Porous Hydrogen-Bonded Frameworks Assembled from Metal-Nucleobase Entities for Xe/Kr Separation

Abstract

It is challenging to obtain high-purity xenon (Xe) and krypton (Kr) from the by-products of the air separation process due to their similar atom size and physical properties. Adsorption using porous materials such as metalorganic frameworks has been considered a promising technology to separate Xe/Kr. Herein, we reported two novel isostructural ionic supramolecular metal-organic frameworks (SMOFs, SMOF-PFSIX-1, and SMOF-AsFSIX-1), in which inorganic anions (PF 6or AsF 6-) and cationic metal-organic entities self-assembled through hydrogen bonds to give three-dimension pore channels. The two kinds of SMOFs can separate Xe/Kr efficiently with IAST selectivity of 6.9 and 6.7 under 298 K and 1.0 bar respectively. The breakthrough experiments further confirmed their industrial application potential. The Grand Canonical Monte Carlo (GCMC) and the Density Functional Theory (DFT) calculations revealed that there were multiple adsorptive sites to catch the Xe atom, and the affinity between Xe and frameworks can be attributed to the inorganic anions and amino groups on the ligands. To the best of our knowledge, it was the first time to report the SMOFs for Xe/Kr separation, and we proposed a new strategy for Xe/Kr separation based on the synergistic effect of amino and inorganic anions.

Porous Pyrene Organic Cage with Unusual Absorption Bathochromic-Shift Enables Visible Light Photocatalysis

“…20,21 Porous organic cages (POCs) constructed from covalently linked molecular building blocks have emerged as new types of nanosized synthons for porous reticular frameworks. [22][23][24][25][26][27][28][29] In comparison with other porous materials, [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] POCs possess both intrinsic intracage cavity and intercage porosity upon assembly, in addition to their advantageous solution processability and regeneration through recrystallization. The unique porous nature of POCs can facilitate the mass transfer of reactants and products in heterogeneous catalysis.…”

Hydrogen‐Bonded Metal–Nucleobase Frameworks for Efficient Separation of Xenon and Krypton

“…As presented in Figure 2a, four ligands and two anions are anchored to two copper centers to generate a neutral metal–nucleobase cluster as the secondary building units. Unlike the previously reported hydrogen‐bonded frameworks, [2e, 14f, 26, 27] the solvent molecules coordinated to the copper in the axial location of the paddle‐wheel cluster are replaced by hexafluoro anions in HOF‐ZJU‐201 and HOF‐ZJU‐202. Four ligands in the cluster extend along the a and b axes at approximately perpendicular angles (Figure S6).…”

Multifunctional Porous Hydrogen-Bonded Organic Frameworks: Current Status and Future Perspectives

“…For example, a paddle-wheel metal complex [Cu 2 (ade) 4 ] (ade = adenine, Figure 3), formed by the coordination of copper ions with adenines, is demonstrated to be a very good tecton to build microporous HOFs. Based on this tecton, several HOFs including SMOF-1/SMOF-2, 27 MPM-1-TiFSIX, 28 HOF-21, 29 HOF-ZJU-101/HOF-ZJU-102, 30 and SMOF-PFSIX-1/ SMOF-AsFSIX-1 31 have been prepared, which exhibited very good performances in gas adsorption and separation. Metal− organic cages also can serve as metalated organic building blocks for the preparation of HOFs.…”

“…An ultrastable HOF termed TAPM-1 was explored as the stationary phase in the high-solution gas chromatographic separation of benzene and cyclohexane or toluene and methylcyclohexane . HOF-ZJU-103/HOF-ZJU-104, HOF-ZJU-201/HOF-ZJU-202, and HOF-40 exhibit a superior separation performance for Xe/Kr mixtures.…”