Mesoporous ZrIVand HfIVmetal–organic frameworks with reo topology

During last two decades, a rapid development of metal-organic frameworks (MOFs) chemistry was achieved exploring the widely applicable modular construction principles and the broad application potential [1].Among thousands of MOFs, the Zr-based materials show ultimate thermal and especially chemical stability, and could be successfully applied in catalysis [3], hydrogen generation [4], and selective adsorption [5].All previously reported Zr-based materials were based on 12 coordinated zirconium cluster Zr 6 O 4 (OH) 4 (CO 2 ) 12 , forming 12-connected framework with fcu topology limiting the availability of pore shape and size, and especially on pore windows size [5,6].In this work, we pursued a strategy that focuses on reducing the ability of [Zr 6 O 4 (OH) 4 ] 12+ cluster to coordinate multifunctional linker molecules.As a result, using modulator synthesis approach and bent dithienothiophene dicarboxylate as a linker, new porous crystalline materials, namely DUT-51(Zr) and DUT-51(Hf) (DUT -Dresden University of Technology), were synthesized.Crystal structures of both materials were determined by single crystal X-ray diffraction using synchrotron radiation [7].Crystal structures involve 8-connected SBU (Secondary Building Unit), interconnected by linker molecules forming 8-connected uninodal framework that can be referred to reo topology.As a result of such combination of SBU and linker geometry, octahedral (15.6 Å in diameter) and cubo-octahedral pores (18.8 Å in diameter) are created.Resulted square and triangular pore windows have a diameters 9.0 and 4.2 Å correspondingly, allowing to adsorb relative large dyes molecules (Nile blue, Rhodamine 6G etc.) as well as fullerenes C 60 and C 70 .Both materials are highly porous showing specific surface area (multi-point BET model) of 2335 m 2 g -1 for DUT-51(Zr) and 1859 m 2 g -1 for DUT-51(Hf).They are stable against hydrolysis and can be stored at ambient conditions without loss of crystallinity and porosity.