Using operando Microspectroscopy to Uncover the Correlations Between the Electronic Properties of Dendrimer-Encapsulated Metallic Nanoparticles and their Catalytic Reactivity in π-Bond Activation Reactions

A main challenge in catalysis research is the development of novel catalytic systems, which combine the recyclability of heterogeneous catalysts and the high tunability of homogeneous catalysts. In this review paper we demonstrate that dendrimer encapsulated metallic nanoparticles combine these two advantages in one catalytic system and can be activated as catalysts toward reactions that are mainly activated by homogeneous catalysts. Following their encapsulation in a dendrimer matrix, the metallic nanoparticles were oxidized into metal ions. The encapsulated metal ions showed high reactivity toward a wide range of π-bond activation reactions. High and controllable products selectivity was obtained by adjusting the molecular properties of the dendrimer matrix. Kinetic studies have demonstrated the important role of the dendrimer matrix in stabilizing the catalytically-active species and preventing its leaching to the solution phase. Operando high spatiotemporal spectroscopy measurements, such as IR and XAS microspectroscopy, elucidated the properties of the active catalyst along the flow reactor and the mechanism of the catalytic reaction.