Preparation and the activity of novel silsesquioxane-based catalysts

Abstract

Preparation of novel oligosilsesquioxanes-based materials and metal-containing ones as homogeneous and heterogeneous catalysts of excellent activity are reviewed. The authors examined the activity of a V-containing silsesquioxane as a homogeneous catalyst for the photo-oxidation of simple alkanes. For the epoxidation of alkenes catalyzed by Ti-silsesquioxanes, the presence of alkenylsilyl substituents around the Ti center shows significant promotional effects. By utilizing silsesquioxanes bearing appropriate functional groups, novel caged molecules with organic-inorganic hybrid structures were prepared as well as soluble cooligomers, starburst-type polymers, and a dendrimer containing metallasilsesquioxanes. Furthermore, the authors found that these metal-containing silsesquioxanes can be good precursors of oxide catalysts with high BET surface areas and uniformly-controlled pores. Remarkably, the catalysts containing V and Al species were found to show excellent activity for photo-assisted aerobic oxidation of methane into methanal and the cracking of cumene, respectively.