Synthesis, Single-Crystal X-ray Microdiffraction, and NMR Characterizations of the Giant Pore Metal-Organic Framework Aluminum Trimesate MIL-100

Abstract

This contribution deals with the hydrothermal synthesis of the metal-organic framework aluminum trimesate, analogous to the MIL-100-type, previously reported with chromium(III) and iron(III). MIL-100(Al) crystallizes within a very narrow pH range (0.5−0.7) after heating a mixture of aluminum nitrate, trimethyl 1,3,5-benzenetricarboxylate (Me 3 btc), nitric acid, and water at 210 °C for 3.5 h. The resulting product consists of tiny octahedral shaped crystals of 2 μm size, which have been used for the atomic structure determination. It was carried out by means of single crystal using the microdiffraction setup together with microfocalized synchrotron radiation at station ID13 (ESRF, France). Solid-state NMR characterization was fully consistent with XRD structure but with higher local symmetry. The three-dimensional open framework obtained from direct methods calculations reveals the arrangement of supertetrahedral (ST) building blocks based on the MTN topology (related to the zeolite ZSM-39). Each ST motif is built up from four μ 3 -oxo-centered trinuclear unit (Al 3 O) located at each corner and linked to the four btc ligands located on each face of the tetrahedron. MIL-100 (Al) exhibits BET and Langmuir surface area of 2152(39) m 2 g −1 and 2919(44) m 2 g −1, respectively (pore volume: 0.82 cm 3 g −1 ).