STUDY THE STABLE STRUCTURES OF ScGe6 BY GA-DFT AND THE CO ADSORPTION ON ScGe6− CLUSTER

The structures of ScGe6 and ScGe6− clusters were investigated by a combination of genetic algorithm with quantum chemical calculations (GA-DFT and DLPNO-CCSD(T)). Results show that the two most stable isomers of the ScGe6 cluster have a pentagonal bipyramid structure with a Sc atom at the vertex and a Ge atom capping the face of tetragonal bipyramid with a Sc atom at the vertex with Cs symmetry. The pentagonal bipyramid with the scandium atom at the vertex with C5v symmetry is the most stable ScGe6− cluster. The CO adsorption on the most stable isomer of the anionic cluster was studied by PBE functional. The isomer A1 of ScGe6− cluster can adsorb CO molecule as well. The most stable structure has CO along with the Sc-Ge bond. In two adsorption models at the Sc atom along the main axis, the Sc-CO adsorption model is more favorable than the Sc-OC model.

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A topological quantum-chemical study of the chemisorption of carbon monoxide on the fcc (112) surfaces of Ni, Pt, Pd, Rh, and Ir

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19901907 ◽

1990 ◽

Vol 55 (8) ◽

pp. 1907-1919

Author(s):

Jiří Pancíř ◽

Ivana Haslingerová

Keyword(s):

Carbon Monoxide ◽

Quantum Chemical ◽

Co Adsorption ◽

Quantum Chemical Study ◽

Chemical Study ◽

Dissociative Chemisorption ◽

Frontier Orbitals ◽

Surface Sites ◽

Charged Surfaces ◽

Topological Quantum

A semiempirical quantum-chemical topological method is applied to the study of the fcc (112) surfaces of Ni, Pt, Pd, Rh, and Ir and the nondissociative as well as dissociative chemisorption of carbon monoxide on them. On Ni, dissociative chemisorption is preferred to linear capture, whereas on Pd and Pt, linear capture is preferred although dissociative chemisorption is also feasible. On Rh and, in particular, on Ir, dissociative chemisorption is energetically prohibited. The high dissociative ability of the Ni surface can be ascribed to a rather unusual charge alteration and to the degeneracy of the frontier orbitals. Negative charges at the surface level are only found on the Ni and Pt surfaces whereas concentration of positive charges is established on the Rh and Ir surfaces; the Pd surface is nearly uncharged. Metals with negatively charged surfaces seem to be able to dissociate molecules of carbon monoxide. It is demonstrated that CO adsorption can take place on all metal surface sites, most effectively in the valley of the step. In all the cases studied, the attachment to the surface is found to be energetically more favourable for the carbon than for the oxygen.

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The Face-to-Face σ-Hole···σ-Hole Stacking Interactions: Structures, Energies, and Nature

Crystals ◽

10.3390/cryst11080877 ◽

2021 ◽

Vol 11 (8) ◽

pp. 877

Author(s):

Yu Zhang ◽

Weizhou Wang

Keyword(s):

Quantum Chemical ◽

Noncovalent Interactions ◽

Electrostatic Energy ◽

Stacking Interactions ◽

Energy Component ◽

Stacking Interaction ◽

Face To Face ◽

The Face ◽

Π Stacking Interaction ◽

Induction Energy

The existence of the π···π stacking interaction is well-known. Similarly, it is reasonable to assume the existence of the σ-hole···σ-hole stacking interaction. In this work, the structures, energies, and nature of the face-to-face σ-hole···σ-hole stacking interactions in the crystal structures have been investigated in detail by the quantum chemical calculations. The calculated results clearly show that the face-to-face σ-hole···σ-hole stacking interactions exist and have unique properties, although their strengths are not very significant. The energy component analysis reveals that, unlike many other dispersion-dominated noncovalent interactions in which the induction energies always play minor roles for their stabilities, for the face-to-face σ-hole···σ-hole stacking interaction the contribution of the induction energy to the total attractive energy is close to or even larger than that of the electrostatic energy. The structures, energies, and nature of the face-to-face σ-hole···σ-hole stacking interactions confined in small spaces have also been theoretically simulated. One of the important findings is that encapsulation of the complex bound by the face-to-face σ-hole···σ-hole stacking interaction can tune the electronic properties of the container.

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ADSORPTION SITES OF THE PRODUCTS OF GeH4 ON ASYMMETRIC Si(100)(2×1) SURFACE

International Journal of Modern Physics B ◽

10.1142/s0217979204024033 ◽

2004 ◽

Vol 18 (08) ◽

pp. 1191-1202

Author(s):

ŞENAY KATıRCıOĞLU

Keyword(s):

Density Functional ◽

Geometry Optimization ◽

Density Functional Theory Method ◽

Adsorption Model ◽

Functional Theory ◽

Adsorption Models ◽

Adsorption Sites ◽

Asymmetric Dimer ◽

Adsorption Energies ◽

Relative Adsorption

The decomposition of GeH 4 on Si (100)(2×1) was investigated on different adsorption models of fragments using density functional theory method. The most probable adsorption model of fragments corresponding to the growth steps of SiGe film has been obtained by geometry optimization and single value total energy calculations. The relative adsorption energies of GeH 3, GeH 2 and GeH have been found to be -5.6, -5.1, and -4.5 eV for their most probable adsorption models respectively. It has been found that, the asymmetric dimer bond rows of Ge on Si (100) surface can be constructed by following the adsorption models corresponding to the relative adsorption energies of GeH 3, GeH 2 and GeH .

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Structural Study of Flavonoids and Their Protonated Forms

Zeitschrift für Naturforschung C ◽

10.1515/znc-1996-11-1204 ◽

1996 ◽

Vol 51 (11-12) ◽

pp. 784-790 ◽

Cited By ~ 5

Author(s):

Jaroslav Tóth ◽

Milan Remko ◽

Milan Nagy

Keyword(s):

Carbonyl Group ◽

Quantum Chemical ◽

Phenyl Ring ◽

Chemical Methods ◽

Quantum Chemical Methods ◽

Ring Rotation ◽

Protonated Forms ◽

Conformational Properties ◽

Ether Oxygen ◽

Stable Structures

The highly successful semiempirical quantum chemical methods AM1 (Austin Model 1) and PM3 (a reparametrization of AM1) were applied to an investigation of the conformational properties of flavone, 3-hydroxyflavone, isoflavone and 2-hydroxyisoflavone. The most stable structures correspond to the non-planar forms with an angle of phenyl ring rotation out of the chromone moiety from a relatively narrow interval (28° - 38°). The mono- and diprotonation of these compounds was also investigated. The prominent site of protonation is the oxygen of the carbonyl group with a protonation enthalpy from the interval of about 900 -920 kJ.mol-1. The protonation enthalpy for protonation of the ether oxygen was computed to be about 200 kJ.mol-1 lower. Adding a second proton to monoprotonated species studied resulted in much lower protonation enthalpies compared to monoprotonation. The geometry of the studied compounds upon protonation changed considerably.

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Discriminative interactions between chiral molecules: internal discrimination in 1,2-difluorohydrazine

Canadian Journal of Chemistry ◽

10.1139/v85-275 ◽

1985 ◽

Vol 63 (7) ◽

pp. 1639-1641 ◽

Cited By ~ 2

Author(s):

Rudolf Zahradník ◽

Bohdan Schneider ◽

Pavel Hobza ◽

Zdenêk Havlas ◽

Hanspeter Huber

Keyword(s):

Thermodynamic Properties ◽

Quantum Chemical ◽

Short Range ◽

Energy Surface ◽

Saddle Points ◽

Ideal Gas ◽

Chiral Molecules ◽

Standard State ◽

Transition Complex ◽

Stable Structures

1,2-Difluorohydrazine represents a model for studying short-range discriminative interactions between two chiral radicals. Possible diastereomeric structures of the system were theoretically investigated by means of nonempirical SCF quantum chemical calculations. Four minima and six saddle points separating them were found on the potential energy surface. All the stable structures and one transition complex were completely optimized. Thermodynamic properties for the equilibrium between the two most stable conformers (meso and chiral) of difluorohydrazine are as follows (in kJ/mol): [Formula: see text], [Formula: see text] (standard state: ideal gas at 101.325 kPa, 298 K).

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KAJIAN TEORITIS KEMAMPUAN CAPPING KATEKIN, KATEKU TANAT DAN QUARSETIN TERHADAP NANOPARTIKEL PERAK DENGAN MENGGUNAKAN METODA DFT-B

Jurnal Riset Kimia ◽

10.25077/jrk.v9i1.256 ◽

2017 ◽

Vol 9 (1) ◽

pp. 27

Author(s):

Syukri Arief ◽

Emriadi ◽

Ade Saputra

Keyword(s):

Experimental Data ◽

Silver Nanoparticles ◽

Molecular Dynamic ◽

Molecular Dynamic Simulations ◽

Capping Agent ◽

Adsorption Model ◽

Dynamic Simulations ◽

Adsorption Models ◽

Quantum Parameter ◽

Theoretical Results

Interdiffusion mechanism of catechin, catechutannic acid and quercetin are studied by using DFT-B method. But before conducting these experiment, we perform molecular dynamic simulations to find adsorption models probability of each compound. Two models adsorption of quarcetin, four models for catechin and three models for catechutannic acid have been obtained from molecular dynamic simulations. Quantum parameter of each compound, energy and properties adsorption models have been calculated and discussed. The theoretical results were found to be consistent with the experimental data reported. Futhermore, optimization adsorption model samples show that all of adsorbents have weak bonds on the surface of silver nanoparticles. The mechanism can be classified as strong physisorption, so that catechin, catechutannic acid and quercetin can be categorized as good capping agent in synthesis of silver nanoparticles.

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The Immobilization Effect of Natural Mineral Materials on Cr(VI) Remediation in Water and Soil

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17082832 ◽

2020 ◽

Vol 17 (8) ◽

pp. 2832 ◽

Cited By ~ 1

Author(s):

Dading Zhang ◽

Yanqiu Xu ◽

Xiaofei Li ◽

Lina Wang ◽

Xuwen He ◽

...

Keyword(s):

Aqueous Solutions ◽

Freundlich Isotherm ◽

Soil Toxicity ◽

Adsorption Model ◽

X Ray Diffraction ◽

Isothermal Adsorption ◽

Adsorption Models ◽

Natural Mineral ◽

Isotherm Adsorption ◽

Molecular Bond

The effects of sepiolite, montmorillonite, and attapulgite on the removal and immobilization of Cr(VI) in water and soil were studied. X-ray diffraction (XRD) characterizations showed that the purities of these three mineral materials decreased in the following order: montmorillonite > attapulgite > sepiolite, and that their surface molecular bond types were similar. The adsorption potential of Cr(VI) in aqueous solutions of the three mineral materials was in the following order: sepiolite > attapulgite > montmorillonite. The adsorption mechanism for attapulgite was consistent with the Freundlich isotherm adsorption model, whereas that for montmorillonite was more consistent with the Langmuir model. Sepiolite had a good fitting effect for both isothermal adsorption models. For montmorillonite and attapulgite, a lower pH corresponded to a higher removal of Cr(VI). For sepiolite, however, the removal efficiency of Cr(VI) from an aqueous solution was the lowest at a pH of approximately 5.0. The results of the soil toxicity characteristic leaching procedure showed that, following the addition of 15% sepiolite, attapulgite, or montmorillonite to the contaminated soil, Cr(VI) concentrations in the leachates decreased by 16.8%, 18.9%, and 15.9%, respectively, and the total Cr concentrations in the leachates were reduced by 21.2%, 29.2%, and 17.6%. Of the three mineral materials, attapulgite demonstrated the highest Cr(VI) immobilization efficiency in soil. This study emphasizes the effect of attapulgite on the immobilization of Cr(VI) in soil and aqueous solutions, thus providing a theoretical basis for the potential application of natural mineral material remediation of Cr(VI)-contaminated aqueous solutions and soils.

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Heavy Metal Ions Adsorption from Wastewater Using Activated Carbon from Orange Peel

E-Journal of Chemistry ◽

10.1155/2012/383742 ◽

2012 ◽

Vol 9 (2) ◽

pp. 926-937 ◽

Cited By ~ 16

Author(s):

Juan Carlos Moreno-Piraján ◽

Liliana Giraldo

Keyword(s):

Heavy Metal ◽

Activated Carbon ◽

Metal Ions ◽

Adsorption Isotherms ◽

Heavy Metal Ions ◽

Copper Ions ◽

Orange Peel ◽

Adsorption Model ◽

Immersion Enthalpy ◽

Adsorption Models

Activated carbon obtained from orange peel (ACOP) was synthesized and used for the removal of heavy metal ions (Cr, Cd, and Co) from aqueous solutions. Two different adsorption models were used for analyzing data. Adsorption capacities were determined: copper ions exhibit the greatest adsorption on activated carbon orange peel because of its size and pH conditions. Adsorption capacity varies as a function of pH. Adsorption isotherms from aqueous solution of heavy metals on ACOP were determined. Adsorption isotherms are consistent with Langmuir's adsorption model. Adsorbent quantity and immersion enthalpy were studied.

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