Design and Synthesis of Novel Lanthanide MOFs by Unique in Situ Organic and Inorganic Reactions

Four novel metal-organic frameworks (MOFs), H3O[Ln(Ox)(1.5)(formate)] (Ln = Tb (1), Dy (2), Ho (3), Er (4), Ox = oxalate) were synthesized, and their structures and properties were analyzed. They were prepared by solvothermal reaction under acidic condition with structure-directing agents (H(4)dobpdc; 4,4 '-dihydroxy-[1,1 '-biphenyl]-3,3 '-dicarboxylic acid) and the corresponding Ln metal ion(s). Single-crystal X-ray diffraction analysis revealed that 1 and 2 (Group I) are isostructural as Cmca space group to 3 and 4 (Group II) as Pnma space group, respectively. This result probably comes from the change in structure according to the size of the lanthanide metal. TGA showed that the framework is thermally stable up to about 300 degrees C for all 1-4. Furthermore, we measured N-2 adsorption at 77 K and CO2 adsorption at 195 K, and compound 2-4 had a type I adsorption isotherm graph and adsorbed CO2. In the study, we prepared and characterized four novel Ln-MOFs, H3O[Ln(Ox)(1.5)(formate)] (Ln = Tb (1), Dy (2), Ho (3), Er (4), Ox = oxalate) by an unique in situ synthetic method.