scholarly journals Prediction of heptagonal bipyramidal nonacoordination in highly viable [OB-M©B7O7-BO]− (M = Fe, Ru, Os) complexes

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Bo Jin ◽  
Hai-Ru Li ◽  
Zhihong Wei ◽  
Miao Yan ◽  
Caixia Yuan ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Computational Prediction ◽  
Condensed Phases ◽  
Experimental Realization ◽  
Metal Interactions ◽  
Spherical Distributions ◽  
Anionic Complexes ◽  
Homo Lumo ◽  
Equatorial Ligand ◽  
Very High

AbstractNon-spherical distributions of ligand atoms in coordination complexes are generally unfavorable due to higher repulsion than for spherical distributions. To the best of our knowledge, non-spherical heptagonal bipyramidal nonacoordination is hitherto unreported, because of extremely high repulsion among seven equatorial ligand atoms. Herein, we report the computational prediction of such nonacoordination, which is constructed by the synergetic coordination of an equatorial hepta-dentate centripetal ligand (B7O7) and two axial mono-dentate ligands (-BO) in the gear-like mono-anionic complexes [OB-M©B7O7-BO]– (M = Fe, Ru, Os). The high repulsion among seven equatorial ligand B atoms has been compensated by the strong B–O bonding. These complexes are the dynamically stable (up to 1500 K) global energy minima with the HOMO-LUMO gaps of 7.15 to 7.42 eV and first vertical detachment energies of 6.14 to 6.66 eV (being very high for anions), suggesting their high probability for experimental realization in both gas-phase and condensed phases. The high stability stems geometrically from the surrounded outer-shell oxygen atoms and electronically from meeting the 18e rule as well as possessing the σ + π + δ triple aromaticity. Remarkably, the ligand-metal interactions are governed not by the familiar donation and backdonation interactions, but by the electrostatic interactions and electron-sharing bonding.

scholarly journals Molecular weight control in organochromium olefin polymerization catalysis by hemilabile ligand–metal interactions

2016 ◽  
Vol 12 ◽  
pp. 1372-1379 ◽  
Author(s):  
Stefan Mark ◽  
Hubert Wadepohl ◽  
Markus Enders
Keyword(s):  
Ethylene Polymerization ◽  
Weight Control ◽  
Transfer Reactions ◽  
High Catalytic Activity ◽  
Co Catalyst ◽  
Metal Centers ◽  
Molecular Weights ◽  
Metal Interactions ◽  
Polymerization Catalysis ◽  
Very High

A series of Cr(III) complexes based on quinoline-cyclopentadienyl ligands with additional hemilabile side arms were prepared and used as single-site catalyst precursors for ethylene polymerization. The additional donor functions interact with the metal centers only after activation with the co-catalyst. Evidence for this comes from DFT-calculations and from the differing behavior of the complexes in ethylene polymerization. All complexes investigated show very high catalytic activity and the additional side arm minimizes chain-transfer reactions, leading to increase of molecular weights of the resulting polymers.

Computational Prediction and Experimental Realization of p-Type Carriers in the Wide-Band-Gap Oxide SrZn1–xLixO2

2018 ◽  
Vol 57 (19) ◽  
pp. 11874-11883 ◽  
Author(s):  
Christos A. Tzitzeklis ◽  
Jyoti K. Gupta ◽  
Matthew S. Dyer ◽  
Troy D. Manning ◽  
Michael J. Pitcher ◽  
...  
Keyword(s):  
Band Gap ◽  
Wide Band ◽  
Computational Prediction ◽  
Wide Band Gap ◽  
Experimental Realization ◽  
P Type

Conductance Study of Benzyl Bromide Reaction with Cyclicamines in Aqueous-Ethanol Medium

2018 ◽  
Vol 7 (3.3) ◽  
pp. 143
Author(s):  
Veerati Radhika ◽  
. .
Keyword(s):  
Electrostatic Interactions ◽  
Mixed Solvent ◽  
Aqueous Ethanol ◽  
Benzyl Bromide ◽  
Frontier Molecular Orbital ◽  
Orbital Interactions ◽  
R Factor ◽  
Ethanol Medium ◽  
Solvation Of Ions ◽  
Homo Lumo

Nucleophilic substitution reaction of benzyl bromide and cyclicamines in ethanol aqueous intermediate reactivity can suggest that the nucleophile increases through their pKa values. A linear correlation exists between computed values of the dipole moment, rate and electronegativity of the nucelophiles. The two reactants suggest that frontier molecular orbital interactions ion-solvation and correlation of time with the HOMO-LUMO breach of that the reaction.  But it is not orbital controlled as well as forbidden by the electrostatic interactions along with mixed solvent composition between the reactants. The influence on the solvation of ions before reaction has been discuss with facilitate by R-factor. Thermodynamic properties are evaluate and report. The consequences of the learning to be interpreted in terms of ion-solvent exchanges and solvent properties comparing with electrostatic interaction between the reactants.   

scholarly journals Computational Discovery of Promising New n-type Dopable ABX Zintl Thermoelectric Materials

2020 ◽  
Author(s):  
Prashun Gorai ◽  
Alex Ganose ◽  
Alireza Faghaninia ◽  
Anubhav Jain ◽  
Vladan Stevanovic
Keyword(s):  
Experimental Studies ◽  
Computational Prediction ◽  
Structure Type ◽  
High Electron ◽  
First Principles Calculations ◽  
Zintl Phases ◽  
Experimental Realization ◽  
Native Defects ◽  
Computational Discovery ◽  
P Type

<div> <div> <div> <p>Computational prediction of good thermoelectric (TE) performance in several n-type doped Zintl phases, combined with successful experimental realization, has sparked interest in discovering new n-type dopable members of this family of materials. However, most known Zintls are typically only p-type dopable; prior successes in finding n-type Zintl phases have been largely serendipitous. Here, we go beyond previously synthesized Zintl phases and perform chemical substitutions in known n-type dopable ABX Zintl phases to discover new ones. We use first-principles calculations to predict their stability, potential for TE performance as well as their n-type dopability. Using this approach, we find 17 new ABX Zintl phases in the KSnSb structure type that are predicted to be stable. Several of these newly pre- dicted phases (KSnBi, RbSnBi, NaGeP) are predicted to exhibit promising n-type TE performance and are n-type dopable. We propose these compounds for further experimental studies, especially KSnBi and RbSnBi, which are both predicted to be good TE materials with high electron concentrations due to self-doping by native defects, when grown under alkali-rich conditions. </p> </div> </div> </div>

scholarly journals Organosulfur Materials with High Photo- and Photo-Oxidation Stability: 10-Anthryl Sulfoxides and Sulfones and Their Photophysical Properties Dependent on the Sulfur Oxidation State

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3506
Author(s):  
Piotr Bałczewski ◽  
Emilia Kowalska ◽  
Ewa Różycka-Sokołowska ◽  
Paweł Uznański ◽  
Joanna Wilk ◽  
...  
Keyword(s):  
Photophysical Properties ◽  
Oxidation Stability ◽  
Sulfur Oxidation ◽  
Frontier Orbitals ◽  
Leading Role ◽  
Full Symmetry ◽  
Homo Lumo ◽  
Very High ◽  
Enhanced Photostability

While few studies show only symmetrical and poorly mono-SOn (n = 0–2) substituted acenes, in this study, we present a synthesis of a new group of unsymmetrical, significantly substituted derivatives, which revealed unique photophysical properties. Both sulfides (S), sulfoxides (SO) and sulfones (SO2) showed very high photochemical stabilities, unusual for these groups, during UV-irradiation at 254/365 nm (air O2 and Ar), which was higher than any found in the literature. For the (S)/(SO) series (254 nm), the stabilities of 80–519 min. (air O2 and Ar) were found. At 365 nm, stabilities of 124—812 min./(air O2) for (S)/(SO) and higher for (SO2) were observed. Photoluminescence lifetimes of (SOn) of the lower anthryl symmetry remained in the following order: (SO2) < (S) < (SO); those with full symmetry were in the following order: (S) < (SO) < (SO2). The enhanced photostability was explained with DFT/MS/Hammett’s constants, which showed the leading role of the SOn groups in stabilization of HOMO/LUMO frontier orbitals. The SOn (n = 0–2) substituted acenes turned out to be tunable violet/blue/green emitters by oxidation of S atoms and the introduction of rich substitution.

scholarly journals Data-driven computational prediction and experimental realization of exotic perovskite-related polar magnets

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Yifeng Han ◽  
Meixia Wu ◽  
Churen Gui ◽  
Chuanhui Zhu ◽  
Zhongxiong Sun ◽  
...  
Keyword(s):  
High Throughput ◽  
Rational Design ◽  
Spin Structure ◽  
Computational Prediction ◽  
Data Driven ◽  
Experimental Realization ◽  
Precise Prediction ◽  
Pressure Synthesis ◽  
Applied Approach ◽  
High Throughput Manner

AbstractRational design of technologically important exotic perovskites is hampered by the insufficient geometrical descriptors and costly and extremely high-pressure synthesis, while the big-data driven compositional identification and precise prediction entangles full understanding of the possible polymorphs and complicated multidimensional calculations of the chemical and thermodynamic parameter space. Here we present a rapid systematic data-mining-driven approach to design exotic perovskites in a high-throughput and discovery speed of the A2BB’O6 family as exemplified in A3TeO6. The magnetoelectric polar magnet Co3TeO6, which is theoretically recognized and experimentally realized at 5 GPa from the six possible polymorphs, undergoes two magnetic transitions at 24 and 58 K and exhibits helical spin structure accompanied by magnetoelastic and magnetoelectric coupling. We expect the applied approach will accelerate the systematic and rapid discovery of new exotic perovskites in a high-throughput manner and can be extended to arbitrary applications in other families.

scholarly journals Self-antigen driven affinity maturation is required for pathogenic monovalent IgG4 autoantibody development

2020 ◽  
Author(s):  
Miriam L. Fichtner ◽  
Casey Vieni ◽  
Rachel L. Redler ◽  
Ljuvica Kolich ◽  
Ruoyi Jiang ◽  
...  
Keyword(s):  
Myasthenia Gravis ◽  
Electrostatic Interactions ◽  
Somatic Hypermutation ◽  
Affinity Maturation ◽  
Autoimmune Response ◽  
High Affinity ◽  
Autoimmune Myasthenia ◽  
Self Antigen ◽  
Very High ◽  
Shed Light

AbstractPathogenic IgG4 autoantibodies in autoimmune myasthenia gravis (MG) are functionally monovalent as a result of Fab-arm exchange. The origin and development of these unique autoantibodies are not well understood. We examined MG patient-derived monoclonal autoantibodies (mAbs), their corresponding germline-encoded unmutated common ancestors (UCA) and monovalent antigen-binding fragments (Fabs) to investigate how antigen-driven affinity maturation contributes to both binding and immunopathology. Mature mAbs, their UCA counterparts and mature monovalent Fabs bound to the autoantigen and retained their pathogenic capacity. However, monovalent UCA Fabs still bound the autoantigen but lost their pathogenic capacity. The mature Fabs were characterized by very high affinity (sub-nanomolar) driven by a rapid on-rate and slow off-rate. However, the UCA affinity was approximately 100-fold less than that of the mature Fabs, which was driven by a rapid off-rate. Crystal structures of two Fabs shed light on how mutations acquired during affinity maturation may contribute to increased MuSK binding affinity. These collective findings indicate that the autoantigen initiates the autoimmune response in MuSK MG and drives autoimmunity through the accumulation of somatic hypermutation such that monovalent IgG4 Fab-arm exchanged MG autoantibodies reach a high affinity threshold required for pathogenic capacity.SummaryIgG4 autoantibodies in autoimmune myasthenia gravis are functionally monovalent, requiring a high affinity threshold featuring fast on/slow off rates, to reach pathogenic capacity. This capacity is dependent on self-antigen initiated and driven maturation, which includes the accumulation of indispensable somatic hypermutations that may alter electrostatic interactions with the antigen.

I. An Apparatus for Use with Condensed Phases at 10,000°. II. Some Thermodynamic and Rate Considerations at Very High Temperatures

1958 ◽  
Vol 62 (3) ◽  
pp. 346-351 ◽  
Author(s):  
Tracy Hall ◽  
Billings Brown ◽  
Bruce Nelson ◽  
Lane A. Compton
Keyword(s):  
High Temperatures ◽  
Condensed Phases ◽  
Very High

scholarly journals Analysis of NMR Spectral Analysis and Molecular Electronic Potential Maps on L-Arginine Phosphate Crystals for Non-Linear Optical Applications

2021 ◽  
Vol 12 (6) ◽  
pp. 8353-8366
Keyword(s):  
Natural Bond Orbital ◽  
Slow Evaporation ◽  
Crystalline Perfection ◽  
Charge Delocalization ◽  
Different Temperatures ◽  
Optical Applications ◽  
High Degree ◽  
Homo Lumo ◽  
Very High ◽  
Electronic Potential

L-Arginine Phosphate (LAP) is a possible material for applications involving nonlinear optical properties. Slow evaporation was used to generate single LAP crystals with a very high degree of transparency from an aqueous solution. The solubility of the pure and doped LAP crystals was measured at different temperatures in the double-distilled water. Natural bond orbital (NBO) research investigated the molecule's stability and charge delocalization. The HOMO-LUMO energies describe the charge transfer between molecules. The electrostatic potential of molecules has been investigated. The correlation found between crystalline perfection and SHG potency was mentioned.

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