A novel chemosensor for the distinguishable detections of Cu and Hg by off-on fluorescence and ratiometric UV-visible absorption.

A novel dual-functional chemosensor, derived from the conjugation of rhodamine B with a quinoline derivative (RHQ), was firstly synthesized with high efficiency and cost-effectiveness for the distinguishable detections of Cu and Hg via ring-opening and ring-forming mechanism. The chemosensor exhibits highly selective and distinguishable responses for Cu and Hg in CHCN-HO (4:1, v/v) with off-on fluorescence and ratiometric ultraviolet-visible (UV-Vis) absorption changes. Additionally, Cu is identified by opening a rhodamine spirocycle with a UV-Vis absorption band, at around 560 nm and fluorescence turn-on. Interestingly, Hg is discerned by opening the rhodamine spirocycle and by generating a new special cycle for the quinoline unit. Resultantly, there were two UV-Vis absorption bands at around 365 nm and 560 nm, which were accompanied by fluorescence turn-on. Moreover, the chemosensor can quantitatively detect Cu and Hg by off-on fluorescence and ratiometric UV-Vis absorption changes, respectively. Furthermore, the chemosensor with low cytotoxicity could be successfully administered to monitor Cu and Hg in living cells. This work may pay the way for the development of dual-functional chemosensor for quantificationally detecting metal ions in environmental and biological systems.