A novel copper-based MOF material: Synthesis, characterization and adsorption studies

摘要

Synthesis and crystal structure of a novel copper-based MOF material are presented. The tetragonal crystal structure of _∞~3[(Cu4(μ(4-O)(μ2-OH)2(Me2trzpba)4] possesses a calculated solvent-accessible pore volume of 57%. Besides the preparation of single crystals, synthesis routes to microcrystalline materials are reported. While PXRD measurements ensure the phase purity of the as-synthesized material, TD-PXRD measurements and coupled DTA-TG-MS analysis confirm the stability of the network up to 230 °C. The pore volume of the microcrystalline material determined by nitrogen adsorption at 77 K depends on the synthetic conditions applied. After synthesis in DMF/H2O/MeOH the pores are blocked for nitrogen, whereas they are accessible for nitrogen after synthesis in H2O/EtOH and subsequent MeOH Soxhleth extraction. The corresponding experimental pore volume was determined by nitrogen adsorption to be V_(Pore) = 0.58cm~3g~(-1). In order to characterize the new material and to show its adsorption potential, comprehensive adsorption studies with different adsorptives such as nitrogen, argon, carbon dioxide, methanol and methane at different temperatures were carried out. Unusual adsorption-desorption isotherms with one or two hysteresis loops are found - a remarkable feature of the new flexible MOF material.