Synthesis And Photocatalytic Amine Oxidation Of Gold Complex-MOF Host-Guest Materials

Metal–organic frameworks(MOFs)constructed from metal ions and organic linkers via covalent bonds have emerged as a class of highly promising porous materials with appealing applications in gas storage/separation,heterogeneous catalysis,biomedicines,sensing,and proton/electrical conductivity.In the functional application of MOFs,photocatalysis is one of the most rapidly developing application fields.Taking advantage of tremendous choices of traditional inorganic and organic materials with active catalytic sites,catalytic properties of MOF materials can be engineered.The catalytic activity of MOF materials can not only be generated from skeletons but also arise from by guest species.Pore size of MOF materials varied from a few angstroms to several nanometers,making them ideal for incorporating species ranging from small gas molecules to large inorganic and organic species.Encapsulation of guest catalytic species into the pores of MOFs provides an attractive avenue to realize MOF functionalization.The defined pore conditions in MOFs provide a unique platform to confine and stabilize guest species.Encapsulation of functional guest species into the pores of MOFs by cation exchange approach has been a facile and convenient post-synthetic method to realize MOF functionalization.In this regard,the luminescent metal complexes were incorporated into the pore of MOFs to synthesize luminescent gold(Ⅲ)complexes@MOF composited materials by employ the cation exchange method.And investigate their emission properties so as to develop the selective heterogeneous photocatalysis applications:Thus,in this work,one gold(Ⅲ)complex with C^N^C ligand was employed as photocatalytic guest species being incorporated into two MOFs(Au~Ⅲ@MOF1 and Au~Ⅲ@ZJU-28)with different porous structures.The resultant Au~Ⅲ@MOF composites displayed phosphorescent emission between 400 nm and 750 nm with lifetimes around 4μs in the presence of air at room temperature.Comparing with gold(Ⅲ)complex in solution,emission intensity,lifetime and quantum yield of Au~Ⅲ@MOFs were enhanced obviously.Furthermore,Au~Ⅲ@MOFs are efficient,selective,and recyclable catalysts for light-induced aerobic amine oxidation.When using Au~Ⅲ@ZJU-28 as heterogeneous catalysts for oxidizing secondary amines to corresponding imines,high TONs of 876-1548 is achieved which is around 2.8-3.5 folds higher than that of homogenous Au~Ⅲ complex.And different selectivity to oxidize mixture substrates is realized based on different host MOFs which demonstrate that encapsulating active Au~Ⅲ complex into an appropriate MOFs could obtain the needed product.Inherent shortage of homogeneous catalyst in cyclic issue is also overcome by using composite catalysts and a high conversion of Au~Ⅲ@ZJU-28 catalyst is still observed after ten cycles.