Magnetothermally responsive C/Co@PNIPAM-nanoparticles enable preparation of self-separating phase-switching palladiumcatalysts

Abstract

We synthesized highly ferromagnetic, thermoresponsive nanomagnets with a graphene coated cobalt metal core to which amphiphilic N-isopropylacrylamide polymer branches were covalently attached. This novel hybrid material could be further end-group modified with a Pd–phosphine complex to catalyze Suzuki–Miyaura cross-coupling reactions. The heterogenized metal-complex could act as a ‘self-separating’ catalyst. Thermally triggered switching of poly-NIPAM coated C/Co-nanoparticles in typical biphasic water/toluene reaction systems allowed controlled shift from the organic to water phase and back. This enabled catalysis in the organic layer (reaction temperature) and return into the aqueous layer once the reaction mixture was cooled (ambient temperature; magnetic removal and reuse of the catalyst). Thus, the product phase was isolated via simple extraction/decantation. Moreover, the supported catalyst was recycled from the aqueous phase by taking advantage of the magnetic cores and reused over ten times.