Flexible and hydrophobic Zn-based metal-organic framework
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Contributors
Abstract
A zinc-based metal-organic framework Zn2(adb)2(dabco) ·4.5 DMF (K) (DUT-30(Zn), DUT = Dresden University of Technology, adb = 9,10-anthracene dibenzoate, dabco =1,4-diazabicyclo[2.2.2]octane, DMF = N,N-dimethylformamide) was synthesized using a solvothermal route. This MOF exhibits six crystallographic guest dependent phases. Two of them were characterized via single crystal X-ray analysis. The as-synthesized phase K crystallizes in the orthorhombic space group Fmmm, with a = 9.6349(9), b = 26.235(3), and c = 28.821(4) Å and consists of two interpenetrated pillar-layer networks with pcu topology. When the substance loses 0.5 DMF molecules per formula unit, a phase transition from the kinetic phase K to a thermodynamic phase T occurs. Zn2(adb)2(dabco) ·4 DMF (T) crystallizes in the tetragonal space group I4/mmm, with a = 19.5316(8) and c = 9.6779(3) Å. During the evacuation the DUT-30(Zn) undergoes again the structural transformation to A. The activated compound A shows the gate pressure effect in the low pressure region of nitrogen physisorption isotherm and has a BET surface area of 960 m2g-1 and a specific pore volume of 0.43 cm3 g-1. Furthermore, DUT-30(Zn) exhibits a hydrogen storage capacity of 1.12 wt % at 1 bar, a CO2 uptake of 200 cm3 g-1 at-78 °C and 0.9 bar, and a n-butane uptake of 3.0 mmol·g-1 at 20 °C. The N 2 adsorption process was monitored in situ via X-ray powder diffraction using synchrotron radiation. A low temperature induced transformation of phase A to phase V could be observed if the compound was cooled under vacuum to-196 °C. A further crystalline phase N could be identified if the framework was filled with nitrogen at-196 °C. Additionally, the treatment of activated phase A with water leads to the new phase W.
Details
Original language | English |
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Pages (from-to) | 8367-8374 |
Number of pages | 8 |
Journal | Inorganic chemistry |
Volume | 50 |
Issue number | 17 |
Publication status | Published - 5 Sept 2011 |
Peer-reviewed | Yes |