Formation of reactive microporous networks from alkoxyvinylsilylated siloxane cages

A bifunctional siloxane cage, where double four-membered ring (D4R) silicate was capped with alkoxyvinylsilyl groups, was synthesized as a novel building block for the formation of inorganicorganic microporous solids in order to show its usefulness for synthesizing silica-based nanomaterials with unique structures and properties. The nanobuilding blocks were connected to each other either by hydrolysis and condensation of alkoxysilyl groups to form SiOSi linkages or by hydrosilylation of vinyl groups with hydrogen-terminated D4R (H₈Si₈O₁₂), which was used as a linking agent, to form Si-CH₂CH₂-Si linkages. Xerogel obtained by hydrosilylation showed a significant increase in the surface area upon removal of alkoxy groups by post treatment. The molecular design of bifunctionally- silylated D4R units provides a new approach to the formation of microporous networks with uniform distribution of reactive groups that allow post-modification.