(redirected from chiral)
Also found in: Dictionary, Medical, Wikipedia.
Related to chiral: Achiral


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 ?
Changing the geometry of the chiral auxetic cellular solids can allow the material to respond differently to certain things like temperature, humidity, light, or impact," said Yaning Li, assistant professor of mechanical engineering.
Chiral molecules have shown up in meteorites with a slight preference for one configuration.
Chiral Technologies, a leader in enantioselective chromatography, serves pharmaceutical and other life science industries and offers a portfolio of chiral stationary phases and analytical and preparative chiral columns for the separation of racemic mixtures into single enantiomers.
12,13) (-)-Sp is a commercially-available natural alkaloid, which had been used in 1968 as a chiral ligand in the pioneering research about asymmetric reactions by Nozaki, Aratani and Noyori.
However, the need for skilled professionals and high costs of instruments hamper the growth of the global chiral separation chromatography columns market.
Strict standards have been devised to deal with chiral compounds and their purity.
Urbanc and Zeks [11] suggested that the spontaneous polarization (Ps) induced by a 'Type II' chiral dopant is influenced by steric interactions with the surroundings of host molecules that affects the rotational distribution of the core transverse dipole moment - with respect to the polar axis of the SmC phase [10].
Historically, chiral separations of fragrance compounds have primarily been carried out using chiral stationary phases (CSPs) in capillary gas chromatography (GC).
Its operations in Foshan were limited in scope and its value will be better capitalized by Chiral, which will add marketing and manufacturing capabilities, allowing development of its portfolio and reinforcing its position in the Chinese market, he said.
Chiral metamaterials are made of unit cells without any mirror symmetry so that the cross-coupling between electric and magnetic fields exists at the resonance.
When linearly polarized wave falls on a slab of chiral medium, it splits into two circularly polarized waves: one left circularly polarized and the other right circularly polarized [8-10].
3(a), similar to the previous designed novel dual-band structure [20], the real part of chiral parameter Re([kappa]) curve also exhibits four resonances; the first couple is 4.