Molecular Chirality: From Structure to the Quantum Dynamics of Tunnelling, Parity Violation, a Molecular Quantum Switch and the Possible Astrophysical Detection of Homochirality as a Signature of Extraterrestrial Life

Abstract

We briefly review the development of fundamental concepts in the current theory and experiments on molecular chirality, including the small effects arising from parity violating weak nuclear interaction. After a short summary of the history of theory and experiments in this field, we discuss the five basic hypotheses on the structure of chiral molecules. One of these introduces parity violation as the dominant effect in isolated molecules. We then provide a brief description of current experiments for measuring the parity violating energy difference Δ_pvE between the ground states of enantiomers of chiral molecules by an approach which can also be used for the construction of a molecular quantum switch and for testing other hypotheses of molecular chirality. We finally introduce the long-standing open question of the origin of biomolecular homochirality. We stress the important distinction between hypotheses postulating a selection either by a ‘de facto’ (chance) or by a ‘de lege’ mechanism (necessity because of parity violation). This leads to the recent astrophysical detection of chiral molecules in the interstellar medium as a basis for a future possible spectroscopic detection of extra-terrestrial and exoplanetary homochirality as a signature of life.