We are investigating the design and synthesis of metal-organic frameworks in an effort to create new types of porous crystalline solids. Molecular building blocks with appropriate structures can be designed to self-assemble via metal coordination into crystalline solids with different 1-D, 2-D and 3-D architectures. Accordingly, we are studying crystalline framework materials constructed from building blocks with varying geometries that feature metal-binding functional groups. Reaction of these molecules with transition metals generates crystalline solids with a range of metal-organic frameworks. The design, synthesis, characterization and properties of these materials will be discussed.