Fluorinated near-infrared fluorescent probes for specific detection of Hg2+ in an aqueous medium and mitochondria of living cells

Mitochondria are one of the major targets for localization of mercury ions, where serious mercury-induced toxicity has been well documented. Here, we design two heptamethine cyanine dyes coupled with thymines on the N-alkyl chains, which can specifically chelate with Hg2+ by forming a T–Hg–T complex to sensitively detect Hg2+ in both aqueous solution and the mitochondria of living cells. Further studies revealed that the introduction of fluorine atoms on thymines would significantly enhance the binding ability of T–Hg–T, providing clues to develop more specific and sensitive Hg2+ sensors.