Separation of chiral molecules by enantio-specific interactions using magnetic surfaces.

It is commonly assumed that recognition of chirality and enantio-selectivity, both in nature and in artificial systems, are solely related to a spatial geometrical effect, with the recognition process typically described by a “lock and key” model. In recent years, it has been suggested that as electrons move through or as charge is redistributed in chiral molecules, an enantio-specific electron spin orientation is preferred via the effect we address as the chiral induced spin selectivity (CISS) effect. These results led to the proposal that the spin polarization may affect enantio-recognition. Here, we show experimentally that the interaction of chiral molecules with a perpendicularly magnetized magnetic substrate is enantio-specific. Thus, one enantiomer adsorbs preferentially when the magnetic dipole is pointing up, whereas the other is adsorbed faster for the opposite alignment of the magnetic field. The interaction is not controlled by the magnetic field, but rather by the electron spin. This approach allows the development of a generic method for enantiomeric separations.