Cu 4OCl 6(DABCO) 2]·0.5DABCO·4CH 3OH (“ MFU-5”): Modular synthesis of a zeolite-like metal-organic framework constructed from tetrahedral {Cu 4OCl 6} secondary building units and linear organic linkers

Abstract

A novel metal-organic framework (MOF) based on a tetranuclear copper cluster and a linear organic ligand formulated as [Cu 4OCl 6(DABCO) 2] ·0.5DABCO ·4CH 3OH (denoted as MFU-5, MFU=Metal-Organic Framework, Ulm University; DABCO=1,4-diazabicyclo[2.2.2]octane), was prepared via solvothermal synthesis. In contrast with common MOF synthesis strategies, MFU-5 is assembled from pre-defined molecular secondary building units, i.e. {Cu 4OCl 6} moieties, which become the nodes of the coordination framework. The title compound was characterized by single crystal X-ray diffraction, variable temperature powder diffraction (VT-XRPD), thermal analysis, as well as IR- and UV/Vis spectroscopy. Crystal data for MFU-5: hexagonal, P6/ mcc (no. 192), a=25.645(9), c=17.105(11) Å, V=9742(8) Å 3, Z=12, 1690 structure factors, R[ F 2>2 σ( F 2)]=0.049. MFU-5 is a 3D metal-organic framework with 1D channels running along the c-axis hosting DABCO and methanol solvent molecules. The framework displays a zeolite-like structure constructed from mso cages, which represents the composite building units in the zeolites SSF, MSO and SZR. Two-fold interpenetration is observed between these building units. TG/DTA-MS and VT-XRPD characterization reveal a stepwise release of methanol and DABCO molecules upon heating, eventually resulting in a structural change into a non-porous material.