Stereoisomerism

Stereoisomerism is a concept in chemistry that refers to the spatial arrangement of atoms in molecules. It is a type of isomerism where molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space. This difference can have significant effects on the properties and reactions of the different isomers.

Types of Stereoisomerism

Stereoisomerism can be divided into two main types: geometric isomerism (or cis-trans isomerism) and optical isomerism.

Geometric Isomerism

Geometric isomerism occurs when there is restricted rotation in a molecule, which can happen due to the presence of a double bond or a cyclic structure. The most common example is the cis-trans isomerism, where the isomers differ in the position of substituents relative to a plane of reference.

Optical Isomerism

Optical isomerism occurs when a molecule can exist in two forms that are non-superimposable mirror images of each other, known as enantiomers. This type of isomerism is due to the presence of a chiral center, usually a carbon atom with four different groups attached to it.

Importance of Stereoisomerism

Stereoisomerism is of great importance in several fields, including pharmacology, biochemistry, and material science. In pharmacology, for example, different stereoisomers of a drug can have different levels of efficacy and side effects. In biochemistry, the three-dimensional arrangement of atoms in biomolecules determines their function in biological systems.

See Also

• Chirality
• Enantiomers
• Diastereomers
• Racemates