Theoretical and experimental studies of IR and NMR spectra of gem-2,2-diamino-4,4,6,6-tetraphenoxy-1,3,5-cyclo-triaza-λ5-phosphorine

2010 ◽  
Vol 75 (11) ◽  
pp. 1125-1138
Author(s):  
Lenka Dastychová ◽  
Dalibor Dastych ◽  
Pavel Kubáček ◽  
Milan Alberti
Keyword(s):  
Density Functional ◽  
Nmr Spectra ◽  
Experimental Studies ◽  
Normal Modes ◽  
Chemical Calculation ◽  
Functional Theory ◽  
Calculation Results ◽  
Vibrational Bands ◽  
First Time ◽  
C Nmr

The vibrational spectra of gem-2,2-diamino-4,4,6,6-tetraphenoxy-1,3,5-cyclo-triaza-λ5-phosphorine were studied using density functional theory. Selected vibrational bands were assigned to normal modes on the basis of DFT calculation with the ADF program package. The 1H and 13C NMR spectra, the higher order 31P, 31P{1Ham.(sel.)} and 31P{1Harom.(sel.)} NMR spectra were measured and the values of 1J(C,H), 2J(C,H) and 2J(PI,PII) were found. Nearly the complete spin system (ABB′M4X4X4′) for the symmetry C2 was simulated with the gNMR simulation program and the values of 2J(PI,Ham.), 4J(PII,Ham.), 4J(PII,Harom.), 6J(PI,Harom.) and 6J(PII,H′arom.) were determined for the first time. The experimental NMR data were also compared with quantum chemical calculation results.

Structures, Theoretical Vibrational Frequency and 1H-NMR Spectral Analysis of Pyrazine-Dibenzylsulfoxide Platinum(II) Complexes

2011 ◽  
Vol 391-392 ◽  
pp. 1375-1382
Author(s):  
Zheng Ping Wu ◽  
Ian S. Butler
Keyword(s):  
Vibrational Frequency ◽  
Density Functional ◽  
Nmr Spectra ◽  
Mixed Ligand ◽  
High Symmetry ◽  
Dft Methods ◽  
Functional Theory ◽  
H Nmr ◽  
Calculation Results ◽  
Cis And Trans

Mixed-ligand Pt(II) complexes containing pyrazine (C4N2H4, pz) and dibenzyl sulfoxide [C6H5CH2)2SO, DBzSO] ligands have been studied using density functional theory (DFT) methods with a particular emphasis on the theoretical1H-NMR spectra of the methylene protons. The DFT optimization calculations on Pt(DBzSO)Cl2(pz) and {Pt(DBzSO)Cl2}2(pz) predicted the structure parameters, vibrational frequency and1H-NMR spectra. Different structures of DBzSO will affect the bond lengths and angles in the complexes, except for the pz ligands. The [shift(Pt(II)complex)-shift(sulfoxide)] values of trans-Pt(DBzSO)(pz)Cl2were smaller than those for cis-Pt(DBzSO)(pz)Cl2and the calculation results appear to be reasonable. The1H-NMR spectra of the methylene protons of cis- and trans-{Pt(DBzSO)Cl2}2(pz) indicate that these two structures have high symmetry.

Conformational stability, barriers to internal rotations, and normal coordinate analysis of acetone and its2H-isotopomers

2016 ◽  
Vol 94 (10) ◽  
pp. 818-826 ◽  
Author(s):  
Mahboobeh Gholamhoseinpour ◽  
Sayyed Faramarz Tayyari ◽  
Saeedreza Emamian
Keyword(s):  
Density Functional ◽  
Conformational Stability ◽  
Normal Modes ◽  
Normal Coordinate Analysis ◽  
Basis Set ◽  
Basis Sets ◽  
Potential Energy Distribution ◽  
Normal Coordinate ◽  
Functional Theory ◽  
Vibrational Bands

Molecular structure and vibrational spectra of acetone, acetone-d3, and acetone-d6were investigated by means of ab initio and density functional theory (DFT) calculations. The harmonic and anharmonic vibrational frequencies of the acetone isotopomers were calculated at the B3LYP (using the 6–311++G(3df,3pd) basis set) and B2PLYP (using the 6–31+(2d,p) and 6–311G(2df,p) basis sets) levels. The calculated frequencies and the Raman and infrared (IR) intensities were compared with the experimental results. Excellent agreement between calculated and observed vibrational wavenumbers was obtained. Additionally, a normal coordinate analysis (NCA) was also done by using the normal mode eigenvectors obtained at the B3LYP/6–311++G(3df,3pd) level. All fundamental vibrational bands were assigned to the normal modes with the aid of the potential energy distribution (PED) values obtained from normal coordinate calculations. To study the internal rotation of CH3groups, single CH3rotation and synchronous rotations of both CH3groups (clockwise–clockwise and clockwise–counterclockwise) were analyzed using the MP2/6–311++G(3df,2pd) and B3LYP/6–311++G(3df,2pd) levels.

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 Single-crystalline epitaxial TiO film: A metal and superconductor, similar to Ti metal

2021 ◽  
Vol 7 (2) ◽  
pp. eabd4248
Author(s):  
Fengmiao Li ◽  
Yuting Zou ◽  
Myung-Geun Han ◽  
Kateryna Foyevtsova ◽  
Hyungki Shin ◽  
...  
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Tight Binding ◽  
Crystal Form ◽  
Titanium Monoxide ◽  
Binding Model ◽  
Functional Theory ◽  
Single Crystalline ◽  
First Time ◽  
Lattice Matched

Titanium monoxide (TiO), an important member of the rock salt 3d transition-metal monoxides, has not been studied in the stoichiometric single-crystal form. It has been challenging to prepare stoichiometric TiO due to the highly reactive Ti2+. We adapt a closely lattice-matched MgO(001) substrate and report the successful growth of single-crystalline TiO(001) film using molecular beam epitaxy. This enables a first-time study of stoichiometric TiO thin films, showing that TiO is metal but in proximity to Mott insulating state. We observe a transition to the superconducting phase below 0.5 K close to that of Ti metal. Density functional theory (DFT) and a DFT-based tight-binding model demonstrate the extreme importance of direct Ti–Ti bonding in TiO, suggesting that similar superconductivity exists in TiO and Ti metal. Our work introduces the new concept that TiO behaves more similar to its metal counterpart, distinguishing it from other 3d transition-metal monoxides.

scholarly journals Comparative Study on Electronic Structure and Optical Properties of α-Fe2O3, Ag/α-Fe2O3 and S/α-Fe2O3

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 424
Author(s):  
Cuihua Zhao ◽  
Baishi Li ◽  
Xi Zhou ◽  
Jianhua Chen ◽  
Hongqun Tang
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Electronic Structures ◽  
Density Functional ◽  
Peak Strength ◽  
Visible Range ◽  
High Symmetry ◽  
Functional Theory ◽  
Optical Absorption Peak ◽  
Calculation Results

The electronic structures and optical properties of pure, Ag-doped and S-doped α-Fe2O3 were studied using density functional theory (DFT). The calculation results show that the structure of α-Fe2O3 crystal changes after Ag and S doping, which leads to the different points of the high symmetry of Ag-doped and S-doped α-Fe2O3 with that of pure α-Fe2O3 in the energy band, as well as different Brillouin paths. In addition, the band gap of α-Fe2O3 becomes smaller after Ag and S doping, and the optical absorption peak shifts slightly toward the short wavelength, with the increased peak strength of S/α-Fe2O3 and the decreased peak strength of Ag/α-Fe2O3. However, the optical absorption in the visible range is enhanced after Ag and S doping compared with that of pure α-Fe2O3 when the wavelength is greater than 380 nm, and the optical absorption of S-doped α-Fe2O3 is stronger than that of Ag-doped α-Fe2O3.

Study on adsorption of CO and CO2 by graphene gas sensor

2021 ◽  
pp. 2150154
Author(s):  
Wenchao Tian ◽  
Jiahao Niu ◽  
Wenhua Li ◽  
Xiaohan Liu
Keyword(s):  
Gas Sensors ◽  
Active Sites ◽  
Density Functional ◽  
Gas Adsorption ◽  
Experimental Studies ◽  
Detection Accuracy ◽  
Functional Theory ◽  
Vacancy Defects ◽  
Adsorption Of Co ◽  
Detection Characteristics

The two-dimensional (2D) plane of graphene has many active sites for gas adsorption. It has broad application prospects in the field of MEMS gas sensors. At present, there are many experimental studies on graphene gas sensors, but it is difficult to accurately control various influencing factors in the experiments. Therefore, this paper applies the first principle based on density functional theory to study the adsorption and detection characteristics of graphene on CO and CO2. The first-principles analysis method was used to study the adsorption characteristics and sensitivity of graphene. The results show that the inductive graphene has a sensitivity of 1.55% and 0.77% for CO and CO2, respectively. The Stone–Wales defects and multi-vacancy defects have greatly improved the sensitivity of graphene to CO, which is 35.25% and 4.14%, respectively. Introduction of defects increases the sensitivity of detection of CO and CO2, but also improves the selective gas detection material of these two gases. Thus, the control and selectively introducing defects may improve the detection accuracy of the graphene CO and CO2.

Experimental and computational investigations of TiIrB: a new ternary boride with Ti1+x Rh2−x+y Ir3−y B3-type structure

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jan P. Scheifers ◽  
Kate A. Gibson ◽  
Boniface P. T. Fokwa
Keyword(s):  
Density Functional ◽  
Ternary Phase ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Arc Melting ◽  
Ternary Boride ◽  
Charge Analysis ◽  
First Time ◽  
Bader Charge Analysis

Abstract A new ternary phase, TiIrB, was synthesized by arc-melting of the elements and characterized by powder X-ray diffraction. The compound crystallizes in the orthorhombic Ti1+x Rh2−x+y Ir3−y B3 structure type, space group Pbam (no. 55) with the lattice parameters a = 8.655(2), b = 15.020(2), and c = 3.2271(4) Å. Density Functional Theory (DFT) calculations were carried out to understand the electronic structure, including a Bader charge analysis. The charge distribution of TiIrB in the Ti1+x Rh2−x+y Ir3−y B3-type phase has been evaluated for the first time, and the results indicate that more electron density is transferred to the boron atoms in the zigzag B4 units than to isolated boron atoms.

Thermodynamic Properties of CaSiO3 Perovskite at High Pressure and High Temperature

2009 ◽  
Vol 64 (5-6) ◽  
pp. 399-404 ◽  
Author(s):  
Zi-Jiang Liu ◽  
Xiao-Ming Tan ◽  
Yuan Guo ◽  
Xiao-Ping Zheng ◽  
Wen-Zhao Wu
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
High Pressures ◽  
Local Density ◽  
Harmonic Approximation ◽  
Debye Model ◽  
Functional Theory ◽  
Casio3 Perovskite ◽  
First Time

The thermodynamic properties of tetragonal CaSiO3 perovskite are predicted at high pressures and temperatures using the Debye model for the first time. This model combines the ab initio calculations within local density approximation using pseudopotentials and a plane wave basis in the framework of density functional theory, and it takes into account the phononic effects within the quasi-harmonic approximation. It is found that the calculated equation of state is in excellent agreement with the observed values at ambient condition. Based on the first-principles study and the Debye model, the thermal properties including the Debye temperature, the heat capacity, the thermal expansion and the entropy are obtained in the whole pressure range from 0 to 150 GPa and temperature range from 0 to 2000 K.

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