N-hydroxyphthalimide-TiO2 complex visible light photocatalysis

TiO 2 is the most established semiconductor photocatalyst . The prominence of TiO 2 is becoming increasingly obvious because its interfacial redox reactions have implication on a wide range processes such as energy conversion and environmental remediation. Herein, we exploited the surface complex created by the interaction between organic molecules with binding sites and accommodating surface of TiO 2 for visible light-driven selective aerobic oxidation reactions. A novel surface complex formed between N -hydroxyphthalimide (NHPI) and TiO 2 was discovered. The NHPI-TiO 2 complex turned out to be an outstanding visible light photocatalyst and was successfully used in the selective oxidation of amines into imines with atmosphere O 2 under blue LED irradiation. The stability of the NHPI-TiO 2 complex was preserved by 3 mol% of (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) acting as a cooperative catalyst. Moreover, selectivities for the imine products were also promoted by TEMPO. Superoxide anion radical (O 2 − ) were evidenced to be the primary reactive oxygen species (ROS) to execute the oxidative conversions. This work suggests that TiO 2 surface complexes can be robust photocatalysts for visible light-driven selective aerobic reactions, provided that an appropriate cooperative redox catalyst exists to channel the photocatalytic electron transfer.