Recognition of Hg²⁺ Ion through Restricted Imine Isomerization: Crystallographic Evidence and Imaging in Live Cells

Abstract

A newly synthesized imine-based receptor (<b>L</b>) showed remarkable specificity toward the Hg²⁺ ion in aqueous media over other metal ions. Coordination of <b>L</b> to Hg²⁺ induces a <i>turn-on</i> fluorescence response. This was explained based on the restricted imine isomerization along with PET on coordination to Hg²⁺. X-ray structural evidence tends to favor a C–C bond rotation rather than CN isomerization for adopting a favorable conformation in <b>L</b> for coordination to Hg²⁺. This reagent could be used for imaging the accumulation of Hg²⁺ ions in HeLa cells