• materials
• N2 adsorption
• CO2 adsorption
• gas-sorption analysis
• ATR-IR
• PXRD MOF
• solvothermal synthesis
• Cerium based MOF
• MIL_140A
• linker functionalization
• fluorination
• terephthalic acid
• MOF

Metal organic frameworks (MOFs) are a class of crystalline materials that consist of metal ions or clusters connected by organic linkers to form porous structures. These materials are suitable for many applications (e.g., gas separation, gas storage and catalytic reactions) due to their tuneable pore sizes, the high surface area, and the possibility of modifying properties of the material by changing the metal centre or the organic linkers. In the MIL-140 topology, well known for tetravalent metals, edge-sharing CeO8 units , carboxylate groups and μ3-oxide bridges form the Inorganic Building Units (IBUs). These IBUs are connected to each other through terephthalate ions (BDC2-) to form a 3D network characterised by 1D pores with triangular shape.
It is known that the presence of four fluorine atoms in the terephthalic moiety imparts a unique CO2 step-shaped adsorption isotherm that enhances the selectivity over N2 and C2H2. To investigate how fluorine influences adsorption properties, a series of new CeIV-based MOFs with MIL-140 topology and characterized by a different degree of fluorination of the organic linker has been synthesized.
oF2_MIL-140A(Ce) (where oF2-BDC is 2,3-difluoroterephthalic acid), pF2_MIL-140A(Ce) (where pF2-BDC is 2,5-difluoroterephthalic acid) and F1_MIL-140A(Ce) (where F1-BDC is 2-fluoroterephthalic acis) were obtained through the same synthesis procedure and the powders were characterized by powder X-ray diffraction (PXRD), attenuated total reflectance infrared (ATR-IR) spectroscopy, 1H and 19F nuclear magnetic resonance (NMR) spectroscopy, in situ infrared spectroscopy and gas-sorption analysis. The morphology of the obtainded products was evaluated with Scanning Electron Microscopy (SEM).