SO₂ Capture Using Porous Organic Cages

Abstract

We report the first experimental investigation of porous organic cages (POCs) for the demanding challenge of SO 2 capture.T hree structurally related N-containing cage molecular materials were studied. An imine-functionalized POC (CC3) showed modest and reversible SO 2 capture,while as econdary-amine POC (RCC3) exhibited high but irreversible SO 2 capture.Atertiary amine POC (6FT-RCC3) demonstrated very high SO 2 capture (13.78 mmol g À1 ; 16.4 SO 2 molecules per cage) combined with excellent reversibility for at least 50 adsorption-desorption cycles.T he adsorption behavior was investigated by FTIR spectroscopy, 13 CCP-MAS NMR experiments,a nd computational calculations.

Sulfur Dioxide Capture in Metal‐Organic Frameworks, Metal‐Organic Cages, and Porous Organic Cages

“…PXRD analysis corroborates the retention of the crystalline structure after SO 2 exposure, indicating the total reversibility of the physisorption process. [61] High structural stability of CC3 upon SO 2 exposure is well-documented in the study reported by Zhu and coworkers. [65] More importantly, homochiral CC3 cages show a loss in crystallinity after aqueous SO 2 exposure, which could be prevented by fabricating lowcost heterochiral cages.…”

“…[61] Three organic cages were employed as potential candidates for SO 2 adsorption due to their N-rich surface functional groups (CC3, RCC3, and 6FT-RCC3 containing imine, secondary amine, and tertiary amine groups, respectively) (Figure 6a). Previously, these molecular cages were applied in catalysis, [62] adsorption of chiral [61] Copyright 2021, John Wiley & Sons. molecules and rare gases, [63] and deuterium/hydrogen selectivity (isotopic separation).…”

“…Closed symbols (adsorption isotherm), open symbols (desorption isotherm). Reproduced with permission [61]. Copyright 2021, John Wiley & Sons.…”

Hierarchically Porous Poly(ionic liquid) – Organic Cage Composite Membrane for Efficient Iodine Capture

“…[22] The characteristic peaks of the CC3 cage at 1649, 1448 and 1155 cm À 1 were assigned to the stretching vibrations of C=N, CH 2 , and CÀ N bonds. [24] The characteristic peaks of the PIL@CC3 membrane simultaneously comprise some peaks of the pristine PIL membrane and CC3, suggesting the successful incorporation of CC3 into the PIL membrane. The hierarchical pores of the PIL@CC3 membrane were verified by the N 2 sorption isotherm at 77 K. As illustrated in Figure 1c, a typical hysteresis loop at a relative pressure p/p 0 of 0.50-1.0 indicated the existence of mesopores, [25] which is presumably attributed to the interparticle voids of cage nanocrystals as well as the interspace between cage nanocrystals and PIL pore walls.…”

Porous Organic Compounds – Small Pores on the Rise

“…[12a] Such modification can either happen at the periphery of the imine groups, which increases stability and crystallinity, but is expected to only yield a small influence on the binding behavior inside the cavity, or employing functional groups that point towards the center of the cavity, like amino or hydroxyl groups. [14,15] Mastalerz et al were among the first to selectively functionalize reactive hydroxyl groups inside the cavity after successful synthesis of a salicylbisimine Tri 4 Di 6 POC SC1 (Figure 3). When reacting the exposed hydroxyl groups by means of a sixfold Williamson ether synthesis, alkylation of all six hydroxyl groups proceeded in very good yields with ether moieties ranging from simple methyl groups to 4-nitrobenzyl groups.…”