Novel (3,4,6)-Connected Metal–Organic Framework with High Stability and Gas-Uptake Capability

A microporous and noninterpenetrated metal–organic framework [Cu3(L)2(DABCO)­(H2O)]·15H2O·9DMF (1) has been synthesized using two different ligands, [1,1′:3′,1″-terphenyl]-4,4″,5′-tricarboxylic acid (H3L) and 1,4-diazabicyclo[2.2.2]­octane (DABCO). As revealed by variable-temperature powder X-ray diffraction (VT-PXRD) measurements, N,N′-ditopic DABCO plays an important role for stabilization of the Cu–L framework. The three-dimensional framework of 1 exhibits high stability and excellent adsorption capacity for H2 (54.3 mg g–1 at 77 K and 20 bar), CO2 (871 mg g–1 at 298 K and 20 bar), CH4 (116.7 mg g–1, 99 cm3 (STP) cm–3 at 298 K and 20 bar), and n-pentane (686 mg g–1 at 298 K and 1 bar). Interestingly, the excellent selectivity toward CO2 over N2 at ambient temperature (273 and 298 K) and 1 bar makes complex 1 possess practical application in gas separation and purification.本研究采用两种不同配体——[1,1′:3′,1″-三联苯]-4,4″,5′-三羧酸（H3L）与1,4-二氮杂双环[2.2.2]辛烷（1,4-diazabicyclo[2.2.2]octane, DABCO）——合成了一种微孔非互穿金属有机框架（metal–organic framework, MOF）配合物[Cu₃(L)₂(DABCO)(H₂O)]·15H₂O·9N,N-二甲基甲酰胺（N,N-Dimethylformamide, DMF）（记为化合物1）。变温粉末X射线衍射（variable-temperature powder X-ray diffraction, VT-PXRD）测试结果显示，具有双配位位点的DABCO对Cu-L骨架的稳定起到关键作用。该化合物1的三维骨架展现出极高的稳定性，且对多种气体及正构烷烃具备优异的吸附性能：氢气（77 K、20 bar下为54.3 mg·g⁻¹）、二氧化碳（298 K、20 bar下为871 mg·g⁻¹）、甲烷（298 K、20 bar下为116.7 mg·g⁻¹，对应标准温度和压力（Standard Temperature and Pressure, STP）下的体积为99 cm³(STP)·cm⁻³）以及正戊烷（298 K、1 bar下为686 mg·g⁻¹）。值得注意的是，在环境温度（273 K与298 K）、1 bar条件下，该配合物对二氧化碳相较于氮气具有优异的吸附选择性，使其具备气体分离与纯化的实际应用价值。