Highly selective chemosensor for the sensitive detection of Hg²⁺ in aqueous media and its cell imaging application

The deleterious toxicity of Hg2+ on ecological and biological system makes it crucial for the precise monitoring of Hg2+. 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 Hg2+ in pure aqueous media, which was estimated to be 1.3 x 10(-9) mol center dot L-1. Moreover, the proposed chemosensor holds the ability of visualizing Hg2+ 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 Hg2+ in real water sample and bioimaging of intracellular Hg2+ prove that MTRH is a promising tool to evaluate the levels of Hg2+ in complex biological systems.