Aza-crown-ether-appended xanthene: selective ratiometric fluorescent probe for silver(I) ion based on arene-metal ion interaction.

In this Communication, we report on the development of a ratiometric fluorescent probe for silver(I) ions (Ag(I)) based on an arene-metal ion interaction. The probe selectively senses Ag(I) among various metal ions with a large-emission red shift under aqueous conditions, enabling the selective ratiometric detection of Ag(I). X-ray crystallography and NMR analyses reveal that Ag(I) comes into close contact with the fluorophore, which induces a large-emission red shift. The high sensing selectivity of the probe toward Ag(I) might be attributable to the restricted rigid conformation of the cyclic aza crown ether, which exclusively binds Ag(I). In addition to Ag(I) sensing, the Ag(I) complex of the probe is also used for the ratiometric sensing of a cyanide anion (CN(-)), highlighting the utility of the reported probe in fluorescence sensing.