Friedel–Crafts Synthesis of Carbazole-Based Hierarchical Nanoporous Organic Polymers for Adsorption of Ethane, Carbon Dioxide, and Methane
Jun Yan, Yan Tan, Lulu Wei, Zhenhua Liu, Qilin Wang, Haiyu Sun, Zhonggang Wang, Dan Li, Yongqiang Qian, Shengwei Guo
Abstract
The Friedel–Crafts (FC) reaction is a prominent synthetic tool for rapidly constructing complex molecular frameworks, but syntheses of carbazole-based nanoporous organic polymers (CNOPs) via FC hydroxyalkylation are rare. Herein we report the acid-catalyzed FC hydroxyalkylation synthesis of two CNOP networks, prepared (using p-phthalaldehyde) from 1,3,5-tris(9-carbazolyl)benzene and tris[4-(9H-carbazol-9-yl)phenyl]amine. The specific surface areas of the CNOPs ranged from 1374 to 1546 m2/g, and the CNOPs had a hierarchical porous structure with pore sizes ranging from 0.87 to 6.60 nm. Furthermore, the high porosity in conjunction with abundant carbazole units in the CNOPs enabled excellent adsorption performance toward C2H6, CO2, and CH4. CNOP-2 derived from 1,3,5-tris(9-carbazolyl)benzene and p-phthalaldehyde displayed C2H6, CO2, and CH4 uptakes of up to 98.7, 90.2, and 30.7 cm3/g, respectively, at 1 bar and 273 K. Also, the adsorption selectivities of the CNOPs in conjunction with C2H6/CH4 and CO2/CH4 gas mixtures were 23.4–23.5 and 6.4–7.3, respectively. This work demonstrates a cost-effective FC reaction that can be used to design and construct carbazole-based nanoporous organic polymers.