Highly selective chemosensor for the sensitive detection of Hg in aqueous media and its cell imaging application.

The deleterious toxicity of Hg on ecological and biological system makes it crucial for the precise monitoring of Hg. Herein, we prepared a novel "turn-on" chemosensor N'-(4-(methylthio)butan-2-ylidene) rhodamine B hydrazide (denoted as MTRH) by a simple two-step reaction. MTRH exhibited an ultra-low detection limit (LOD) in fluorescence measurement of Hg in pure aqueous media, which was estimated to be 1.3 × 10 mol·L. Moreover, the proposed chemosensor holds the ability of visualizing Hg by the distinct color change of the solution. The corresponding recognition mechanism was investigated by Job's plots, mass spectrometry and DFT calculation analysis. Importantly, the characteristics such as high sensitivity, low cytotoxicity and good biocompatibility of MTRH exhibited in the application of detecting Hg in real water sample and bioimaging of intracellular Hg prove that MTRH is a promising tool to evaluate the levels of Hg in complex biological systems.