Phenylamino-, Phenoxy-, and Benzenesulfenyl-Linked Covalent Triazine Frameworks for CO2 Capture

Covalent triazine-based frameworks (CTFs) have emerged as an important class of adsorbents for CO 2 capture and storage and have garnered a great deal of attention. However, the systematic study of the relationship between PhNH-, PhO-, and PhS-linked CTFs and CO 2 uptake performance has not yet been conducted. We herein report the synthesis and CO 2 uptake performance of such CTFs. Three similarly structured, nitrile-containing monomers including 2,4,6-tris(4-cyanophenylamino)-1,3,5-triazine (TAT), 2,4,6-tris(4-cyanophenoxy)-1,3,5-triazine (TOT), and 2,4,6-tris(4-cyanobenzenesulfenyl)-1,3,5-triazine (TST) have been employed to synthesize such CTFs through ZnCl 2 -mediated cyclotrimerization by a stepwise heating method for the purpose of keeping the CTF structure intact. The CO 2 capture performances of such CTFs are confirmed to rely on the incorporated heteroatoms and increase in the order of PhNH- > PhO- > PhS-linkage in CTFs. A theoretical calculation demonstrates the same trend of the CO 2 binding energies and are found to be −20.7, −19.3, and −13.5 kJ mol –1 respectively for PhNH-, PhO-, and PhS-bridged CTFs. In addition, the PhNH-linked CTF prepared at high temperature (600 °C) displays a much higher CO 2 adsorption capacity (5.0 mmol g –1 at 273 K/1 bar).