Adsorption and sequential thermal release of F2, Cl2, and Br2 molecules by a porous organic cage material (CC3‐R): Molecular dynamics and grand‐canonical Monte Carlo simulations

The adsorption–desorption behavior of fluorine, chlorine, and bromine molecules onto a crystalline porous organic cage, namely CC3‐R was calculated at different temperatures using molecular dynamics (MD) and grand‐canonical Monte Carlo (GCMC) simulations. Self‐diffusion coefficients, radial distribution functions (RDF), and adsorption isotherms were calculated for this purpose. The results show that CC3‐R has varied capacities to capture these halogens at ambient and high temperatures, so that the thermal release of fluorine is completed with increasing temperature up to around 70°C and chlorine molecules remain at the CC3‐R surface up to 100°C and all bromine molecules are removed from the CC3‐R surface at 200°C. We found that bromine self‐diffusion was almost independent of temperature between 0 and 100°C in contrast to fluorine and chlorine. Among different diffusion regimes, Knudsen diffusion appears to have an important role in the adsorption of heavy halogens at higher temperatures. CC3‐R is one of the important porous organic cage (POC) materials, which can capture the halogen molecules at low and ambient temperatures. Computational studies demonstrate that the sequential separation of the halogens is achievable by this compound with increasing temperature. It appears that the discrepancy in the desorption behavior of the halogens is concerned with the role of different diffusion regimes during temperature gradient.