Enantiomers

Definition

Enantiomers are a pair of molecules that are mirror images of each other and cannot be superimposed. They have identical physical properties but differ in the direction they rotate plane-polarized light.

5 Must Know Facts For Your Next Test

1. Enantiomers occur in chiral coordination complexes where the central metal atom is bonded to ligands in a non-superimposable manner.
2. They exhibit optical activity, meaning one enantiomer will rotate plane-polarized light clockwise (dextrorotatory) and the other counterclockwise (levorotatory).
3. In a chiral complex, enantiomers can have different biological activities and can interact differently with enzymes or receptors.
4. The separation of enantiomers is often achieved through techniques such as chiral chromatography or using a chiral resolving agent.
5. Enantiomeric excess (ee) is a measure used to express the purity of an enantiomer in a mixture, defined as $(| R-S | / (R+S)) \times 100$.

Review Questions

• What property allows enantiomers to rotate plane-polarized light in opposite directions?
• Why can't enantiomers be superimposed on each other?
• How do enantiomers differ in their interactions with biological systems?

Related terms

Chirality: A property of asymmetry important in several branches of science; an object or molecule is chiral if it is not superimposable on its mirror image.

Optical Activity: The ability of a compound to rotate the plane of polarized light, characteristic of chiral substances.

Diastereomers: Stereoisomers that are not mirror images of each other and have different physical properties.