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Variation of Pore Metrics in Metal-Organic Frameworks for Enhanced Storage and Catalytic Applications

Abstract

With the principles of reticular chemistry, metal-organic frameworks (MOFs)

with enhanced storage and catalytic capabilities have been prepared. This dissertation

presents the synthesis of azo-IRMOF-74-III for controllable release of cargo

molecules as well as the catalytic testing of MOF-525-Mn and an isoreticular series

of MOFs based on the MOF-5 framework. The variation of pore metrics in

these frameworks show the versatility of reticular chemistry and their application

in catalytic reactions.

First, an azobenzene containing MOF-74 analogue was prepared by incorporating

the azobenezne moiety into the organic linker used to prepare MOF-74.

Cargo molecules were trapped inside the structure based on size constraints and

controllably released via modulation of UV irradiation to induce a trans to cis

isomerization on the organic linker. The variation in the linker lengh shows that

specic cargo molecules can be trapped by changing the size of the one-dimensional

pore in reticular frameworks.

In addition to changing pore size, density of catalytic sites inside a pore was

investigated through the isoreticular synthesis of a series of MOFs, modeled after MOF-5 but containing various amounts of 2-aminoterephthalic acid. These amine

groups were post-synthetically modied to contain catalytically active Pd sites and

heterogeneous Heck coupling was performed. A inverse relationship was observed

between the amount of framework metalation and reaction yield and selectivity.

This is attributed to pore blocking from post-synthetic modication at higher

metal loadings.

Finally, a manganese porphyrin containing MOF, MOF-525-Mn, was synthesized

and its activity tested through the epoxidation of alkenes using molecular

oxygen. High catalytic activity was observed for all alkenes and this is the rst

instance of MOF epoxidation using molecular oxygen, a ubiquitous industrial oxidant.

Another MOF containing the same catalytically active porphyrin but in a

dierent topology, MOF-545-Mn, was also tested for catalytic activity to determine

the eect of MOF topology on heterogeneous catalysis.

The variation of pore metrics is demonstrated through each chapter and show

how powerful and useful reticular chemistry is through variation of structural

elements for specic uses. While catalytic MOFs are in their infancy, the future is

bright for catalytically active MOFs to come to the forefront of chemical industry.

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