A new high selective and sensitive turn-on fluorescent and ratiometric absorption chemosensor for Cu based on benzimidazole in aqueous solution and its application in live cell.

A new benzimidazole base turn-on fluorescent and ratiometric absorption chemosensor (L) bearing bidentate ligand for detection of Cu was designed and synthesized. Fluorescence and UV-vis spectra studies demonstrated that L can detect Cu ions in aqueous solution using fluorescence enhancement and ratiometric absorption sensing over a wide pH range. Both fluorescent and ratiometric absorption sensing of L for Cu possessed high selectivity and sensitivity over other competitive metal ions and had low detection limit. Job's plot, mass spectra and DFT calculation indicated the sensing mechanism is the complex formation between L and Cu with 1:2 stoichiometry. Fluorescence images of HepG2 in the absence and presence of Cu displayed L had cell permeability and detection ability for Cu in live cells.