Synthesis and Crystal Structures of New Metal-Organic Frameworks Based on Sulfonic Acid Group Functionalized Ligand

To obtain metal-organic frameworks (MOFs) with high proton conductivity, three new MOFs, FeL_0.5(NMP)_2n(BUT-203), NiL_0.5(DMA)_2n (BUT-204), andCoL_0.5(DMA)(dpe)·H₂O (BUT-205) were synthesized through the solvothermal reaction between a sulfonic acid group functionalized ligand, 4, 8-disulfonaphthalene-2, 6-dicarboxylic acid (H₄L) and Fe(NO₃)₃·9H₂O, Ni(CH₃COO)₂·4H₂O, or CoCl₂·6H₂O, respectively, and characterized by single-crystal X-ray diffraction (SXRD), thermogravimetric analysis (TGA), infrared spectroscopy (FT-IR), and elemental analysis (EA). BUT-203 and BUT-204 are isostructural structures with one-dimensional chain, while BUT-205 is a three-dimensional framework with gwg topology. Impendence tests show that BUT-205 with three-dimensional structure possesses proton conductivity with a value of 5.661×10^-4 S/cm, obviously higher than that of one-dimensional BUT-203 and BUT-204. This fact reveals that the three-dimensional structure can effectively improve the proton conductivity of MOFs.