Highly Selective and Sensitive Detection of Hg(I), Hg(II) Ions by a Covalent Organic Framework Embedding Active Sulfur Sites in the Pore Wall

Mercury is a toxic substance that is harmful to human health and the environment. It is a great challenge to overcome the pollution of mercury via designing suitable adsorbent decorated with abundant chelating sites on a solid surface together with high affinity for heavy metals. Herein, we employed a flexible building block 4,4′-dithiodianiline as a connector, and together with tetraphenylethylene tetraaldehyde to construct a periodic 3D extended framework with bright green-yellow luminescence (TPE-S-COF), in which the active sites of sulfur are uniformly distributed in pore walls. This allows TPE-S-COF to be used as a sensitive chemosensor to selectively detect toxic mercury ions; and has an adsorption capacity of 48 and 42.4 mg g−1 for Hg+ or Hg2+, respectively. More interestingly, the detection performance of TPE-S-COF towards mercury ions can be directly observed by the naked eye. And, it can be reused without loss of sensitivity and responsiveness.