New Group 13 MIL-53 Derivates based on 2,5-Thiophenedicarboxylic Acid

A new rigid metal-organic framework (MOF) with MIL-53 topology built of 2,5-thiophenedicarboxylate (TDC) and Al, Ga, or In is reported. Its structure contains chains of trans corner sharing MO₆ octahedra, connected by the linker molecules to form microporous square shaped 1D channels. A combination of powder X-ray diffraction (PXRD), density functional theory (DFT) calculations, and ¹H, ¹³C, and ²⁷Al solid-state NMR spectroscopy (ssNMR) was used to analyse the structures in detail. The synthesis is easily scaled-up using microwave assisted solvothermal conditions. All materials possess a high thermal stability up to 420 °C in air and permanent porosity towards N₂, H₂, CO₂, and CH₄. Al-MIL-53-TDC shows a high specific surface area of a_s,BET = 1150 m²·g^–1 with a micropore volume of V_mic = 0.48 cm³·g^–1 as well as water uptake of 5.5H₂O molecules per sum formula (469 mg·g^–1) with an a sigmoidal shape, advantageous for heat-transformation processes. Noteworthy, this material adsorbs 2.1 wt % H₂ at –196 °C and 1 bar, which surpasses other Al-MIL-53 compounds based on linear functionalized terephthalates.