Soft Porous Crystal Based upon Organic Cages That Exhibit Guest-Induced Breathing and Selective Gas Separation.
Zhifang WangNivedita SikdarShi-Qiang WangXia LiMeihui YuXian-He BuZe ChangXiaolong ZouYao ChenPeng ChengKuang YuMichael J ZaworotkoZhen-Jie ZhangPublished in: Journal of the American Chemical Society (2019)
Soft porous crystals (SPCs) that exhibit stimuli-responsive dynamic sorption behavior are attracting interest for gas storage/separation applications. However, the design and synthesis of SPCs is challenging. Herein, we report a new type of SPC based on a [2 + 3] imide-based organic cage (NKPOC-1) and find that it exhibits guest-induced breathing behavior. Various gases were found to induce activated NKPOC-1 crystals to reversibly switch from a "closed" nonporous phase (α) to two porous "open" phases (β and γ). The net effect is gate-opening behavior induced by CO2 and C3 hydrocarbons. Interestingly, NKPOC-1-α selectively adsorbs propyne over propylene and propane under ambient conditions. Thus, NKPOC-1-α has the potential to separate binary and ternary C3 hydrocarbon mixtures, and the performance was subsequently verified by fixed bed column breakthrough experiments. In addition, molecular dynamics calculations and in situ X-ray diffraction experiments indicate that the gate-opening effect is accompanied by reversible structural transformations. The adsorption energies from molecular dynamics simulations aid are consistent with the experimentally observed selective adsorption phenomena. The understanding gained from this study of NKPOC-1 supports the further development of SPCs for applications in gas separation/storage because SPCs do not inherently suffer from the recyclability problems often encountered with rigid materials.
Keyphrases
- molecular dynamics
- molecular dynamics simulations
- room temperature
- density functional theory
- ionic liquid
- liquid chromatography
- high glucose
- diabetic rats
- water soluble
- metal organic framework
- mental health
- mass spectrometry
- molecular docking
- air pollution
- minimally invasive
- aqueous solution
- particulate matter
- highly efficient
- magnetic resonance
- endothelial cells
- magnetic resonance imaging
- high resolution
- heavy metals
- drug delivery
- reduced graphene oxide
- climate change
- electron microscopy
- stress induced