scholarly journals Cooperation/Competition between Halogen Bonds and Hydrogen Bonds in Complexes of 2,6-Diaminopyridines and X-CY3 (X = Cl, Br; Y = H, F)

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 766
Author(s):  
Barbara Bankiewicz ◽  
Marcin Palusiak
Keyword(s):  
Complex Formation ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Electrostatic Interactions ◽  
Dipole Moments ◽  
Main Role ◽  
Halogen Bonds ◽  
Topological Parameters ◽  
Leading Role ◽  
The Impact

The DFT calculations have been performed on a series of two-element complexes formed by substituted 2,6-diaminopyridine (R−PDA) and pyridine (R−Pyr) with X−CY3 molecules (where X = Cl, Br and Y = H, F). The primary aim of this study was to examine the intermolecular hydrogen and halogen bonds in the condition of their mutual coexistence. Symmetry/antisymmetry of the interrelation between three individual interactions is addressed. It appears that halogen bonds play the main role in the stabilization of the structures of the selected systems. However, the occurrence of one or two hydrogen bonds was associated with the favourable geometry of the complexes. Moreover, the impact of different substituent groups attached in the para position to the aromatic ring of the 2,6-diaminopyridine and pyridine on the character of the intermolecular hydrogen and halogen bonds was examined. The results indicate that the presence of electron-donating substituents strengthens the bonds. In turn, the presence of electron-withdrawing substituents reduces the strength of halogen bonds. Additionally, when hydrogen and halogen bonds lose their leading role in the complex formation, the nonspecific electrostatic interactions between dipole moments take their place. Analysis was based on geometric, energetic, and topological parameters of the studied systems.

scholarly journals Toward a uniform description of hydrogen bonds and halogen bonds: correlations of interaction energies with various geometric, electronic and topological parameters

RSC Advances ◽  
2017 ◽  
Vol 7 (17) ◽  
pp. 10295-10305 ◽  
Author(s):  
Jian-Wei Zou ◽  
Meilan Huang ◽  
Gui-Xiang Hu ◽  
Yong-Jun Jiang
Keyword(s):  
Hydrogen Bonds ◽  
Structural Parameters ◽  
Interaction Energies ◽  
Halogen Bonds ◽  
Topological Parameters

Correlations between interaction energies and various structural parameters were established to reveal the differences between hydrogen bonds and halogen bonds.

scholarly journals Intra- and Interpolyelectrolyte Complexes of Polyampholytes

2018 ◽  
Author(s):  
Sarkyt Kudaibergenov ◽  
Nurxat Nuraje
Keyword(s):  
Complex Formation ◽  
Hydrogen Bonds ◽  
Electrostatic Interactions ◽  
Water Soluble ◽  
Polymer Complex ◽  
Dye Molecules ◽  
Interpolymer Complexes ◽  
Interpolyelectrolyte Complexes ◽  
Points Of View

At present, a large amount of research works from experimental and theoretical points of view have been done on interpolyelectrolyte complexes formed by electrostatic interactions and/or interpolymer complexes stabilized by hydrogen bonds. On the contrary, relatively less attention has been given to polymer-polymer complex formation with synthetic polyampholytes. In this review the complexation of polyampholytes with polyelectrolytes is considered from theoretical and application points of view. Formation of intra- and interpolyelectrolyte complexes of random, regular, block, dendritic polyampholytes are outlined. The separate subchapter is devoted to amphoteric behavior of interpolyelectrolyte complexes. The realization of so-called “isoelectric effect” for interpolyelectrolyte complexes of water-soluble polyampholytes, amphoteric hydrogels and cryogels with respect to surfactants, dye molecules, polyelectrolytes and proteins is demonstrated.

N—H...X (X = Cl and Br) hydrogen bonds in three isomorphous 3,5-dichloropyridinium salts

2017 ◽  
Vol 73 (10) ◽  
pp. 803-809 ◽  
Author(s):  
Ai Wang ◽  
Ulli Englert
Keyword(s):  
Hydrogen Bonds ◽  
Small Molecules ◽  
Crystal Engineering ◽  
Electrostatic Interactions ◽  
Halogen Bond ◽  
Halogen Bonds ◽  
Dipole Orientation ◽  
Halide Ligand ◽  
Van Der Waals Radii ◽  
Short Contacts

Specific short contacts are important in crystal engineering. Hydrogen bonds have been particularly successful and together with halogen bonds can be useful for assembling small molecules or ions into crystals. The ionic constituents in the isomorphous 3,5-dichloropyridinium (3,5-diClPy) tetrahalometallates 3,5-dichloropyridinium tetrachloridozincate(II), (C5H4Cl2N)2[ZnCl4] or (3,5-diClPy)2ZnCl4, 3,5-dichloropyridinium tetrabromidozincate(II), (C5H4Cl2N)2[ZnBr4] or (3,5-diClPy)2ZnBr4, and 3,5-dichloropyridinium tetrabromidocobaltate(II), (C5H4Cl2N)2[CoBr4] or (3,5-diClPy)2CoBr4, arrange according to favourable electrostatic interactions. Cations are preferably surrounded by anions and vice versa; rare cation–cation contacts are associated with an antiparallel dipole orientation. N—H...X (X = Cl and Br) hydrogen bonds and X...X halogen bonds compete as closest contacts between neighbouring residues. The former dominate in the title compounds; the four symmetrically independent pyridinium N—H groups in each compound act as donors in charge-assisted hydrogen bonds, with halogen ligands and the tetrahedral metallate anions as acceptors. The M—X coordinative bonds in the latter are significantly longer if the halide ligand is engaged in a classical X...H—N hydrogen bond. In all three solids, triangular halogen-bond interactions are observed. They might contribute to the stabilization of the structures, but even the shortest interhalogen contacts are only slightly shorter than the sum of the van der Waals radii.

scholarly journals Objective and Subjective Factors in Modern Economy

2021 ◽  
Vol 18 (1) ◽  
pp. 127-140
Author(s):  
Yu. K. Knyazev ◽  
Keyword(s):  
Public Sphere ◽  
Common Denominator ◽  
Main Role ◽  
The Public ◽  
Leading Role ◽  
Modern Economy ◽  
Role Of The State ◽  
Key Characteristics ◽  
The Public Sphere ◽  
The Impact

The paper focuses on the public sphere in modern economy, which co-exists with the market and develops according to its own, non-market logic. The emphasis is made on the correlation between objective and subjective factors in economy. The author describes the evolution of research on these factors’ role in society, and explains the impact of subjective forces from the perspective of methodological dualism, which combines the principles of individualism and collectivism. The duality of human nature, combining individualist instincts with collectivist values acquired in society, explains substantial differences in people’s behaviour under market conditions and in the public sphere. Subjective and objective factors have different significance in the market and non-market spheres of economy: while the market is driven by objective tendencies, which bring people’s individual actions to a certain common denominator, in the public sphere, on the contrary, the main role is played is managed mainly by objective regularities, which reduce people’s subjective actions to a common denominator, whereas in the public sphere, on the contrary, the leading role is played by subjective understanding of public interests, benefit or harm of certain intentions, and the goals and strategies of further development. In the final part of the article, the key characteristics of the public sphere are described and it is shown that this sphere exists along with the market although it is affected by the market’s demands and, therefore, requires a more in-depth research, including the regulating role of the state in market economy.

Conformational Analysis of Eu(III)-(Ethylenedinitrilo)tetrakis(methylphosphonates) (EDTMP)

2008 ◽  
Vol 73 (11) ◽  
pp. 1437-1456 ◽  
Author(s):  
Lidia Smentek ◽  
B. Andes Hess
Keyword(s):  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Metal Ion ◽  
Electrostatic Interactions ◽  
Electric Dipole Transition ◽  
Dipole Transition ◽  
Water Molecules ◽  
Qualitative Comparison ◽  
Lanthanide Ion ◽  
Positively Charged

The optimal geometries obtained from DFT calculations are presented for Eu(III)-EDTMP (the parent system) and cages associated with the water molecules and carbonate and hydroxide ions. The numerical results demonstrate the existence of two conformers of each cage, which might explain the observation of two spectroscopic lines previously assigned to the electric dipole transition 7F0 ↔ 5D0 of Eu3+. It is also found that the water molecules are associated with the chelate via hydrogen bonds with the oxygens of the phoshonate arms, while the carbonate and hydroxide ions are chelated with the lanthanide ion due to strong electrostatic interactions between the negatively charged oxygen atoms and positively charged metal ion. The analysis is illustrated by the qualitative comparison of the energies and is concluded with the relative stability of various chelates and energetically favorable, hypothetical reactions.

scholarly journals Molecular modelling of the interaction of carbocyclic analogues of netropsin and distamycin with d(CGCGAATTCGCG)2.

2000 ◽  
Vol 47 (3) ◽  
pp. 855-866 ◽  
Author(s):  
K Bielawski ◽  
A Bielawska ◽  
D Bartulewicz ◽  
A Rózański
Keyword(s):  
Molecular Structure ◽  
Molecular Dynamics ◽  
Complex Formation ◽  
Hydrogen Bonds ◽  
Electrostatic Interactions ◽  
Minor Groove ◽  
Model Complexes ◽  
Dna Minor Groove ◽  
Energetic Analysis ◽  
Effective Penetration

A molecular mechanics and molecular dynamics approach was used to examine the structure of complexes formed between the d(CGCGAATTCGCG)2 duplex and netropsin, distamycin, and four carbocyclic analogues of netropsin and distamycin (1-4). The resulting structures of the ligand-DNA model complexes and their energetics were examined. It is predicted that the compounds 1-4 should have a decreased affinity for the minor groove of AT-rich regions in comparison to netropsin and distamycin. From the energetic analysis it appears that van der Waals and electrostatic interactions are more important than specific hydrogen bonds in stabilizing the ligand-duplex complexes. We predict that compounds 1 and 2 are effectively isohelical with the DNA minor groove. The superior DNA-binding afforded by 1 and 2 in comparison to 3 and 4 results from their more effective penetration into the minor groove and smaller perturbation of molecular structure upon complex formation.

scholarly journals The Balance between Hydrogen Bonds, Halogen Bonds, and Chalcogen Bonds in the Crystal Structures of a Series of 1,3,4-Chalcogenadiazoles

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4125
Author(s):  
Viraj De Silva ◽  
Boris B. Averkiev ◽  
Abhijeet S. Sinha ◽  
Christer B. Aakeröy
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Dft Calculations ◽  
Crystal Structures ◽  
Intermolecular Interactions ◽  
Electrostatic Potential ◽  
Intermolecular Forces ◽  
Intermolecular Hydrogen Bonding ◽  
Halogen Bonds ◽  
Target Molecules

In order to explore how specific atom-to-atom replacements change the electrostatic potentials on 1,3,4-chalcogenadiazole derivatives, and to deliberately alter the balance between intermolecular interactions, four target molecules were synthesized and characterized. DFT calculations indicated that the atom-to-atom substitution of Br with I, and S with Se enhanced the σ-hole potentials, thus increasing the structure directing ability of halogen bonds and chalcogen bonds as compared to intermolecular hydrogen bonding. The delicate balance between these intermolecular forces was further underlined by the formation of two polymorphs of 5-(4-iodophenyl)-1,3,4-thiadiazol-2-amine; Form I displayed all three interactions while Form II only showed hydrogen and chalcogen bonding. The results emphasize that the deliberate alterations of the electrostatic potential on polarizable atoms can cause specific and deliberate changes to the main synthons and subsequent assemblies in the structures of this family of compounds.

scholarly journals Molecular Hydrogen as a Lewis Base in Hydrogen Bonds and Other Interactions

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3294 ◽  
Author(s):  
Sławomir J. Grabowski
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Hydrogen ◽  
Spectroscopic Properties ◽  
Lewis Base ◽  
Basis Set ◽  
Orbital Method ◽  
Topological Parameters ◽  
Theoretical Approaches ◽  
Strength Of Interaction ◽  
Moller Plesset

The second-order Møller–Plesset perturbation theory calculations with the aug-cc-pVTZ basis set were performed for complexes of molecular hydrogen. These complexes are connected by various types of interactions, the hydrogen bonds and halogen bonds are most often represented in the sample of species analysed; most interactions can be classified as σ-hole and π-hole bonds. Different theoretical approaches were applied to describe these interactions: Quantum Theory of ‘Atoms in Molecules’, Natural Bond Orbital method, or the decomposition of the energy of interaction. The energetic, geometrical, and topological parameters are analysed and spectroscopic properties are discussed. The stretching frequency of the H-H bond of molecular hydrogen involved in intermolecular interactions is considered as a parameter expressing the strength of interaction.

scholarly journals Electric dipole moments, new forces and dark matter

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Pavel Fileviez Pérez ◽  
Alexis D. Plascencia
Keyword(s):  
Dark Matter ◽  
Electric Dipole ◽  
Dipole Moments ◽  
Dark Matter Candidate ◽  
Beyond The Standard Model ◽  
Electric Dipole Moments ◽  
Dark Matter Relic Density ◽  
New States ◽  
Gauge Anomalies ◽  
The Impact

Abstract New sources of CP violation beyond the Standard Model are crucial to explain the baryon asymmetry in the Universe. We discuss the impact of new CP violating interactions in theories where a dark matter candidate is predicted by the cancellation of gauge anomalies. In these theories, the constraint on the dark matter relic density implies an upper bound on the new symmetry breaking scale from which all new states acquire their masses. We investigate in detail the predictions for electric dipole moments and show that if the relevant CP-violating phase is large, experiments such as the ACME collaboration will be able to fully probe the theory.

Intermolecular binding preferences of haloethynyl halogen-bond donors as a function of molecular electrostatic potentials in a family of N-(pyridin-2-yl)amides

2021 ◽  
Author(s):  
Amila M. Abeysekera ◽  
Boris B. Averkiev ◽  
Pierre Le Magueres ◽  
Christer B. Aakeröy
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Halogen Bond ◽  
Electrostatic Potentials ◽  
Halogen Bonds ◽  
Molecular Electrostatic Potentials

The roles played by halogen bonds and hydrogen bonds in the crystal structures of N-(pyridin-2-yl)amides were evaluated and rationalised in the context of calculated molecular electrostatic potentials.

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