chirality

chi·ral·i·ty

C5319450 (kī-răl′ĭ-tē)n. The aspect of a structure or property, such as the configuration of a molecule or the spin of a particle, that renders that structure or property distinguishable from its mirror image or symmetrical opposite. Also called handedness.

chirality

(kaɪˈrælɪtɪ) n (Chemistry) the configuration or handedness (left or right) of an asymmetric, optically active chemical compound. Also called: dissymmetry [C19: from Greek kheir hand + -al¹ + -ity] ˈchiral adj

Translations

Chirality

enUK

chirality

[kī′ral·əd·ē] (chemistry) 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. (physics) The characteristic of an object that cannot be superimposed upon its mirror image.

Chirality

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.

REFERENCE

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

V. I. SOKOLOV

chirality

[ki-ral´ĭ-te] the property of handedness, of not being superimposable on a mirror image; the handedness of an asymmetric molecule, as specified by its optical rotation or absolute configuration.

chi·ral·i·ty

(kī-ral'i-tē), The property of nonidentity of an object with its mirror image; used in chemistry with respect to stereochemical isomers. [G. cheir, hand]

chirality

(kī-răl′ĭ-tē)n. The aspect of a structure or property, such as the configuration of a molecule or the spin of a particle, that renders that structure or property distinguishable from its mirror image or symmetrical opposite. Also called handedness.

The left- or right-sidedness of virtually the entirety of the physical universe, from elementary particles—e.g., electrons and molecules—to highly complex organisms
Organic chemistry The 3-D conformation of a molecule, which has an either left-handed (levo- or l-) orientation, as do most molecules in functioning biologic systems, or right-handed (dextro- or d-) orientation

chi·ral·i·ty

(kī-ral'i-tē) The property of nonidentity of an object with its mirror image; used in chemistry with respect to stereochemical isomers. [G. cheir, hand]

chirality

The state of two molecules having identical structure except that they display ‘handedness’ (as in the right and left hand) and are mirror images of one another. Such pairs of molecules are also known as enantiomers or optical isomers. When dissolved in a fluid they rotate a plane-polarized beam in opposite directions.

chirality

(of STEREOISOMERS) the property of ‘handedness’ (right- or left-handedness) of a molecule, such that the mirror image cannot coincide exactly with the actual image.

单词	chirality
释义	chirality enUK chi·ral·i·ty C5319450 (kī-răl′ĭ-tē)n. The aspect of a structure or property, such as the configuration of a molecule or the spin of a particle, that renders that structure or property distinguishable from its mirror image or symmetrical opposite. Also called handedness. chirality (kaɪˈrælɪtɪ) n (Chemistry) the configuration or handedness (left or right) of an asymmetric, optically active chemical compound. Also called: dissymmetry [C19: from Greek kheir hand + -al¹ + -ity] ˈchiral adj Translations Chirality enUK chirality [kī′ral·əd·ē] (chemistry) 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. (physics) The characteristic of an object that cannot be superimposed upon its mirror image. Chirality 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. REFERENCE Sokolov, V. I. Novoe v stereokhimii. Moscow, 1975. V. I. SOKOLOV chirality enUK chirality [ki-ral´ĭ-te] the property of handedness, of not being superimposable on a mirror image; the handedness of an asymmetric molecule, as specified by its optical rotation or absolute configuration. chi·ral·i·ty (kī-ral'i-tē), The property of nonidentity of an object with its mirror image; used in chemistry with respect to stereochemical isomers. [G. cheir, hand] chirality (kī-răl′ĭ-tē)n. The aspect of a structure or property, such as the configuration of a molecule or the spin of a particle, that renders that structure or property distinguishable from its mirror image or symmetrical opposite. Also called handedness. The left- or right-sidedness of virtually the entirety of the physical universe, from elementary particles—e.g., electrons and molecules—to highly complex organisms Organic chemistry The 3-D conformation of a molecule, which has an either left-handed (levo- or l-) orientation, as do most molecules in functioning biologic systems, or right-handed (dextro- or d-) orientation chi·ral·i·ty (kī-ral'i-tē) The property of nonidentity of an object with its mirror image; used in chemistry with respect to stereochemical isomers. [G. cheir, hand] chirality The state of two molecules having identical structure except that they display ‘handedness’ (as in the right and left hand) and are mirror images of one another. Such pairs of molecules are also known as enantiomers or optical isomers. When dissolved in a fluid they rotate a plane-polarized beam in opposite directions. chirality (of STEREOISOMERS) the property of ‘handedness’ (right- or left-handedness) of a molecule, such that the mirror image cannot coincide exactly with the actual image. ThesaurusSeehandedness
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