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 (AgI) based on an arene–metal ion interaction.
The probe selectively senses AgI among various metal ions
with a large-emission red shift under aqueous conditions, enabling
the selective ratiometric detection of AgI. X-ray crystallography
and NMR analyses reveal that AgI comes into close contact
with the fluorophore, which induces a large-emission red shift. The
high sensing selectivity of the probe toward AgI might
be attributable to the restricted rigid conformation of the cyclic
aza crown ether, which exclusively binds AgI. In addition
to AgI sensing, the AgI 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.