Stereochemistry:
Stereochemistry is a subdivision of chemistry that concentrates on the 3D conformation of a molecule. The word was first recorded in 1885, however “stereo” is from Greek origin, meaning “solid”, or the three-dimensionality of an object. This branch of chemistry studies the spatial arrangement of the molecule, or how the molecule takes up space. Stereochemistry may take into account the effect of the molecule’s behavior based on the spatial arrangement. Molecules of the same configuration, meaning that they have the same chemical formula, may have different stereoisomers, or different spatial arrangements. There are two kinds of stereoisomers, which are classified as enantiomers and diastereomers. Enantiomers define two molecules that have the same configuration that are mirror images of each other. Diastereomers are used to define two molecules with the same configuration, however, are not mirror images to each other.
An example of enantiomers presented through 3D models of two molecules:
An example of diastereomers presented through skeletal structures of two molecules:
Noting the stereochemistry of a molecule is important to chemistry because the spatial arrangement of different molecules may behave and react differently in chemical reactions. Especially when dealing with certain medications, the correct stereoisomer must be used. For example, a certain medication may only be active, containing a specific enantiomer of a molecule.
