Structures and Applications of Porous Coordination Cages

Abstract

Well defined porous coordination cages (PCCs) are cage-like compounds constructed from the self-assembling of organic ligands and metal ions through coordination interactions. These metalorganic materials can exist in solution as standalone cage-like host systems that can be structurally tuned towards specific purpose. The unique environment that PCCs create in solution allows for interesting guest-binding behaviors inside the cavity, which has been exploited as catalytic sites, gas binding and storage and drug binding for cellular delivery. This dissertation work seeks to gain more understanding into the PCC as a host system in the context of structural dynamics in solution and host-guest interactions, which can provide important insights into the application implications in catalysis and drug delivery. In Chapter 2, using PCC-20 as a model PCC system, I aimed to understand how the PCC host systems exist and maintain structural integrity in solution. The structural manipulation and control over the shape and size of PCC-20 were found to be achievable by external stimuli, such as, heat, light, guest molecules and solvent environments. In Chapter 3 and 4, using PCC-2 as a host system, I sought to understand how the electrostatic interactions of PCCs with their guests, including rhodamine B and metal nanoclusters, can induce changes in the guest structures and shape the guest towards certain direction. These host-guest interactions can be exploited to catalytic applications. In Chapter 5, PCC-1, as a model PCC for drug delivery, was assessed for biocompatibility.