scholarly journals Incorporation of Iron(II) and (III) in Hydroxyapatite—A Theoretical Study

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1219
Author(s):  
Olga Nikolaevna Makshakova ◽  
Daria Vladimirovna Shurtakova ◽  
Alexey Vladimirovich Vakhin ◽  
Peter Olegovich Grishin ◽  
Marat Revgerovich Gafurov
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Potential Application ◽  
Density Functional ◽  
Theoretical Study ◽  
Charge Compensation ◽  
Comprehensive Analysis ◽  
Functional Theory ◽  
Experimental Works

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) doped with various transition metals has generated great interest in view of its potential application in a wide variety of fields, including in catalysis as a support with a series of attractive properties. Despite a large number of experimental works devoted to the synthesis and application of iron-substituted hydroxyapatites, problems concerning the location, introduced defects, and charge compensation schemes for Fe2+ and/or Fe3+ cations in the crystal structure of HAp remain unclear. This paper is devoted to the comprehensive analysis of iron (II) and (III) introduction into the HAp lattice by density functional theory (DFT) calculations. We show that the inclusion of Fe2+ in the Ca(1) and Ca(2) positions of HAp is energetically comparable. For the Fe3+, there is a clear preference to be included in the Ca(2) position. The inclusion of iron results in cell contraction, which is more pronounced in the case of Fe3+. In addition, Fe3+ may form a shorter linkage to oxygen atoms. The incorporation of both Fe2+ and Fe3+ leads to notable local reorganization in the HAp cell.

scholarly journals Structure and New Substructure of α-Ti2O3: X-ray Diffraction and Theoretical Study

2021 ◽  
Vol 8 (1) ◽  
pp. 3-11
Author(s):  
Soumia Merazka ◽  
Lamia Hammoudi ◽  
Mohammed Kars ◽  
Mohamed Sidoumou ◽  
Thierry Roisnel
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Relative Stability ◽  
Density Functional ◽  
Theoretical Study ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
High Coordination

The Crystal structure of both α-Ti2O3 and its new substructure with a halved c-axis has been investigated by single-crystal X-ray diffraction and density functional theory (DFT) calculations. The α-Ti2O3 substructure described in the R-3m space group, reveals an unusual 12-fold high coordination of Ti atoms forming edge and face-sharing distorted hexagonal prisms TiO12 stacking along the c-axis. The Hubbard-corrections predict a close bandgap for both α-Ti2O3 and its substructure; whereas a comparative study of their relative stability indicates that the substructure is thermodynamically less stable.

Synthesis, characterization, crystal structure and density functional theory (DFT) calculations of dioxomolybdenum (VI) complexes of an ONS donor ligand derived from benzoylacetone and S-benzyl dithiocarbazate

Polyhedron ◽  
2013 ◽  
Vol 50 (1) ◽  
pp. 602-611 ◽  
Author(s):  
Manashi Chakraborty ◽  
Sathi Roychowdhury ◽  
Nikhil Ranjan Pramanik ◽  
Tapas Kumar Raychaudhuri ◽  
Tapan Kumar Mondal ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Density Functional ◽  
Functional Theory ◽  
Donor Ligand

scholarly journals Crystal structure of vyacheslavite, U(PO4)(OH), solved from natural nanocrystal: a precession electron diffraction tomography (PEDT) study and DFT calculations

RSC Advances ◽  
2019 ◽  
Vol 9 (34) ◽  
pp. 19657-19661 ◽  
Author(s):  
Gwladys Steciuk ◽  
Seyedayat Ghazisaeed ◽  
Boris Kiefer ◽  
Jakub Plášil
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Electron Diffraction ◽  
Dft Calculations ◽  
Density Functional ◽  
Diffraction Tomography ◽  
Functional Theory ◽  
Phosphate Mineral ◽  
Precession Electron Diffraction ◽  
Nano Crystal

The crystal structure of the U(iv)-phosphate mineral vyacheslavite has been solved from precession electron diffraction tomography (PEDT) data from the natural nano-crystal and further refined using density-functional theory (DFT) calculations.

The crystal structure of MoO2(O2)H2O

2018 ◽  
Vol 33 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Joel W. Reid ◽  
James A. Kaduk ◽  
Lidia Matei
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Software Package ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
Functional Theory ◽  
Synchrotron Powder Diffraction ◽  
Monoclinic Lattice ◽  
Strong Agreement

The crystal structure of MoO2(O2)H2O has been solved by analogy with the WO2(O2)H2O structure and refined with synchrotron powder diffraction data obtained from beamline 08B1-1 at the Canadian Light Source. Rietveld refinement, performed with the software package GSAS, yielded monoclinic lattice parameters of a = 12.0417(4) Å, b = 3.87003(14) Å, c = 7.38390(24) Å, and β = 78.0843(11)° (Z = 4, space group P21/n). The structure is composed of double zigzag molybdate chains running parallel to the b-axis. The Rietveld refined structure was compared with density functional theory (DFT) calculations performed with CRYSTAL14, and show strong agreement with the DFT optimized structure.

A theoretical study of weak interactions in phenylenediamine homodimer clusters

2016 ◽  
Vol 18 (42) ◽  
pp. 29249-29257 ◽  
Author(s):  
Chengqian Yuan ◽  
Haiming Wu ◽  
Meiye Jia ◽  
Peifeng Su ◽  
Zhixun Luo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Intermolecular Interactions ◽  
Density Functional ◽  
Theoretical Study ◽  
Natural Bond Orbital ◽  
Weak Interactions ◽  
Interaction Energies ◽  
Functional Theory ◽  
Weak Intermolecular Interactions

Utilizing dispersion-corrected density functional theory (DFT) calculations, we demonstrate the weak intermolecular interactions of phenylenediamine dimer (pdd) clusters, emphasizing the local lowest energy structures and decomposition of interaction energies by natural bond orbital (NBO) and atoms in molecule (AIM) analyses.

scholarly journals Substituent Effects in 3,3’ Bipyrazole Derivatives. X-ray Crystal Structures, Molecular Properties and DFT Analysis

2021 ◽  
Vol 68 (3) ◽  
pp. 718-727
Author(s):  
Ibrahim Bouabdallah ◽  
Tarik Harit ◽  
Mahmoud Rahal ◽  
Fouad Malek ◽  
Monique Tillard ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Solid State ◽  
Dft Calculations ◽  
Single Crystal ◽  
Crystal Structures ◽  
Density Functional ◽  
Substituent Effects ◽  
Functional Theory ◽  
X Ray

The single crystal X-ray structure of new 1,1’-bis(2-nitrophenyl)-5,5’-diisopropyl-3,3’-bipyrazole, 1, is triclinic P I–, a = 7.7113(8), b = 12.3926(14), c = 12.9886(12) Å, α = 92.008(8), β = 102.251(8), γ = 99.655(9)°. The structural arrangement is compared to that of 5,5’-diisopropyl-3,3’-bipyrazole, 5, whose single crystal structure is found tetragonal I41/a, a = b = 11.684(1), c = 19.158(1) Å. The comparison is also extended to the structures previously determined for 1,1’-bis(2-nitrophenyl)-5,5’-propyl-3,3’-bipyrazole, 2, 1,1’-bis(4-nitrophenyl)-5,5’-diisopropyl-3,3’-bipyrazole, 3, and 1,1’-bis(benzyl)-5,5’-diisopropyl-3,3’-bipyrazole, 4. Density Functional Theory (DFT) calculations are used to investigate the molecular geometries and to determine the global reactivity parameters. The geometry of isolated molecules and the molecular arrangements in the solid state are analyzed according to the nature of the groups connected to the bipyrazole core.

XRD Multi-Temperatures Study of N,N'-bis(2-Hydroxyethyl)Benzene-1,4-Dicarboxamide

2010 ◽  
Vol 163 ◽  
pp. 256-259
Author(s):  
Gabriela Bednarek ◽  
Maria Nowak ◽  
Joachim Kusz ◽  
Jerzy Ossowski
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Chemical Reactions ◽  
Title Compound ◽  
Density Functional ◽  
Temperature Analysis ◽  
Functional Theory ◽  
X Ray ◽  
The Stability

N,N’ – bis – (2– hydroxy – ethylene) – terephthalamide (BHETA) has been obtained by aminolysis of polyethylene terephthalate (PET) using excess of monoethanoloamine and it has been physicochemically characterized [1]. In this paper there are shown the results of the multi-temperature X-ray measurement which were performed to provide information about the stability of the structure. Detailed temperature analysis of the crystal structure allows us to determine properties of the compound which is very important product of recycling PET wastes in order to use it for further chemical reactions. The structure of the title compound was also modelled by density functional theory (DFT) calculations.

scholarly journals Theoretical study on the mechanism of iridium-catalyzed γ-functionalization of primary alkyl C–H bonds

2016 ◽  
Vol 94 (12) ◽  
pp. 1028-1037 ◽  
Author(s):  
Zhe Li ◽  
Miaoren Xia ◽  
Russell J. Boyd
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Experimental Observation ◽  
Density Functional ◽  
Theoretical Study ◽  
Reductive Elimination ◽  
Catalytic Cycle ◽  
Catalyst Precursor ◽  
Functional Theory ◽  
Initial Formation

The mechanism of the iridium-catalyzed functionalization of a primary C–H bond at the γ position of an alcohol 5 is investigated by density functional theory (DFT) calculations. A new IrIII–IrV mechanism is found to be more feasible than the previously reported IrI–IrIII mechanism. 10 In the IrIII–IrV mechanism, the reaction begins with the initial formation of (Me4phen)IrIII(H)[Si(OR)Et2]2 from the catalyst precursor, [Ir(cod)OMe]2 (cod = 1,5-cyclooctadiene). The catalytic cycle includes five steps: (1) the insertion of norbornene into the Ir–H bond to produce (Me4phen)IrIII(norbornyl)[Si(OR)Et2]2 (R = –CH(C2H5)C3H7); (2) the Si–H oxidative addition of HSi(OR)Et2 to form (Me4phen)IrVH(norbornyl)[Si(OR)Et2]3; (3) the reductive elimination of norbornane to furnish (Me4phen)IrIII[Si(OR)Et2]3; (4) the intramolecular C–H activation of the primary C–H bond at the γ position; and (5) the Si–C reductive elimination to produce the final product and regenerate the catalyst. The highest barrier in the IrIII–IrV mechanism is 7.3 kcal/mol lower than that of the IrI–IrIII mechanism. In addition, the regioselectivity of the C–H activation predicted by this new IrIII–IrV mechanism is consistent with experimental observation.

Structure-activity relationships in the production of olefins from alcohols and ethers: a first-principles theoretical study

2015 ◽  
Vol 5 (9) ◽  
pp. 4547-4555 ◽  
Author(s):  
Pavlo Kostetskyy ◽  
Giannis Mpourmpakis
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Lewis Acid ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Functional Theory ◽  
Structure Activity Relationships ◽  
Structure Activity

Olefin formation pathways on Lewis acid (LA) sites of Al2O3, Ga2O3 and In2O3 and gallium- and indium-doped alumina were investigated using Density Functional Theory (DFT) calculations.

scholarly journals Distribution of dopant ions around poly(3,4-ethylenedioxythiophene) chains: a theoretical study

2017 ◽  
Vol 19 (15) ◽  
pp. 9889-9899 ◽  
Author(s):  
Jordi Casanovas ◽  
David Zanuy ◽  
Carlos Alemán
Keyword(s):  
Density Functional Theory ◽  
Boundary Conditions ◽  
Dft Calculations ◽  
Density Functional ◽  
Periodic Boundary ◽  
Theoretical Study ◽  
Periodic Boundary Conditions ◽  
Polymer Chains ◽  
Functional Theory

The effect of counterions and multiple polymer chains on the properties and structure of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with ClO4− has been examined using density functional theory (DFT) calculations with periodic boundary conditions (PBCs).

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