Lenantiomers

Lenantiomers are a term occasionally found in chemistry literature to refer to the mirror-image stereoisomers of chiral molecules. In mainstream chemistry, these entities are called enantiomers, and lenantiomers may be considered an alternate or historical name rather than a distinct concept. Enantiomer pairs are non-superimposable mirror images and generally arise when a molecule contains one or more chiral centers. The two members of a pair have opposite configurations (for example, R and S at corresponding centers) and identical physical properties in achiral environments, with the notable exception that they rotate plane-polarized light in opposite directions and may interact differently with chiral surroundings.

In terms of nomenclature, D/L and R/S conventions describe different aspects: D/L relates to historical references to glyceraldehyde, while R/S assigns absolute configuration. Levo- and dextro- prefixes denote the direction of optical rotation, not necessarily the configuration.

Biologically, enantiomers can exhibit markedly different activities, pharmacokinetics, or toxicities; a racemic mixture contains equal amounts of both. Therefore, enantioselective synthesis and chiral resolution are important in pharmaceuticals, agrochemicals, and flavors. Analytical methods include polarimetry to measure optical rotation, and chiral chromatography or crystallization to separate enantiomers.

Notes: Lenantiomer is not a standard term in modern chemistry; for clarity, most discussions adopt enantiomer or the pair of enantiomers. See also enantiomer, chirality, optical activity, racemate, and enantioselective synthesis.