Metal–organic frameworks with open metal sites act as efficient heterogeneous catalysts for Knoevenagel condensation and the Chan–Lam coupling reaction

Abstract

The acylamide functionalized tetra-carboxylic acid (H₄CDA) has been successfully employed for the formation of two robust 3D-MOFs, Cd-CDA-MOF and Cu-CDA-MOF, having open metal sites with two distinct and diverse network topologies namely diamondoid and PCU. The Cd-CDA-MOF is shown to act as an efficient heterogeneous catalyst for the Knoevenagel condensation reaction under mild and ambient conditions. The Cu-CDA-MOF demonstrates excellent catalytic activity for the Chan–Lam coupling reaction with a considerably high turnover number. The heterogeneous catalytic activity of the MOFs can be attributed to the coordinatively unsaturated open metal sites of the activated frameworks. The MOFs are found to be recyclable with almost uniform catalytic activity.