Novel fluorinated MOFs with hydrophobic properties

Novel fluorinated lanthanide-based metal–organic frameworks (Ln-F-MOFs) constructed from the 3,3′-difluorobiphenyl-4,4′-dicarboxylic acid as a ligand (H2L) and M(III) metal ions (M(III) = Dy for UPJS-18(Dy), Tb for UPJS-18(Tb), Ho for UPJS-18(Ho), Er for UPJS-18(Er), Eu for UPJS-19(Eu), UPJS = materials prepared at the University of Pavol Jozef Safárik in Košice) have been successfully synthesized under solvothermal conditions leading to a series of MOFs with the same basic formula and the composition {[M2(L)3(DMF)2]∙xDMF·yH2O}n. Structural analyses revealed that complexes UPJS-18(Dy), UPJS-18(Tb), UPJS-18(Ho), UPJS-18(Er) are isostructural while complex UPJS-19(Eu) has different but a very similar structural motif. These complexes show high surface hydrophobicity with "rose petal effect", thermal stability up to 300 °C and photoluminescence properties determined the characteristic f-f transitions for the individual metal ions. The porosity of some activated coordination polymers was studied by N2, CO2 and H2 adsorption, with the highest N2 and CO2 adsorption capacities observed for the UPJS-18(Dy) complex. Moreover, the H2 sorption capacity was determined for UPJS-19(Eu). The high water-repelling properties and thermal stability predetermines these materials for industrial as well as everyday-life use, while channels lined with fluorine atoms with their high affinity to fluorinated compounds predetermine the possibility of further investigations in the field of sorption fluorinated waste or fluorinated drugs.