Zn@ZIF-67 as Catalysts for the Knoevenagel Condensation of Aldehyde Derivatives with Malononitrile

Abstract Three different bimetallic zinc-cobalt zeolitic imidazolate frameworks (ZIFs) were successfully synthesized at room temperature in water through a green and simple procedure and tested as catalysts for the Knoevenagel condensation reaction between p -Br-benzaldehyde and malononitrile as model reaction. The materials were characterized with various techniques (XRD, ICP-AES, SEM, N 2 adsorption–desorption, TGA) and displayed excellent activities and selectivities. Moreover, the crystalline structure was preserved and the catalysts could be reused at least four times with negligible loss of activity. Graphical Abstract