UiO-66 type MOFs with mixed-linkers - 1,4-Benzenedicarboxylate and 1,4-naphthalenedicarboxylate: Effect of the modulator and post-synthetic exchange

We present a detailed study of the effect of benzoic acid as a modulator on the properties of UiO-66 type MOFs with two linkers 1,4-benzenedicarboxylate (BDC) and 1,4-naphthalenedicarboxylate (NDC). We used four compositions of MOFs with molar ratios BDC/NDC 100/0, 75/25, 50/50, and 0/100. For each composition effect of benzoic acid (BA) additive on volumetric, structural, vibrational properties, and size and shape of crystals were studied. We have revealed that ten equivalents of BA significantly enhance the porosity of obtained materials and lead to the formation of well-shaped nanoparticles. Moreover, the high concentration of BA changes the NDC/BDC ratio in the resulting MOF. In the second part of the work, using a post-synthetic exchange, we have decorated defect pores of UiO-66 type MOFs with 3-phosphonopropionic acid molecules. Using FTIR analysis and DFT calculations, we proved that 3-phosphonopropionic acid molecules bond to the Zr4+ ions by PO4-groups instead of COOH-groups.