Engineering a Nanoscale Primary Amide-Functionalized 2D Coordination Polymer as an Efficient and Recyclable Heterogeneous Catalyst for the Knoevenagel Condensation Reaction

Abstract

This work reports the design, structural characterization, and catalytic behavior of the first example of primary amide-functionalized coordination polymers (CPs), namely, {[Cd2(2-bpbg)(fum)2(H2O)2]·8.5H2O}n (1) (where 2-bpbg = N,N′-bis(2-pyridylmethyl)-1,4-diaminobutane-N,N′-diacetamide and fum = fumarate). CP 1 is synthesized from a one-pot self-assembly of starting materials in methanol under ambient conditions in excellent yield and purity, allowing an easy access to multigram quantities of it within few hours. As an example, CP 1 was used as a highly efficient heterogeneous catalyst in the carbon–carbon bond-forming Knoevenagel condensation reaction for the conversion of benzaldehyde to benzylidene malononitrile. CP 1 possesses both Lewis acidic and Bronsted basic character for the presence of unsaturated metal sites and primary amide groups, respectively, making it a highly competent bifunctional catalyst for such type of reactions. Surprisingly, on the one hand, 100% conversion was observed using o...