The lack of accessible porosity in the framework of ZrTFS limits its ability to adsorb CO2. This suggesting that very small differences exist between these three materials, whereas Zr-TFS displays a larger unit cell. Integration of F-and 1 H-NMR peaks of the digested samples (Figures and) allowed to quantify the relative amounts of FUM 2-, AA and TFS 2-present in the lattice. In the framework structure of MOF-801, the externally added TFS 2-linkers may be incorporated through replacement of either the pristine fumarates or the capping ligands (either acetates or water/hydroxide) placed in its defective sites, given the hypothesis that AA induced missing cluster defects. In the exchanged samples, after treatment with H2TFS the signal of AA disappears. This suggests that the tetrafluorosuccinate replaces AA at defective sites in its monoprotonated form (HTFS -). Based on the combination of NMR analysis (Figures and) and TGA (Figure g -1 reported by Yaghi and co-workers). The accessible surface area then decreases with increasing content of the aliphatic fluorinated linker TFS 2-, passing from 649 and 626 m 2 g -1 for PF-MOF1 and PF-MOF2, respectively, to only 46 m 2 g -1 for ZrTFS. This drastic reduction of the surface area was also found in the hydrogenated counterpart of ZrTFS, zirconium succinate MIP-203-S. In there, it is claimed that this MOF does not show any accessible porosity to N2 at 77 K, presumably because after thermal activation under vacuum to remove the guest molecules, it tends to stay in a closely packed form that it is not accessible to nitrogen. Despite the different crystal topologies, it is reasonable to draw the same kind of conclusion for ZrTFS as well. Even in the presence of bipyridyl-based auxiliary ligands, the framework empty volume is not accessible to N2, as observed in a family of cadmium succinate mixed-linker MOFs. The micropore size distribution of the four samples retrieved from the NLDFT analysis (Figure )