Highly efficient bromine capture and storage using N-containing porous organic cages

Highly volatile and toxic bromine (Br 2 ) molecules can be utilized safely in various chemical processes when coupled with efficient separation systems. Herein, we present two different N-containing porous organic cages (POCs), covalent cage 3-R (CC3-R) and formaldehyde tied-reduced covalent cage 3 (FT-RCC3), for vapor Br 2 capture under ambient conditions. They show outstanding sorption capacities (11.02 mmol g −1 and 11.64 mmol g −1 , respectively) compared with previously reported adsorbents. Reversibility of the Br 2 sorption process has been elucidated experimentally and computationally by identifying bromine species adsorbed at POCs and calculating their binding energies. The strong charge-transfer interactions between adsorbed Br 2 and abundant N atomic sites of the host cages led to the dominant formation of polybromide species (Br 3 − and Br 5 − ). Further host-guest interaction between POCs and polybromides determined the reversibility of the Br 2 sorption process-showing partially reversible (>70% recovery) behavior for CC3-R and irreversible (