Electrosynthesis and electro-separation of chiral compounds at mesoporous metal surfaces

Enantioselective synthesis and separation are of crucial importance for many potential applications ranging from sensing to catalysis. We have successfully elaborated chiral imprinted mesoporous platinum, obtained by the electrochemical reduction of platinum salts in the simultaneous presence of a liquid crystal phase of nonionic surfactants and various chiral template molecules, such as enantiomers of 3,4-dihydroxyphenylalanine (DOPA), mandelic acid and phenylethanol. The chiral encoded mesoporous platinum perfectly retains the chiral information after removal of the template, confirmed by a very significant discrimination between two enantiomers when using these materials as electrodes in Differential Pulse Voltammetry. Interestingly, such nanostructured metals are also able to break the symmetry during the electrosynthesis of chiral molecules such as mandelic acid, and phenylethanol. We were able to demonstrate that by optimizing the electrochemical synthesis parameters it is possible to achieve very high enantiomeric excess (>90 %). Apart from asymmetric synthesis, chiral separation can also be achieved using such imprinted mesoporous platinum as a stationary phase in a microfluidic channel. It is possible to fine-tune the electrostatic interactions between the encoded surfaces and the corresponding chiral molecules by applying an electric field, allowing the complete separation of chiral compounds. Therefore, these novel materials open up new promising perspectives in various fields ranging from electrosynthesis to chiral separation technologies.

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