Chiral Janus emulsions with gold nanocomposite for enantioselective catalysis

Abstract

Chiral emulsions, with the chiral center of chiral-surfactant as the emulsifier, provide opportunities for selective catalysis and inorganic material synthesis. Janus emulsion draws researcher’s attention due to excellent multiple chambers, advanced structures and diverse interfaces. Chiral Janus emulsions are prepared with two immiscible oils of vegetable oil (VO)/dimethyl phthalate (DMP) and 2-(Perfluorooctyl)ethyl methacrylate (PFOEMA)/Ethoxylated trimethylolpropane triacrylate (ETPTA) as inner phases, by emulsified by chiral-surfactant [H-G-C16]FeCl4, in batch-scale by traditional vortex mixing. AuNPs as functional nanomaterials with peroxidase activity are then applied as active centers, adsorbing at the oil/water interface due to the electrostatic interactions between the positive charge of [H-G-C16]FeCl4 at Janus emulsion interfaces and the negative charge of AuNPs modified by SDS. Chiral Janus emulsion is endowed with catalytic activity and enantioselectivity. Catalytic results show two AuNPs@ Janus emulsions show better affinity to catalyze the oxidation of L-DOPA than D-DOPA. By investigating two AuNPs@ Janus emulsions with different inner phases, chiral Janus emulsion of AuNPs@ETPTA/PFOEMA/[H-G-C16]FeCl4(aq) has better catalytic activity and enantioselectivity than AuNPs@DMP/VO/[H-G-C16]FeCl4 (aq) because of the smaller droplets have larger interface areas could adsorb more [H-G-C16]FeCl4 molecules and AuNPs. The findings open an avenue in the production of chiral Janus emulsions with catalytic effect and enantioselectivity, which would push forward future applications in selective catalysis and inorganic material synthesis.