Eco-Friendly Encapsulation of Metal Clusters in Porous Organic Cages for Engineerable Microenvironment and Enhanced Catalysis

Developing artificial catalysts that mimic the functionality of enzymes and adapt to the surrounding microenvironment to achieve specific activity and selectivity is a fascinating research area yet remains a great challenge. In this work, we present a meticulously designed strategy for the successful encapsulation of ultrasmall metal clusters (MCs) within an amine-type porous organic cage (POC) through electrostatic complexation, phase transfer, and alcohol reduction processes. The amine cage showcases an intriguing and customizable feature that allows for the regulation of the surrounding microenvironment of the confined MCs through a feasible postmodification approach. This functionalization of cage skeleton further facilitates precise adjustment to the surface electronic state of Pd cluster, thereby influencing the adsorption behavior of substrate. Consequently, this controlled regulation leads to modified activity and chemoselectivity in the catalytic hydrogenation of halogenated nitrobenzene. Importantly, the investigation of the correlation between the surrounding microenvironment, substrate adsorption, and catalytic performance in the POC-immobilized MCs system has not been previously reported. We anticipate that our research will provide valuable insights in this field.