Inorganic-Organic Hybrid Polyoxoniobates: Polyoxoniobate Metal Complex Cage and Cage Framework.

The combination of polyoxoniobates (PONbs) with 3d metal ions, azoles, and organoamines is a general synthetic procedure for making unprecedented PONb metal complex cage materials, including discrete molecular cages and extended cage frameworks. By this method, the first two PONb metal complex cages K @{[Cu (OH) (H O) (en) (trz) ][Nb O (OH) (H O) ] } and [Cu(en) ]@{[Cu (en) (trz) ] (Nb O )} have been made. The former exhibits a huge tetrahedral cage with more than 120 metal centers, which is the largest inorganic-organic hybrid PONb known to date. The later shows a large cubic cage, which can act as building blocks for cage-based extended assembly to form a 3D cage framework {[Cu(en) ]@{[Cu (trz) (en) ] [H Nb O ]}}. These materials exhibit visible-light-driven photocatalytic H evolution activity and high vapor adsorption capacity. The results hold promise for developing both novel cage materials and largely unexplored inorganic-organic hybrid PONb chemistry.