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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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



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.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
A normal (or achiral) stationary phase capillary column has been used for the separation of the resulting diastereomers due to their different chemical and physical properties.
gas chromatography/mass spectrometry with chiral and achiral stationary
Based on this information, many attempts have been carried out to synthesize optically active polymers with a stable one-handed helicity from optically inactive achiral vinyl monomers, such as styrene and methyl methacrylate.
Chiral and achiral SFG spectra can be selectively collected using different polarization settings.
Keywords: Reidmeister Moves, LR-Graphs, Reduced Alternating Achiral knot, Planar Graphs, Equivalent KnotsMathematics Subject Classification2000: 57M25(15)(27)INTRODUCTIONKnots have been introduced as early as is the story ofAlexander and Gordian but never got scientific status till Nineteen Century.
Mogel, "Monte Carlo study of the self-assembly of achiral bolaform amphiphiles into helical nanofibers," Langmuir, vol.
Tacke, "Novel achiral titanocene anti-cancer drugs synthesised from bis-N,N-dimethylamino fulvene and lithiated heterocyclic compounds," BioMetals, vol.
US and Canadian contributors in pharmacokinetics, pharmacy, experimental therapeutics, and horticulture describe the science and methodology behind techniques used for isolation, separation, and identification in natural product research, specifically in the analysis of achiral and chiral flavonoids.
In the same context, reflection of plane wave from an interface of an achiral dielectric and a chiral/chiral nihility metamaterial was discussed by Qiu et al.
Chico, "Interface states in achiral carbon nanotube junctions: rolling up graphene," Physical Review B, vol.
Piccagli et al., "Identification of an achiral analogue of J-113397 as potent nociceptin/orphanin FQ receptor antagonist," Bioorganic and Medicinal Chemistry, vol.