Comparison of stabilization energy and resonance energy as a measure of the delocalization energy in free radicals

1972 ◽  
Vol 76 (6) ◽  
pp. 918-920 ◽  
Author(s):  
A. S. Rodgers ◽  
M. C. R. Wu ◽  
L. Kuitu
Keyword(s):  
Free Radicals ◽  
Resonance Energy ◽  
Stabilization Energy ◽  
Delocalization Energy

The close relation between cyclic delocalization, energy effects of cycles and aromaticity

2009 ◽  
Vol 74 (1) ◽  
pp. 147-166 ◽  
Author(s):  
Robert Ponec ◽  
Stijn Fias ◽  
Sofie Van Damme ◽  
Patrick Bultinck ◽  
Ivan Gutman ◽  
...  
Keyword(s):  
Resonance Energy ◽  
Close Relation ◽  
Close Correlation ◽  
Delocalization Energy ◽  
Conjugated Circuits ◽  
Polycyclic Aromatic ◽  
New Evidence ◽  
Topological Resonance Energy ◽  
Local Nature

New evidence questioning the multidimensionality of the aromaticity phenomenon exemplified in what is called orthogonality between the classical (structural and energetic) and magnetic aromaticity indices and measures is reported. For this purpose, the recently proposed methodologies for the quantitative characterization of the energy benefits associated with the cyclic arrangement of mobile π-electrons in polycyclic aromatic hydrocarbons are compared with the indices characterizing the extent of cyclic delocalization in the corresponding conjugated circuits. The reported close correlation between both types of indices implies that no discrepancies between classical and magnetic aromaticity measures exist provided the comparison is based on the indices of inherently local nature and/or the interfering contributions of contaminating conjugated circuits is properly taken into account in the description of aromaticity measures like topological resonance energy (TRE) or nucleus independent chemical shift (NICS).

Paradigms and paradoxes: O- and N-protonated amides, stabilization energy, and resonance energy

2011 ◽  
Vol 23 (1) ◽  
pp. 197-199 ◽  
Author(s):  
Jessica Morgan ◽  
Arthur Greenberg ◽  
Joel F. Liebman
Keyword(s):  
Resonance Energy ◽  
Stabilization Energy

scholarly journals The electronic structure of some polyenes and aromatic molecules IV-The nature of the links of certain free radicals.

1938 ◽  
Vol 164 (918) ◽  
pp. 383-396 ◽  
Author(s):  
Charles Alfred Coulson ◽  
John Edward Lennard-Jones
Keyword(s):  
Free Radicals ◽  
Carbon Atom ◽  
Electron Pair ◽  
Resonance Energy ◽  
Molecular Orbitals ◽  
Orbital Theory ◽  
Chain Molecules ◽  
Aromatic Molecules ◽  
Lennard Jones ◽  
The One

In the first two papers of this series (1937 a, b ), referred to as I, II, Lennard-Jones has developed a method for investigating the lengths and energies of the links in some unsaturated molecules. For this purpose he used the method of molecular orbitals. In paper III (1937), Penney obtained similar results, using the electron-pair methods of resonance, developed Pauling and others. It is the purpose of the present paper to extend the calculations to chain molecules and radicals in which the number of carbon atom s is odd, an d in which, therefore, there is one electron which does not form a bond, in the usual picture of the chemist. We shall use the method of molecular orbitals, and this work may be said to be a continuation of I and II. The writer would like to than k Professor Lennard-Jones for suggesting this work, and for the opportunity of discussing it with him during the calculations. In general these free radicals with “trivalent” carbon are not stable, and tend to form dimers; but there are certain of them which do exist either as stable substances or in dissociative equilibrium with their dimers. Hückel (1935) has discussed these radicals, on the earlier form of the theory in which all the links were assumed equal and no allowance was made for their compression. His work needs to be extended because there is no reason why the links should be all equal, and in fact, the bond diagrams of the chemist lead one to suspect otherwise, and to believe that there may be one of the carbon atoms (the one on which the unpaired electron is to be found) different from the others (for which all the electrons are paired). On the molecular orbital theory, in which each electron is supposed free to move throughout the whole molecule in an averaged potential field, it is not so easy to see a t once in what way the presence of the odd electron will alter the arrangement of the links. So the first question that we shall ask will be whether in chain molecules, such as C 2 n +1 H 2 n +3 , there is one carbon atom occupying an essentially different situation from all the others. We shall then compute the resonance energy.

Structural dynamics of P-type ATPase ion pumps

2019 ◽  
Vol 47 (5) ◽  
pp. 1247-1257 ◽  
Author(s):  
Mateusz Dyla ◽  
Sara Basse Hansen ◽  
Poul Nissen ◽  
Magnus Kjaergaard
Keyword(s):  
Structural Dynamics ◽  
Single Molecule ◽  
New Technologies ◽  
Atp Hydrolysis ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Time Resolved ◽  
Dynamics Simulations ◽  
Types Of Information ◽  
P Type

Abstract P-type ATPases transport ions across biological membranes against concentration gradients and are essential for all cells. They use the energy from ATP hydrolysis to propel large intramolecular movements, which drive vectorial transport of ions. Tight coordination of the motions of the pump is required to couple the two spatially distant processes of ion binding and ATP hydrolysis. Here, we review our current understanding of the structural dynamics of P-type ATPases, focusing primarily on Ca2+ pumps. We integrate different types of information that report on structural dynamics, primarily time-resolved fluorescence experiments including single-molecule Förster resonance energy transfer and molecular dynamics simulations, and interpret them in the framework provided by the numerous crystal structures of sarco/endoplasmic reticulum Ca2+-ATPase. We discuss the challenges in characterizing the dynamics of membrane pumps, and the likely impact of new technologies on the field.

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