UoC‐4: A MOF Based on Octahedral ScO₆ Nodes and Fluorinated Trimesate Ligands

Abstract

A new MOF (metal‐organic framework), ∞3 [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.

Synthesis, supramolecular isomerism, and photoluminescence of scandium(iii) complexes with a tetrafluoroterephthalate ligand

“…This has been illustrated by the temperature of thermal decomposition of potassium salts of fluorinated trimesic acid, as well as its barium and copper CPs. 41 The Sc complex containing difluorinated trimesate UoC-4 undergoes decomposition at approximately 500 °C, 28 while its fully fluorinated analogue UoC-6 is stable only below 250 °C. 29 Zr-UiO-66 is stable up to 500 °C, 64 while its fluorinated analogue decomposes above 380–400 °C.…”

“…Our previous attempts to get Sc( iii ) complexes with tFBDC 2− ligand resulted in obtaining a chain-like polymer 25 with the product of H 2 tFBDC decarboxylation, chain-like 26 and layered anionic 27 coordination polymers with tFBDC 2− . Recently, Ruschewitz and coworkers presented scandium CPs based on difluoro- and trifluorosubstituted trimesate linkers UoC-4 28 and UoC-6, 29 respectively. Both of them have very small windows providing no chance for gas adsorption.…”

Sc(iii)-Based metal–organic frameworks

“…Fig.24Representation of UoC-4 along the a-direction. Colour code: C, gray; O, red; Sc, purple; F, blue 58. …”