We study Metal Organic Frameworks (MOFs) as colloidal encapsulants with high porosity and unique host-guest interaction with potential for delivery in aqueous environments.  Our approach to colloidal MOF synthesis is through inducing slow nucleation and modulating growth kinetics by introducing small molecules as modulator and/or capping agents. This produces colloidal-sized MOFs of defined polyhedral shape and with uniform and tunable size from nanometers to micrometers. At these length scales, the effects of physical and chemical decompositions have pronounced influence on the properties. The stability of MOFs in aqueous solution is our focus of special attention. Contrary to non-specific bulk measurements, surface imaging techniques including scanning electron microscopy and atomic force microscopy are used to directly visualize the influence of aqueous environment. We find that this physical susceptibility of colloidal-sized MOFs is comparable to that of their bulk counterparts while susceptibility to chemical etching is more pronounced due to their large surface to volume ratio. Having identified metal ion and ligand combinations that generate water stable colloidal-sized MOF, we demonstrate their versatility in various aqueous reactions including surface functionalization with silica coating and dye tagging. Moreover, simple interparticle interactions such as charge screening can be used to produce clusters, microdomains, and crystals of water-stable MOF assemblies.

Colloidal metal organic frameworks in aqueous environments

246th National Meeting (2013)

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