MOF-based Pd catalysts: a controllable and efficient platform towards cyclization reactions of isonitriles

Abstract

Catalytic efficiency is crucial to a reaction system and is intrinsically related to the physical and chemical conditions. One of the challenges to enhance the catalytic efficiency has been the limited activity of metal catalysts for their state transformation. Usually, metal centers in homogeneous systems show better catalytic activity than their heterogeneous counterparts but lower stability due to the thermodynamic instability. Combining the features of both systems, herein, we report the “homogenization of heterogeneous catalysis” to illustrate the state transformation of Pd(II)_x-UiO-67-bpy, which exhibits good catalytic properties and stability in the cyclization of isonitriles with N-acyl-o-alkynylanilines. The regulation of UiO-67-bpy on palladium active species at different stages of the reaction time realizes the efficient utilization of the Pd catalyst with high TONs (turnover numbers) and further decreases the loadings of metal species and alkali. This state transformation of the catalyst not only endows the Pd(II) species with high catalytic activity and stability, but also offers new insights into the catalytic behavior of heterogeneous catalysts.