Direct synthesis of ordered macroporous silica materials functionalized with polyoxometalate clusters

Three-dimensionally ordered macroporous (3DOM) silica materials functionali zed with highly dispersed polyoxometalate clusters have been prepared via d irect synthesis. Lacunary gamma -decatungstosilicate clusters were incorpor ated into the wall structures of macroporous silica by reaction of the clus ters in acidic solution with tetraethoxysilane, with or without addition of the polyfunctional linking group 1,2-bis (triethoxysilyl) ethane, followed by condensation around polystyrene colloidal crystals. Removal of the poly styrene template by extraction with a tetrahydrofuran/acetone solution prod uced the porous hybrid materials. The products were characterized by IR, so lid-state Si-29 and C-13 NMR, scanning electron microscopy (SEM:), transmis sion electron microscopy, X-ray energy-dispersive spectroscopy, and chemica l analysis. The polyoxometalate clusters remained intact in the hybrid stru ctures and were nearly molecularly dispersed throughout the walls of the 3D OM materials. High incorporation levels of cluster were obtained, with no b ulk particles on the external surfaces. The materials were demonstrated to exhibit catalytic activity for the epoxidation of cyclooctene with an anhyd rous H2O2/t-BuOH solution at room temperature.