Alkanes versus Oligosilanes: Conformational Effects on σ-Electron Delocalization

2021 ◽  
Author(s):  
Milena Jovanovic ◽  
Josef Michl
Keyword(s):  
Electron Delocalization ◽  
Conformational Effects

Carbo-[3]oxocarbon and its isomers: evaluation of the stability and of the electron delocalization

2008 ◽  
Vol 10 (24) ◽  
pp. 3578 ◽  
Author(s):  
Mickaël Gicquel ◽  
Jean-Louis Heully ◽  
Christine Lepetit ◽  
Remi Chauvin
Keyword(s):  
Electron Delocalization ◽  
The Stability

scholarly journals Quantitative Analysis of the Membrane Affinity of Local Anesthetics Using a Model Cell Membrane

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 579
Author(s):  
Wanjae Choi ◽  
Hyunil Ryu ◽  
Ahmed Fuwad ◽  
Seulmini Goh ◽  
Chaoge Zhou ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Local Anesthetics ◽  
Electrophysiological Study ◽  
Local Area ◽  
Membrane Properties ◽  
Dominant Factor ◽  
Free Standing ◽  
Membrane Affinity ◽  
Conformational Effects ◽  
Model Protein

Local anesthesia is a drug that penetrates the nerve cell membrane and binds to the voltage gate sodium channel, inhibiting the membrane potential and neurotransmission. It is mainly used in clinical uses to address the pain of surgical procedures in the local area. Local anesthetics (LAs), however, can be incorporated into the membrane, reducing the thermal stability of the membrane as well as altering membrane properties such as fluidity, permeability, and lipid packing order. The effects of LAs on the membrane are not yet fully understood, despite a number of previous studies. In particular, it is necessary to analyze which is the more dominant factor, the membrane affinity or the structural perturbation of the membrane. To analyze the effects of LAs on the cell membrane and compare the results with those from model membranes, morphological analysis and 50% inhibitory concentration (IC50) measurement of CCD-1064sk (fibroblast, human skin) membranes were carried out for lidocaine (LDC) and tetracaine (TTC), the most popular LAs in clinical use. Furthermore, the membrane affinity of the LAs was quantitatively analyzed using a colorimetric polydiacetylene assay, where the color shift represents their distribution in the membrane. Further, to confirm the membrane affinity and structural effects of the membranes, we performed an electrophysiological study using a model protein (gramicidin A, gA) and measured the channel lifetime of the model protein on the free-standing lipid bilayer according to the concentration of each LA. Our results show that when LAs interact with cell membranes, membrane affinity is a more dominant factor than steric or conformational effects of the membrane.

scholarly journals Understanding Topological Insulators in Real Space

Molecules ◽  
2021 ◽  
Vol 26 (10) ◽  
pp. 2965
Author(s):  
Angel Martín Pendás ◽  
Francisco Muñoz ◽  
Carlos Cardenas ◽  
Julia Contreras-García
Keyword(s):  
Quantum Theory ◽  
Chiral Symmetry ◽  
Topological Insulator ◽  
Real Space ◽  
Electron Delocalization ◽  
Electron Localization ◽  
Visualization Tool ◽  
Atom Pairs ◽  
Chemical Concepts ◽  
Bulk Behavior

A real space understanding of the Su–Schrieffer–Heeger model of polyacetylene is introduced thanks to delocalization indices defined within the quantum theory of atoms in molecules. This approach enables to go beyond the analysis of electron localization usually enabled by topological insulator indices—such as IPR—enabling to differentiate between trivial and topological insulator phases. The approach is based on analyzing the electron delocalization between second neighbors, thus highlighting the relevance of the sublattices induced by chiral symmetry. Moreover, the second neighbor delocalization index, δi,i+2, also enables to identify the presence of chirality and when it is broken by doping or by eliminating atom pairs (as in the case of odd number of atoms chains). Hints to identify bulk behavior thanks to δ1,3 are also provided. Overall, we present a very simple, orbital invariant visualization tool that should help the analysis of chirality (independently of the crystallinity of the system) as well as spreading the concepts of topological behavior thanks to its relationship with well-known chemical concepts.

Tuning the tautomeric behavior of tris(salicylaldimines)

2017 ◽  
Vol 15 (39) ◽  
pp. 8418-8424 ◽  
Author(s):  
S. Hessam M. Mehr ◽  
Hiroya Oshima ◽  
Veronica Carta ◽  
Brian O. Patrick ◽  
Nicholas G. White ◽  
...  
Keyword(s):  
Electron Delocalization

The tautomeric state of the versatile tris(salicylaldimine) (TSAN) motif is shown to be tunable through the electron delocalization properties of its peripheral groups.

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