senantiomers

Senantiomers, more commonly called enantiomers in English, are pairs of molecules that are non-superimposable mirror images of each other. They arise from molecular chirality, meaning a molecule lacks an internal plane of symmetry and contains stereogenic centers. A mirror image of a chiral molecule cannot be aligned with the original by rotation alone, giving two distinct forms that have the same connectivity but different spatial arrangement.

In achiral environments, enantiomers have identical physical properties such as melting points, boiling points, and densities; however, they rotate plane-polarized light in equal magnitude but opposite directions. In chiral environments, such as living systems or with biological receptors, enantiomers can interact very differently, often producing distinct biological activities or pharmacokinetic profiles.

Enantiomers are related as mirror images. For molecules with multiple stereocenters, the two enantiomers are non-superimposable reflections of each other, while diastereomers are non-mirror-image stereoisomers with different properties. Enantiomers differ in their interaction with other chiral substances and with biological targets, even when many physical properties are the same in an achiral setting. Quantifying purity often involves enantiomeric excess and related measures.

Applications and terminology: separating enantiomers (enantiomeric resolution) or synthesizing them asymmetrically are central tasks in chemistry and pharmacology. Techniques include chromatography on chiral stationary phases and the use of resolving agents. In medicine, many drugs are marketed as single enantiomers due to differing efficacy or safety between forms; racemic mixtures contain equal amounts of both enantiomers. The term senantiomer appears in some languages and older literature; the standard English term is enantiomer.