A dual-functional 3D cerium MOF heterogeneous catalyst for catalysing Knoevenagel condensation and cyanosilylation

Abstract

A three-dimensional (3D) lanthanide metal–organic framework (Ln-MOF, Ce-4L (H₄L = 5,5′-azanediyldiisophthalic acid)), with both Lewis acid and base sites in its pores was synthesised as a dual-functional heterogeneous catalyst for Knoevenagel condensation and cyanosilylation at room temperature. Ce-4L was shown to have a high turnover number of 480 for cyanosilylation as a catalyst under solvent-free conditions. The dynamics of Knoevenagel condensation and cyanosilylation catalysed by Ce-4L were found to be well fitted using a one-order dynamic equation. The 3D structure of Ce-4L was shown to be stable; it could be reused in the Knoevenagel condensation and cyanosilylation reactions at least five times without collapsing of its pores. In addition, a possible mechanism of cyanosilylation using Ce-4L was also studied.