A selective turn-on fluorescent chemosensor based on rhodamine for Hg2+ and its application in live cell imaging

A new rhodamine derivative (Rh-D) was designed and synthesized, and its fluorescent behaviors toward various metal ions were investigated. Rh-D exhibits high selectivity and sensitivity in both absorbance and fluorescence detection of Hg2+ in methanol–water (30:70, v/v, pH 7.0, 20 mM HEPES buffer) medium. It was found that mercury ions coordinate reversibly to Rh-D and the spirolactam ring of Rh-D was opened, forming a 1:1 metal–ligand complex. In addition, fluorescence imaging experiments of Hg2+ in HL-7702 living cells demonstrated that its value of practical applications in biological systems.