scholarly journals Investigation about electrostatic three-wall carbon nanotubes (MWCNT), including doping with BN: a model for the nano capacitor

2020 ◽  
Vol 11 (29) ◽  
pp. 79-97
Author(s):  
Nabieh Farhami ◽  
Majid Monajjemi
Keyword(s):  
Charge Distribution ◽  
Density Functional ◽  
Theoretical Study ◽  
Energy Gap ◽  
Outer Cylinder ◽  
Functional Theory ◽  
Structure And Stability ◽  
Nano Structures ◽  
Carbon Nano Tubes ◽  
Cylindrical Capacitor

Three-walled boron & nitride nanotubes are used for a theoretical study of a cylindrical molecular capacitor, including an inner cylinder with a positive charge distribution and an outer cylinder with a negative charge distribution. Due to the semiconductor characteristic and dielectric functionality of SWBNTs, DWBNTs and TW (B&C) NTs can be used as a capacitor. Although the SWBNTs @ SWCNTs behave like Nano cylindrical capacitors, we have shown in this study that a dopant of BN in the inner cylinder reduces the energy gap and yields a better capacitance. The dopant of BN in the outer cylinder results in an inverse charge distribution (outer is positive and inner is negative). Therefore under these circumstances, the term capacitor would be meaningless, thought, the gap and the interaction energy decreases compared to the non-dopant form of those capacitors. Density functional theory (DFT) calculations have performed for the structure and stability of three wall carbon Nano tubes (TW (BN&C) NTs). In this work, it was calculated the geometrical structure, and stability to predict NMR and thermodynamics parameters. A mixing of SWBNNTs @ DWCNTs has been modeled and calculated for the suitable structures to storage the H2 molecules for increasing the dielectric. We have found these kinds of Nano-structures are useful for maximum storages of charges compare to other cylindrical capacitor.

A Theoretical Study of Carbohydrates as Corrosion Inhibitors of Iron

2013 ◽  
Vol 68 (8-9) ◽  
pp. 581-586 ◽  
Author(s):  
Salim M. Khalil ◽  
Elbashir E. Ali-Shattle ◽  
Nozha M. Ali
Keyword(s):  
Density Functional ◽  
Inhibition Efficiency ◽  
Theoretical Study ◽  
Energy Gap ◽  
Chemical Parameters ◽  
Iron Corrosion ◽  
Electrophilicity Index ◽  
Functional Theory ◽  
Quantum Chemical Parameters ◽  
Highest Occupied Molecular Orbital

The inhibitive effect of fructose, glucose, lactose, maltose, and sucrose against the iron corrosion is investigated using density functional theory at the B3LYP/6-31 G level (d) to search the relation between the molecular structure and corrosion inhibition. The electronic properties such as the energy of the highest occupied molecular orbital (HOMO), the energy of lowest unoccupied orbital (LUMO), the energy gap (LUMO-HOMO), quantum chemical parameters such as hardness, softness, the fraction of the electron transferred, and the electrophilicity index are reported. The inhibition efficiency of the investigated carbohydrates follows the trend: maltose <sucrose<lactose<fructose<glucose.

scholarly journals Electronic structure of complexes of oligomers of 3,4-ethylene-dietoxythiophene with polystyrlesulphonic acid

Surface ◽  
2021 ◽  
Vol 13(28) ◽  
pp. 84-93
Author(s):  
M. I. Terebinska ◽  
O. I. Tkachuk ◽  
A. M. Datsyuk ◽  
O. V. Filonenko ◽  
V. V. Lobanov
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Charge Distribution ◽  
Electronic Structures ◽  
Density Functional ◽  
Spiral Structure ◽  
Energy Gap ◽  
Conductive Polymer ◽  
Functional Theory ◽  
Method Of Density Functional

By the method of density functional theory (B3LYP, 6-31G **) the electronic structures of poly 3,4-ethylenedioxythiophene containing 12 links in charge states 0, +1, +2, +3 and +4 were calculated. It is shown that the oligomer of 12 units is sufficient to reflect the properties of the conductive polymer. To estimate the probability of electron density movement along the polymer chain, the width of the energy gap between NOMO and LUMO was calculated. It is shown that the molecules of oligomers EDOT and SS do not remain parallel to each other after polymerization, but rather, with increasing chain length, the latter gradually bends around the anionic unit SS; the charge distribution in the EDOT and SS oligomer complexes indicates the presence of two separated polarons at the two ends of the chain, and the asymmetry in the charge distribution also implies the presence of a curved spiral structure of the formed complex.

Synthesis and Theoretical Study of a Series of 3,5-disubstitutes Pyrazoles

2020 ◽  
Vol 17 (12) ◽  
pp. 932-938
Author(s):  
Karine Braga Enes ◽  
Ana Clara Alves Branco ◽  
Maria Eduarda Toledo Lima ◽  
Marcella Fernandes Mano Mateus ◽  
Luciana Guimaráes ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Chemical Nature ◽  
Theoretical Study ◽  
Energy Gap ◽  
Aromatic Rings ◽  
Frontier Orbitals ◽  
Functional Theory ◽  
Synthesis Yield ◽  
Homo Lumo

In this work, we proposed the synthesis of a series of pyrazoles derivatives with different substituents on the aromatic rings. We aim to evaluate their influence on the reactivity of the compounds in reactions of α,β-unsaturated chalcones and sulfonyl hydrazide catalyzed by iodine. In order to explain their high and low yields, or the impossibility of obtaining some compounds by applied synthetic methodology, Density Functional Theory (DFT) calculations were performed. The reaction Gibbs free energy (ΔG) as well as the energy gap of the HOMO-LUMO frontier orbitals (ΔE) of some selected reactants could explain qualitatively the experimental observations in terms of synthesis yield. In this way, we believe that the chemical nature of aromatic ring substituents is relevant for the reactivity of the starting materials as well as the formation of the desired products.

scholarly journals Estimation of the Efficiency of Corrosion Inhibition by Zn-Dithiocarbamate Complexes: a Theoretical Study

2021 ◽  
pp. 3323-3335
Author(s):  
Mustafa M. Kadhim ◽  
Layla A. Al. Juber ◽  
Ahmed S. M. Al-Janabi
Keyword(s):  
Electron Density ◽  
Density Functional ◽  
Room Temperature ◽  
Theoretical Study ◽  
Energy Gap ◽  
Basis Set ◽  
Total Electron Density ◽  
Functional Theory ◽  
Total Electron ◽  
Homo Lumo

    Seven Zn-dithiocarbamate complexes were suggested as corrosion inhibitors. Density functional theory (DFT) was used to predict the ability of inhibition. Room temperature conditions were applied to suggest the optimization of complexes, physical properties, and corrosion parameters. In addition, the HOMO, LUMO, dipole moment, energy gap, and other parameters were used to compare the inhibitors efficiency. Gaussian 09 software with LanL2DZ basis set was used. Total electron density (TED) and electrostatic surface potential (ESP) were utilized to show the sites of adsorption according to electron density.

scholarly journals A theoretical study of structure, bonding and property of platinum(II)-8-hydroxyquinolines complexes with carbene and heavier homologues

2020 ◽  
Vol 129 (1B) ◽  
Author(s):  
Huynh Thi Phuong Loan ◽  
Hoang Van Duc ◽  
Nguyen Thi Ai Nhung
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Significant Contribution ◽  
Theoretical Study ◽  
Energy Gap ◽  
Functional Theory ◽  
Dissociation Energies ◽  
First Time ◽  
Equilibrium Geometries ◽  
Insight Into

<p>In this work, a theoretical study for platinum(II)-8-hydroxyquinolines-tetrylene complexes [{PtCl-C<sub>9</sub>H<sub>6</sub>NO}-NHE<sub>Ph</sub>] (<strong>Pt-EPh</strong>)<strong> </strong>are investigated for the first time using density functional theory (DFT). Quantum chemical calculations using DFT and charge methods at the BP86 level with basic sets SVP, TZVPP have been carried out to get insight into the structures and property for <strong>Pt-EPh</strong>. The optimization of equilibrium geometries of the ligands<strong> EPh</strong> in <strong>Pt-EPh</strong> are bonded in distorted end-on way to <strong>Pt</strong> fragment with the bending angle, a, slightly decreases from carbene <strong>Pt-CPh</strong> to germylene <strong>Pt-GePh</strong>. Quantum chemical parameters such as <em>E</em><sub>HOMO</sub>, <em>E</em><sub>LUMO</sub>, the energy gap (<em>E</em><sub>LUMO </sub>– <em>E</em><sub>HOMO</sub>), electronegativity (χ), global hardness (η), and global softness (<em>S</em>) in the neutral molecules have been calculated and discussed. Bond dissociation energies (BDEs), D<sub>e </sub>(kcal.mol<sup>-1</sup>), decrease from the slighter to the heavier homologues. The hybridization of atoms E have large p characters while the hybridization of atom Pt has greater d character which lead to the Pt-E bond possesses not only NHE<sub>Ph</sub>→{ PtCl-C<sub>9</sub>H<sub>6</sub>NO} strong σ-donation but also a significant contribution π-donation NHE<sub>Ph</sub>→{PtCl-C<sub>9</sub>H<sub>6</sub>NO} and a weak π-backdonation metal-ligand NHE<sub>Ph</sub>←{PtCl-C<sub>9</sub>H<sub>6</sub>NO} in complexes <strong>Pt-Eph </strong>was also considered.</p>

scholarly journals A theoretical study of structure, bonding and property of platinum(II)-8-hydroxyquinolines complexes with carbene and heavier homologues

2020 ◽  
Vol 129 (1B) ◽  
pp. 41-48
Author(s):  
Huynh Thi Phuong Loan ◽  
Hoang Van Duc ◽  
Nguyen Thi Ai Nhung
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Theoretical Study ◽  
Energy Gap ◽  
Functional Theory ◽  
Dissociation Energies ◽  
The Density Functional Theory ◽  
First Time ◽  
Equilibrium Geometries ◽  
Insight Into

In this work, a theoretical study for platinum(II)-8-hydroxyquinoline-tetrylene complexes [{PtCl–C9H6NO}–NHEPh] (Pt–EPh) is carried out for the first time by using the density functional theory (DFT). Quantum chemical calculations with DFT and charge methods at the BP86 level with basic sets SVP and TZVPP have been perfomed to get insight into the structures and property of Pt–EPh. The optimization of equilibrium geometries of the ligands EPh in Pt–EPh, bonded in the distorted end-on way to the Pt fragment is studied, in which the bending angle slightly decreases from carbene Pt–CPh to germylene Pt–GePh. Quantum chemical parameters such as EHOMO, ELUMO, the energy gap (ELUMO – EHOMO), electronegativity, global hardness, and global softness in the neutral molecules have been calculated and discussed. Bond dissociation energies decrease from the slighter to the heavier homologues. The hybridization of atoms E has large p characters, while the hybridization of atom Pt has a greater d character. Thus, the Pt–E bond possesses not only NHEPh→{PtCl–C9H6NO} strong -donation but also a significant contribution of π-donation NHEPh→{PtCl–C9H6NO}, and a weak π-backdonation metal-ligand NHEPh←{PtCl-C9H6NO} in complexes Pt-EPh is also considered.

Molecular Investigations of the Newly Synthesized Azomethines as Antioxidants: Theoretical and Experimental Studies

2019 ◽  
Vol 19 (6) ◽  
pp. 419-433 ◽  
Author(s):  
Siyamak Shahab ◽  
Masoome Sheikhi ◽  
Liudmila Filippovich ◽  
Evgenij Dikusar ◽  
Anhelina Pazniak ◽  
...  
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Experimental Studies ◽  
Antioxidant Property ◽  
Nbo Analysis ◽  
Antioxidant Potential ◽  
Functional Theory ◽  
Homo And Lumo ◽  
Intramolecular Hydrogen ◽  
Activity Mechanism

: In this study, the antioxidant property of new synthesized azomethins has been investigated as theoretical and experimental. Methods and Results: Density functional theory (DFT) was employed to investigate the Bond Dissociation Enthalpy (BDE), Mulliken Charges, NBO analysis, Ionization Potential (IP), Electron Affinities (EA), HOMO and LUMO energies, Hardness (η), Softness (S), Electronegativity (µ), Electrophilic Index (ω), Electron Donating Power (ω-), Electron Accepting Power (ω+) and Energy Gap (Eg) in order to deduce scavenging action of the two new synthesized azomethines (FD-1 and FD-2). Spin density calculations and NBO analysis were also carried out to understand the antioxidant activity mechanism. Comparison of BDE of FD-1 and FD-2 indicate the weal antioxidant potential of these structures. Conclusion: FD-1 and FD-2 have very high antioxidant potential due to the planarity and formation of intramolecular hydrogen bonds.

scholarly journals Exo⇔Endo Isomerism, MEP/DFT, XRD/HSA-Interactions of 2,5-Dimethoxybenzaldehyde: Thermal, 1BNA-Docking, Optical, and TD-DFT Studies

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5970
Author(s):  
Nabil Al-Zaqri ◽  
Mohammed Suleiman ◽  
Anas Al-Ali ◽  
Khaled Alkanad ◽  
Karthik Kumara ◽  
...  
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Structural Parameters ◽  
Population Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Optical Energy Gap ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
Td Dft

The exo⇔endo isomerization of 2,5-dimethoxybenzaldehyde was theoretically studied by density functional theory (DFT) to examine its favored conformers via sp2–sp2 single rotation. Both isomers were docked against 1BNA DNA to elucidate their binding ability, and the DFT-computed structural parameters results were matched with the X-ray diffraction (XRD) crystallographic parameters. XRD analysis showed that the exo-isomer was structurally favored and was also considered as the kinetically preferred isomer, while several hydrogen-bonding interactions detected in the crystal lattice by XRD were in good agreement with the Hirshfeld surface analysis calculations. The molecular electrostatic potential, Mulliken and natural population analysis charges, frontier molecular orbitals (HOMO/LUMO), and global reactivity descriptors quantum parameters were also determined at the B3LYP/6-311G(d,p) level of theory. The computed electronic calculations, i.e., TD-SCF/DFT, B3LYP-IR, NMR-DB, and GIAO-NMR, were compared to the experimental UV–Vis., optical energy gap, FTIR, and 1H-NMR, respectively. The thermal behavior of 2,5-dimethoxybenzaldehyde was also evaluated in an open atmosphere by a thermogravimetric–derivative thermogravimetric analysis, indicating its stability up to 95 °C.

scholarly journals Theoretical Study of Zirconium Isomorphous Substitution into Zeolite Frameworks

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4466
Author(s):  
Duichun Li ◽  
Bin Xing ◽  
Baojun Wang ◽  
Ruifeng Li
Keyword(s):  
Acid Site ◽  
Density Functional ◽  
Theoretical Study ◽  
Atomic Radius ◽  
Acid Sites ◽  
Isomorphous Substitution ◽  
Dispersion Correction ◽  
Brønsted Acidity ◽  
Functional Theory ◽  
Brönsted Acidity

Systematic periodic density functional theory computations including dispersion correction (DFT-D) were carried out to determine the preferred location site of Zr atoms in sodalite (SOD) and CHA-type topology frameworks, including alumino-phosphate-34 (AlPO-34) and silico-alumino-phosphate-34 (SAPO-34), and to determine the relative stability and Brönsted acidity of Zr-substituted forms of SOD, AlPO-34, and SAPO-34. Mono and multiple Zr atom substitutions were considered. The Zr substitution causes obvious structural distortion because of the larger atomic radius of Zr than that of Si, however, Zr-substituted forms of zeolites are found to be more stable than pristine zeolites. Our results demonstrate that in the most stable configurations, the preferred favorable substitutions of Zr in substituted SOD have Zr located at the neighboring sites of the Al-substituted site. However, in the AlPO-34 and SAPO-34 frameworks, the Zr atoms are more easily distributed in a dispersed form, rather than being centralized. Brönsted acidity of substituted zeolites strongly depends on Zr content. For SOD, substitution of Zr atoms reduces Brönsted acidity. However, for Zr-substituted forms of AlPO-34 and SAPO-34, Brönsted acidity of the Zr-O(H)-Al acid sites are, at first, reduced and, then, the presence of Zr atoms substantially increased Brönsted acidity of the Zr-O(H)-Al acid site. The results in the SAPO-34-Zr indicate that more Zr atoms substantially increase Brönsted acidity of the Si-O(H)-Al acid site. It is suggested that substituted heteroatoms play an important role in regulating and controlling structural stability and Brönsted acidity of zeolites.

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