Friedel–Crafts Synthesis of Carbazole-Based Hierarchical Nanoporous Organic Polymers for Adsorption of Ethane, Carbon Dioxide, and Methane

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.

Construction of a Carbazole-Based Nanoporous Organic Polymer via an AB2 Monomer for Adsorption/Separation of C1–C3 Alkanes and CO2

“…The BET specific surface area ( S BET ), microporous surface area, microporous volume, and total pore volume for CNOP-5 are 1425 m 2 ·g –1 , 1038 m 2 ·g –1 , 0.85 cm 3 ·g –1 , and 1.18 cm 3 ·g –1 , respectively. The value of S BET obtained for the CNOP-5 polymer exceeds or competes with those of other previously reported carbazole-based nanoporous organic polymers, such as PCNs (393–674 m 2 ·g –1 ), CTF-CAR (278 m 2 ·g –1 ), CNOPs (769–1546 m 2 ·g –1 ), , CSU-CPOPs (269–1032 m 2 ·g –1 ), Car-COFs (721–1334 m 2 ·g –1 ), CPOPs (510–1430 m 2 ·g –1 ), and other types of porous polymers. , Figure (b) illustrates the pore size distribution of CNOP-5 based on nonlocal density functional theory (NLDFT). As displayed in Figure (b), the CNOP-5 polymer has micropores centered at 0.97/1.37 nm and mesopores centered at 3.98 nm.…”

“…The BET specific surface area (S BET ), microporous surface area, microporous volume, and total pore volume for CNOP-5 are 1425 m 2 •g −1 , 1038 m 2 • g −1 , 0.85 cm 3 •g −1 , and 1.18 cm 3 •g −1 , respectively. The value of S BET obtained for the CNOP-5 polymer exceeds or competes with those of other previously reported carbazole-based nanoporous organic polymers, such as PCNs (393−674 m 2 • g −1 ), 18 CTF-CAR (278 m 2 •g −1 ), 19 CNOPs (769−1546 m 2 • g −1 ), 2,17 CSU-CPOPs (269−1032 m 2 •g −1 ), 20 Car-COFs (721−1334 m 2 •g −1 ), 21 CPOPs (510−1430 m 2 •g −1 ), 22 and In addition, at both temperatures and pressures, the adsorption isotherms for CNOP-5 differ significantly, with gas uptakes uniformly decreasing in the order C 3 H 8 > C 2 H 6 > CO 2 > CH 4 for the four gases. Moreover, we observed that the polarizability and critical temperatures of the four gases are arranged in the same order as their adsorption capacities at both temperatures (Figure S5), indicating that these factors are crucial for gas adsorption.…”

“…Bhaumik and co-workers have prepared porous organic networks based on terephthalaldehyde and carbazole, which exhibited good CO 2 uptake . Our group has prepared carbazole-based nanoporous organic polymers derived from multifunctionality aldehyde, and carbazole monomers show excellent light hydrocarbon (e.g., C 3 H 8 , C 2 H 6 , and CH 4 ) adsorption/separation properties because of rich microporosity and rich carbazole units. , However, most of the reported CNOPs are typically synthesized by two-component co-condensation bearing, respectively, different functional groups. Furthermore, the preparation of CNOPs has controlled the proportion of monomers and screened the synthetic conditions, such as solvents, temperature, reaction time, and concentration, thus resulting in a complicated synthetic process.…”

Synthesis of Ultramicroporous Materials via Cross-Linking Reaction of Polynaphthalene

“…The N 2 adsorption capacity at 273.15 K/1.0 bar is 0.61 mmol/g, and CH 4 adsorption capacities at 273.15 K/1.0 bar and 298.15 K/1.0 bar are 1.57 and 1.14 mmol/g, respectively. The adsorption data of CH 4 at 273.15 K/1.0 bar are higher than those of some materials prepared in the past two years, such as SNNU-5-Sc (1.21 mmol g −1 ), CNOP-2 (1.37 mmol g −1 ), CTP-1-NH 2 (1.50 mmol g −1 ), and MOF-2 (0.63 mmol g −1 ) . Moreover, we also gained important data about the separations of CO 2 from N 2 and CH 4 .…”

Porous Triptycene Network Based on Tröger’s Base for CO2 Capture and Iodine Enrichment

“…However, the continuous growth of carbon dioxide concentration in the atmosphere and the nuclear waste (such as radioactive iodine) produced by nuclear energy are affecting the normal life and health of human beings. − It is generally believed that using a solid adsorbent to capture carbon dioxide and enrich iodine is one of the most effective strategies. So, extensive efforts have been focused on exploiting gas capture and sequestration technologies by preparing high-performance solid sorbents. − …”