The Synthesis And Characterization Of A Series Of Porous Scandium Terephthalates

Since the 1990s, the materials based on Metal-Organic Frameworks (MOFs) have entered into a highly developed stage, especially for the third generation of MOFs, when get rid of guest molecules, they still maintain their porous structure and have high thermal stability. With the development of the study in the area, the controllable synthesis and preparation of the target MOFs become available and at the same time, the porous MOFs with specific features could be constructed via a deliberated synthetic strategy. In this dissertation, our thesis is purposely on synthesis of the MOF with a topology for generating high porosity and stability.In recent years, Ferey and co-workers have reported potentially applicable hybrid materials MIL-100 and MIL-101, of which trivalent metal (Cr³⁺, Al³⁺, Fe³⁺) trimesate and terephthalate with MTN topology show not only high porosity, but also excellent stability. According to: (ⅰ) there existsμ₃-oxo-centered trigonal trimer in the rare-earth element scandium terephthalate compounds; (ⅱ) scandium(Ш) is the lightest rare-earth element and larger radii than other trivalent metal ions in the same period; Scandium(Ш) is more expected to form MIL-101 structure. However, to our surprise, not only both of scandium terephthalate with the structure of MIL-101, but also scandium 2-aminoterephthalate and 2-nitroterephthalate with the structure of MIL-101 were facilely prepared under solvothermal condition. Moreover we have also synthesized solvothermally other isomorphic members of MIL materials, such as MIL-53(Sc), MIL-88(Sc), MIL-88(Sc)-NDC and MIL-68(Sc).In addition, by simulating zeolitic silicate or SiO₂, we choose 2-position substituted 2-nitroimidazole and Cd(NO₃)₂·4H₂O(or Cd(ClO₄)₂·6H₂O) as reactants to get zeolitic structures. As a result, we obtained two novel cadmium imidazolates 8 and 9. Complex 8 has a distorted diamond topology with orthorhombic system and space group Pbcn, and Complex 9 has open 8-ring pores in the structure with orthorhombic system and space group Pbcm.