Synthesis of Isotypic Giant Polymolybdate Cages for Efficient Photocatalytic C–C Coupling Reactions

Abstract

The construction of isotypic high-nuclearity inorganic cages with identical pristine parent structure and increasing nuclearity is highly important for molecular growth and structure− property relationship study, yet it still remains a great challenge. Here, we provide an in situ growth approach for successfully synthesizing a series of new giant hollow polymolybdate dodecahedral cages, Mo 250 , Mo 260 -I, and Mo 260 -E, whose structures are growth based on giant polymolybdate cage Mo 240 . Remarkably, they show two pathways of nuclear growth based on Mo 240 , that is, the growth of 10 and 20 Mo centers on the inner and outer surfaces to afford Mo 250 and Mo 260 -I, respectively, and the growth of 10 Mo centers both on the inner and outer surfaces to give Mo 260 -E. To the best of our knowledge, this is the first study to display the internal and external nuclear growth of a giant hollow polyoxometalate cage. More importantly, regular variations in structure and nuclearity confer these polymolybdate cages with different optical properties, oxidative activities, and hydrogen atom transfer effect, thus allowing them to exhibit moderate to excellent photocatalytic performance in oxidative crosscoupling reactions between different unactivated alkanes and N-heteroarenes. In particular, Mo 240 and Mo 260 -E with better comprehensive abilities can offer the desired coupling product with yield up to 92% within 1 h.