Azine-Based Receptor for Recognition of Hg2+ Ion: Crystallographic Evidence and Imaging Application in Live Cells

A newly synthesized azine-based receptor (L) is found to show remarkable specificity toward the Hg2+ ion in aqueous media over other metal ions. Coordination of L to Hg2+ induces a detectable change in color and a turn-on fluorescence response. Restricted C=N isomerization of the azine moieties in the excited state as well as the Photoinduced Electron Transfer (PET) involving the lone pair of electrons of N-1/N-2 on coordination of L to the Hg2+ ion account for the turn-on fluorescence response. This reagent could be used for imaging the accumulation of Hg2+ ions in Epithelial cell line KB 31 cells.