UoC‐4: A MOF Based on Octahedral ScO 6 Nodes and Fluorinated Trimesate Ligands

Abstract

A new MOF (metal-organic framework), [Sc(dF-BTC)6/6]⋅solvent with dF-BTC3−=2,4-difluoro-1,3,5-benzene-tricarboxylate, termed UoC-4 (UoC≡University of Cologne), was synthesized by solvothermal reaction in an ethanol/water solvent mixture. The crystal structure of UoC-4 was solved and refined from X-ray single crystal data (I41/amd, Z=8). In the crystal structure each of the three carboxylate groups of the dF-BTC3− linker coordinates to two Sc3+ cations, resulting in an almost ideal ScO6 octahedron. The connectivity of these ScO6 and dF-BTC3− building units leads to a 3D framework structure with a new unprecedented topology. Small voids with a diameter of <5 Å are formed, in which most likely disordered ethanol molecules reside. UoC-4 is stable against moisture, but in water a slow hydrolysis occurs. Thermal decomposition in an inert atmosphere starts above 400 °C. Activation of the material failed so that no gas sorption isotherm with N2 as test gas could be recorded. The small pores within UoC-4 are obviously not accessible for gases like N2 due to very small opening windows.