Porous imine-based networks with protonated imine linkages for carbon dioxide separation from mixtures with nitrogen and methane

Abstract

Porous imine-linked networks (PINs) have been prepared by catalyst-free Schiff base condensation of 2,4,6-(4-aminophenyl)1,3,5-triazine with 9,10-anthracene-dicarboxaldehyde (PIN1 and PIN1_2) and with 4,4 0 ,4 00 ,4 000 -methanetetrakis-benzaldehyde (PIN2). Even after synthesis optimisation, only with DMSO (PIN1 and PIN2) microporous frameworks were obtained, whereas DMF (PIN1_2) and other solvents led to nonporous systems, estimated by argon measurements. Furthermore, 15 N solid state NMR and IR spectroscopy reveal the influence of the decomposition products of DMSO leading to protonation of the imine linkage and resulting in an ionic structure with an incorporated sulfonic counterion. Until now, protonation of an imine function due to the usage of DMSO as solvent has not been discussed in the literature. In contrast, for PIN1_2 the imine linkage remains neutral. Argon sorption isotherms for PIN1 and PIN2 exhibit surface areas of 458 m 2 g À1 and 325 m 2 g À1 and the pore structure displays micro-and small mesopores with pore diameters from 0.6 to 5 nm. Additionally, CO 2 isotherms at 273 K demonstrate ultramicropores for all three polymers with similar pore size distributions. Despite their different network structures, similar CO 2 uptakes (1.8-1.06 mmol g À1 at 273 K at 1.0 bar) and heat of adsorption Q st values of 30 kJ mol À1 were obtained. In line with the polyionic character of PIN1 and PIN2, both compounds adsorb three times more water than the more hydrophobic, neutral PIN1_2 at room temperature indicating two different adsorption mechanisms. IAST selectivity calculations show good CO 2 /N 2 (30-31) and CO 2 /CH 4 (8-12) selectivity factors. Despite their moderate BET-surface areas, the PINs show good CO 2 uptakes and selectivity factors.

Carbon dioxide capture in amorphous porous organic polymers

“…Besides, covalent triazine frameworks (CTFs) constitute a nitrogen-rich subclass of porous polymers, which are always used for CO 2 capture. [82][83][84][85] A CTFs (fl-CTF-350) was synthesized by ZnCl 2 both as "solvent" and Lewis acidic catalyst. 86 , respectively.…”

Tuning the adsorption and fluorescence properties of aminal‐linked porous organic polymers through N‐heterocyclic group decoration

“…[15][16][17][18] It has been revealed that the properties of polymer depend mainly on the polymer architecture as well as the intrinsic properties of synthons. For example, the polymers comprising of larger conjugated system is of benefit to the adsorption of H 2 19,20 as well as the fluorescent detection of Nitro-benzene derivatives, while the polymers with large N content usually exhibits promoted adsorption affinity toward CO 2 .…”

Two‐Photon Absorption Properties and Structures of BODIPY and Its Dyad, Triad and Tetrad

“…Synthesis of tetrakis(4‐formylphenyl)methane : A solution of tetrakis(4‐bromophenyl)methane (8.0 g, 12.58 mmol) in THF (250 mL) was cooled down to −78°C. Under stirring a solution of n ‐butyllithium (2.5 M in hexane, 50 mL, 125 mmol) was added dropwise.…”