# Highly Selective Adsorption of Fluorinated Gases by Porous Organic Cages – Effects of Fluorinated Side‐Chains

## TL;DR

This paper introduces new materials that selectively capture potent greenhouse gases like fluorinated gases using fluorinated side-chains in porous organic cages.

## Contribution

The study introduces a homologous series of porous organic cages with fluorinated side-chains that achieve new benchmark selectivities for capturing fluorinated greenhouse gases.

## Key findings

- Porous organic cages with fluorinated side-chains show high selectivity for fluorinated greenhouse gases like PFC-218 and PFC-318.
- Fluorine-fluorine interactions are exploited for the first time in adsorbing sulfur hexafluoride and nitrogen trifluoride.
- Structure-property relationships of the cages are systematically studied for gas sorption.

## Abstract

Perfluorocarbons (PFCs) as well as related gases such as sulfur hexafluoride (SF6) or nitrogen trifluoride (NF3) are examples of F‐gases, a subclass of per‐ and polyfluoroalkyl substances (PFAS). F‐gases are anthropogenic greenhouse gases with the highest global warming potentials known and thus contribute significantly to global warming. To reduce their amount in the atmosphere, selectively adsorbing materials would be beneficial, but such materials are rare. A homologous series of porous organic cages with fluorinated side‐chains is synthesized and depending on the targeted gas as well as operating temperature, different cages have high selectivities for certain F‐gases against N2, CO2, and O2. Within this series, new benchmark selectivities against, e.g., perfluoro propane (PFC‐218) and perfluoro cyclobutane (PFC‐318) have been achieved based on attractive fluorine‐fluorine interactions. Furthermore, these interactions are exploited for the first time in the adsorption of sulfur hexafluoride and nitrogen trifluoride.

A systematic study of a series of porous organic cages with perfluorinated alkyl side‐chains of different lengths is presented. The structure‐property relationship of the various cages on gas sorption of highly potent greenhouse gases, such as perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and nitrogen trifluoride (NF3) is investigated. Very high selectivities have been obtained especially for PFC‐218 and PFC‐318.