scholarly journals A computational NPA and NMR study of Li-capped armchair GaN nanotubes

2010 ◽  
Vol 8 (4) ◽  
pp. 913-918 ◽  
Author(s):  
Ahmad Seif ◽  
Temer Ahmadi
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Geometrical Structure ◽  
Population Analysis ◽  
Dft Method ◽  
Basis Sets ◽  
Chemical Shielding ◽  
Natural Population Analysis ◽  
Nmr Parameters ◽  
Nmr Study ◽  
First Time

AbstractThe geometrical structure, the nuclear magnetic resonance (NMR) parameters and natural population analysis (NPA) of the H-capped (raw) and Li-capped armchair single-walled gallium nitride nanotubes (GaNNTs) are computed and reported for the first time. Our results show that the variation of isotropic chemical shielding (ICS) parameters at the sites of 15N and 71Ga along the length of both models-raw and Li-capped- are reversed. The calculations were carried out with B3LYP-DFT method and 6–31G (d) standard basis sets using the Gaussian 03 suite of programs.

Density functional theory study of the geometrical and electronic structures of GenV(0,±1)(n=1–9) clusters

2017 ◽  
Vol 31 (05) ◽  
pp. 1750022 ◽  
Author(s):  
Shun-Ping Shi ◽  
Yi-Liang Liu ◽  
Bang-Lin Deng ◽  
Chuan-Yu Zhang ◽  
Gang Jiang
Keyword(s):  
Density Functional Theory ◽  
Natural Population ◽  
Density Functional ◽  
Population Analysis ◽  
Basis Sets ◽  
Functional Theory ◽  
Natural Population Analysis ◽  
B3lyp Level ◽  
Calculation Results ◽  
Homo Lumo

Geometrical and electronic properties of Ge[Formula: see text]V[Formula: see text] clusters containing 1–9 Ge atoms and one V atom are calculated by using density functional theory (DFT) at the B3LYP level and the LanL2DZ basis sets. The growth pattern behavior, natural population analysis, relative stability, electronic property and magnetism of these clusters are discussed in detail. The calculation results of the geometrical show that the relative stable structures of Ge[Formula: see text]V[Formula: see text] clusters adopt 3D structures from [Formula: see text] to [Formula: see text]. The results of natural population analysis show that electrons transfer from the Ge atoms to the V atoms when [Formula: see text] while the electrons transfer from the V atoms to the Ge atoms when [Formula: see text]. The Ge[Formula: see text]V[Formula: see text] clusters possess higher stability and the GeV[Formula: see text], Ge3V[Formula: see text], Ge5V[Formula: see text], Ge7V[Formula: see text], and Ge9V[Formula: see text] have larger HOMO–LUMO gaps. Furthermore, the VIPs of Ge[Formula: see text]V clusters show a reverse trend in contrast to the AIPs.

Basis Sets and Nuclear Magnetic Resonance Shielding Effects for Mixing of MWBN and CNTs

2016 ◽  
Vol 13 (10) ◽  
pp. 6440-6445
Author(s):  
Roghieh Tarlani Bashiz ◽  
Sara Shahriari ◽  
Neda Samiei Soofi ◽  
Naime Attarikhasraghi ◽  
Maryam Ahadi ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Hybrid Methods ◽  
Atomic Orbital ◽  
Density Functional Theory Calculations ◽  
Basis Sets ◽  
Chemical Shielding ◽  
Functional Theory ◽  
Nmr Parameters ◽  
Shielding Effects

Density functional theory calculations (DFT), as well as hybrid methods (B3LYP) and HF method for MWCNTs have been carried out to study structural stability. The geometry of the MWCNTs have been optimized at DFT and HF methods within CCPTZ-CCPVZ, EPR-II, EPR-II, 6-31G* and 6-31++G** basis sets. According to GIAO method, NMR parameters have been evaluated. The Gaussian quantum chemical package is used for all calculations. The gauge including atomic orbital (GIAO) approach was applied for chemical shielding calculations of (5, 5)@(10, 10), (3, 3)@(7, 7), (4, 4)@(8, 8) DWCNTs.

A Computational Study on Structural and Electronic Properties of 1-(4-Chlorophenyl)-2-{[5-(4-Chlorophenyl)-1,2,3-Oxadiazol-2-Yl]Sulfanyl}Ethanone

2019 ◽  
Vol 892 ◽  
pp. 1-7
Author(s):  
Pek Lan Toh ◽  
Montha Meepripruk ◽  
Rosfayanti Rasmidi
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Molecular System ◽  
Population Analysis ◽  
Atomic Charge ◽  
Dft Method ◽  
Basis Sets ◽  
Hydrogen Atoms ◽  
Mulliken Population ◽  
Total Energies

In this paper, a first principle Density Functional Theory (DFT) method was conducted to study the geometric and electronic structures of 1-(4-chlorophenyl)-2-{[5-(4-chlorophenyl) -1,3,4-oxadiazol-2-yl] sulfanyl} ethanone, C16H10Cl2N2O2S. Using B3LYP level of theory with four basis sets of 6-31G**, 6-31++G**, 6-311G**, and 6-311++G**, the equilibrium structure of the title molecule was used to determine the total energies, Frontier molecular orbital’s energies, Mulliken atomic charges, and others. The computed findings present that four total energies obtained are close to each other, with the corresponding values of-59716.06 eV, -59709.42 eV, -59708.56 eV, and-59716.51 eV, respectively for B3LYP/6-31G**, B3LYP/6-31++G**, B3LYP/6-311G**, and B3LYP/6-311++G** methods. The calculated HOMO-LUMO energy gaps were predicted in the range of 4.001 eV - 4.089 eV. In this study, the atomic charge values of molecular system were also determined using Mulliken Population Analysis (MPA) approach. For DFT/B3LYP/6-311G** level of calculation, the computed results show that the atom of C8 accommodates the highest negative charge in the title molecular system. All the oxygen, nitrogen, and chloride atoms are having negative charges, whereas all the hydrogen atoms are having positive charges. In addition, the dipole moment value was also determined to be 1.4758 Debye by employing DFT/B3LYP/6-311G** level of theory.

Theoretical study of metallasilatranes; Bonding nature and prediction of new metallasilatrane

2011 ◽  
Vol 76 (5) ◽  
pp. 619-629 ◽  
Author(s):  
Shigeyoshi Sakaki ◽  
Daisuke Kawai ◽  
Shinya Tsukamoto
Keyword(s):  
Charge Transfer ◽  
Dft Calculation ◽  
Theoretical Study ◽  
Population Analysis ◽  
Dft Method ◽  
Basis Sets ◽  
Equilibrium Geometry ◽  
Polarization Function ◽  
Species Population ◽  
Polarization Functions

The new bond between Pt atom and hypervalent six-coordinate Si species in platinum-silatrane reported recently was theoretically investigated mainly with DFT method and in part with MP2 method. The DFT method with B3PW91 and M06 functionals reproduces well the Pt–Si, Pt–Cl and Si–N bond distances. Though the Si–Cl distance is overestimated by all functionals employed here when one d polarization function is added to each of Si and Cl, the M06-optimized Si–Cl distance is close to the experimental value when two d polarization functions are added to each of Si and Cl, suggesting that the functional and basis sets must be carefully employed in theoretical calculation of hypervalnet six-coordinate Si species. Population analysis clearly indicates that the Pt–Si bond is formed by the charge-transfer (CT) from the occupied dσ orbital of Pt to the empty p orbital of Si, which enhances the CT from the S atoms and Cl ligand to the Pt center. Besides platinum- and palladium-silatranes, no metallasilatrane has been reported so far. Based on the knowledge of bonding nature, we presented theoretical prediction that iridium(I) can form a similar metallasilatrane. Actually, the DFT calculation indicates that iridium-silatrane has essentially the same equilibrium geometry and bonding nature as those of platinum-silatrane.

Phosphorus-31 chemical shieldings in a fused cis-1,2,3-benzothiadiphosphole: a dipolar NMR study

1992 ◽  
Vol 70 (4) ◽  
pp. 1229-1235 ◽  
Author(s):  
Gang Wu ◽  
Roderick E. Wasylishen ◽  
William P. Power ◽  
Graziano Baccolini
Keyword(s):  
Line Shape ◽  
Magic Angle Spinning ◽  
Pair Approximation ◽  
Magic Angle ◽  
Single Bond ◽  
Chemical Shielding ◽  
Spin Pair ◽  
Nmr Study ◽  
Shielding Tensors ◽  
Angle Spinning

Phosphorus-31 NMR static powder spectra and high-resolution magic angle spinning spectra have been obtained for a new heterocyclic compound, cis-2,10-dimethyl[1,2,3]benzothiadiphospholo[2,3b][1,2,3]benzothiadiphosphole (1), which contains a P(III)—P(III) single bond. The homonuclear 31P–31P dipolar interaction manifests itself in both the magic angle spinning spectra and the non-spinning line shape. Under the AX spin pair approximation, analysis of the spinning sidebands in the MAS experiment yields a full characterization of the two 31P chemical shielding tensors. This approximation is confirmed by the exact powder line shape simulation for a homonuclear spin pair. Analysis of the dipolar subspectra also yields the absolute sign of 1J(P,P), which is found to be negative. Keywords: phosphorus–phosphorus single bond, chemical shielding tensors, dipolar NMR, MAS, static line shape.

scholarly journals A proton NMR study of the effect of a new intravasal injectable male contraceptive RISUG on seminal plasma metabolites

Reproduction ◽  
2001 ◽  
pp. 431-436 ◽  
Author(s):  
U Sharma ◽  
K Chaudhury ◽  
NR Jagannathan ◽  
SK Guha
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Seminal Plasma ◽  
Vas Deferens ◽  
Plasma Metabolites ◽  
Obstructive Azoospermia ◽  
Male Contraceptive ◽  
Nmr Study ◽  
Significant Difference ◽  
Styrene Maleic Anhydride ◽  
Prostatic Diseases

Nuclear magnetic resonance (NMR) spectroscopy was used to quantify citrate, glucose, lactate, glycerophosphorylcholine and choline in seminal plasma from subjects injected with a new male contraceptive RISUG, a copolymer of styrene maleic anhydride dissolved in dimethyl sulphoxide, and in seminal plasma from normal ejaculates. No significant difference in the concentration of citrate was observed between the groups, indicating that the prostate is not affected by the contraceptive. The concentrations of glucose, lactate, glycerophosphorylcholine and choline were significantly lower (P < 0.01) in subjects injected with RISUG compared with controls. In addition, metabolite ratios such as choline:citrate, citrate:lactate, choline:lactate and glycerophosphorylcholine:choline were calculated. Citrate:lactate and glycerophosphorylcholine:choline ratios were significantly lower in RISUG-injected subjects than in controls (P < 0.01), thereby indicating the occurrence of partial obstructive azoospermia. The most important finding of the present study was that the intervention of RISUG in the vas deferens even for a period as long as 8 years is absolutely safe and does not lead to prostatic diseases.

scholarly journals Synthesis, Modeling Study and Antioxidants Activity of New Heterocycles Derived from 4-Antipyrinyl-2-Chloroacetamidothiazoles

2018 ◽  
Vol 8 (11) ◽  
pp. 2128 ◽  
Author(s):  
Sraa Abu-Melha
Keyword(s):  
Antioxidant Activity ◽  
Dipole Moments ◽  
Ammonium Thiocyanate ◽  
Dft Method ◽  
Basis Sets ◽  
Spectroscopic Techniques ◽  
Mass Analysis ◽  
Antioxidants Activity ◽  
Material Studio ◽  
Properties Of Materials

The present work reports the preparation of twelve new heterocyclic scaffolds containing an antipyrinyl-thiazole hybrid through the reaction of 4-antipyrinyl-2-chloroacetamido-thiazoles 1 and 6 with various types of nucleophiles, namely; ethyl thioglycolate, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, ammonium thiocyanate, malononitrile, and salicylaldehyde. The constructed compounds were characterized by conventional spectroscopic techniques (IR, 1H NMR, 13C NMR, and mass analysis). A DFT method (material studio package) was used to predict the geometry, bond lengths, bond angles, and dipole moments as well as other global chemical reactivities of the constructed antipyrinyl-thiazole compounds. Also, their semi-core pseudopods calculations (dspp) were carried out with DNP (double numerical basis sets plus polarization functional) to predict the properties of materials. In addition, the antioxidant activity of these antipyrinyl-thiazole scaffolds has been screened by the ABTS method. The results indicated that 2-(4-antipyrinylthiazolylamino)-5-substituitedbenzylidene-thiazol-4(5H)-ones 10b and 10c exhibited the best antioxidant activity with a percentage inhibition of 85.74% and 83.51%, respectively.

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