Separation of enantiomers by their enantiospecific interaction with achiral magnetic substrates

TLDR

Chirality recognition is usually attributed to spatial effects, but recent work shows that charge redistribution in chiral molecules can create an enantiospecific preference for electron spin orientation. The study aims to test whether induced spin polarization influences enantiorecognition via exchange interactions. The authors experimentally demonstrate that chiral molecules interact enantiospecifically with a perpendicularly magnetized substrate. The experiments show that one enantiomer preferentially adsorbs when the substrate’s magnetic dipole points up, the other when it points down, indicating that electron spin orientation—not the magnetic field itself—drives the enantiospecific interaction and suggests a new route for enantiomer separation.

Abstract

It is commonly assumed that recognition and discrimination of chirality, both in nature and in artificial systems, depend solely on spatial effects. However, recent studies have suggested that charge redistribution in chiral molecules manifests an enantiospecific preference in electron spin orientation. We therefore reasoned that the induced spin polarization may affect enantiorecognition through exchange interactions. Here we show experimentally that the interaction of chiral molecules with a perpendicularly magnetized substrate is enantiospecific. Thus, one enantiomer adsorbs preferentially when the magnetic dipole is pointing up, whereas the other adsorbs faster for the opposite alignment of the magnetization. The interaction is not controlled by the magnetic field per se, but rather by the electron spin orientations, and opens prospects for a distinct approach to enantiomeric separations.