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

Abstract

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 as,BET = 1150 m2·g–1 with a micropore volume of Vmic = 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.