Porosity Enhancement of Carbazolic Porous Organic Frameworks Using Dendritic Building Blocks for Gas Storage and Separation

We report a facile synthesis of carbazolic porous organic frameworks (Cz-POFs) via FeCl3 promoted oxidative polymerization. Using bulky, dendritic building blocks with high connectivity, the porosity of Cz-POFs was significantly enhanced. Specifically, Cz-POF-1 and Cz-POF-3 show high surface areas of 2065 and 1927 m2 g–1, respectively. These surface areas are 3.1 and 2.1 times larger than those of Cz-POF-2 and Cz-POF-4 constructed from less branched building blocks, respectively. At 1 bar and 273 K, Cz-POF-3 exhibits the highest CO2 uptake (21.0 wt %) and CH4 uptake (2.54 wt %), while Cz-POF-1 has the highest H2 uptake (2.24 wt %) at 77 K. These values are among the highest reported for porous organic polymers. In addition, Cz-POFs exhibit good ideal CO2/N2 selectivities (19–37) and CO2/CH4 selectivities (4.4–7.1) at 273 K, showing great promise for gas storage and separation applications.