Metal-Organic Materials (MOMs) are an emerging class of crystalline solids that offer the potential for utilitarian design, as one of the greatest scientific challenges is to design functional materials with foreordained properties and eventually synthesize custom designed compounds for projected applications. Polytopic organic ligands with accessible heteroatom donor groups coordinate to single-metal ions and/or metal clusters to generate networks of various dimensionality. Advancements in synthesis of solid-state materials have greatly impacted many areas of research, including, but not limited to, communication, computing, chemical manufacturing, and transportation.
Design approaches based on building blocks provide a means to conquer the challenge of constructing premeditated solid-state materials. Single-metal ion-based molecular building blocks, MNx(CO2)y+x, constructed from heterochelating ligands offer a new route to rigid and predictable MOMs. Specific metal bonds are considered responsible for directing the geometry or topology of metal-organic assemblies; these bond geometries constitute the building units, MNxOy. When these building units are connected through appropriate angles, nets or polyhedra can be targeted and synthesized, such as metal-organic cubes and Kagomé lattices. MNx(CO2)y+x MBBs can result in MN2O2 building units with square planar or see-saw geometries, depending on the mode of chelation. Using a 6-coordinate metal and a heterochelating ligand with bridging functionality, TBUs can be targeted for the synthesis of valuable networks, such as Zeolite-like Metal-Organic Frameworks (ZMOFs).
Zeolitic nets, constructed from tetrahedral nodes connected through ~145° angles, are valuable targets in MOMs, as they inherently contain cavities and/or channel systems and lack interpenetration. Other design approaches have been explored for the design of ZMOFs from TBUs, such as the use of hexamethylenetetramine (HMTA) as an organic TBU. When this TBU coordinates to a 2-connected metal with appropriate angles, zeolite-like nets rare to metal-organic crystal chemistry can be accessed. Additionally, MNx(CO2)y MBBs have been used to construct metal-organic polyhedra (MOPs), used as supermolecular building blocks (SBBs), that can be peripherally functionalized and ultimately extended into threedimensional ZMOFs.
Rational synthesis, mainly based on building block approaches, advances bridging the gap between design and construction of solid-state materials. However, some challenges still arise for the establishment of reaction conditions for the formation of intended MBBs and thus targeted frameworks.
| Identifer | oai:union.ndltd.org:USF/oai:scholarcommons.usf.edu:etd-1147 |
| Date | 10 July 2008 |
| Creators | Brant, Jacilynn A |
| Publisher | Scholar Commons |
| Source Sets | University of South Flordia |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Graduate Theses and Dissertations |
| Rights | default |
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