallization processes of the neat PLLA and PLLA/BPACH samples indicated that the BPACH could provide the effective nucleation site to accelerate the crystallization of PLLA, but the crystallization accelerating effect was still further improved compared to some reported nucleating agents. The melting behaviors of PLLA/BPACH samples after crystallization depended on the crystallization temperatures and heating rates; additionally, the melting processes could also effectively reflect the previous crystallization behaviors.

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