Ligand Symmetry Modulation for Designing Mixed-Ligand Metal–Organic Frameworks: Gas Sorption and Luminescence Sensing Properties

2016-08-05T15:52:23Z (GMT) by Di-Ming Chen Jia-Yue Tian Chun-Sen Liu
Herein, we report the synthesis of a new mixed-linker Zn­(II)-based metal–organic framework (MOF), {[Zn<sub>2</sub>(atz)<sub>2</sub>­(bpydb)]­(DMA)<sub>8</sub>}<sub><i>n</i></sub> (<b>1</b>) (atz = deprotonated 3-amino-1,2,4-triazole, bpydb = deprotonated 4,4′-(4,4′-bipyridine-2,6-diyl) dibenzoic acid, DMA = <i>N</i>,<i>N</i>-dimethylacetamide), through symmetry modulation of a triazole ligand. The desymmetrized triazole linkers not only bond to the Zn­(II) ions to result in a new helical Zn-triazolate chain building unit but also lead to the formation of a highly porous framework (N<sub>2</sub> uptake: 617 cm<sup>3</sup>/g; BET surface area: 2393 m<sup>2</sup>/g) with 1D helical channels. The adsorption properties of desolved <b>1</b> were investigated by H<sub>2</sub>, C<sub>2</sub>H<sub>2</sub>, CO<sub>2</sub>, and CH<sub>4</sub> sorption experiments, which showed that <b>1</b> exhibited high uptake capacity for H<sub>2</sub> at 77 K and C<sub>2</sub>H<sub>2</sub> around room temperature. More importantly, the high C<sub>2</sub>H<sub>2</sub> uptake capacity but low binding energy makes this MOF a promising candidate for effective C<sub>2</sub>H<sub>2</sub> capture from C<sub>2</sub>H<sub>2</sub>/CO<sub>2</sub> and C<sub>2</sub>H<sub>2</sub>/CH<sub>4</sub> mixed gases with low regenerative energy cost. In addition, <b>1</b> shows potential application for the luminescence sensing of small aromatic molecules picric acid (PA) and <i>p</i>-xylene (PX).