A dual thiourea-appended perylenebisimide "turn-on" fluorescent chemosensor with high selectivity and sensitivity for Hg2+ in living cells.

Sensing heavy metal ions particularly for the most toxic Hg2+ is a long-term pursuit for chemists because of its obvious and extreme harmfulness to both the environment and human health. Herein, a novel 'turn-on' perylenebisimide-thiourea fluorescent probe PBI-BTB is achieved for rapid detection of Hg2+ in a DMSO/H2O (5/1, v/v) solution through a typical Hg2+-promoting desulfurization reaction, which has been investigated through Job's plot titration, FT-IR, 1H NMR and HRMS analysis. A remarkable fluorescence emission enhancement at 540 and 580 nm is observed in the presence of Hg2+, which is visible to the naked eye with high selectivity and sensitivity. Moreover, probe PBI-BTB combined strong anti-interference recognition with short response time (< 1 min). The rapid fluorescence response with low limit of detection (0.35 μM) in a wide pH range of 3.0-11.0 makes PBI-BTB a promising candidate for detection of Hg2+ without any buffer system. Furthermore, the practicability of probe PBI-BTB upon the Hg2+ recognition in human liver cancer cells (HepG-2) has been studied through fluorescent live cell imaging which reveals the probe's low toxicity to organism as well as the favorable cell permeability of PBI-BTB for detecting Hg2+ in biological systems.