A new high selective and sensitive turn-on fluorescent and ratiometric absorption chemosensor for Cu2+ based on benzimidazole in aqueous solution and its application in live cell

Abstract

A new benzimidazole base turn-on fluorescent and ratiometric absorption chemosensor (L) bearing bidentate ligand for detection of Cu²⁺ was designed and synthesized. Fluorescence and UV-vis spectra studies demonstrated that L can detect Cu²⁺ 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 Cu²⁺ 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 Cu²⁺ with 1:2 stoichiometry. Fluorescence images of HepG2 in the absence and presence of Cu²⁺ displayed L had cell permeability and detection ability for Cu²⁺ in live cells.

Keywords: Benzimidazole; Cell imaging; Copper ion; Fluorescence sensing; Ratiometric absorption.