Specific Recognition of Methanol Using a Symmetric Tetramethylcucurbit[6]uril-Based Porous Supramolecular Assembly Incorporating Adsorbed Dyes

2020 ◽  
Vol 73 (11) ◽  
pp. 1065 ◽  
Author(s):  
Fei Yang Tian ◽  
Rui Xue Cheng ◽  
Yun Qian Zhang ◽  
Zhu Tao ◽  
Qian Jiang Zhu
Keyword(s):  
Electrostatic Potential ◽  
Outer Surface ◽  
Supramolecular Assembly ◽  
Dipole Interaction ◽  
Carbonyl Oxygen ◽  
Polycyclic Compounds ◽  
Dipole Interactions ◽  
Fluorescence Characteristics ◽  
Volatile Organic ◽  
Positive Electrostatic Potential

A symmetric tetramethylcucurbit[6]uril-based porous supramolecular assembly was prepared in an aqueous H2SO4 solution (5M). The driving force for the formation of this assembly is mainly the outer surface interaction of Q[n], which includes the ion-dipole interaction of SO42− anions and the positive electrostatic potential of the outer surface of the symmetric tetramethylcucurbit[6]uril (TMeQ[6]), the dipole-dipole interactions between the positive electrostatic potential of the outer surface of TMeQ[6] and portal carbonyl oxygens of TMeQ[6], and the hydrogen bonding between lattice water molecules and portal carbonyl oxygen atoms in TMeQ[6]. The TMeQ[6]-based porous supramolecular assembly exhibits the characteristics of absorbed fluorophore guests (FGs), such as dyes and polycyclic compounds with different fluorescence characteristics. Moreover, the resulting luminescent assemblies (FG@As) can respond to certain volatile organic compounds; in particular, the luminescent assemblies of rhodamine B or pyrene display a unique fluorescence enhancement in response to methanol.

scholarly journals The Cyclobutanocucurbit[5–8]uril Family: Electronegative Cavities in Contrast to Classical Cucurbituril while the Electropositive Outer Surface Acts as a Crystal Packing Driver

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7343
Author(s):  
Minghua Chen ◽  
Naixia Lv ◽  
Weiwei Zhao ◽  
Anthony I. Day
Keyword(s):  
Single Crystal ◽  
Electrostatic Potential ◽  
Outer Surface ◽  
Crystal Packing ◽  
Structural Parameters ◽  
Near Neighbor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dipole Interactions

The structural parameters for the cyclobutanoQ[5–8] family were determined through single crystal X-ray diffraction. It was found that the electropositive cyclobutano methylene protons (CH2) are important in forming interlinking crystal packing arrangements driven by the dipole–dipole interactions between these protons and the portal carbonyl O of a near neighbor. This type of interaction was observed across the whole family. Electrostatic potential maps also confirmed the electropositive nature of the cyclobutano CH2 but, more importantly, it was established that the cavities are electronegative in contrast to classical Q[5–8], which are near neutral.

Halogen bonds as a tool in the design of high energetic materials: evidence from crystal structures and quantum chemical calculations

CrystEngComm ◽  
2021 ◽  
Author(s):  
Aleksandra B. Đunović ◽  
Dušan Ž Veljković
Keyword(s):  
Crystal Structures ◽  
Quantum Chemical Calculations ◽  
Electrostatic Potential ◽  
Energetic Materials ◽  
Quantum Chemical ◽  
Central Area ◽  
Molecular Surface ◽  
Halogen Bonds ◽  
Positive Electrostatic Potential

Positive electrostatic potential over the central area of the molecular surface is one of the main characteristics of high energetic materials (HEM) that determines their sensitivity towards detonation. The influence...

scholarly journals σ-Holes vs. Buildups of Electronic Density on the Extensions of Bonds to Halogen Atoms

Inorganics ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 71 ◽  
Author(s):  
Peter Politzer ◽  
Jane S. Murray
Keyword(s):  
Electrostatic Potential ◽  
Local Minimum ◽  
Halogen Atom ◽  
Local Maximum ◽  
Outer Side ◽  
Electronic Density ◽  
Halogen Atoms ◽  
Positive Electrostatic Potential

Our discussion focuses upon three possible features that a bonded halogen atom may exhibit on its outer side, on the extension of the bond. These are (1) a region of lower electronic density (a σ-hole) accompanied by a positive electrostatic potential with a local maximum, (2) a region of lower electronic density (a σ-hole) accompanied by a negative electrostatic potential that also has a local maximum, and (3) a buildup of electronic density accompanied by a negative electrostatic potential that has a local minimum. In the last case, there is no σ-hole. We show that for diatomic halides and halogen-substituted hydrides, the signs and magnitudes of these maxima and minima can be expressed quite well in terms of the differences in the electronegativities of the halogen atoms and their bonding partners, and the polarizabilities of both. We suggest that the buildup of electronic density and absence of a σ-hole on the extension of the bond to the halogen may be an operational indication of ionicity.

Magnetic dipole interactions in dysprosium ethyl sulphate - I. Susceptibility and specific heat between 20 and 1°K

1959 ◽  
Vol 252 (1269) ◽  
pp. 246-259 ◽  
Keyword(s):  
Specific Heat ◽  
Magnetic Dipole ◽  
Ground State ◽  
Optical Rotation ◽  
Dipole Interaction ◽  
Crystal Axis ◽  
Dipole Interactions ◽  
Degenerate Ground State ◽  
Magnetic Ions ◽  
Good Agreement

Measurements have been made of the magnetic susceptibility and the magnetic contributions to the specific heat of dysprosium ethyl sulphate, at temperatures between 20 and 1°K. It is shown that below about 3°K these properties, and also the earlier optical rotation measure­ments of Becquerel et al ., can be accounted for satisfactorily in terms of a doubly degenerate ground state of the magnetic ions, with spectroscopic splitting factors parallel and perpen­dicular to the crystal axis g 1 = 10.8 and g ┴ = 0, together with an unusually strong coupling between the ions arising from magnetic dipole-dipole interaction. The effect of other inter­actions is shown to be small. Because of this, and the extreme anisotropy of the g -tensor, the properties of this substance at very low temperatures (~ 0.1°K) should closely resemble those of a classical Ising model with known, dipolar forces between the ions. At temperatures above 3°K other states of the ions become populated and it is shown that the first of these lies at an energy of (23 ± 3) k , in good agreement with other experiments.

Caractérisation physicochimique et électronique de la structure Pt–a-Si: H–c-Si(n)

1991 ◽  
Vol 69 (3-4) ◽  
pp. 357-360 ◽  
Author(s):  
S. Belkouch ◽  
L. Paquin ◽  
A. Deneuville ◽  
E. Gheeraert
Keyword(s):  
Infrared Absorption ◽  
Electrostatic Potential ◽  
Potential Drop ◽  
Localized States ◽  
Electrical Measurements ◽  
Potential Barriers ◽  
Infrared Absorption Spectra ◽  
Hydrogenated Amorphous ◽  
Positive Electrostatic Potential ◽  
Absorption Measurements

Infrared absorption spectra, and electrical measurements I(V, T) and C(V) at 100 Hz of the Pt–a-Si:H–c-Si structure are presented. The thickness, d, of the hydrogenated amorphous silicium, a-Si:H, varies between 4800 and 180 Å(1 Å = 10−10 m). Infrared absorption measurements on a-Si:H show that with the decrease in d there is an increase in the number of defects and the hydrogen concentration on Si-H sites. The electrical results I(V, T) show a Schottky-like structure whose ideality factor increases with decreasing T, but remains limited even for small values of d (1.4 at 300 K for d = 180 Å). Two potential barriers are also deduced: at high temperature [Formula: see text] and is independent of d. This barrier is attributed to the Pt–a-Si:H interface. At low temperature, [Formula: see text] increases from 0.23 to 0.5 eV as d decreases from 2400 to 180 Å. This barrier is attributed to the a-Si = H–c-Si, interface, the transport in a-Si:H taking place by tunnelling between localized states. The C(V) measurements allow the separation between the c-Si and the a-Si:H responses. Above 100 kHz, there is no response from a-Si:H, which behaves then as a dielectric. The electrostatic potential drop in c-Si is deduced as a function of the applied voltage V for each value of d. A positive electrostatic potential is found when V = 0 for d ≤ 500 Å.[Journal translation]

scholarly journals Unusual Effects of Intramolecular Hydrogen Bonds and Dipole Interaction on FTIR and NMR of Some Imines

2019 ◽  
pp. 1-6 ◽  
Author(s):  
Elham Abdalrahem Bin Selim ◽  
Mohammed Hadi Al–Douh
Keyword(s):  
Hydrogen Bonds ◽  
Chemical Shifts ◽  
Dipole Interaction ◽  
Intramolecular Hydrogen Bonds ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dipole Interactions ◽  
Intramolecular Hydrogen

Unusual effects of intramolecular hydrogen bonds and dipole interactions are investigated using FTIR, NMR and X-Ray crystallography analyses of some imines. These phenomena affect both FTIR absorptions and chemical shifts.

The leading role of the steric hindrance effect and dipole–dipole interaction in superlattice nanostructures formed via the assembly of discotic liquid crystals

2018 ◽  
Vol 42 (24) ◽  
pp. 20087-20094 ◽  
Author(s):  
Zhenhu Zhang ◽  
Huanzhi Yang ◽  
Jingze Bi ◽  
Ao Zhang ◽  
Yi Fang ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Steric Hindrance ◽  
Dipole Interaction ◽  
Discotic Liquid Crystals ◽  
Leading Role ◽  
Dipole Interactions

The effect of steric hindrance and dipole–dipole interactions are a prerequisite for the formation of ordered plastic phases.

scholarly journals The σ-hole revisited

2017 ◽  
Vol 19 (48) ◽  
pp. 32166-32178 ◽  
Author(s):  
Peter Politzer ◽  
Jane S. Murray ◽  
Timothy Clark ◽  
Giuseppe Resnati
Keyword(s):  
Electrostatic Potential ◽  
Electronic Density ◽  
Covalently Bonded ◽  
Positive Electrostatic Potential

A covalently-bonded atom typically has a region of lower electronic density, a “σ-hole,” on the side of the atom opposite to the bond, approximately along its extension. There is often a positive electrostatic potential (strongest shown in red) associated with a σ-hole, although it may deviate from the extension of the bond.

Increased Positive Electrostatic Potential inp-Hydroxybenzoate Hydroxylase Accelerates Hydroxylation but Slows Turnover†

Biochemistry ◽  
2004 ◽  
Vol 43 (6) ◽  
pp. 1569-1579 ◽  
Author(s):  
Mariliz Ortiz-Maldonado ◽  
Lindsay J. Cole ◽  
Sara M. Dumas ◽  
Barrie Entsch ◽  
David P. Ballou
Keyword(s):  
Electrostatic Potential ◽  
Hydroxybenzoate Hydroxylase ◽  
Positive Electrostatic Potential

scholarly journals How aromatic system size affects the sensitivities of highly energetic molecules?

RSC Advances ◽  
2021 ◽  
Vol 11 (51) ◽  
pp. 31933-31940
Author(s):  
Ivana S. Veljković ◽  
Jelena I. Radovanović ◽  
Dušan Ž. Veljković
Keyword(s):  
Dft Calculations ◽  
Electrostatic Potential ◽  
System Size ◽  
Aromatic System ◽  
Positive Electrostatic Potential

DFT calculations showed that with the increase of the aromatic system size, values of positive electrostatic potential above the central areas of energetic molecules decrease, leading to the decrease in the sensitivities towards detonation.

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