Reexamination of the notion of .pi.-electron delocalization energy as a theoretical index to the empirical resonance energy

1987 ◽  
Vol 52 (11) ◽  
pp. 2323-2324 ◽  
Author(s):  
Masahiro Kataoka ◽  
Takeshi Nakahima
Keyword(s):  
Resonance Energy ◽  
Electron Delocalization ◽  
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).

The conformation of some biaryl radicals

1970 ◽  
Vol 48 (14) ◽  
pp. 2158-2164 ◽  
Author(s):  
W. G. Laidlaw ◽  
R. B. Flewwelling
Keyword(s):  
Electron Delocalization ◽  
Delocalization Energy

The conformations of the radicals of biphenyl, diphenylmethyl, and some of their methyl substituted derivatives were investigated by calculating the π-electron delocalization energy and the non-bonded repulsions between the rings. The barriers to rotation are also reported.

Evaluating the cyclic π-electron delocalization energy through a double cut of conjugated rings

2007 ◽  
Vol 31 (11) ◽  
pp. 1918 ◽  
Author(s):  
Jean-Paul Malrieu ◽  
Christine Lepetit ◽  
Mickaël Gicquel ◽  
Jean-Louis Heully ◽  
Patrick W. Fowler ◽  
...  
Keyword(s):  
Electron Delocalization ◽  
Delocalization Energy

A study on the aromaticity and ring currents of dithienopyridines and dithienobenzene

2018 ◽  
Vol 17 (01) ◽  
pp. 1850006
Author(s):  
Bi Xiao Yun ◽  
Ablikim Kerim
Keyword(s):  
Ring Current ◽  
Resonance Energy ◽  
Ring Structure ◽  
Electron Delocalization ◽  
Aromaticity Index ◽  
Ring Currents ◽  
Middle Ring ◽  
Topological Resonance Energy ◽  
Local Aromaticity

The global aromaticity of dithienopyridine and dithienobenzene isomers was investigated using the topological resonance energy (TRE) and percentage topological resonance energy (%TRE) methods. The effect of variations in the positions of sulfur and nitrogen atoms on [Formula: see text]-electron delocalization is analyzed. The local aromaticity of these isomers is described based on the bond resonance energy (BRE) and circuit resonance energy (CRE) methods. Our BRE and CRE results show that structure of the central six-membered rings has a strong effect on global aromaticity. The aromaticity of these dithienopyridine isomers is enhanced when a complete pyridine unit exists in their middle ring structure, while the aromaticity of the dithienobenzene isomers is enhanced when a complete benzene unit exists in their middle ring structure. For dithienopyridines, our results obtained using the TRE method correlate well with the Bird aromaticity index as reported in the literature. Our ring-current results show that all these compounds are diatropic systems.

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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