High Quality Content by WIKIPEDIA articles! A silsesquioxane is a compound with the empirical chemical formula RSiO3/2 where Si is the element silicon, O is oxygen and R is either hydrogen or an alkyl, alkene, aryl, arylene group. These materials can be used as a support for catalysts, and recently on pH-responsive material. Silsesquioxanes can have a cage like structure, see Figure 1, which is most commonly cubes, hexagonal prisms, octagonal prisms, decagonal and dodecagonal prisms.<