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. In this work, an amine-linked cage constructed with phenolphthalein as a backbone was synthesized via a simple method. The cage exhibits good uptake capacity toward various VOCs both in a gaseous and aqueous phase, accompanied by an obvious allochroic response. 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 in the phenolphthalein skeleton. The allochroic cage will endow this class of materials to be used as energy-efficient adsorption and separation media in dealing with wastewater and polluted air. [Display omitted] •An allochroic Organic Cage containing phenolphthalein moiety was prepared.•The allochroic cage realized simultaneous VOC sensing and capturing.•The allochroic cage could remove VOCs from both the gas and liquid phases.•This cage possessed good recyclability and practical application potential.•The discoloration mechanism reveals that a reversible C–O bond plays a key role.