scholarly journals Quantum Chemical Study of Mixed-Ligand Monometallic Ruthenium(II) Complex of Composition [(bpy)2Ru(H3Imbzim)](ClO4)2·2H2O

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Mohsin Yousuf Lone ◽  
Prakash Chandra Jha
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Mixed Ligand ◽  
Excitation Energies ◽  
Functional Theory ◽  
Effect Of Solvent ◽  
The Density Functional Theory ◽  
Metal Ligand

On the basis of density functional theoretical approach, we have assessed the ground state geometries and absorption spectra of recently synthesized monometallic ruthenium (II) complex of composition [(bpy)2Ru(H3Imbzim)](ClO4)2·2H2O where bpy = 2,2′-bypyridine and H3Imbzim = 4,5-bis(benzimidazol-2-yl)imidazole. The all different kinds of charge transfers such as ligand-ligand, and metal-ligand have been quantified, compared, and contrasted with the experimental results. In addition, the effect of solvent on excitation energies has been evaluated. In spite of some digital discrepancies in calculated and observed geometries, as well as in absorption spectra, the density functional theory (DFT) seems to explain the main features of this complex.

Quantum-chemical study of nitrogen and magnesium co-doping in α-Cr2O3

2016 ◽  
Vol 30 (14) ◽  
pp. 1650219
Author(s):  
Soraya Jácome ◽  
Arvids Stashans
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Text Type ◽  
Co Doping ◽  
The Density Functional Theory

Study of corundum-type chromium oxide ([Formula: see text]-Cr2O3) crystal doped with the nitrogen and magnesium impurities has been carried out through the use of first-principles calculations based on the density functional theory (DFT) and generalized gradient approximation (GGA). Three cases corresponding different impurity–impurity distances have been considered. Structural, electronic and magnetic properties have been studied for all co-doping cases. The [Formula: see text]-type electrical conductivity was found when distance between the Mg and N atoms is equal to 4.10 Å. The results obtained are consistent with the available experimental data.

scholarly journals A GRADIENT-CORRECTED HYBRID HF–DFT STUDY OF STRUCTURE AND VIBRATIONAL SPECTROSCOPIC PROPERTIES OF THE DICHLORODIOXOCHROMIUM(VI) COMPLEX WITH 1,10-PHENANTHROLINE

2017 ◽  
Vol 27 (1-2) ◽  
Author(s):  
Ljupčo Pejov ◽  
Mira Trpkovska ◽  
Bojan Šoptrajanov
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Dft Method ◽  
Chemical Study ◽  
Spectroscopic Properties ◽  
Stationary Points ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Gradient Optimization

A b s t r a c t: In order to get a more exact basis for the band assignments in the case of dichlorodioxochromium(VI) complex with 1,10-phenanthroline (especially regarding the order of appearance of the antisymmetric and symmetric CrO2 stretching bands) a quantum chemical study of this system was carried out. Two levels of theory were employed – the HF/6-31++G(d,p) and the density-functional-theory-based (DFT) method B3–LYP/6- 31++G(d,p). Full geometry optimizations of the title complex were carried out, employing Schlegel's gradient optimization algorithm. Harmonic vibrational analyses of the stationary points located on both potential energy hypersurfaces were subsequently carried out in order to test their character and to compute the harmonic vibrational frequencies of the complex. Predictions of the ab initio and DFT quantum chemical approaches regarding the order of appearance of the antisymmetric and symmetric CrO2 stretching bands in the case of the studied complex were compared to the cases of analogous 2,2'-bipyridine and 2,2'-biquinoline complexes containing the CrO2 group, which were previously studied by us [1–6].

scholarly journals Quantum Chemical Study of Spin Transitions in the Bimetallic Fe/Co Complexes with the Bis(catecholate) Bridging Ligand

2021 ◽  
Vol 47 (9) ◽  
pp. 601-609
Author(s):  
M. G. Chegerev ◽  
A. G. Starikov ◽  
A. A. Starikova
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Density Functional Theory Method ◽  
Chemical Study ◽  
Functional Theory ◽  
Energy Characteristics ◽  
Bridging Ligand ◽  
The Density Functional Theory ◽  
Spin Transitions

Abstract The computational modeling of the spatial and electronic structures, energy characteristics, and magnetic properties of the bimetallic iron and cobalt complexes with 9,10-dimethyl-9,10-ethano-9,10-dihydro-2,3,6,7-tetrahydroxyanthracene and terminal tris(2-pyridylmethyl)amine bases is performed using the density functional theory method (DFT UTPSSh/6-311++G(d,p)). The chosen tetradentate redox ligand is shown to be a promising precursor for the production of magnetically active compounds. The calculations make it possible to establish a relationship between the relative energies of the electronic isomers of the complexes and the structures of the ancillary N-donor moieties. The coordination compounds prone to the manifestation of spin transitions accompanied by a change in the magnetic properties are revealed.

Structures and Absorption Spectrum of 1D and 2D ZnS Nanoparticles

2020 ◽  
Vol 5 (1) ◽  
pp. 26-35
Author(s):  
Spyros Papantzikos ◽  
Alexandos G. Chronis ◽  
Fotios I. Michos ◽  
Mihail M. Sigalas
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Toxic Elements ◽  
Visible Region ◽  
Visible Spectrum ◽  
Zns Nanoparticles ◽  
Major Drawback ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Optimized Geometries

Background: ZnS nanoparticles (NPs) are attractive for quantum dots applications because they consist of abundant and non-toxic elements. Their major drawback is that they absorb in the UV region, ultimately limiting their applications. Objective: In the present study, 1D and 2D ZnS NPs have been found. The goal of this study is to find NPs that have absorption in the visible spectrum. Methods: Calculations based on the Density Functional Theory (DFT) have been used to find the optimized geometries. Their absorption spectra have been calculated with the Time-Dependent DFT. Results: Several shapes were examined, such as nanorod, and it is observed that these shapes move the absorption spectra in lower energies, into the visible spectrum, while the 3D NPs have absorption edges in the UV region. Conclusion: NPs with the shape of nanorod in different directions showed that their absorption spectra moved to lower energies well inside the visible spectrum with significantly high oscillator strength. In contrast with the mostly used CdSe NPs, the ZnS NPs are made from more abundant and less toxic elements. Therefore, by making them absorb in the visible region, they may find significant applications in solar cells and other photonic applications.

scholarly journals Structural, Electronic, and Vibrational Properties of Isoniazid and Its Derivative N-Cyclopentylidenepyridine-4-carbohydrazide: A Quantum Chemical Study

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Anoop kumar Pandey ◽  
Abhishek Bajpai ◽  
Vikas Baboo ◽  
Apoorva Dwivedi
Keyword(s):  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Basis Sets ◽  
Ground State Structure ◽  
Vibrational Modes ◽  
Functional Theory ◽  
Complete Assignment ◽  
Experimental Values ◽  
Homo Lumo

Isoniazid (Laniazid, Nydrazid), also known as isonicotinylhydrazine (INH), is an organic compound that is the first-line medication in prevention and treatment of tuberculosis. The optimized geometry of the isoniazid and its derivative N-cyclopentylidenepyridine-4-carbohydrazide molecule has been determined by the method of density functional theory (DFT). For both geometry and total energy, it has been combined with B3LYP functionals having LANL2DZ and 6-311 G (d, p) as the basis sets. Using this optimized structure, we have calculated the infrared wavenumbers and compared them with the experimental data. The calculated wavenumbers by LANL2DZ are in an excellent agreement with the experimental values. On the basis of fully optimized ground-state structure, TDDFT//B3LYP/LANL2DZ calculations have been used to determine the low-lying excited states of isoniazid and its derivative. Based on these results, we have discussed the correlation between the vibrational modes and the crystalline structure of isoniazid and its derivative. A complete assignment is provided for the observed FTIR spectra. The molecular HOMO, LUMO composition, their respective energy gaps, and MESP contours/surfaces have also been drawn to explain the activity of isoniazid and its derivative.

scholarly journals The transition metal to ligand bonding nature: A quantum chemical study of π-allyl-ruthenacycle molecule

2018 ◽  
Vol 58 (3) ◽  
Author(s):  
Aušra Vektarienė
Keyword(s):  
Transition Metal ◽  
Physical Properties ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Decomposition Analysis ◽  
Computational Procedure ◽  
Chemical Study ◽  
Hartree Fock ◽  
Charge Decomposition Analysis ◽  
The Density Functional Theory

Understanding of the transition metal (TM) to ligand (L) bonding nature is important for characterization of experimental observations. One of the methods to explain the TM to L interactions is the Dewar–Chatt–Duncanson (DCD) model. However, in most applications the validity of the DCD model is based on assumptions in order to explain trends in vibrational spectroscopy or other physical properties of TM complexes. In this paper the computational methodology for treatment of the π-allyl-ruthenacycle complex based on the density functional theory, restricted Hartree–Fock method, natural bond orbital and charge decomposition analysis is reported. It is shown how the DCD model emerges from the presented calculation scheme and how it relates with the physical properties and stability of this complex. It is important to note that in this work the determination of the DCD model operation is based on the defined computational procedure, not postulated beforehand. The calculated geometry parameters, vibrational frequencies and electron density arrangement for the π-allyl-ruthenacycle complex are in good agreement with the experiment and support the DCD model.

Effective corrosion inhibition of mild steel in acidic medium using inexpensive kermes natural dye: experimental and quantum chemical study

2018 ◽  
Vol 65 (6) ◽  
pp. 626-636 ◽  
Author(s):  
Nobl F. El Boraei ◽  
Shimaa Abdel Halim ◽  
Magdy A.M. Ibrahim
Keyword(s):  
Mild Steel ◽  
Corrosion Inhibition ◽  
Density Functional ◽  
Steel Surface ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Functional Theory ◽  
Content Type ◽  
Visible Spectra ◽  
Corrosion Of Steel

PurposeThe purpose of this paper is to test the Natural Kermes dye (NKD) as a cheap and stable corrosion inhibitor for mild steel in 1.0 M HCl and its adsorption mechanism on the steel surface.Design/methodology/approachThe inhibition action of NKD was studied using AC impedance, potentiodynamic polarization, scanning electron microscope (SEM) and UV-visible spectra techniques complemented with quantum study.FindingsHere, the authors show that addition of NKD inhibits effectively the corrosion of steel in HCl solution via its adsorption on the steel surface. The inhibition efficiency of NKD increases with increase in its concentration and decreases with temperature. Potentiodynamic results revealed that NKD acts as a mixed–type inhibitor. Thermodynamic parameters for corrosion and adsorption process were obtained from the experimental data. Moreover, the experimental inhibition efficiencies were correlated with the electronic properties of NKD using density functional theory.Originality/valueTo the best of the authors’ knowledge, this is the first report showing the effect of NKD on the corrosion inhibition of steel.

scholarly journals Photo-Induced Charge Separation vs. Degradation of a BODIPY-Based Photosensitizer Assessed by TDDFT and RASPT2

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 520 ◽  
Author(s):  
Karl Ziems ◽  
Stefanie Gräfe ◽  
Stephan Kupfer
Keyword(s):  
Density Functional ◽  
Parent Compound ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Catalytic Performance ◽  
Triplet States ◽  
Spin Orbit Coupling ◽  
Functional Theory ◽  
Component Approach ◽  
Turn Over

A meso-mesityl-2,6-iodine substituted boron dipyrromethene (BODIPY) dye is investigated using a suite of computational methods addressing its functionality as photosensitizer, i.e., in the scope of light-driven hydrogen evolution in a two-component approach. Earlier reports on the performance of the present iodinated BODIPY dye proposed a significantly improved catalytic turn-over compared to its unsubstituted parent compound based on the population of long-lived charge-separated triplet states, accessible due to an enhanced spin-orbit coupling (SOC) introduced by the iodine atoms. The present quantum chemical study aims at elucidating the mechanisms of both the higher catalytic performance and the degradation pathways. Time-dependent density functional theory (TDDFT) and multi-state restricted active space perturbation theory through second-order (MS-RASPT2) simulations allowed identifying excited-state channels correlated to iodine dissociation. No evidence for an improved catalytic activity via enhanced SOCs among the low-lying states could be determined. However, the computational analysis reveals that the activation of the dye proceeds via pathways of the (prior chemically) singly-reduced species, featuring a pronounced stabilization of charge-separated species, while low barriers for carbon-iodine bond breaking determine the photostability of the BODIPY dye.

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