Enantio-separation is an extremely important process in the pharmaceutical and chemical industries. It is commonly assumed that the recognition of chirality and enantio-selection, both in nature and in artificial systems, is solely related to spatial effects. We observe that the interaction of chiral molecules with the perpendicularly magnetized substrate is enantiospecific. When the chiral molecules approach to the magnetic substrate, they become charged-polarized. According to Chiral Induced Spin Selectivity (CISS), this charge polarization is accompanied with spin polarization. When the spin orientation of the molecule becomes parallel to the spin orientation of the substrate, the interaction between the molecule and the surface is not preferred due to high spin interaction. On the other side, when the spin orientation of the molecule is anti-parallel to the spin of the magnetic surface, the interaction is favorable due to low spin interaction.
We demonstrated the enantiospecific adsorption of the racemic solution of thiolated L- and D- oligopeptide on gold-coated ferromagnetic substrate. This enantio-selective interaction of chiral molecules with a magnetic substrate provides a generic chromatographic method for enantio-separation. Now, our goal is to fabricate a recyclable column.
We also demonstrated enantiospecific crystallization of the three amino acids asparagine (Asn), glutamic acid hydrochloride (Glu·HCl) and threonine (Thr), induced by ferromagnetic (FM) substrates.
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