Graduation Year

2008

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Chemistry

Major Professor

Mohamed Eddaoudi, Ph.D.

Keywords

Chiral, Coordination polymer, Metal-organic framework, Mof, Topology

Abstract

Design of targeted functional solid-state materials for desired applications remains a scientific challenge. To overcome this hurdle, numerous synthetic strategies have been devised. It has been shown that molecules and/or clusters with pre-selected shapes, molecular building blocks (MBBs), can be utilized as units of chemical construction toward a final structure composed of those units. Typically, in metal-organic structures metal-ligand directed assembly of the MBBs, via coordination chemistry in situ, leads to the final structure. The strength of the MBB formed and, consequently, the overall rigidity of the framework are essential in their use as porous materials for applications. Lack of rigidity, i.e. instability, will ultimately lead to the collapse of the open framework upon evacuation, resulting in inaccessible pores.

This phenomenon has been demonstrated repeatedly in labile metal-organic materials (MOMs) constructed via flaccid metal-nitrogen coordination (MN[subscript]x) between nitrogen-based ligands and metal ions. The structures of simple metal-carboxylate clusters are welldocumented, but only recently have they been targeted for the construction of MOMs. They often possess multiple metal-oxygen coordination bonds (M(CO2)[subscript]x) that result in the generation of rigid nodes with fixed geometry. Our research group has utilized heterofunctional organic linkers, taking advantage of both pyridine- and carboxylate-based functions (MN[subscript]y(CO2)[subscript]z), which has allowed the construction of single-metal-ion-based MBBs resulting in stabile, rigid MOMs with targeted topologies.

In this dissertation, I will discuss our single-metal-ion-based design strategy and the utilization of heterofunctional ligands for MN[subscript]y(CO2)[subscript]z coordination of single-metal ions. I have employed this strategy to specifically target threeconnected MOMs from 3,5-pyridinedicarboxylate and MN[subscript]y(CO2)[subscript]z coordination of various single-metal ions, especially chiral framworks such as (10,3)-a. In addition, I have explored the MOM diversity that can be obtained via various ligand modifications, including isomerism, expansion, and functionalization. I also will show that other heterofunctional ligands can be utilized to target novel MOMs, specifically via M(CO)[subscript]y(CO2)[subscript]z coordination, and, resultantly, I have achieved metal-ligand directed organic synthesis and mixed-metal MOMs with magnetic tunability.

I have also explored applications for MOMs, including H2 storage, and studied the barriers to rotation of the H2 molecules inside MOMs using inelastic neutron scattering to better understand the MOM-H2 interactions.

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