Zirconium-based Metal-Organic Polyhedra and rht-net Metal-Organic Frameworks

Abstract

Coordination polymer materials are widely studied in chemistry, and as one of the coordination polymer materials, Metal-organic materials have been attracted many researchers for their future application as well as being able to investigate the beauty of nature. Metal-organic polyhedra (MOPs) and metal-organic frameworks (MOFs) are touting their tunability thanks to various organic linkers constructing the materials and various metal nodes. Also they are usually analyzed in perspective of polyhedra and connection between metal node and linker. The Platonic and Archimedean solids are useful to fill the 3-dimensional space of the framework or polyhedra itself. Metal-organic polyhedra constructed by zirconium-based cluster are built in the Platonic solids shape. New MOPs, using C3-symmetric zirconium cluster, UMOP-11 and UMOP-12 were prepared in tetrahedral coordination cage. They were confirmed by single-crystal X-ray diffraction data and fundamental characterization. UMOP-11 showed high surface area through nitrogen adsorption and remained crystallinity after thermal activation, which is very rare in MOPs. One of the network found in MOFs, (3,24)-connected network which is also called rht-net, has been analyzed with polyhedral perspective and the relation between hexatopic ligands and cages in the frame was studied and formulated. At last, Cu-TDPAT (also reported in the name of rht-MOF-7) was investigated. It showed unusual thermal expansion phenomenon, negative thermal expansion (NTE) and its NTE property was revealed by single-crystal X-ray diffraction data. Also, two isostructural Cu-TDPAT with different morphology were prepared via simple solvothermal reaction and metal exchange. Gas sorption experiments were conducted and sorption properties upon different morphology were observed.