scholarly journals Properties of Metal-Doped Covalent Organic Frameworks and Their Interactions with Sulfur Dioxide

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Ju Wang ◽  
Jia Wang ◽  
Wenchang Zhuang ◽  
Xiaoqin Shi ◽  
Xihua Du
Keyword(s):  
Metal Atom ◽  
Density Functional ◽  
Gas Adsorption ◽  
Lone Pair ◽  
Density Functional Theory Calculations ◽  
Open Architecture ◽  
Covalent Organic Frameworks ◽  
Gas Molecule ◽  
Donor Acceptor ◽  
Metal Doped

Covalent organic frameworks are unique for their highly open architecture and attractive for use as promising gas adsorption and storage carriers. In this work, density functional theory calculations have been performed to investigate the properties of metal-doped covalent organic frameworks and their interactions with the SO2 gas molecule. It is found that a single metal atom (including Li, Na, K, and Sc) doped at the top of phenyls within the tetra(4-dihydroxyborylphenyl) silane (TBPS) building block of covalent organic frameworks can easily lose its valence electrons and can be positively charged. The SO2 gas molecule could be stably absorbed onto the metal-doped covalent organic frameworks. The absorbed SO2 molecule interacts with Li, Na, K, and Sc metal-doped covalent organic frameworks by the dominant donor-acceptor delocalization between 1-center lone pair of an oxygen atom within SO2 and 1-center non-Lewis lone pairs of the doped metal atom.

scholarly journals Adenine as a Halogen Bond Acceptor: A Combined Experimental and DFT Study

Crystals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 224 ◽  
Author(s):  
Yannick Roselló ◽  
Mónica Benito ◽  
Elies Molins ◽  
Miquel Barceló-Oliver ◽  
Antonio Frontera
Keyword(s):  
Density Functional ◽  
Halogen Bond ◽  
Lone Pair ◽  
Halogen Bonding ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Adenine Ring ◽  
Bonding Interaction ◽  
Donor Ability ◽  
Adenine Derivative

In this work, we report the cocrystallization of N9-ethyladenine with 1,2,4,5-tetrafluoro-3,6-diiodobenzene (TFDIB), a classical XB donor. As far as our knowledge extends, this is the first cocrystal reported to date where an adenine derivative acts as a halogen bond acceptor. In the solid state, each adenine ring forms two centrosymmetric H-bonded dimers: one using N1···HA6–N6 and the other N7···HB6–N6. Therefore, only N3 is available as a halogen bond acceptor that, indeed, establishes an N···I halogen bonding interaction with TFDIB. The H-bonded dimers and halogen bonds have been investigated via DFT (Density Functional Theory) calculations and the Bader’s Quantum Theory of Atoms In Molecules (QTAIM) method at the B3LYP/6-311+G* level of theory. The influence of H-bonding interactions on the lone pair donor ability of N3 has also been analyzed using the molecular electrostatic potential (MEP) surface calculations.

scholarly journals Expression and interactions of stereochemically active lone pairs and their relation to structural distortions and thermal conductivity

IUCrJ ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 480-489 ◽  
Author(s):  
Kasper Tolborg ◽  
Carlo Gatti ◽  
Bo B. Iversen
Keyword(s):  
Thermal Conductivity ◽  
Density Functional ◽  
Lone Pair ◽  
Density Functional Theory Calculations ◽  
Orbital Interaction ◽  
Void Space ◽  
Metal Compounds ◽  
Bond Angles ◽  
Lone Pairs ◽  
Bonding Effect

In chemistry, stereochemically active lone pairs are typically described as an important non-bonding effect, and recent interest has centred on understanding the derived effect of lone pair expression on physical properties such as thermal conductivity. To manipulate such properties, it is essential to understand the conditions that lead to lone pair expression and provide a quantitative chemical description of their identity to allow comparison between systems. Here, density functional theory calculations are used first to establish the presence of stereochemically active lone pairs on antimony in the archetypical chalcogenide MnSb2O4. The lone pairs are formed through a similar mechanism to those in binary post-transition metal compounds in an oxidation state of two less than their main group number [e.g. Pb(II) and Sb(III)], where the degree of orbital interaction (covalency) determines the expression of the lone pair. In MnSb2O4 the Sb lone pairs interact through a void space in the crystal structure, and their their mutual repulsion is minimized by introducing a deflection angle. This angle increases significantly with decreasing Sb—Sb distance introduced by simulating high pressure, thus showing the highly destabilizing nature of the lone pair interactions. Analysis of the chemical bonding in MnSb2O4 shows that it is dominated by polar covalent interactions with significant contributions both from charge accumulation in the bonding regions and from charge transfer. A database search of related ternary chalcogenide structures shows that, for structures with a lone pair (SbX 3 units), the degree of lone pair expression is largely determined by whether the antimony–chalcogen units are connected or not, suggesting a cooperative effect. Isolated SbX 3 units have larger X—Sb—X bond angles and therefore weaker lone pair expression than connected units. Since increased lone pair expression is equivalent to an increased orbital interaction (covalent bonding), which typically leads to increased heat conduction, this can explain the previously established correlation between larger bond angles and lower thermal conductivity. Thus, it appears that for these chalcogenides, lone pair expression and thermal conductivity may be related through the degree of covalency of the system.

Wechselwirkungen in Molekülkristallen, 166 [1, 2]. Polyiod-Moleküle I2C=CI2, (IC)4S, (IC)4NH, (IC)4N-CH3 und HCI3: Strukturbestimmung nach Kristallzüchtung oder durch Dichtefunktionaltheorie-Berechnung / Interaction in Molecular Crystals, 166 [1, 2], Polyiodo Molecules I2C=CI2, (IC)4S, (IC)4 NH, (IC)4N-CH and HCI3: Structure Determination Following Crystallization or by Density Functional Theory Calculation

2001 ◽  
Vol 56 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Hans Bock ◽  
Sven Holl ◽  
Volker Krenzel
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Crystal Packing ◽  
Density Functional Theory Calculation ◽  
Density Functional Theory Calculations ◽  
Structural Data ◽  
Basis Sets ◽  
Functional Theory ◽  
Donor Acceptor ◽  
Density Functional Theory Optimization

Abstract The structures of tri-and tetraiodo-substituted carbon compounds are determined either expe­rimentally by X-Ray Structure Analysis or, because crystallization of tetraiodothiophene could not be achieved, approximated by Density Functional Theory optimization of structural data from a donor/acceptor complex. The structures show noteworthy details such as a second po­lymorph of tetraiodoethene crystallized by sublimation or herringbone crystal packing patterns of tetraiodopyrrole derivatives. All molecular geometries are discussed and compared based on relativistic density functional theory calculations with 6 -31G* basis sets including iodine pseudopotentials. They reproduce even finer structural details due to van der Waals repulsion of the bulky iodo substituents. Natural Bond Orbital (NBO) charge distributions suggest positive partial charges at all iodine centers with the strongest polarization Cδ㊀ → Iδ㊉ in HCI3, which contains well over 97% iodine.

scholarly journals Nitrogen-rich covalent organic frameworks with multiple carbonyls for high-performance sodium batteries

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ruijuan Shi ◽  
Luojia Liu ◽  
Yong Lu ◽  
Chenchen Wang ◽  
Yixin Li ◽  
...  
Keyword(s):  
High Performance ◽  
Density Functional ◽  
Specific Capacity ◽  
Density Functional Theory Calculations ◽  
Rechargeable Batteries ◽  
High Rate ◽  
Ex Situ ◽  
Covalent Organic Frameworks ◽  
Rate Performance ◽  
Practical Applications

AbstractCovalent organic frameworks with designable periodic skeletons and ordered nanopores have attracted increasing attention as promising cathode materials for rechargeable batteries. However, the reported cathodes are plagued by limited capacity and unsatisfying rate performance. Here we report a honeycomb-like nitrogen-rich covalent organic framework with multiple carbonyls. The sodium storage ability of pyrazines and carbonyls and the up-to twelve sodium-ion redox chemistry mechanism for each repetitive unit have been demonstrated by in/ex-situ Fourier transform infrared spectra and density functional theory calculations. The insoluble electrode exhibits a remarkably high specific capacity of 452.0 mAh g−1, excellent cycling stability (~96% capacity retention after 1000 cycles) and high rate performance (134.3 mAh g−1 at 10.0 A g−1). Furthermore, a pouch-type battery is assembled, displaying the gravimetric and volumetric energy density of 101.1 Wh kg−1cell and 78.5 Wh L−1cell, respectively, indicating potentially practical applications of conjugated polymers in rechargeable batteries.

scholarly journals Large CO2 uptake on a monolayer of CaO

2017 ◽  
Vol 5 (5) ◽  
pp. 2110-2114 ◽  
Author(s):  
G. R. Berdiyorov ◽  
M. Neek-Amal ◽  
I. A. Hussein ◽  
M. E. Madjet ◽  
F. M. Peeters
Keyword(s):  
Density Functional Theory ◽  
Greenhouse Gases ◽  
Strong Interaction ◽  
Density Functional ◽  
Gas Adsorption ◽  
Density Functional Theory Calculations ◽  
Adsorption Properties ◽  
Co2 Uptake ◽  
Uptake Capacity ◽  
Functional Theory

Density functional theory calculations are used to study gas adsorption properties of a recently synthesized CaO monolayer. Due to its topology and strong interaction with the CO2 molecules, this material possesses a remarkably high CO2 uptake capacity and is highly selective towards CO2 against other major greenhouse gases.

scholarly journals A theoretical-electron-density databank using a model of real and virtual spherical atoms

2017 ◽  
Vol 73 (4) ◽  
pp. 610-625 ◽  
Author(s):  
Ayoub Nassour ◽  
Slawomir Domagala ◽  
Benoit Guillot ◽  
Theo Leduc ◽  
Claude Lecomte ◽  
...  
Keyword(s):  
Charge Density ◽  
Electron Density ◽  
Density Functional ◽  
Lone Pair ◽  
Density Functional Theory Calculations ◽  
Ligand Complex ◽  
Urea Molecule ◽  
Covalent Bonds ◽  
Similar Chemical ◽  
Chemical Groups

A database describing the electron density of common chemical groups using combinations of real and virtual spherical atoms is proposed, as an alternative to the multipolar atom modelling of the molecular charge density. Theoretical structure factors were computed from periodic density functional theory calculations on 38 crystal structures of small molecules and the charge density was subsequently refined using a density model based on real spherical atoms and additional dummy charges on the covalent bonds and on electron lone-pair sites. The electron-density parameters of real and dummy atoms present in a similar chemical environment were averaged on all the molecules studied to build a database of transferable spherical atoms. Compared with the now-popular databases of transferable multipolar parameters, the spherical charge modelling needs fewer parameters to describe the molecular electron density and can be more easily incorporated in molecular modelling software for the computation of electrostatic properties. The construction method of the database is described. In order to analyse to what extent this modelling method can be used to derive meaningful molecular properties, it has been applied to the urea molecule and to biotin/streptavidin, a protein/ligand complex.

scholarly journals Tailoring Long-Range Superlattice Chirality in the Molecular Selfassemblies via Weak Fluorine-Mediated Interactions

2021 ◽  
Author(s):  
Mykola Telychko ◽  
Lulu Wang ◽  
Chia-Hsiu Hsu ◽  
Guangwu Li ◽  
Xinnan Peng ◽  
...  
Keyword(s):  
Long Range ◽  
Density Functional ◽  
Chiral Recognition ◽  
Lone Pair ◽  
Density Functional Theory Calculations ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Controllable Fabrication

Controllable fabrication of the enantiospecific molecular superlattices is a matter of imminent scientific and technological interest. Herein, we demonstrate that long-range superlattice chirality in molecular self-assemblies can be tailored by tuning the interplay of weak intermolecular non-covalent interactions. Different chiral recognition patterns are achieved in the two molecular self-assemblies comprised by two molecular enantiomers with identical steric conformations, derived from the hexaphenylbenzene – the smallest star-shaped polyphenylene. By means of high-resolution scanning tunneling microscopy measurements, we demonstrate that functionalization of star-shaped polyphenylene with fluorine (F) atoms leads to the formation of molecular self-assemblies with the distinct long-range chiral recognition patterns. We employed the density functional theory calculations to quantify F-mediated lone pair F ···π, C-H··· F, F···F interactions attributed to the tunable enantiospecific molecular self-organizations. Our findings underpin a viable route to tailor long-range chiral recognition patterns in supramolecular assemblies by engineering the weak non-covalent intermolecular interactions.

scholarly journals Effects of Axial Solvent Coordination to Dirhodium Complexes on Reactivity and Selectivity in C–H Insertion Reactions: A Computational Study

2021 ◽  
Author(s):  
Croix Laconsay ◽  
Anna Pla-Quintana ◽  
Dean Tantillo
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Diazo Compounds ◽  
Insertion Reactions ◽  
Functional Theory ◽  
Axial Ligation ◽  
Donor Acceptor ◽  
Solvent Molecules ◽  
Dirhodium Complexes

Density functional theory calculations were used to systematically explore the effects of axial ligation by solvent molecules on the reactivity and selectivity of dirhodium tetracarboxylates with diazo compounds in the context of C–H insertion into propane. Insertions on three types of diazo compounds—acceptor/acceptor, donor/acceptor, and donor/donor—promoted by dirhodium tetraformate were tested with and without axial solvent ligation for no surrounding solvent, dichloromethane, isopropanol, and acetonitrile. Magnitudes, origins, and consequences of structural and electronic changes arising from axial ligation were characterized. The results suggest that axial ligation affects barriers for N2 extrusion and C–H insertion, the former to a larger extent.

scholarly journals High-Throughput Screening Single-Atom Alloy for Electroreduction of Dinitrogen to Ammonia

2021 ◽  
Author(s):  
Guokui Zheng ◽  
Ziqi Tian ◽  
Xingwang Zhang ◽  
Liang Chen ◽  
Xu Qian ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
Density Functional ◽  
Ammonia Synthesis ◽  
Density Functional Theory Calculations ◽  
Reduction Reaction ◽  
Single Atom ◽  
Functional Theory ◽  
Metal Doped ◽  
Single Atom Alloy ◽  
Single Atom Alloys

<p></p><p>Exploring electrocatalyst with high activity, selectivity and stability is essential for development of applicable electrocatalytic ammonia synthesis technology. By performing density functional theory calculations, we systematically investigated a series of transition-metal doped Au-based single atom alloys (SAAs) as promising electrocatalysts for nitrogen reduction reaction (NRR). For Au-based electrocatalyst, the first hydrogenation step (*N<sub>2</sub>→*NNH) normally determines the limiting potential of the overall reaction process. Compared with pristine Au(111) surface, introducing single atom can significantly enhance the binding strength of N<sub>2</sub>, leading to decreased energy barrier of the key step, i.e., ΔG(*N<sub>2</sub>→*NNH). According to simulation results, three descriptors were proposed to describe ΔG(*N<sub>2</sub>→*NNH), including ΔG(*NNH), <i>d</i>-band center, and . Eight doped elements (Ti, V, Nb, Ru, Ta, Os, W, and Mo) were initially screened out with limiting potential ranging from -0.75V to -0.30 V. Particularly, Mo- and W-doped systems possess the best activity with limiting potentials of -0.30 V, respectively. Then the intrinsic relationship between structure and the potential performance was further analyzed by using machine-learning. The selectivity, feasibility, stability of these candidates were also evaluated, confirming that SAA containing Mo, Ru ,Ta, and W could be outstanding NRR electrocatalysts. This work not only broadens the understating of SAA application in electrocatalysis, but also devotes to the discovery of novel NRR electrocatalysts.</p><br><p></p>

scholarly journals New information of dopaminergic agents based on quantum chemistry calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Guillermo Goode-Romero ◽  
Ulrika Winnberg ◽  
Laura Domínguez ◽  
Ilich A. Ibarra ◽  
Rubicelia Vargas ◽  
...  
Keyword(s):  
Density Functional ◽  
Clinical Decision Making ◽  
Chemical Reactivity ◽  
Density Functional Theory Calculations ◽  
Clinical Decision ◽  
Underlying Mechanism ◽  
New Information ◽  
Quantum Chemistry Calculations ◽  
Wide Range ◽  
Donor Acceptor

AbstractDopamine is an important neurotransmitter that plays a key role in a wide range of both locomotive and cognitive functions in humans. Disturbances on the dopaminergic system cause, among others, psychosis, Parkinson’s disease and Huntington’s disease. Antipsychotics are drugs that interact primarily with the dopamine receptors and are thus important for the control of psychosis and related disorders. These drugs function as agonists or antagonists and are classified as such in the literature. However, there is still much to learn about the underlying mechanism of action of these drugs. The goal of this investigation is to analyze the intrinsic chemical reactivity, more specifically, the electron donor–acceptor capacity of 217 molecules used as dopaminergic substances, particularly focusing on drugs used to treat psychosis. We analyzed 86 molecules categorized as agonists and 131 molecules classified as antagonists, applying Density Functional Theory calculations. Results show that most of the agonists are electron donors, as is dopamine, whereas most of the antagonists are electron acceptors. Therefore, a new characterization based on the electron transfer capacity is proposed in this study. This new classification can guide the clinical decision-making process based on the physiopathological knowledge of the dopaminergic diseases.

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