MFU-4-Br, [Zn5Br4(bbta)3]n: The MOF was prepared following the procedure for MFU-4, except that anhydrous ZnBr2 was used as a metal salt, the reaction time was prolonged to 15 min and the reaction temperature increased to 165 °C (the last two parameters were changed in order to improve the reaction yield and to prepare crystals of similar sizes to MFU-4). ZnBr2 (560 mg, 2.487 mmol) and H2-BBTA (100 mg, 0.624 mmol) were dissolved in DMF (5 mL) and placed in a Pyrex sample tube (30 mL). The reaction mixture was heated in a microwave synthesizer (CEM, Discover S) to 165 °C at 300 W, kept under these conditions for 15 min, and then cooled to ambient temperature. The formed precipitate was isolated by centrifugation, washed with DMF (3 x 5 mL) and dried in air at ambient conditions to give an off-white crystalline material (254 mg). The reaction was carried out several times to produce enough material and to ensure its reproducibility.