Metal–Organic Frameworks with Organogold(III) Complexes for Photocatalytic Amine Oxidation with Enhanced Efficiency and Selectivity

: Luminescent organogold(III) complex AuIII with highly emissive triplet excited state was encapsulated in two metal-organic frameworks (MOFs) with different pore sizes and structures (MOF1 and ZJU-28). Compared with the AuIII complex in solution, the resultant composites AuIII @MOF1 and AuIII @ZJU-28 exhibit enhanced emission intensity, lifetime, and quantum yield. Under irradiation, AuIII @MOFs are efficient, selective, and recyclable catalysts for light-induced aerobic C-N bond formation. When used as a heterogeneous catalyst for oxidizing secondary amines to the corresponding imines, AuIII @ZJU-28 achieved high TONs of 876-1548, which are about 2.8-3.5 times higher than that of the homogenous AuIII complex. In addition, different selectivities in oxidizing mixed substrates is realized by means of different host MOFs, and thus encapsulating the AuIII complex in an appropriate MOF allowed the desired product to be obtained. Inherent shortcomings of homogeneous catalysts in cyclic use are also overcome by using composite catalysts, and high conversion of the AuIII @ZJU-28 catalyst was still observed after ten cycles.