UoC‐2: A Fluorinated Derivative of the Robust Metal‐Organic Framework MFM‐300

Abstract By solvothermal reactions of fluoro substituted biphenyl‐3,3’,5,5’‐tetracarboxylic acids (H 4 BPTC) with the respective metal salts, four new MOFs with the MFM‐300 topology were synthesized, namely [M III 2 (OH) 2 (L)] with M III =Ga 3+ , In 3+ and L=4‐ mF ‐BPTC 4− and 4,4’‐ dF ‐BPTC 4− . Three of them were refined from X‐ray single crystal diffraction data ( I 4 1 22, Z =4), [Ga 2 (OH) 2 (4,4’‐ dF ‐BPTC)] was confirmed by Le Bail fits based on synchrotron powder diffraction data. To the best of our knowledge, these four compounds represent the very first examples of MFM‐300 type MOFs with a substituted BPTC 4− linker. With increasing fluorination of the linker, the thermal stability decreases, as the decarboxylation of the linker is facilitated. On the other hand, the gas uptake is enhanced significantly. E.g. the CO 2 uptake (273 K, 1 bar) increases from 124 cm 3 /g for [Ga 2 (OH) 2 (4‐ mF ‐BPTC)] to 136 cm 3 /g for [Ga 2 (OH) 2 (4,4’‐ dF ‐BPTC)]. Surprisingly, the exact determination of specific surface areas ( S BET ) turned out to be difficult. It is supposed that due to transient open metal sites, complete removal of solvent molecules (DMF, acetone) is not always possible before degradation of the framework starts.