enantiomorph

An enantiomorph is a mirror-image form of a structure that cannot be superimposed on its mirror image. In chemistry, the term is used alongside enantiomer to describe each of two stereoisomers that are non-superposable mirror images. In crystallography and mineralogy, enantiomorph refers to one of two crystal forms that are mirror images of each other and cannot be superimposed; such pairs arise in chiral, non-centrosymmetric crystal systems and are called enantiomorphic forms.

Enantiomorphs and enantiomers share the same chemical composition and, in an achiral environment, nearly identical physical properties. They differ in how they interact with chiral environments and in the direction of plane-polarized light rotation, a property known as optical activity. In biological systems, enantiomers can exhibit markedly different activities or toxicities due to selective interactions with chiral biomolecules.

Racemates are mixtures containing equal amounts of both enantiomorphs and may behave similarly to the pure compound in some contexts but differently in others, particularly in chiral environments. Separation of enantiomorphs—resolution or asymmetric synthesis—is important in fields such as pharmacology, where one enantiomer may be more efficacious or safer than the other.

Common examples include lactic acid, which has D- and L- forms, and the two enantiomorphic forms of quartz, described as left- and right-handed. The concept of enantiomorph highlights how mirror-image symmetry influences structure, properties, and interactions across chemistry and crystallography.