Functionalized double-decker oligomeric silsesquioxanes (DDSQs) can serve as nano-building blocks for the construction of new polymeric materials with engineering applications. DDSQs are obtained by edge capping DDSQ(OH)₄ with various chlorosilanes. Until recently, most compounds so generated have been symmetric products where both open ends of the incompletely condensed DDSQ have been transformed into closed D₂T₈ cages. Using D₂T₈ cages as linkers to polymer backbones has resulted in significant property enhancements of the resultant materials due to interactions between the polymer chain and the DDSQ. Given such property enhancement, DDSQs that can anchor two dissimilar polymer matrices became synthetic targets for a number of research groups. We previously developed and reported on a protecting group strategy that allows for the generation of a diverse array of asymmetrically capped D₂T₈ cages. This poster presents a new and more efficient approach to asymmetrically capped D₂T₈ cages and enables isolation and characterization of mono-capped D₁T₈ cages, aka bird nest-shaped silsesquioxane disilanols. In addition to their use as precursors for entry into closed asymmetrically functionalized D₂T₈, this mono-capped D₁T₈ cages are ideal molecular template that can be fastened onto solid support materials. This new protocol and how it surmounts other limitations encountered in our previous approaches to asymmetric DDSQs will be presented.

Badru-Deen Barry

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