Journal
RESEARCH
Volume 2019, Issue -, Pages -Publisher
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.34133/2019/9463719
Keywords
-
Categories
Funding
- NSFC [21731007, 21821003]
- Guangdong Pearl River Talents Program [2017BT01C161]
Ask authors/readers for more resources
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 to alpha-[Cu-2(pypz)(2)] with discrete small cavities, and further heating gives a nonporous isomer beta-[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 from alpha- [Cu-2(pypz)(2)] to beta-[Cu-2(pypz)(2)] decreased from similar to 270 degrees C to similar to 150 degrees C 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, alpha-[Cu (2)(pypz)(2)] and beta-[Cu-2(pypz),] show unprecedentedly high p-xylene selectivities of 16 and 51, respectively, as well as ultrafast adsorption kinetics (<2 minutes), for xylene isomers.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available