Post-synthetic metalation of organic cage for enhanced porosity and catalytic performance

Porous organic cages (POCs) have shown great potential in many applications, and post-synthetic modification (PSM) has been confirmed to be an effective strategy to tailor their structures and related functionalities. However, it is extremely challenging to develop a general platform for simple-to-make functional POCs for advanced applications by PSM method. Herein, we reported that octahedral calix[4]resorcinarene-based hydrazone-linked porous organic cage (HPOC-401) provides an excellent platform for post-synthetic metalation by various transition metal (TM) ions under mild conditions due to the abundance of coordination sites in its skeleton. Such metalated products (HPOC-401-TM) exhibit Brunauer-Emmett-Teller (BET) surface area up to 1,456 m(2) g(-1), much higher than that of the pristine HPOC-401, which has a BET value of 474 m(2) g(-1). Moreover, the metalation and porosity increases further influence their gas capture, separation, as well as catalytic performance. For instance, HPOC-401-TM products exhibit higher CO2, H-2, and C2 hydrocarbon gas uptake, as well as higher C2H6/C2H4 selectivity than HPOC-401. Moreover, the HPOC-401-TM also shows better catalytic performance in the cycloaddition of CO2 with epoxides compared to HPOC-401. These findings uncover a simple yet effective approach for modifying the porosity characteristics of organic cages, which will undoubtedly expand their future implementations.

Automated summary

This article reports an octahedral calix[4]resorcinarene-based hydrazone-linked porous organic cage (HPOC-401) that provides an excellent platform for post-synthetic metalation by various transition metal ions under mild conditions. The metalated products (HPOC-401-TM) exhibit significantly higher BET surface area and improved gas capture, separation, and catalytic performance compared to the pristine HPOC-401. This simple yet effective approach for modifying the porosity characteristics of organic cages has great potential for future applications.