Combining Linker Design and Linker-Exchange Strategies for the Synthesis of a Stable Large-Pore Zr-Based Metal-Organic Framework.

Abstract

A Zr(IV)-based metal-organic framework (MOF), termed reo-MOF-1 [Zr6O8(H2O)8(SNDC)4], composed of 4-sulfonaphthalene-2,6-dicarboxylate (HSNDC2-) linkers and Zr6O8(H2O)8(CO2)8 clusters was synthesized by solvothermal synthesis. Structural analysis revealed that reo-MOF-1 adopts the reo topology highlighted with large cuboctahedral cages (23 Å). This structure is similar to that found in DUT-52 (fcu topology), however, reo-MOF-1 lacks the body-centered packing of the 12-connected Zr6O4(OH)4(CO2)12 clusters, which is attributed to the subtle, but crucial influence in the bulkiness of functional groups on the linkers. The control experiments, where the ratio of H3SNDC/naphthalene-2,6-dicarboxylate linkers was varied, also support our finding that the bulky functionalities play a key role for defect-controlled synthesis. The reo-MOF-1A framework was obtained by linker exchange to yield a chemically and thermally stable material despite its large pores. Remarkably, reo-MOF-1A exhibits permanent porosity (Brunauer-Emmett-Teller and Langmuir surface areas of 2104 and 2203 m2 g-1, respectively). Owing to these remarkable structural features, reo-MOF-1A significantly enhances the yield in Brønsted acid-catalyzed reactions.