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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 ?
'Existing methods for sorting these molecules usually rely on selective crystallization or on chemical reactions with chiral catalysts in a solution,' says Prof.
The global chiral chemicals market is estimated to reach to USD 96,894.20 million at a CAGR of around 13.67% during the forecast period, 2017-2023.
Although a large number of research on the chiral metal complexes have been published so far [18-28] few studies have been carried out on chiral copper(II) complexes [29-36] and their DNA binding and biological properties [37-39].
Furthermore, both skyrmions and the newly-discovered chiral bobbers are very small, with diameters of typically only a few tens of nanometers.
Consider a PEC rough surface placed in a chiral medium as shown in Figure 1.
proposed the application of a chiral honeycomb in electromagnetic absorbers [10]; later, in 2010, Kopyt et al.
Generally, the principle of chiral separation can be summarized by two different techniques: direct and indirect chiral separation.
Tretyakov, et al., Electromagnetic Waves in Chiral and Bi-isotropic Media, Artech House, London, 1994.
Since the chiral auxetic cellular solids are a foam, they are very flexible in volume change and are a good candidate for energy absorption and enhanced protection applications, such as cushioning for helmets, packing materials and sports or military protective armor, the researchers say.
In fact, anisotropic chiral medium plays a crucial role by having negative refractive index (left-handed) materials that has opened new horizons in optics and becomes subject of important scientific interests [6-9].
The idea was to use quantum field theory but replacing quarks and gluons degrees of freedom by pions and nucleons, keeping the fundamental properties of the underlying theory like chiral symmetry.
For the first time, researchers have detected a chiral molecule, propylene oxide, in interstellar space.