scholarly journals Halogen bonding. The role of the polarizability of the electron-pair donor

2016 ◽  
Vol 18 (10) ◽  
pp. 7300-7309 ◽  
Author(s):  
Darío J. R. Duarte ◽  
Gladis L. Sosa ◽  
Nélida M. Peruchena ◽  
Ibon Alkorta
Keyword(s):  
Theoretical Calculation ◽  
Electron Pair ◽  
Decomposition Analysis ◽  
Halogen Bonding ◽  
Atoms In Molecules ◽  
Molecular Polarizability ◽  
Aim Analysis ◽  
Molecular Potential

The nature of F–Br⋯X–R interactions (with X = Cl, Br, I and R = –H, –F) has been investigated through theoretical calculation of molecular potential electrostatic (MEP), molecular polarizability, atoms in molecules (AIM) analysis and energetic decomposition analysis (EDA).

Article

1999 ◽  
Vol 77 (8) ◽  
pp. 1340-1348
Author(s):  
Alex D Bain ◽  
P Hazendonk ◽  
P Couture
Keyword(s):  
Chemical Exchange ◽  
Substituent Effects ◽  
Theoretical Work ◽  
Atoms In Molecules ◽  
Amide Bond ◽  
Resonance Spectroscopy ◽  
Carbonyl Carbon ◽  
Aim Analysis ◽  
Recent Theoretical Work

Recent theoretical work on amide systems has brought into question the application of the concept of resonance. In particular, the role of the oxygen atom was questioned, since the calculations showed little change in its properties when the amide bond was rotated. This paper investigates, both experimentally and computationally, the effect of a substituent on the carbonyl carbon on the amide barrier, in order to test this view. The barriers to the amide rotation in seven spiro-fused oxazolidines were measured by NMR, to within 1 kJ mol-1. A subset of three of them was modelled to the 6-31G** level. For all three substituents the computed and measured barriers corresponded to within 7 kJ mol-1. The electron densities were analyzed using the Atoms in Molecules (AIM) theory. The AIM analysis revealed that the oxazolidines behaved similarly to formamide. The substituent effect was described in terms of the atomic populations and energies of the amide C, O, and N. A substituent on the carbonyl carbon caused electron redistributions between N and C, changing their basin attractive energies. Neither the population nor the energy of oxygen changed significantly. When interactions outside the basin of interest were considered, the energy of C was seen to be more sensitive to changing the substituent than the energy of N. However, the atomic parameters from the AIM analysis did not fully reflect the substituent effects observed. For these molecules, the barrier includes contributions from several sources - there is no single, dominant contribution.Key words: amides, barrier, substituent, nuclear magnetic resonance spectroscopy, chemical exchange, atoms in molecules, slow exchange, NMR lineshape analysis.

Expenditure Inequality in Indonesia, 2008-2010: A Spatial Decomposition Analysis and the Role of Education

2014 ◽  
Vol 28 (4) ◽  
pp. 389-411 ◽  
Author(s):  
Mitsuhiro Hayashi ◽  
Mitsuhiko Kataoka ◽  
Takahiro Akita
Keyword(s):  
Decomposition Analysis ◽  
Spatial Decomposition

Molecular polarizability and polarizability derivatives in cyclohexane analyzed with the theory of atoms in molecules

1994 ◽  
Vol 98 (3) ◽  
pp. 771-776 ◽  
Author(s):  
Kathlene M. Gough ◽  
Hemant K. Srivastava ◽  
Katarina Belohorcova
Keyword(s):  
Atoms In Molecules ◽  
Molecular Polarizability

scholarly journals Thermomechanical effect of molecular crystals and role of halogen bonding

2017 ◽  
Vol 73 (a2) ◽  
pp. C707-C707
Author(s):  
Sudhir Mittapalli ◽  
D. Sravanakumar Perumalla ◽  
Ashwini Nangia
Keyword(s):  
Molecular Crystals ◽  
Halogen Bonding ◽  
Thermomechanical Effect

scholarly journals Calculation of Higher Protonation States and of a New Resting State for Vanadium Chloroperoxidase Using QM/MM, with an Atom-in-Molecules Analysis

2020 ◽  
Author(s):  
Gregory Anderson ◽  
Raghu Nath Behera ◽  
Ravi V. Gomatam
Keyword(s):  
Hydrogen Bonding ◽  
Electronic Structure ◽  
Resting State ◽  
Natural Bond Orbital ◽  
Atoms In Molecules ◽  
Aim Analysis ◽  
Neutral Ph

<p></p><p><b>ABSTRACT</b>. <a></a><a></a><a>Earlier QM/MM studies of the resting state of vanadium chloroperoxidase (VCPO) focused on the diprotonated states of the vanadate cofactor. Herein, we report a new extensive QM/MM study that includes the tri- and quadprotonated states of VCPO at neutral pH. We identify certain di- and triprotonated states as being candidates for the resting state based on a comparison of relative energies. The quadprotonated states as well as some of the triprotonated states are ruled out as the resting state. An Atoms-in-Molecules (AIM) analysis of the complex hydrogen bonding around the vanadate cofactor helps to explain the relative energies of the protonation states considered herein, and it also indicates new hydrogen bonding which has not been recognized previously. A Natural Bond Orbital (NBO) study is presented to give a better understanding of the electronic structure of the vanadate co-factor.</a></p><br><p></p>

scholarly journals Halogen Bonding: An Underestimated Player in Membrane–drug Interactions

2020 ◽  
Author(s):  
Rafael Nunes ◽  
Diogo Vila Viçosa ◽  
Paulo J. Costa
Keyword(s):  
Drug Discovery ◽  
Chemical Space ◽  
Noncovalent Interactions ◽  
Halogen Bonding ◽  
Lewis Bases ◽  
Protein Ligand Interactions ◽  
Biochemical Systems ◽  
Ligand Interactions ◽  
Dynamics Simulations

<div>Halogen bonds (HaBs) are noncovalent interactions where halogen atoms act as electrophilic species interacting with Lewis bases. These interactions are relevant in biochemical systems being increasingly explored in drug discovery, mainly to modulate protein–ligand interactions. In this work, we report evidence for the existence of HaB-mediated halogen–phospholipid recognition phenomena as our molecular dynamics simulations support the existence of favorable interactions between halobenzene derivatives and both phosphate (PO) or ester (CO) oxygen acceptors from model phospholipid bilayers, thus providing insights into the role of HaBs in driving the permeation of halogenated drug like molecules across biological membranes. This represents a relevant molecular mechanism, previously overlooked, determining the pharmacological activity of halogenated molecules with implications in drug discovery and development, a place where halogenated molecules account for a significant part of the chemical space. Our data also shows that, as the ubiquitous hydrogen bond, HaBs should be accounted for in the development of membrane permeability models.</div>

scholarly journals Halogen bonding, chalcogen bonding, pnictogen bonding, tetrel bonding: origins, current status and discussion

2017 ◽  
Vol 203 ◽  
pp. 485-507 ◽  
Author(s):  
Lee Brammer
Keyword(s):  
Solid State ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Main Group ◽  
Solution Phase ◽  
Current Status ◽  
Solid State Chemistry ◽  
Main Group Elements ◽  
Past Work

The role of the closing lecture in a Faraday Discussion is to summarise the contributions made to the Discussion over the course of the meeting and in so doing capture the main themes that have arisen. This article is based upon my Closing Remarks Lecture at the 203rdFaraday Discussion meeting on Halogen Bonding in Supramolecular and Solid State Chemistry, held in Ottawa, Canada, on 10–12thJuly, 2017. The Discussion included papers on fundamentals and applications of halogen bonding in the solid state and solution phase. Analogous interactions involving main group elements outside group 17 were also examined. In the closing lecture and in this article these contributions have been grouped into the four themes: (a) fundamentals, (b) beyond the halogen bond, (c) characterisation, and (d) applications. The lecture and paper also include a short reflection on past work that has a bearing on the Discussion.

scholarly journals Decomposition Analysis of Factor Cost Shares: The Case of Greek Agriculture

1996 ◽  
Vol 28 (2) ◽  
pp. 369-379 ◽  
Author(s):  
Giannis Karagiannis ◽  
Stelios Katranidis ◽  
Kostas Velentzas
Keyword(s):  
Scale Effect ◽  
Technical Change ◽  
Decomposition Analysis ◽  
Demand Functions ◽  
Input Demand ◽  
Alternative Version ◽  
Factor Substitution

AbstractAn alternative version of decomposition analysis, based on factor cost shares rather than input demand functions, is presented and applied to Greek agriculture. Decomposition analysis shows that most of the changes in factor cost shares during the period from 1973 to 1989 are attributed to technical change and factor substitution, while the role of the scale effect is small, except that of fertilizer. The decomposition analysis results are then used to analyze the implications of Greece's fertilizer and feed subsidy removal, which took place in 1990.

scholarly journals Isospin Conservation in Neutron Rich Systems of Heavy Nuclei

2018 ◽  
Vol 178 ◽  
pp. 05007 ◽  
Author(s):  
Ashok Kumar Jain ◽  
Swati Garg
Keyword(s):  
Theoretical Calculation ◽  
Fission Fragment ◽  
Nuclear Fission ◽  
Heavy Ion ◽  
Mass Region ◽  
Fission Reactions ◽  
Heavy Nuclei ◽  
Practical Applications ◽  
Heavy Ion Fusion

It is generally believed that isospin would diminish in its importance as we go towards heavy mass region due to isospin mixing caused by the growing Coulomb forces. However, it was realized quite early that isospin could become an important and useful quantum number for all nuclei including heavy nuclei due to neutron richness of the systems [1]. Lane and Soper [2] also showed in a theoretical calculation that isospin indeed remains quite good in heavy mass neutron rich systems. In this paper, we present isospin based calculations [3, 4] for the fission fragment distributions obtained from heavy-ion fusion fission reactions. We discuss in detail the procedure adopted to assign the isospin values and the role of neutron multiplicity data in obtaining the total fission fragment distributions. We show that the observed fragment distributions can be reproduced rather reasonably well by the calculations based on the idea of conservation of isospin. This is a direct experimental evidence of the validity of isospin in heavy nuclei, which arises largely due to the neutron-rich nature of heavy nuclei and their fragments. This result may eventually become useful for the theories of nuclear fission and also in other practical applications.

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