scholarly journals Theoretical Study on Molecular Structure and Electronic Properties of New 1,3-Diaza-adamantan-6-ones Derivatives

2020 ◽  
Vol 20 (3) ◽  
pp. 638
Author(s):  
Haithem Abdulhasan ◽  
Ahmed Al-Yasari ◽  
Rahman Alasadi
Keyword(s):  
Electronic Properties ◽  
Theoretical Study ◽  
Dft Method ◽  
Molecular Orbitals ◽  
Molecular Structures ◽  
Computational Method ◽  
Basis Set ◽  
Highest Occupied Molecular Orbitals ◽  
Lowest Unoccupied Molecular Orbitals ◽  
Vibrational Wavenumbers

In this study, the structural geometry and vibrational frequencies (IR) of 1,3-Diaza-adamantane-6-ones derivatives including Adamantane (A), 1,3-Diaza-adamantan (D), 1,3-Diaza-adamantan-6-one (DO), 5-Benzyl-1,3-diaza-adamantan-6-one (BD), 5-(4-Hydroxybenzyl)-1,3-diaza-adamantan-6-one (HBD), 5-(4-Methoxybenzyl)-1,3-diaza-adamantan-6-one (MBD), and 5-(4-Hydroxy-3-methoxybenzyl)-1,3-diaza-adamantan-6-one (HMBD) were theoretically studied. In addition, molecular orbital energies, including the highest occupied molecular orbitals (HOMOs), and lowest unoccupied molecular orbitals (LUMOs), and electronic properties of the titled molecules were theoretically studied using the computational method. Optimized molecular structures were obtained by DFT method with the hybrid B3LYP functional at a relatively small basis set of 6-31G. The calculated vibrational wavenumbers were obtained using the same level of the theory mentioned above. The contributions to the molecular orbitals of adamantane and substituted-phenyl groups in the title compounds were determined. Moving from A to HMBD, a decrease in the value of LUMO and total energy are noticed, while an increase in the value of HOMO is noted. These findings are supported by the decreasing in the EHOMO-LUMO gap values. Furthermore, a decrease in the value of ionization potential (IP) is obtained, while an increase in the electronegativity (EA) is observed.

scholarly journals Molecular Structure Modulated Trap Distribution and Carrier Migration in Fluorinated Epoxy Resin

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3071 ◽  
Author(s):  
Jin Li ◽  
Yufan Wang ◽  
Zhaoyu Ran ◽  
Hang Yao ◽  
Boxue Du ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Surface Charge ◽  
Epoxy Resin ◽  
Mobility Model ◽  
Molecular Orbitals ◽  
Chemical Calculation ◽  
Dissipation Process ◽  
Highest Occupied Molecular Orbitals ◽  
Lowest Unoccupied Molecular Orbitals ◽  
Positively Charged

Surface charge accumulation on epoxy insulators is one of the most serious problems threatening the operation safety of the direct current gas-insulated transmission line (GIL), and can be efficiently inhibited by the surface modification technology. This paper investigated the mechanisms of fluorination modulated surface charge behaviors of epoxy resin through quantum chemical calculation (QCC) analysis of the molecular structure. The results show that after fluorination, the surface charge dissipation process of the epoxy sample is accelerated by the introduced shallow trap sites, which is further clarified by the carrier mobility model. The electron distribution probability of the highest occupied molecular orbitals (HOMO) under positive charging and the lowest unoccupied molecular orbitals (LUMO) under negative charging shows distinctive patterns. It is illustrated that electrons are likely to aggregate locally around benzenes for the positively charged molecular structure, while electrons tend to distribute all along the epoxy chain under negatively charging. The calculated results verify that fluorination can modulate surface charge behaviors of epoxy resin through redesigning its molecular structure, trap distribution and charging patterns.

Tests of second-generation and third-generation density functionals for electron affinities of the alkylthio radicals

2014 ◽  
Vol 13 (04) ◽  
pp. 1450030 ◽  
Author(s):  
Aifang Gao ◽  
Aiguo Li
Keyword(s):  
Dft Method ◽  
Absolute Error ◽  
Molecular Structures ◽  
Basis Set ◽  
Density Functionals ◽  
Electron Affinities ◽  
Generalized Gradient ◽  
Experimental Values ◽  
P Type ◽  
Good Agreement

The molecular structures and electron affinities of the R – S / R – S -( R = CH 3, C 2 H 5, n- C 3 H 7, n- C 4 H 9, n- C 5 H 11, i- C 3 H 7, i- C 4 H 9, t- C 4 H 9) species have been studied using 17 pure and hybrid density functionals (five generalized gradient approximation (GGA) methods, six hybrid GGAs, one meta GGA method and five hybrid meta GGAs). The basis set used in this work is of double-ζ plus polarization quality with additional diffuse s- and p-type functions, denoted by DZP++. The geometries are fully optimized with each DFT method and discussed. Harmonic vibrational frequencies are found to be within 3.5% of available experimental values for most functionals. Three different types of the neutral-anion energy separations have been presented. The theoretical electron affinities of alkylthio radicals are in good agreement with the experiment data. The M06 method is very good for the adiabatic electron affinity calculations, and the average absolute error is 0.0439 eV. The HCTH method performs better for EA prediction. The M06-HF, mPWPW91, VSXC and B98 are also reasonable. The most reliable adiabatic electron affinities are predicted to be 1.864 eV ( CH 3 S ), 1.946 eV ( C 2 H 5 S ), 1.959 eV (n- C 3 H 7 S ), 1.970 eV (n- C 4 H 9 S ), 1.982 eV (n- C 5 H 11 S ), 2.053 eV (i- C 3 H 7 S ), 1.991 eV (i- C 4 H 9 S ) and 2.100 eV (t- C 4 H 9 S ) at the M06/DZP++ level of theory, respectively.

Ab Initio Calculations of the Molecular Structures and the Electronic Properties of Sulfur-containing Compounds: III. Thioacrolein (CH2=CH–CH=S) and Thioglyoxal (S = CH–CH=S)

1982 ◽  
Vol 37 (2) ◽  
pp. 125-128
Author(s):  
Tae-Kyu Ha ◽  
M. T. Nguyen ◽  
L. Vanquickenborne
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electronic Properties ◽  
Gradient Method ◽  
Molecular Structures ◽  
Basis Set ◽  
Double Zeta ◽  
Scf Calculations ◽  
Sulfur Containing ◽  
Sulfur Containing Compounds

Abstract Results of ab initio SCF calculations on thioacrolein (CH2=CH-CH=S) and thioglyoxal (S=CH-CH=S) are reported. The geometries are optimized by the analytical gradient method using the double zeta (DZ) basis set. The trans conformers of these molecules are calculated to be more stable than the cis conformer by 2.06 and 4.31 kcal/mol, respectively.

scholarly journals DFT study of Anti Sars-Cov-2 EIDD-1931 and EIDD-2801 molecular structures

2020 ◽  
Author(s):  
Antonio L. de Almeida ◽  
João B. L. Martins
Keyword(s):  
Antiviral Activity ◽  
Electronic Properties ◽  
Molecular Structures ◽  
Basis Set ◽  
Dft Study ◽  
B3lyp Functional ◽  
Structural And Electronic Properties ◽  
The World

Scientists around the world are joining efforts in the study of the current SARS-CoV-2 virus and the Covid-19 disease. As a result, several compounds have been studied for the treatment of SARS-CoV-2, among them there are N4-hydroxycytidine prodrug (NHC; EIDD-1931), and EIDD-2801, that have shown antiviral activity against SARS-CoV-2. We have studied the structural and electronic properties of these molecules using B3LYP functional and aug-cc-pVDZ basis set.

Density functional theory studies of conformational stabilities and rotational barriers of 2- and 3-thiophenecarboxaldehydes

2016 ◽  
Vol 57 (8) ◽  
pp. 1640
Author(s):  
Y. Umar ◽  
J. Tijani ◽  
S. Abdalla
Keyword(s):  
Density Functional ◽  
Dipole Moments ◽  
Structural Parameters ◽  
Conformational Stability ◽  
Energy Difference ◽  
Polarizable Continuum Model ◽  
Molecular Structures ◽  
Basis Set ◽  
Potential Energy Distribution ◽  
Vibrational Wavenumbers

The molecular structures, conformational stabilities, and infrared vibrational wavenumbers of 2-thiophenecarboxaldehyde and 3-thiophenecarboxaldehyde are computed using Becke-3—Lee—Yang—Parr (B3LYP) with the 6-311++G** basis set. From the computations, cis-2-thiophenecarboxaldehyde is found to be more stable than the transfer conformer with an energy difference of 1.22 kcal/mol, while trans-3-thiophenecarboxaldehyde is found to be more stable than the cis conformer by 0.89 kcal/mol. The computed dipole moments, structural parameters, relative stabilities of the conformers and infrared vibrational wavenumbers of the two molecules coherently support the experimental data in the literature. The normal vibrational wavenumbers are characterized in terms of the potential energy distribution using the VEDA4 program. The effect of solvents on the conformational stability of the molecules in nine different solvents is investigated using the polarizable continuum model.

Observational studies of imperfect carbon cage structures of C 60 by high-resolution scanning tunnelling microscopy

1994 ◽  
Vol 444 (1921) ◽  
pp. 325-332 ◽  
Keyword(s):  
High Resolution ◽  
Molecular Orbitals ◽  
Scanning Tunnelling Microscopy ◽  
Carbon Cage ◽  
Scanning Tunnelling ◽  
Tunnelling Microscopy ◽  
Dynamics Simulations ◽  
First Time ◽  
Highest Occupied Molecular Orbitals ◽  
Lowest Unoccupied Molecular Orbitals

Anomalies in the morphology of the carbon cage of C 60 clusters have been investigated with atomic level resolution using high-resolution scanning tunnelling microscopy. The imperfect carbon cages have been resolved in the finest detail, which, for the first time, provide a remarkable confirmation of a variety of theoretical defect structures recently predicted by molecular dynamics simulations. The observed tunnelling spectra are consistent with the theoretical contention that the gap between the highest occupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitals (LUMO) for the clusters is decreased with the presence of defects.

scholarly journals Prototropic and metallotropic migration of isolobal fragments on indol rings. Theoretical study and NBO analysis

2009 ◽  
Vol 5 (1) ◽  
pp. 614-625
Author(s):  
Saeed Jameh-Bozorghi ◽  
Zahra Javanshir ◽  
D. Nori Shargh
Keyword(s):  
Activation Energy ◽  
Ambient Temperature ◽  
Ab Initio ◽  
Theoretical Study ◽  
Nbo Analysis ◽  
Molecular Structures ◽  
Basis Set ◽  
Lower Amount ◽  
Temperature Calculation ◽  
Calculation Results

Molecular structures, energies, NBO analysis and sigmatropic behaviour of 1-Indenyl(dihydro)borane (1) and 1-Indenyl-threecarbonylcobalt(I) (2) were investigated using DFT and ab initio molecular orbital methods. In these compounds BH2 and Co(CO)3 fragments areisolobal. The Results of calculations using B3LYP, HF and MP2methods [Basis set 6-311+G**] showed that -BH2 and -Co(CO)3 had similar behaviour in sigmatropic shifts. Prototropic shifts in compounds 1 and 2 have similar mechanisms too. Results showed that metallotrotropic shift is faster than Prototrpic shift in compounds 1 and 2. The activation energies (Ea) of Prototropic shift in compounds 1 and 2 are 18.83 and 17.38 kcal.mol-1. These energies are higher than -BH2 shifts in compound 1 (10.11 kcal.mol-1) or migration of -Co(CO)3 fragment in compound 2 (12.39 kcal.mol-1). Lower amount of activation energy in borotropic shift and cobalt`s fragment shift show that rotation of boron and cobalt on the indol ring can happen in the ambient temperature. Calculation results revealed that migration of proton and Co(CO)3 was carried out via suprafacial[1,2]-sigmatropic mechanism while -BH2 shift took place via antrafacial [1,3]-rearangment. 

Experimental (FT-IR, Laser-Raman and NMR) and theoretical spectroscopic analysis of 3-[(N-methylanilino)methyl]-5-(thiophen-2-yl)-1,3,4-oxadiazole-2(3H)-thione

2017 ◽  
Vol 16 (03) ◽  
pp. 1750024 ◽  
Author(s):  
Yusuf Sert ◽  
Nuri Öztürk ◽  
Fatmah A. M. Al-Omary ◽  
Can Alaşalvar ◽  
Mona M. Al-Shehri ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Chemical Shifts ◽  
Molecular Structures ◽  
Basis Set ◽  
Spectroscopic Techniques ◽  
Nmr Chemical Shifts ◽  
Laser Raman ◽  
Ft Ir ◽  
Experimental Values ◽  
Vibrational Wavenumbers

The structure of a potential bioactive agent namely, 3-[([Formula: see text]-methylanilino)methyl]-5-(thiophen-2-yl)-1,3,4-oxadiazole-2(3[Formula: see text]-thione was characterized by proton and carbon-13 nuclear magnetic resonance (NMR) chemical shifts, Fourier transform infrared (FT-IR) and Laser-Raman spectroscopic techniques. The quantum chemical computations of molecular structures (disorder I and disorder II forms), vibrational wavenumbers, carbon-13 and proton chemical shifts and UV-Vis spectroscopic parameters have been performed with DFT/B3LYP method at 6-311[Formula: see text]G(d,p) basis set. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), nonlinear optical (NLO) properties and natural bond orbital (NBO) analyses have been theoretically examined with the mentioned calculation level. The calculated values have been compared with the recorded experimental data. The computed molecular geometric parameters, vibrational wavenumbers, NMR chemical shifts, and UV-Vis wavelengths have been found to be in a good harmony with the experimental values and spectral results of similar structures in the literature. We believe that the work will be of considerable interest to anyone working in the area of theoretical chemistry, whether in industry or academics.

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