scholarly journals Electronic Spectra of ortho-Substituted Phenols: An Experimental and DFT Study

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Samuel Tetteh ◽  
Ruphino Zugle ◽  
John Prosper Kwaku Adotey ◽  
Andrews Quashie
Keyword(s):  
Electronic Spectra ◽  
Density Functional ◽  
Population Analysis ◽  
Halogen Bonding ◽  
Substituted Phenols ◽  
Dft Methods ◽  
Functional Theory ◽  
Spectral Changes ◽  
Full Interaction ◽  
Interaction Map

The electronic spectra of phenol, 2-chlorophenol, 2-aminophenol, and 2-nitrophenol have been studied both experimentally and computationally. The effect of the substituents on the solvatochromic behavior of the phenols were investigated in polar protic (methanol) and aprotic (dimethyl sulfoxide (DMSO)) solvents. The spectra of 2-nitrophenol recorded the highest red shift in methanol. The observed spectral changes were investigated computationally by means of density functional theory (DFT) methods. The gas phase compounds were fully optimized using B3LYP functionals with 6-31++G(d,p) bases set. The effects of the substituents on the electron distribution in the σ-bonds as well as the natural charge on the constituent atoms were analyzed by natural bond orbital (NBO) and natural population analysis (NPA). Second-order perturbation analyses also revealed substantial delocalization of nonbonding electrons on the substituents onto the phenyl ring, thereby increasing its electron density. Full interaction map (FIM) also showed regions of varying propensities for hydrogen and halogen bonding interactions on the phenols.

scholarly journals Coordination Behavior of Ni2+, Cu2+, and Zn2+ in Tetrahedral 1-Methylimidazole Complexes: A DFT/CSD Study

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Samuel Tetteh
Keyword(s):  
Density Functional ◽  
Population Analysis ◽  
Substantial Reduction ◽  
Nbo Analysis ◽  
Basis Sets ◽  
Dft Methods ◽  
Functional Theory ◽  
Formal Charge ◽  
Coordination Behavior ◽  
The Stability

The interaction between nickel (Ni2+), copper (Cu2+), and zinc (Zn2+) ions and 1-methylimidazole has been studied by exploring the geometries of eleven crystal structures in the Cambridge Structural Database (CSD). The coordination behavior of the respective ions was further investigated by means of density functional theory (DFT) methods. The gas-phase complexes were fully optimized using B3LYP/GENECP functionals with 6-31G∗ and LANL2DZ basis sets. The Ni2+ and Cu2+ complexes show distorted tetrahedral geometries around the central ions, with Zn2+ being a perfect tetrahedron. Natural bond orbital (NBO) analysis and natural population analysis (NPA) show substantial reduction in the formal charge on the respective ions. The interaction between metal d-orbitals (donor) and ligand orbitals (acceptor) was also explored using second-order perturbation of the Fock matrix. These interactions followed the order Ni2+ > Cu2+ > Zn2+ with Zn2+ having the least interaction with the ligand orbitals. Examination of the frontier orbitals shows the stability of the complexes in the order Ni2+ > Cu2+ < Zn2+ which is consistent with the Irving–Williams series.

scholarly journals Theoretical Study of Terminal Vanadium(V) Chalcogenido Complexes Bearing Chlorido and Methoxido Ligands

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Samuel Tetteh ◽  
Ruphino Zugle
Keyword(s):  
Density Functional ◽  
Lone Pair ◽  
Basis Sets ◽  
Dft Methods ◽  
Hydrogen Bond Interactions ◽  
Strong Stabilization ◽  
Distorted Octahedral ◽  
Full Interaction ◽  
Interaction Map ◽  
Lone Pair Electrons

Solvent (methanol) coordinated vanadium(V) chalcogenido complexes bearing chlorido and methoxido ligands have been studied computationally by means of density functional (DFT) methods. The gas phase complexes were fully optimized using B3LYP/GEN functionals with 6-31+G⁎⁎ and LANL2DZ basis sets. The optimized complexes show distorted octahedral geometries around the central vanadium atom. The ligand pπ-vanadium dπ interactions were analyzed by natural bond order (NBO) and natural population analyses (NPA). These results show strong stabilization of the V=O bond as was further confirmed by the analyses of the frontier molecular orbitals (FMOs). Second-order perturbation analyses also revealed substantial delocalization of lone pair electrons from the oxido ligand into vacant non-Lewis (Rydberg) orbitals as compared to the sulfido and seleno analogues. These results show significant ligand-to-metal charge transfer (LMCT) interactions. Full interaction map (FIM) of the reference complex confirms hydrogen bond interactions involving the methanol (O-H) and the chlorido ligand.

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 A machine learning platform for the discovery of materials

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Carl E. Belle ◽  
Vural Aksakalli ◽  
Salvy P. Russo
Keyword(s):  
Machine Learning ◽  
Density Functional ◽  
Gw Approximation ◽  
Dft Methods ◽  
Functional Theory ◽  
Unit Cell Size ◽  
Learning Platform ◽  
Photovoltaic Materials ◽  
Wide Range ◽  
Quantum Espresso

AbstractFor photovoltaic materials, properties such as band gap $$E_{g}$$ E g are critical indicators of the material’s suitability to perform a desired function. Calculating $$E_{g}$$ E g is often performed using Density Functional Theory (DFT) methods, although more accurate calculation are performed using methods such as the GW approximation. DFT software often used to compute electronic properties includes applications such as VASP, CRYSTAL, CASTEP or Quantum Espresso. Depending on the unit cell size and symmetry of the material, these calculations can be computationally expensive. In this study, we present a new machine learning platform for the accurate prediction of properties such as $$E_{g}$$ E g of a wide range of materials.

A Density Functional Theory Study on the Ring-Opening Polymerization of D-Lactide Catalyzed by a Bifunctional-Thiourea Catalyst

2009 ◽  
Vol 62 (2) ◽  
pp. 157 ◽  
Author(s):  
Rong-Xiu Zhu ◽  
Ruo-Xi Wang ◽  
Dong-Ju Zhang ◽  
Cheng-Bu Liu
Keyword(s):  
Density Functional Theory ◽  
Ring Opening ◽  
Density Functional ◽  
Population Analysis ◽  
Density Functional Theory Calculations ◽  
Ring Opening Polymerization ◽  
Acyl Transfer ◽  
Frontier Molecular Orbital ◽  
Functional Theory ◽  
Elimination Pathway

The thiourea-catalyzed methanolysis of d-lactide, a model system for the initiation and propagation of the organocatalyzed ring-opening polymerization (ROP) of lactide, has been studied by performing density functional theory calculations. Both the catalyzed and uncatalyzed reactions are explored along two possible pathways: one involves the stepwise addition–elimination pathway and the other is related to the concerted pathway. It is found that the reaction without the presence of the catalyst is difficult because the barrier involved is as high as 176 kJ mol–1. With the aid of a thiourea catalyst, the barrier is reduced to 88 kJ mol–1 with a preference for the stepwise addition–elimination mechanism over the concerted one. The role of the catalyst has been rationalized by analyzing the frontier molecular orbital interactions between the catalyst and substrates and by performing natural population analysis. Finally, another mechanism involving acyl transfer is discussed for the thiourea-catalyzed ROP.

scholarly journals Adenine as a Halogen Bond Acceptor: A Combined Experimental and DFT Study

Crystals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 224 ◽  
Author(s):  
Yannick Roselló ◽  
Mónica Benito ◽  
Elies Molins ◽  
Miquel Barceló-Oliver ◽  
Antonio Frontera
Keyword(s):  
Density Functional ◽  
Halogen Bond ◽  
Lone Pair ◽  
Halogen Bonding ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Adenine Ring ◽  
Bonding Interaction ◽  
Donor Ability ◽  
Adenine Derivative

In this work, we report the cocrystallization of N9-ethyladenine with 1,2,4,5-tetrafluoro-3,6-diiodobenzene (TFDIB), a classical XB donor. As far as our knowledge extends, this is the first cocrystal reported to date where an adenine derivative acts as a halogen bond acceptor. In the solid state, each adenine ring forms two centrosymmetric H-bonded dimers: one using N1···HA6–N6 and the other N7···HB6–N6. Therefore, only N3 is available as a halogen bond acceptor that, indeed, establishes an N···I halogen bonding interaction with TFDIB. The H-bonded dimers and halogen bonds have been investigated via DFT (Density Functional Theory) calculations and the Bader’s Quantum Theory of Atoms In Molecules (QTAIM) method at the B3LYP/6-311+G* level of theory. The influence of H-bonding interactions on the lone pair donor ability of N3 has also been analyzed using the molecular electrostatic potential (MEP) surface calculations.

Vibrational Structure in the Electronic Spectra of C60 and Fullerene Derivatives as Studied by Time-Dependent Density Functional Theory

2019 ◽  
Vol 2 (12) ◽  
pp. 121-132
Author(s):  
Alexey A. Popov ◽  
Vitaly Korepanov ◽  
Vladimir M. Senyavin ◽  
Sergey Troyanov ◽  
B. S. Razbirin ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Spectra ◽  
Density Functional ◽  
Vibrational Structure ◽  
Time Dependent ◽  
Functional Theory ◽  
Fullerene Derivatives ◽  
Dependent Density

scholarly journals Analysis of the structural and electronic properties of 1-(5-Hydroxymethyl - 4 –[ 5 – (5-oxo-5-piperidin-1-yl-penta- 1,3dienyl)-benzo[1,3]dioxol-2-yl] -tetrahydro-furan-2-yl)-5- methyl-1H-pyrimidine-2,4dione molecule

2018 ◽  
Vol 33 (1) ◽  
pp. 71
Author(s):  
Ali Hashem Essa ◽  
A. F. Jalbout
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Ground State ◽  
Density Functional ◽  
Molecular Orbital Calculations ◽  
Active Molecule ◽  
Dft Methods ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Semi Empirical

The structural and electronic properties of 1-(5-Hydroxymethyl - 4 –[ 5 – (5-oxo-5-piperidin- 1 -yl-penta- 1,3 -dienyl)-benzo [1,3] dioxol- 2 -yl]- tetrahydro -furan-2 -yl)-5-methy l-1Hpyrimidine-2,4dione (AHE) molecule have been investigated theoretically by performing density functional theory (DFT), and semi empirical molecular orbital calculations. The geometry of the molecule is optimized at the level of Austin Model 1 (AM1), and the electronic properties and relative energies of the molecules have been calculated by density functional theory in the ground state. The resultant dipole moment of the AHE molecule is about 2.6 and 2.3 Debyes by AM1 and DFT methods respectively, This property of AHE makes it an active molecule with its environment, that is AHE molecule may interacts with its environment strongly in solution.

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