An Efficient Bifunctional Core-Shell ZIF-90@ZIF-67 Composite as a Stable Pickering Interfacial Catalyst for the Deacetalization–Knoevenagel Tandem Reaction

Graphical Here, the core-shell structure of ZIF-90@ZIF-67 was applied for the first time to catalyze the tandem reaction in Pickering emulsion system, which exhibited excellent catalytic performance with 99.9 % yield. Furthermore, ZIF-90@ZIF-67 has high stability and maintains good reproducibility after five cycles. This work provides a platform for the design of structurally and functionally diverse MOF-based interfacial catalysis for Pickering emulsions. Exploiting advanced solid particles is crucial to the construction of Pickering emulsions catalysis. Recently, metal-organic frameworks (MOFs) have been used as ideal emulsifiers stabilizing Pickering emulsions for interfacial catalysis. Although Pickering emulsions stabilized by core-shell MOFs have significant importance in practical studies, to date there have been very limited reports on this topic. Herein, ZIF-90@ZIF-67, a core-shell material with simultaneous acid-base bifunctionality, was synthesized by seeded epitaxial growth. It was firstly applied as an emulsifier in Pickering emulsions to catalyze the deacetalization-Knoevenagel tandem reaction, which exhibited excellent catalytic properties and achieved extremely high yields. Additionally, ZIF-90@ZIF-67 showed high stability and remained well repeatable after five cycles. This work provides a platform for the design of structurally and functionally diverse MOF-based Pickering emulsions interfacial catalysis.