Br2-free method for XBr3 (X = Cs, C8H20N, C16H36N) synthesis: Br2 solid storage and separation from aqueous solution

Bromine is essential to scientific study and industrial application. However, the high toxicity, volatility and corrosivity of Br 2 increase the risk of leakage or explosion. Using solid materials to capture bromine gas can alleviate the leakage and explosion. Herein, X Br 3 ( X  = Cs, C 8 H 20 N and C 16 H 36 N) polybromide compounds, were synthesized by the one-pot Br 2 -free solvothermal method. CsBr 3 can reversibly decompose and generate along with the release and capture of Br 2 gas, while Br 2 can be separated from aqueous solution in the form of Et 4 NBr 3 (Et = Ethyl) or Bu 4 NBr 3 (Bu = Butyl). CsBr 3 can release 42.89% Br 2 per molecular formula, which is the highest in reported crystalline materials so far. Bu 4 NBr can enrich Br 2 in water with approximately 73% yield through the hydrophilic-hydrophobic effect. Our study presents an alternative method for solidification and efficient recycle of Br 2 .