Flexibility of Metal-Organic Framework Tunable by Crystal Size at the Micrometer to Submillimeter Scale for Efficient Xylene Isomer Separation  

作　　者：Xiao Yang Hao-Long Zhou Chun-Ting He Zong-Wen Mo Jia-Wen Ye Xiao-Ming Chen Jie-Peng Zhang 

机构地区：[1]MOE Key Laboratory of Bioinorganic and Synthetic Chemistry,School of Chemistry,Sun Yat-Sen University,Guangzhou 510275,China

出　　处：《Research》2019年第1期433-441,共9页研究（英文）

基　　金：This work was supported by the NSFC(21731007 and 21821003);the Guangdong Pearl River Talents Program(2017BT01C161).

摘　　要：Understanding,controlling,and utilizing the flexibility of adsorbents are of great importance and difficulty.Analogous with conventional solid materials,downsizing to the nanoscale is emerging as a possible strategy for controlling the flexibility of porous coordination polymers(or metal-organic frameworks).We report a unique flexibility controllable by crystal size at the micrometer to submillimeter scale.Template removal transforms[Cu_(2)(pypz)_(2)]·0.5p-xylene(MAF-36,Hpypz=4-(1H-pyrazol-4-yl)pyridine)with one-dimensional channels toα-[Cu_(2)(pypz)_(2)]with discrete small cavities,and further heating gives a nonporous isomerβ-[Cu_(2)(pypz)_(2)].Both isomers can adsorb p-xylene to give[Cu_(2)(pypz)_(2)]·0.5p-xylene,meaning the coexistence of guest-driven flexibility and shape-memory behavior.The phase transition temperature fromα-[Cu_(2)(pypz)_(2)]toβ-[Cu_(2)(pypz)_(2)]decreased from~270℃ to~150℃ by increasing the crystal size from the micrometer to the submillimeter scale,ca.2-3 orders larger than those of other size-dependent behaviors.Single-crystal X-ray diffraction showed coordination bond reconstitution and chirality inversion mechanisms for the phase transition,which provides a sufficiently high energy barrier to stabilize the metastable phase without the need of downsizing to the nanoscale.By virtue of the crystalline molecular imprinting and gate-opening effects,α-[Cu_(2)(pypz)_(2)]andβ-[Cu_(2)(pypz)_(2)]show unprecedentedly high p-xylene selectivities of 16 and 51,respectively,as well as ultrafast adsorption kinetics(<2 minutes),for xylene isomers.

关 键 词：ISOMERS coordination ADSORBENT 

分 类 号：O62[理学—有机化学]