Acetylene, an important petrochemical raw material, is very difficult to store safely under compression because of its highly explosive nature. Here we present a porous metal-organic framework named FJI-H8, with both suitable pore space and rich open metal sites, for efficient storage of acetylene under ambient conditions. Compared with existing reports, FJI-H8 shows a record-high gravimetric acetylene uptake of 224 cm3 (STP) g−1 and the second-highest volumetric uptake of 196 cm3 (STP) cm−3 at 295 K and 1 atm. Increasing the storage temperature to 308 K has only a small effect on its acetylene storage capacity (∼200 cm3 (STP) g−1). Furthermore, FJI-H8 exhibits an excellent repeatability with only 3.8% loss of its acetylene storage capacity after five cycles of adsorption–desorption tests. Grand canonical Monte Carlo simulation reveals that not only open metal sites but also the suitable pore space and geometry play key roles in its remarkable acetylene uptake.

Reticular chemistry offers the possibility of systematic design of porous materials with different pores by varying the building blocks, while the emerging porous organic cage (POC) system remains generally unexplored. A series of new POCs with dimeric cages with odd−even behaviors, unprecedented trimeric triangular prisms, and the largest recorded hexameric octahedra have been prepared. These POCs are all constructed from the same tetratopic tetraformylresorcin[4]arene cavitand by simply varying the diamine ligands through Schiff-base reactions and are fully characterized by X-ray crystallography, gas sorption measurements, NMR spectroscopy, and mass spectrometry. The odd−even effects in the POC conformation changes of the [2 + 4] dimeric cages have been confirmed by density functional theory calculations, which are the first examples of odd−even effects reported in the cavitand-based cage system. Moreover, the "V" shape phenylenediamine linkers are responsible for the novel [3 + 6] triangular prisms. The window size and environment can be easily functionalized by different groups, providing a promising platform for the construction of multivariate POCs. Use of linear phenylenediamines led to record-breakingly large [6 + 12] truncated octahedral cages, the maximum inner cavity diameters and volumes of which could be readily modulated by increasing the spacer length of the phenylenediamine linkers. This work can lead to an understanding of the self-assembly behaviors of POCs and also sheds light on the rational design of POC materials for practical applications.

The effective capture and storage of volatile radionuclide iodine from the nuclear waste stream is of paramount importance for environment remediation. In this work, we report the first examples of azo-bridged calix[4]resorcinarene-based porous organic frameworks (CalPOFs), synthesized by diazocoupling reaction of 4,4′-biphenyldiamine and C-alkylcalix[4]resorcinarenes (RsC n s; n stands for the associated alkyl chain length) under mild conditions. The resulting CalPOFs are permanently porous, and their porous properties could be adjusted by varying the alkyl chain lengths of RsC n s. With the alkyl chain length increasing from methyl, ethyl to propyl, the Brunauer−Emmett−Teller surface areas are decreasing from 303, 154 to 91 m 2 g −1 for CalPOF-1, CalPOF-2 and CalPOF-3, respectively. The presence of a great many of effective sorption sites including azo (−NN−) groups, macrocyclic π-rich cavities and phenolic units in the skeleton as well as permanent porous structures provides these materials with ultrahigh iodine vapor uptake up to 477 wt %. Further, thorough studies revealed that the capacities for removing iodine vapor are in the order of CalPOF-1 (477 wt %) > CalPOF-2 (406 wt %) > CalPOF-3 (353 wt %), which are dependent on their surface areas, and also the densities of the azo and RsC n units. In addition, detailed analyses of iodine-loaded CalPOF-1 suggested that chemisorption is the major process in this adsorbent, illustrating the big chance to explore versatile CalPOFs to capture volatile toxic vapors.