Ultrasmall Ag nanoparticles on photoactive metal-organic framework boosting aerobic cross-dehydrogenative coupling under visible light

The application of heterogeneous photocatalyst to conduct organic transformation is attractive in sustainable chemistry. Metal-organic frameworks (MOFs) are crystalline materials with diverse structures and rich components, which exhibit great potential to achieve heterogeneous photocatalysis. Herein, we report the synthesis of new photocatalysts of MOF-based nanocomposites to achieve cross-dehydrogenation coupling (CDC). A series of nanocomposites of Ag/MOF were prepared by simple photoreduction method. The resulting nanocomposites exhibit efficient and recyclable photocatalytic performance for CDC reactions under visible light. Experiments show that the photocatalytic activity of the MOF was promoted significantly upon the decoration of ultrasmall Ag nanoparticles (NPs), where the particle size and loading amount of Ag NPs play an important role to improve the photocatalytic performance. Ultrasmall Ag NPs not only boost the photoinduced charge generation by Schottky junction in the nanocomposite, but also promote the reaction by direct interaction with amine substrate. Reactive oxygen species (ROS) of singlet oxygen and superoxide radical were simultaneously generated from molecular oxygen in the photocatalytic reaction, owing to the photoinduced energy and electron transfer of the MOF. The study presents a rare example of photocatalytic CDC using MOF-based nanocomposite, providing more insights into the synergy effect of MOFs and metal nanoparticles for organic transformation.