Boosting photocatalytic oxidative coupling of amines by a Ru-complex-sensitized metal-organic framework

Visible-light-driven selective photocatalytic organic synthesis has recently become a topic of great interest due to its environmental friendliness and sustainability. It is demanding for photocatalysis to utilize the wider range of light, such as visible light, and its performance is often plagued by the sluggish separation of photogenerated charge carriers. An approach is now reported to address these issues by incorporating light harvesting Ru-II-polypyridyl complexes into a semiconductor-type metal-organic framework (MIL-125). Delightedly, the obtained Ru(bpy)(3)@MIL-125 photocatalyst presents a remarkably stable and high photoactivity toward the selective oxidative coupling of amines under ambient air with visible light irradiation (lambda > 440 nm). The mechanistic investigation unveiled that both effectively photoexcited electrons transfer from [Ru(bpy)(3)]Cl-2 to MIL-125 and the interaction of C-H bonds with superoxide radical (O-2(center dot-)) play a critical role in photo-catalyzing selective aerobic oxidative coupling of amines. This work highlights a significant role of MOFs as heterogeneous photocatalysts in photocatalytic organic transformations. (C) 2019 Elsevier Inc. All rights reserved.