A new rhodamine derivative bearing benzothiazole and thiocarbonyl moieties as a highly selective fluorescent and colorimetric chemodosimeter for Hg ²⁺

A novel rhodamine-based sensor 1 was designed and synthesized, which bears thiospirolactam chromophore and benzomidazole moieties. Sensor 1 showed a selective fluorescence enhancement and colorimetric change for Hg ²⁺ in CH ₃CN-HEPES buffer (0.01 M, pH 7.4) (3:7, v/v). As high as 180-fold fluorescence enhancement was observed for Hg ²⁺, which was attributed to the selective spirolactam-ring opening process followed by subsequent desulfurization. Furthermore, chemodosimeter 1 was successfully applied to microfluidic device.