scholarly journals Research on the Effect of Carbon Defects on the Hydrophilicity of Coal Pyrite Surface from the Insight of Quantum Chemistry

Molecules ◽  
2019 ◽  
Vol 24 (12) ◽  
pp. 2285 ◽  
Author(s):  
Peng Xi ◽  
Ruixin Ma ◽  
Wenli Liu
Keyword(s):  
Water Molecule ◽  
Quantum Chemistry ◽  
Bond Strength ◽  
Dft Calculation ◽  
Covalent Bond ◽  
Ortho Position ◽  
Pyrite Surface ◽  
Meta Position ◽  
Doping Position ◽  
The Ideal

To investigate the effect of carbon defects on the hydrophilicity of the whole surface of the coal pyrite, the adsorption of the single H2O molecule at different sites of the coal pyrite surface was studied with the DFT calculation. It was found that, like the ideal pyrite, the single H2O molecule can stably adsorb at the doping-position, the ortho-position and the meta-position of the coal pyrite. The covalent bond and anti-bond were formed between O (water molecule) and Fe (the coal pyrite) through the Fe 3d orbital and O 2p orbital. Meanwhile, the S–H bond was replaced by the C–H bond. But away from the carbon defect centre, the adsorption of the single H2O molecule increased gradually and the Fe–O covalent bond strength between the single H2O molecule and the pyrite strengthened, which eventually became close to that of the undoped coal pyrite surface.

scholarly journals DFT Study into the Influence of Carbon Material on the Hydrophobicity of a Coal Pyrite Surface

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3534 ◽  
Author(s):  
Peng Xi ◽  
Donghui Wang ◽  
Wenli Liu ◽  
Changsheng Shi
Keyword(s):  
Carbon Atom ◽  
Water Molecule ◽  
Density Functional ◽  
Valence Bond ◽  
Covalent Bond ◽  
Point Of View ◽  
Pyrite Surface ◽  
Adsorbed Carbon ◽  
Single Water Molecule ◽  
The Impact

From the macroscopic point of view, the hydrophilicity of symbiotic carbon pyrite is weakened overall compared to that of pure pyrite. It is very important to explain the impact of elemental carbon accreted on a pyrite surface on the surface’s hydrophobicity from the perspective of quantum chemistry. To study the influence of adsorbed carbon atoms on the hydrophilicity of a coal pyrite surface versus a pyrite surface, the adsorption of a single water molecule at an adjacent Fe site of a one-carbon-atom-covered pyrite surface and a carbon atom monolayer were simulated and calculated with the first-principles method of density functional theory (DFT). The water molecules can be stably adsorbed at the adjacent Fe site of the carbon-atom-covered pyrite surface. The hybridization of the O 2p (H2O) and Fe 3d (pyrite surface) orbitals was the main interaction between the water molecule and the pyrite surface, forming a strong Fe–O covalent bond. The water molecule only slightly adsorbs above a C atom on the carbon-atom-covered pyrite and the carbon atom monolayer surfaces. The valence bond between the water molecule and the pyrite surface changed from an Fe–O bond to an Fe–C–O bond, in which the C–O bond is very weak, resulting in a weaker interaction between water and the surface.

Infrared Studies of Water in Crystalline Hydrates: Sodium Nitroprusside Dihydrate, Na2[Fe(CN)5NO]•2H2O

1971 ◽  
Vol 49 (9) ◽  
pp. 1413-1424 ◽  
Author(s):  
Michaela Holzbecher ◽  
Osvald Knop ◽  
Michael Falk
Keyword(s):  
Water Molecule ◽  
Sodium Nitroprusside ◽  
Infrared Spectra ◽  
Structure Determination ◽  
The Other ◽  
Water Molecules ◽  
Infrared Studies ◽  
Increasing Temperature ◽  
Crystalline Hydrates ◽  
The Ideal

Infrared spectra of polycrystalline Na2[Fe(CN)5NO] 2H2O at different degrees of deuteration were studied as a function of temperature. The single peaks observed for the bending fundamentals of isotopically dilute H2O and D2O show that all the water molecules are equivalent, as required by Manoharan and Hamilton's structure determination; the doublets observed for the three fundamentals of isotopically dilute HDO show that the water molecules are asymmetric. Doublet separation decreases gradually with increasing temperature, indicating decreasing asymmetry. The water molecule appears to orient itself so as to maximize the strength of one [Formula: see text] bond, while the other OH group interacts only very weakly with another CN group. The hitherto unknown extent to which the nitroprusside ion deviates from the ideal C4v symmetry has been estimated from the 13C14N stretching spectrum. The 15N16O and 14N18O stretching spectrum was used to confirm that only one type of NO group is present in the crystal, and hence that all nitroprusside ions are equivalent.

Coulomb couplings in solubilised light harvesting complex II (LHCII): challenging the ideal dipole approximation from TDDFT calculations

2017 ◽  
Vol 19 (28) ◽  
pp. 18311-18320 ◽  
Author(s):  
P. López-Tarifa ◽  
Nicoletta Liguori ◽  
Naudin van den Heuvel ◽  
Roberta Croce ◽  
Lucas Visscher
Keyword(s):  
Quantum Chemistry ◽  
Light Harvesting ◽  
Dipole Approximation ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Coulomb Coupling ◽  
Tddft Calculations ◽  
Quantum Chemistry Calculations ◽  
Light Harvesting Complex Ii ◽  
The Ideal

We investigate the coulomb coupling interactions of natural chromophores in the solubilised light harvesting complex II (LHCII) using DFT quantum chemistry calculations.

scholarly journals Halogen Bonding in the Complexes of Brominated Electrophiles with Chloride Anions: From a Weak Supramolecular Interaction to a Covalent Br–Cl Bond

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1075
Author(s):  
Cody Loy ◽  
Matthias Zeller ◽  
Sergiy V. Rosokha
Keyword(s):  
Bond Strength ◽  
Halogen Bond ◽  
Covalent Bond ◽  
Halogen Bonding ◽  
Halogen Bonds ◽  
Nucleophilic Reaction ◽  
X Ray ◽  
Wide Range ◽  
Judicious Choice ◽  
Range Variation

The wide-range variation of the strength of halogen bonds (XB) not only facilitates a variety of applications of this interaction, but it also allows examining the relation (and interconversion) between supramolecular and covalent bonding. Herein, the Br…Cl halogen bonding in a series of complexes of bromosubstituted electrophiles (R-Br) with chloride anions were examined via X-ray crystallographic and computational methods. Six co-crystals showing such bonding were prepared by evaporation of solutions of R-Br and tetra-n-propylammonium chloride or using Cl− anions released in the nucleophilic reaction of 1,4-diazabicyclo[2.2.2]octane with dichloromethane in the presence of R-Br. The co-crystal comprised networks formed by 3:3 or 2:2 halogen bonding between R-Br and Cl−, with the XB lengths varying from 3.0 Å to 3.25 Å. Analysis of the crystallographic database revealed examples of associations with substantially longer and shorter Br…Cl separations. DFT computations of an extended series of R–Br…Cl− complexes confirmed that the judicious choice of brominated electrophile allows varying halogen Br…Cl bond strength and length gradually from the values common for the weak intermolecular complexes to that approaching a fully developed covalent bond. This continuity of halogen bond strength in the experimental (solid-state) and calculated associations indicates a fundamental link between the covalent and supramolecular bonding.

Vacancy-induced elastic properties and hardness of CrB4: A DFT calculation

2017 ◽  
Vol 31 (13) ◽  
pp. 1750096 ◽  
Author(s):  
Yong Pan ◽  
Song Chen ◽  
Yuanhua Lin
Keyword(s):  
Mechanical Properties ◽  
Dft Calculation ◽  
Covalent Bond ◽  
Elastic Stiffness ◽  
First Principle ◽  
Triangular Pyramid ◽  
First Principle Calculations ◽  
3D Network ◽  
Metal Borides ◽  
The Relationship

Vacancy plays a crucial role in mechanical properties of transition metal borides (TMBs). However, the influence of vacancy on hardness of TMBs is unknown. In this paper, the relationship between boron vacancy and mechanical properties of CrB4 is investigated by first-principle calculations. Two different vacancies including boron monovacancy (MV) and boron bivacancy (BV) are considered. We find that CrB4 with boron MV is more stable than that of boron BV. The removed atom weakens the deformation resistances, and reduces the elastic stiffness and hardness. The calculated shear modulus, Young’s modulus and theoretical hardness of boron MV are larger than that of boron BV. The reason is that the removed atom weakens the localized hybridization between B and B atoms, and damages the 3D-network B–B covalent bond. However, the bulk modulus of B[Formula: see text] is slightly larger than that of perfect CrB4. This reason is attributed to the formation of triangular pyramid bonding in B[Formula: see text] vacancy.

scholarly journals Investigation of Characteristics as Endodontic Sealer of Novel Experimental Elastin-Like Polypeptide-Based Mineral Trioxide Aggregate

2020 ◽  
Author(s):  
Hyun-Jung Kim ◽  
Ji-Hyun Jang ◽  
Sun-Young Kim
Keyword(s):  
Electron Microscope ◽  
Bond Strength ◽  
Flow Rate ◽  
Mineral Trioxide Aggregate ◽  
Clinical Use ◽  
Intimate Contact ◽  
Endodontic Sealers ◽  
Push Out ◽  
Scanning Electron ◽  
The Ideal

Abstract Although mineral trioxide aggregates (MTA) have been adopted as an endodontic sealer because of excellent sealing effect and bioactive property and been modified with improvement of its characteristics, the developed MTA sealers have not yet satisfied all the ideal requirements of endodontic sealers. The aim of this study was to assess the characteristics of elastin-like polypeptide (ELP)-incorporated MTA for use as an endodontic sealer and compare them with those of commercial MTA sealers. Two commercial MTA sealers and three experimental ELP-incorporated MTA sealers with 0.3, 0.4, and 0.5 liquid/powder (L/P) ratio for 10 wt% ELP liquid were evaluated. The push-out bond strength, flow rate, sealer penetrability and wash-out resistance were tested and the sealer-dentin interface was observed using a scanning electron microscope (SEM). Our study revealed the ELP-incorporated MTA exhibited the higher push-out bond strength, flow rate, sealer penetration and remarkable wash-out resistance than commercial MTA sealers, especially in 0.4 L/P ratio. The groups of ELP-based experimental sealers also exhibited more intimate contact with dentin compared to the commercial MTA sealers. Our research will suggest the possible adoption of the ELP-incorporated MTA as endodontic sealer for clinical use.

The Study of Pyrite Surface Properties and Effect Mechanism with Xanthate Caused by the Microscopic Crystal Structure and Defects

2012 ◽  
Vol 538-541 ◽  
pp. 363-367
Author(s):  
Jin Xi Yu ◽  
Wen Li Liu
Keyword(s):  
Crystal Structure ◽  
Surface Properties ◽  
Electrochemical Reaction ◽  
Covalent Bond ◽  
Point Of View ◽  
Surface Element ◽  
Pyrite Surface ◽  
Process Studies ◽  
Equilibrium Defects ◽  
Semiconductor Properties

The pyrite in the nature, due to the differences of the semiconductor properties caused by crystal structure and the presence of defects, will be bound to seriously affect the surface state and surface-activity of the mineral, eventually make the process of electrochemical reaction and flotation behavior change in the solution. Starting from the microscopic point of view, this article would study the affect mechanism of crystal structure and defects on the pyrite surface properties and the electrochemical reaction process. Studies have shown, because of the existence of the strong Fe-S covalent bond and determinate equilibrium defects, make the Fermi level and valence state of partial surface element change, accordingly lead to special semiconductor and surface properties of pyrite, ultimately affect the process of pyrite electrochemical flotation.

Sign in / Sign up

Export Citation Format

Share Document