Definition Of Chirality Research Articles

On the Definition of Chirality and Enantioselective Fields

AbstractIn solid state physics, any symmetry breaking is known to be associated with emergence of an order parameter. However, the order parameter for molecular and crystal chirality, which is a consequence of parity and mirror symmetry breaking, has not been known since its discovery. In this article, the authors show that the order parameter for chirality can be defined by electric toroidal monopole . By this definition, one becomes able to discuss external field that can distinguish two different enantiomers only by physical fields. In addition, dynamics and fluctuations of the order parameter can be discussed, with which one can obtain fruitful insights on a spin filtering effect called CISS (Chirality Induced Spin Selectivity). Emergence of time‐reversal‐odd dipole by time propagation of quantities is discussed to explain the enantioselective effect (chiral resolution) at a ferromagnetic surface.

Molecular Chirality in Classical Spacetime: Solving the Controversy about the Spinning Cone Model of Rotating Molecules.

The spinning cone is a model of rotating molecules used by Barron in 1986 in relation to asymmetric synthesis and to parity violation. He considered that the non-translating cone spinning about its symmetry axis has false chirality (i.e., it is not chiral), whereas Mislow concluded in 1999 that it is indeed chiral and severely criticized the true versus false chirality nomenclature introduced by Barron, who still disagreed in 2013 with the conclusion of Mislow. Here, it is shown that this controversy comes from an ambiguity in the spinning cone model and that in fact both authors were right. Light is thrown on the true chirality versus false chirality controversy with a very recently published result, which was thus unavailable to both authors: this is a new definition of chirality that encompasses the one introduced by Lord Kelvin at the end of the 19th century.

Chirality of Dirac Spinors Revisited

We emphasize the differences between the chirality concept applied to relativistic fermions and the ususal chirality concept in Euclidean spaces. We introduce the gamma groups and we use them to classify as direct or indirect the symmetry operators encountered in the context of Dirac algebra. Then we show how a recent general mathematical definition of chirality unifies the chirality concepts and resolve conflicting conclusions about symmetry operators, and particularly about the so-called chirality operator. The proofs are based on group theory rather than on Clifford algebras. The results are independent on the representations of Dirac gamma matrices, and stand for higher dimensional ones.

結晶カイラリティの定義に関して

結晶カイラリティの定義に関して

Orientation-Dependent Handedness and Chiral Design

Chirality occupies a central role in fields ranging from biological self-assembly to the design of optical metamaterials. The definition of chirality, as given by Lord Kelvin, associates chirality with the lack of mirror symmetry: the inability to superpose an object on its mirror image. While this definition has guided the classification of chiral objects for over a century, the quantification of handed phenomena based on this definition has proven elusive, if not impossible, as manifest in the paradox of chiral connectedness. In this work, we put forward a quantification scheme in which the handedness of an object depends on the direction in which it is viewed. While consistent with familiar chiral notions, such as the right-hand rule, this framework allows objects to be simultaneously right and left handed. We demonstrate this orientation dependence in three different systems - a biomimetic elastic bilayer, a chiral propeller, and optical metamaterial - and find quantitative agreement with chirality pseudotensors whose form we explicitly compute. The use of this approach resolves the existing paradoxes and naturally enables the design of handed metamaterials from symmetry principles.

Cholinesterases and Unified Neurophysics

The enigmatic diseases of the ‘Mad Cow’ type (BSE) were approached from the fundamental level of ethereal particle spin (chirality). A revised definition of chirality then gave a logical explanation for structure and function in both physics and biology. Cholinesterases (ChEs) appeared to govern stereo-chemical hydrodynamics by the release of free protons to activate hem-transported molecular oxygen. Oxidation will increase stability of bio-molecules and recycle hydrogen to water. Biology stands for the only break in universal symmetry (parity violation) by its ChE-oxidative hydrodynamics and explains the matter-antimatter issue. In the brain, basic physical events will be inhibited, delayed or converted by ChE’s hydrodynamic autonomy, which basically equals continuous inflammation. The pathophysiology in a lot of neurological diseases of the Bowine Spongioform Encephalitis -scrapie- Alzheimer’s disease - Creutzfeldt-Jakob Disease type in cattle, sheep and man, like the relentless process of aging by long-term oxidative effects was elucidated by the present short glimpses into physics.

Reply to “On the Definition of Chirality”: Further Comments on the Chirality of Large Random Objects

Chemistry – A European JournalVolume 2, Issue 6 p. 744-746 Correspondence Reply to “On the Definition of Chirality”: Further Comments on the Chirality of Large Random Objects Prof. David Avnir, Corresponding Author Prof. David Avnir david@granite.fh.huji.ac.il Institute of Chemistry and Institute of Advanced Studies The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)Institute of Chemistry and Institute of Advanced Studies The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)Search for more papers by this authorOmer Katzenelson, Omer Katzenelson Institute of Chemistry and Institute of Advanced Studies The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)Search for more papers by this authorDr. Hagit Zabrodsky Hel-Or, Dr. Hagit Zabrodsky Hel-Or Institute of Chemistry and Institute of Advanced Studies The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)Search for more papers by this author Prof. David Avnir, Corresponding Author Prof. David Avnir david@granite.fh.huji.ac.il Institute of Chemistry and Institute of Advanced Studies The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)Institute of Chemistry and Institute of Advanced Studies The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)Search for more papers by this authorOmer Katzenelson, Omer Katzenelson Institute of Chemistry and Institute of Advanced Studies The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)Search for more papers by this authorDr. Hagit Zabrodsky Hel-Or, Dr. Hagit Zabrodsky Hel-Or Institute of Chemistry and Institute of Advanced Studies The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)Search for more papers by this author First published: June 1996 https://doi.org/10.1002/chem.19960020620Citations: 10AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume2, Issue6June 1996Pages 744-746 RelatedInformation

On the Definition of Chirality

Should Lord Kelvin's definition of chirality be modified to accommodate concepts associated with the chirality of large random supramolecular structures? Stimulated by a recent article by D. Avnir et al. (Chem. Eur. J. 1996, 2, 174), L. D. Barron discusses this question. In their reply D. Avnir et al. further clarify and discuss their original thesis.

Two-dimensional rotational dynamic chirality and a chirality scale

A scale for the quantitative assessment of the degree of shape chirality and for the absolute assignment of handedness is developed. The scale is based on a new definition of chirality, which, in turn, is based on the dynamic rotational properties of molecules. These concepts and their demonstration are carried out for the case of two-dimensional chirality, i.e., for chirality issues associated with adsorbate-surface interaction

Chirality of field induced natural and magnetic optical activity

The symmetry and chirality of field induced natural and magnetic optical activity are investigated with Barron's definition of chirality and the third principle of group theoretical statistical mechanics (g.t.s.m.). The results for several different external field symmetries are given for the point group R h(3) of achiral ensembles and for R(3) of chiral ensembles. The distinction is made between natural and magnetic optical rotation/dichoroism and the field symmetries necessary for these to appear are defined in both point groups. The analysis resolves some recent literature confusion and suggests new field induced dichroic phenomena.

Fundamental symmetry aspects of chirality

Physical systems which exhibit distinguishable enantiomers under space inversion are not necessarily chiral. A new definition of chirality is proposed that enables true and false chirality to be distinguished. Although spatial enantiomorphism is sufficient to guarantee chirality in a stationary object, enantiomorphous systems are not necessarily chiral when motion is involved. Only a truly chiral influence can induce absolute asymmetric synthesis in a reaction mixture at thermodynamic equilibrium, but false chirality might suffice if equilibrium is not attained. Parity violation lifts only the degeneracy of enantiomers of truly chiral systems, the true enantiomers (i.e. strictly degenerate) being interconverted by space inversion together with charge conjugation. The time-independence of optical activity arising from parity violation is contrasted with the time-dependence of that arising from spontaneous parity breaking.

True and false chirality and parity violation

Systems that exhibit distinguishable enantiomers under space inversion are not necessarily chiral. A new definition of chirality is proposed that enables true and false chirality to be distinguished. This definition is reinforced by a consideration of parity violation, which lifts only the degeneracy of the space-inverted enantiomers of truly chiral systems.