(609a) Nanocages: A New Form Of Catalytic Materials

Nanocages with 2-6 nm cavities are potentially very interesting materials for chemical reactions. Since these cavities are molecular-size, reactants and transition states inside the nanocages are in close proximity to the cage wall and any encapsulated core, they can interact with any chemically active groups anchored inside. Thus, it is possible to effect transition state stabilization, spatial orientation of reactants, and preferential binding of reaction intermediates, reactants, and products with these material. Although such nanocages can be prepared by templating with immolative micelles, the immolative dendrimer-templating method offers a higher degree of control of the cavity size and a greater flexibility in the types of functional groups that can be incorporated into the structure. We have explored successfully using a fourth generation carbamate dendrimer to prepare nanocage containing a 4.5 nm cavity. We will present experimental evidence of the successful preparation of the dendrimer and the nanocage. The preparation method results in a structure that contains an encapsulated core molecule with amine groups, hydroxyl groups on the cage wall, and a carbosilane shell. We will discuss the results of characterization of the amine groups and modification of the hydroxyl groups, as well as using another type of immolative dendrimers that contain acyloxysilyl bonds to prepare nanocages.