Off-On Fluorescence Response of a Cysteine-based Perylene Diimide for Mercury Detection in Water

The development of simple, low-cost and selective methods for quantitative detection of mercury ions in aqueous media is still a challenge. Herein, we employ a cysteine based perylene diimide (PDI-Cys) as sensing probe for Hg2+ ions in water. The probe selectively detects the mercury ions in 100% aqueous solution by a fluorescence turn-on response. The binding stoichiometry reveals a 1:2 complexation of PDI-Cys/Hg2+, in which two Hg2+ ions are bound to one PDI-Cys molecule. The detection limit is as low as 20 ppb, close to the sensitivity requirement for drinking water, indicating the potentiality of PDI-based probes for mercury analysis in both environmental and biological field.