A polypyridyl-pyrene based off-on Cd²⁺ fluorescent sensor for aqueous phase analysis and living cell imaging.

By retaining the quadrapyridyl receptor of polypyridylhexaazatriphenylene (a Cd(2+) sensor reported by us) and extending its chromophoric group with pyrene, a chemical sensor (1) was designed and synthesized in this work. This sensor exhibit selective off-on fluorescence response to Cd(2+) over other metal ions, and the detection limit is as low as 0.02 μM. The Cd(2+) sensing of 1 has high water toleration and can be carried out in the media with the water content up to 70%. Additionally, 1 was successfully applied to the in vivo imaging of intracellular Cd(2+) in living HaLa cells, and showed low cytotoxicity and cell membrane permeability in these experiments. These results suggest that 1 has potential application in the Cd(2+) analysis of environmental and biological samples.