Size-Tunable Ultrafine Pt Nanoparticles in Soluble Metal–Organic Cages: Displaying Highly Stereoselective Hydrogenation of α-Pinene

Highly stereoselective hydrogenation of α-pinene under mild conditions in the utilization of natural products is important but challenging. Here, we report a facile strategy for the size-controlled synthesis of ultrafine Pt nanoparticles using a versatile metal–organic cage (Cu-MOC) as a soluble confinement template. The Cu-MOC consists of 12 Cu2(CO2)4 paddlewheel structures, forming a highly symmetric cuboctahedral geometric structure with a cavity of 1.5 nm diameter. Utilizing the space confinement effect of Cu-MOC, the ultrafine Pt nanoparticles can be tuned between 0.88 and 1.35 nm and be highly dispersed in solution. Catalytic investigations indicate that the obtained Pt@Cu-MOC exhibits excellent activity for the hydrogenation of α-pinene to cis-pinane under mild conditions. Both the stereoselectivity and conversion can reach 99%, which are much higher than those of the commercial Pt/C and traditional Pt@PVP catalysts. In addition, this method can also enable other metal to be encapsulated into Cu-MOC, which may bring new inspiration for stereoselective hydrogenation of natural products.