Inherent chirality

In chemistry, inherent chirality is a property of asymmetry in molecules arising, not from a stereogenic or chiral center, but from a twisting of the molecule in 3-D space. The term was first coined by Volker Boehmer in a 1994 review, to describe the chirality of calixarenes arising from their non-planar structure in 3-D space.

This phenomenon was described as resulting from "the absence of a place of symmetry or an inversion center in the molecule as a whole".^[1] Boehmer further explains this phenomenon by suggesting that if an inherently chiral calixarene macrocycle were opened up it would produce an "achiral linear molecule".^[1] There are two commonly used notations to describe a molecules inherent chirality: cR/cS (arising from the notation used for classically chiral compounds, with c denoting curvature) and P/M.^{[2][irrelevant citation]} Inherently chiral molecules, like their classically chiral counterparts, can be used in chiral host–guest chemistry, enantioselective synthesis, and other applications.^[3] There are naturally occurring inherently chiral molecules as well. Retinal, a chromophore in rhodopsin. exists in solution as a racemic pair of enantiomers due to the curvature of an achiral polyene chain.^[4]