Porous organic cages (POCs), as a new type of porous materials, are intrinsically porous given their hollow cavities, have shown promising applications in selective guest inclusion, gas storage and separation, host-guest chemistry, and nanoscale reaction vessels for catalysis.
Since 2009, POCs have attracted increasing attention and significant progress has been made in preparation and use of organic cages with different shapes and sizes to generate new porous organic solids. However, robust POCs with large cavities and high surface areas are still few, which greatly restrain their practical applications.
In a study published in J. Am. Chem. Soc., a research group led by Prof. YUAN Daqiang from Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences reported 11 novel POCs, including dimeric cages with odd-even behaviors, unprecedented trimeric triangular prisms, and the largest recorded hexameric octahedra.
These POCs are all constructed from the same tetratopic tetraformylresorcin[4]arene cavitand by simply varying the diamine linkers through Schiff-base reactions and are fully characterized by X-ray crystallography, gas sorption measurements, nuclear magnetic resonance(NMR) spectroscopy, and mass spectrometry.
The researchers revealed that calix[4]resorcinarene is a good building block to construct versatile molecule cage assemblies with continuously tunable window diameters from 3.8 to 11.6 , and cavity volumes from 358 to 11243 3.
Gas sorption measurements suggest that they are all porous materials, especially for the [3+6] and [6+12] POCs with Brunauer–Emmett–Teller(BET) more than 1000 m2 g-1, which exceeds that of the majority of POCs. The BET value of calix[4]resorcinarene-based porous organic cage(CPOC)-303 is up to 2803 m2 g-1, which presents the highest in POCs synthesized by Schiff-base reaction.
This study helps to understand the self-assembly behaviors of POCs and sheds light on the rational design of POC materials for practical applications.
Schematic representation of the systematic construction of calix[4]resorcinarene-based POCs. (Image by Prof. YUAN’s Group)
Contact:
Prof. YUAN Daqiang
Fujian Institute of Research on the Structure of Matter
Chinese Academy of Sciences
Email: ydq@fjirsm.ac.cn