What is Chirality?
Chirality is an asymmetric quality that is relevant in many fields of science. The word chirality comes from the Greek (kheir), which means “hand,” a common chiral item. A chiral item or system is distinct from its mirror image; that is, it cannot be overlaid onto it.
Golf clubs, scissors, shoes, and a corkscrew are examples of chiral objects that have a “handedness.” As a result, right-handed and left-handed golf clubs and scissors are available. Gloves and shoes, like everything else, come in pairs, a right and a left. Chirality roughly translates to “mirror-image, non-superimposable molecules,” and to claim that a molecule is chiral indicates that its mirror image (which it must have) is not the same as it is. A series of overlapping requirements determines whether a molecule is chiral or achiral.
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Stereoisomers
Stereoisomers are molecules with the same molecular formula that differ solely in how their atoms are arranged in three-dimensional space, and there are various subgroups under the stereoisomer category. Geometrical isomers and optical isomers are the two basic types of stereoisomers.
- The three-dimensional arrangement of the atoms that make up a molecule can change its structure. Stereochemistry is concerned with the modulation of these atoms’ arrangements.
- Because it concentrates on stereoisomers, this discipline of chemistry is usually referred to as 3-D chemistry (chemical compounds with the same chemical formula but a different spatial arrangement in three dimensions).
- One branch of stereochemistry studies molecules having chirality, which is a geometric characteristic of molecules that prevents them from being superimposed on their mirror copies.
- Dynamic stereochemistry is another branch of 3-D chemistry that studies the influence of diverse spatial arrangements of atoms in a molecule on the pace of a chemical reaction.
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Enantiomers
In chemistry, an enantiomer is one of two stereoisomers that are mirror images of each other but cannot be superposed, similar to how one’s left and right hands are mirror images of each other but cannot be superposed.
Except for their influence on plane-polarized light, enantiomers share the same physical and molecular properties. Plane-polarized light is light that has had its waves filtered onto a single plane. In a polarimeter, plane-polarized light is used to test the optical characteristics of enantiomers. Enantiomers are commonly referred to as optical isomers because of this.
Chiral recognition is the process of distinguishing between a chiral molecule’s two enantiomers. It is difficult to distinguish enantiomers from one another since the physical features that are generally used to distinguish molecular types are similar. Physical distinctions can only be recognised through interactions with a discriminating secondary species.
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Diastereomers
Diastereomers are stereoisomers that are not enantiomers and are not associated as object and mirror image. Diastereomers are not mirror images of each other and are non-superimposable, unlike enantiomers, which are mirror images of each other and non-superimposable. Different physical traits and reactivity can be found in diastereomers. Their melting and boiling points, as well as their densities, are all distinct. There are two or more stereocenters in their system.
- Melting temperatures, boiling points, densities, solubilities, refractive indices, dielectric constants, and specific rotations are all different physical properties of diastereomers. Except for the opposite sign of specific rotation, enantiomers have similar physical characteristics.
- Unlike geometrical isomers, other diastereomers may or may not be optically active.
- Diastereomers have chemical characteristics that are similar but not identical. If the reagent is not rapidly active, the rates of reactions of the two diastereomers with that reagent.
- Diastereomers can be separated from one another using techniques such as fractional crystallisation, fractional distillation, and chromatography, among others, due to changes in their physical properties. This is in contrast to enantiomers, which cannot be distinguished using these methods.
Read more:Diastereomers
Frequently Asked Questions on Chirality
What is chirality and why is it important?
Because chiral molecules make up the majority of cells, chirality is a crucial term in biology. Amino acids and sugars are small chiral compounds that serve as building blocks for larger chiral molecules like proteins and nucleic acids.
What is chirality in amino acids?
A key feature of amino acids is that the α carbon is chiral. When a carbon atom is bound to four unique groups, it creates a chiral center (also known as a stereocenter). Simply put, a chiral molecule is one that cannot be superimposed with its mirror image.
What is an example of a chiral carbon?
Molecules that are non superimposable mirror images of each other are said to be chiral (pronounced “ky-ral,” from the Greek cheir, meaning “hand”). Examples of some familiar chiral objects are your hands, feet, and ears
What is a helical compound?
Helicenes are polycyclic aromatic compounds in which the benzene rings are connected in ortho positions leading to screw-shaped molecules. They exhibit helical chirality even though they do not contain any asymmetric carbon.
What is handedness of chirality?
Chirality is defined by the lack of certain features of symmetry, which lead to an object not being superimposable on its mirror image. Handedness is a different phenomenon relating to the ability to classify chiral objects into right-handed and left-handed objects.
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