Electrostatic Potential Differences and Halogen-Bond Selectivity

2016 ◽  
Vol 16 (5) ◽  
pp. 2662-2670 ◽  
Author(s):  
Christer B. Aakeröy ◽  
Tharanga K. Wijethunga ◽  
John Desper ◽  
Marijana Đaković
Keyword(s):  
Electrostatic Potential ◽  
Halogen Bond ◽  
Bond Selectivity

scholarly journals Studies of Halogen Bonding Induced by Pentafluorosulfanyl Aryl Iodides: A Potential Group of Halogen Bond Donors in a Rational Drug Design

2019 ◽  
Author(s):  
Yuji Sumii ◽  
Kenta Sasaki ◽  
Seiji Tsuzuki ◽  
Norio Shibata
Keyword(s):  
Drug Design ◽  
Ab Initio ◽  
13C Nmr ◽  
Electrostatic Potential ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Rational Drug Design ◽  
Molecular Orbital Calculations ◽  
Nmr Titration ◽  
Rational Drug

The activation of halogen bonding by the substitution of the pentafluorosulfanyl (SF5) group was studied using a series of SF5-substituted iodobenzenes. The simulated electrostatic potential values of SF5-substituted iodobenzenes, ab initio molecular orbital calculations of intermolecular interactions of SF5-substituted iodobenzenes with pyridine, and the 13C NMR titration experiments of SF5-substituted iodobenzenes in the presence of pyridine or tetra (n-butyl) ammonium chloride (TBAC) indicated the obvious activation of halogen bonding, although this was highly dependent on the position of SF5-substitution on the benzene ring. 3,5-Bis-SF5-iodobenzene was the most effective halogen bond donor followed by o-SF5-substituted iodobenzene, while the m- and p-SF5 substitutions did not activate the halogen bonding of iodobenzenes. The 2:1 halogen bonding complex of 3,5-bis-SF5-iodobenzene and 1,4-diazabicyclo[2.2.2]octane (DABCO) was also confirmed. Since SF5-containing compounds have emerged as promising novel pharmaceutical and agrochemical candidates, the 3,5-bis-SF5-iodobenzene unit should be an attractive fragment of rational drug design capable of halogen bonding with biomolecules.

scholarly journals Molecular electrostatic potential of the reaction center as a descriptor of the reactivity of arylsulfonyl halides

2020 ◽  
Vol 64 (11) ◽  
pp. 33-41
Author(s):  
Evgeny N. Krylov ◽  
◽  
Lyudmila V. Virzum ◽  
Keyword(s):  
Sulfur Atom ◽  
Electrostatic Potential ◽  
Molecular Electrostatic Potential ◽  
Halogen Bond ◽  
Structural Parameters ◽  
Bond Cleavage ◽  
Nucleophilic Attack ◽  
Acetone Water ◽  
Hydroxyl Anion ◽  
Hydrolysis Of

To study the reactivity of arylsulfonyl halides, the molecular electrostatic potential (MEP) was considered for the first time as a descriptor. The reaction of hydrolysis of aromatic sulfonyl halides in the medium of mixed acetone-water solvents (according to the literature data of rate constants) was used as a model. The calculation of the structural parameters of the molecules of substituted arylsulfonyl halides was carried out using the ADF2014 software package at the level of the DFT/M06/6-311+G* (PCM) theory. It was found that the magnitude of the MEP on the sulfonyl sulfur atom is very sensitive to changes in the structure of substrates, which makes it possible to determine the change in the ratio between the rate of nucleophilic attack and anionoid abstraction of the leaving group. In particular, using the example of the hydrolysis reaction of substituted thiophenesulfonyl chlorides, it was shown that the acceleration of the reaction is observed with an increase in the donor properties of the substituents and the associated increase in the negative MEP value on the sulfonyl sulfur atom. The antibate character of the dependence of the hydrolysis constant values on the IEP value indicates that not the nucleophilic attack is the rate determining in the interaction of thiophene sulfonyl chlorides and the hydroxyl anion in this sample, but the abstraction of the chloride anion. This reaction has an unstable mechanism, when the ratio between the degree of S-nucleophile bond formation and S-halogen bond cleavage changes. This makes it possible to use MEP as a descriptor of reactivity in the hydrolysis of aryl sulfonyl halides and to elucidate the details of changes in the structure of transition states during the implementation of mechanisms other than pure SN2 mechanism.

Measurement System of Surface Electrostatic Potential on Insulation Board in Vacuum and its Application

2012 ◽  
Vol 132 (1) ◽  
pp. 95-100
Author(s):  
Hiroshi Morita ◽  
Ayumu Hatanaka ◽  
Toshiyuki Yokosuka ◽  
Yoshitaka Seki ◽  
Yoshiaki Tsumuraya ◽  
...  
Keyword(s):  
Electrostatic Potential ◽  
Measurement System ◽  
Surface Electrostatic Potential

VISUAL DESIGN TOOL FOR ELECTROSTATIC LELSES

2014 ◽  
Vol 5 (2) ◽  
pp. 778-789
Author(s):  
Hassan Nouri Al-Obaidi ◽  
Ali A. Rashead Al-Azawy
Keyword(s):  
Programming Languages ◽  
Electrostatic Potential ◽  
Electric Energy ◽  
Visual Basic ◽  
Visual Programming ◽  
Design Tool ◽  
Mesh Point ◽  
Visual Design ◽  
Computational Tool ◽  
Electrostatic Lenses

Current research presents a visual-computational tool to design and investigate round electrostatic lenses in sense of analysis procedure. The finite elements methods is adopted to find the electrostatic potential in the lens region. Laplace’s equation is first replaced by a certain functional which physically represent the electric energy stored in the electric field. This functional is then minimized at each mesh point with respect to the nearest eight ones. This minimization process is proved to be entirely equivalent to solving Laplace’s equation. The requirement that the functional being minimized is then yields a set of nine point equations which inter relate the potentials at adjacent mesh points. Finally this set of equations is solved to find the electrostatic potential at each mesh point in the region of the lens under consideration. The procedure steps mention above are coded to program written in visual basic. Hence an interface tool for analyzing and designing electrostatic lenses has been built up. Designing results proved that the introduced tools has an excellent outputs in comparison with the others written in not visual programming languages. Furthermore it easier for researchers and designer to use such a tool over their counterpart ones.

Mukaiyama Aldol Reaction Catalyzed by (Benz)imidazolium-Based Halogen Bond Donors

2020 ◽  
Author(s):  
Revannath L. Sutar ◽  
Nikita Erochok ◽  
Stefan Huber
Keyword(s):  
Halogen Bond ◽  
Aldol Reaction ◽  
Mukaiyama Aldol Reaction ◽  
Mukaiyama Aldol ◽  
Background Reaction ◽  
Strong Performance ◽  
The Stability ◽  
Elemental Iodine

A series of cationic monodentate and bidentate iodo(benz)­imidazolium-based halogen bond (XB) donors were employed as catalysts in a Mukaiyama aldol reaction. While 5 mol% of a monodentate variant showed noticeable activity, a <i>syn</i>-preorganized bidentate XB donor provided a strong performance even with 0.5 mol% loading. In contrast to the very active BAr<sup>F</sup><sub>4</sub> salts, PF<sub>6</sub> or OTf salts were either inactive or showed background reaction. Repetition experiments clearly ruled out a potential hidden catalysis by elemental iodine and demonstrated the stability of our catalyst over three consecutive cycles.

Surfactant Impurities Can Explain the Jones-Ray Effect

2018 ◽  
Author(s):  
Timothy Duignan ◽  
Marcel Baer ◽  
Christopher Mundy
Keyword(s):  
Surface Tension ◽  
Electrostatic Potential ◽  
Driving Forces ◽  
Salt Water ◽  
Fundamental Property ◽  
Apparent Contradiction ◽  
Low Salt ◽  
Air Water Interface ◽  
Added Salt ◽  
Effect Of Surface

<div> <p> </p><div> <div> <div> <p>The surface tension of dilute salt water is a fundamental property that is crucial to understanding the complexity of many aqueous phase processes. Small ions are known to be repelled from the air-water surface leading to an increase in the surface tension in accordance with the Gibbs adsorption isotherm. The Jones-Ray effect refers to the observation that at extremely low salt concentration the surface tension decreases in apparent contradiction with thermodynamics. Determining the mechanism that is responsible for this Jones-Ray effect is important for theoretically predicting the distribution of ions near surfaces. Here we show that this surface tension decrease can be explained by surfactant impurities in water that create a substantial negative electrostatic potential at the air-water interface. This potential strongly attracts positive cations in water to the interface lowering the surface tension and thus explaining the signature of the Jones-Ray effect. At higher salt concentrations, this electrostatic potential is screened by the added salt reducing the magnitude of this effect. The effect of surface curvature on this behavior is also examined and the implications for unexplained bubble phenomena is discussed. This work suggests that the purity standards for water may be inadequate and that the interactions between ions with background impurities are important to incorporate into our understanding of the driving forces that give rise to the speciation of ions at interfaces. </p> </div> </div> </div> </div>

Analysis of Retention Time Degradation Caused by Electrostatic Potential Variation between Adjacent Bit-Line and Adjacent Contact Node in DRAM

2016 ◽  
Author(s):  
Jungil Mok ◽  
Byungki Kang ◽  
Daesun Kim ◽  
Hongsun Hwang ◽  
Sangjae Rhee ◽  
...  
Keyword(s):  
Electric Field ◽  
Electrostatic Potential ◽  
Critical Dimension ◽  
Data Retention ◽  
Signal Line ◽  
Adjacent Node ◽  
Storage Node ◽  
Retention Characteristics ◽  
Node Voltage ◽  
The Relationship

Abstract Systematic retention failure related on the adjacent electrostatic potential is studied with sub 20nm DRAM. Unlike traditional retention failures which are caused by gate induced drain leakage or junction leakage, this failure is influenced by the combination of adjacent signal line and adjacent contact node voltage. As the critical dimension between adjacent active and the adjacent signal line and contact node is scaled down, the effect of electric field caused by adjacent node on storage node is increased gradually. In this paper, we will show that the relationship between the combination electric field of adjacent nodes and the data retention characteristics and we will demonstrate the mechanism based on the electrical analysis and 3D TCAD simulation simultaneously.

Conformational Stability, FMO, NMR, MEP and NBO Analysis of 2,5-Di-methyl-2,5-bis(methylthio)-1,4-dithiane and Dimethoxy compounds by DFT Approach

2021 ◽  
Vol 17 ◽  
Author(s):  
Nasrin Masnabadi
Keyword(s):  
Computational Methods ◽  
Electrostatic Potential ◽  
Conformational Stability ◽  
Nbo Analysis ◽  
Dft Methods ◽  
Geometrical Properties ◽  
Stereoelectronic Effect ◽  
Nmr Parameters ◽  
Electron Transfers ◽  
Stability Energy

Abstract: Conformational behaviors of 2,5-dimethoxy-2,5-dimethyl-1,4-dithiane (compound 1) and 2,5-dimethyl-2,5-bis (methylthio)-1,4-dithiane (compound 2) investigated by computational methods including B3LYP/6-311+G** and M06-2X/6-311+G** levels of theory and NBO analysis. The stereoelectronic effect of axial, axial (ax, ax) and equatorial, equa-torial (eq, eq) conformations were studied using NBO analysis. Using NBO analysis, the values of the stereoelectronic effects were calculated through the energy of stability associated with the electron transfers of compounds 1 and 2. The results showed that the eq, eq conformations of the studied compounds were more stable than their corresponding ax, ax conformations, and LP2X→σS1-C2 and LP2S→σ*C2-X electron transfers play important roles in the conformational be-havior of the studied compounds. The main purpose of the present work was to study the effects of stereoelectronic inter-actions and steric on the conformational superiority of the di-methoxy (compound 1) and di-thiomethyl compounds (com-pound 2). Thus, the values of resonance stability energy, non-diagonal elements, and orbital populations were investigated. Also, active electrophilic and nucleophilic centers were identified using fronting orbitals analysis obtained by DFT methods. The electrostatic potential maps of the title compounds were investigated at the B3LYP/6-311+G* level of theory. All of the NMR parameters and geometrical properties of both compounds were determined in this study.

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