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The handedness of an asymmetric molecule.
(particle physics)
The characteristic of particles of spin ½ ℏ that are allowed to have only one spin state with respect to an axis of quantization parallel to the particle's momentum; if the particle's spin is always parallel to its momentum, it has positive chirality; antiparallel, negative chirality.
The characteristic of an object that cannot be superimposed upon its mirror image.



a concept in chemistry characterizing the property of nonsuperimposability of an object with its mirror image. It was first formulated in 1884 by Lord Kelvin (W. Thomson), but it gained common acceptance only after 1966, when it was introduced into stereochemistry by V. Prelog.

In addition to configuration and conformation, chirality is a basic concept of modern stereochemistry. A distinction is made between centric, axial, and planar chirality, to which chiral elements correspond: center, axis, and plane (see Figure 1). For enantiomorphic crystals and some types of molecules, the consideration of chiral space is worthwhile. A chiral center is a broader

Figure 1. Examples of molecules with different chiral elements: (a) center, (b) axis, (c) plane. A, B, C, and D represent different groupings of atoms.

concept than an asymmetric atom, since molecules exist in which the chiral centers do not coincide with any of their atoms. Planar chirality is characteristic of metallo-organic compounds, for example, π-complexes of olefins and arenes. Chirality is a necessary condition for natural molecular optical activity, since chiral objects exist as pairs of enantiomorphs.

The absence of chirality is indicated by the term “achirality.” Achiral molecules may demonstrate induced optical activity. A molecule is prochiral if it may be converted into a chiral molecule by the replacement of a single atom, for example, the replacement of a hydrogen atom in CH2BrCl by a fluorine atom. When chiral and prochiral fragments are combined in one molecule, the phenomenon of nuclear diastereotopy arises, which is observed in nuclear magnetic resonance spectra. The newest method of determining molecular chirality is based on this effect.


Sokolov, V. I. Novoe v stereokhimii. Moscow, 1975.


References in periodicals archive ?
New kinds of metamaterials are being designed with a specific orientation, or chirality, to put an unnatural twist on light, even with T-rays, a frequency of light that has been difficult to harness.
Effect of earth's orbital chirality on elementary particles and unification of chiral asymmetries in life on different levels.
As a result, a new chiral center is formed, and in respect to the given chirality in the backbone, the two possible N-configurations result in two possible diastereomers.
Reason number three concerns how many manufacturers ignore chirality simply because they do not believe that the skin requires the same care as do the internal organs of the body.
Among the topics are valence photoelectronic circular dichroism of gas phase enantiomers, the infrared and Raman detection of transient chirality recognition in the gas phase with ethanol as a case study, enantioselectivity in gas-phase ion-molecule reactions, equilibrium methods, deoxy oligonucliotides as chiral references for discriminating enantiomeric amino acids under mass spectrometry, solution-phase versus gas-phase chiral recognition by electrospray ionization mass spectrometry with a case study of two chiral selector classes.
Since the layers of MWNT are structurally independent of one another, the chirality of the layers may be different.
Nanotechnology--RS provides determination of nanocrystal, chirality, semidiameters in nanomaterials.
The section on chirality is particularly well written and covers this important area in considerably more detail than that found in most other pharmacology or anaesthesia texts.
A molecule's chirality is detectable only when the substance interacts with other chiral things such as circularly polarized light, whose electric field traces out a helical pattern, like a Slinky, while moving through space.
Also important is chirality of the chemical reference material.
To get a sense of the importance of chirality in the pharmaceutical industry, all one needs to do is look at the numbers.
d] with increment v(j) on chirality j, with unitary chirality operator U has generating matrix