This project is founded on the premise that metal-organic clusters that approximate the shape of simple polygons (e.g. triangles and squares) can be self-assembled using well-known geometric constraints and appropriate angular multifunctional ligands, thereby building discrete and infinite structures that are based upon faceted polyhedra. Such polyhedra, exemplified by the small rhombihexahedron, contain open faces. Preliminary studies have demonstrated that such structures can form nanoporous 3D frameworks with predictable architecture and dimensions. The new structures are exemplified by polymeric nanoporous and high molecular weight (6,800) discreet compounds based upon faceted polyhedra. Since the principles of self-assembly are used to generate the prototypal structures, they are likely to be representative of a large group of compounds. The primary objective of the proposed research is to confirm the generality of the design concept, to expand it to discreet structures, and to determine the structure, chemical and physical properties of compounds that are based upon faceted polyhedra..
Chemists have recently demonstrated that the principles of self-assembly can be invoked to design novel nanostructures that are based upon closed surface polyhedra, more commonly known as Platonic and Archimedean solids. Such structures are based upon edge-sharing of polygons and represent approaches to the design of both discrete (porous spheroidal nanostructures) and infinite (nanoporous) structures. We propose to exploit sharing of the vertices as the primary design principle and therefore generate prototypes for new compounds that are fundamentally different from Platonic and Archimedean structures.
Partially open uniform polyhedra or faceted polyhedra are fundamentally different from closed surface polyhedra in that they are linked by the vertices of their building blocks rather than by their edges. The resulting structures are therefore necessarily porous in a manner that is predictable. Furthermore, they are prototypal for a much wider range of structures based upon faceted polyhedra formed from other molecular triangles and squares. For example, our structures can be prepared from a wide range of metals, including catalytically active metals such as rhodium and cadmium and magnetically active metals such as Fe and Cu.
Moulton, B.; Lu, J.; Mondal, A.; Zaworotko, M.J. "Polygons and Polyhedra and Nanoporous Networks." Angew. Chem, Int. Ed. Engl. 40, 2113-2116, 2001.
Moulton, B.; Lu, J.; Mondal, A. Zaworotko, M.J. "Nanoballs: nanoscale faceted polyhedra with large windows and cavities", Chem. Commun., 863-864, 2001.