An allochroic organic cage for efficient volatile organic compounds sensor and capture both in gaseous and aqueous phase

Environmental security caused by volatile organic compounds (VOCs) such as air and water pollution seriously endangering global human health. Removing VOCs with porous adsorption materials is very effective, but there are still many challenges. Herein, an allochroic amine porous organic cage containing phenolphthalein moiety is designed by a simple method. The amine cage shows excellent uptake capacity toward various VOCs both in the gaseous and aqueous phases, accompanied by an obvious allochroic response. A high dichloromethane vapor uptake capacity of up to ∼3000 mg g−1 is obtained with remarkable regeneration cycle performance. The allochroic response to VOCs and discoloration mechanism were further investigated and revealed a structural change related to a revisable break-reform of a weak C–O bond. The inner relationships between adsorption behavior and allochroic phenomenon are also discussed.