A disulfide-linked naphthalimide dimer for Hg(II) detection in aqueous solution

A disulfide linked naphthalimide dimer probe was designed for mercury ion (Hg ²⁺) recognition in this work. The recognition was based on the strong affinity of mercury for sulfur. The experimental results revealed that the probe exhibited high selectivity and sensitivity toward Hg ²⁺ in comparison to other metal ions via a turn-on and reversible response to Hg ²⁺ in neutral buffer solution. More importantly, the probe demonstrated a linear response for Hg ²⁺ over a concentration range from 0 to 150 μM with a detection limit of 0.38 μM, which is just the limit of the safe concentration for humans. Upon addition of 150 μM Hg ²⁺, the enhancement of fluorescence reached a maximum (~7-fold). The performances of the probe indicated that it could meet the selectivity requirements for biomedical and environmental application and also was sensitive enough to detect Hg ²⁺ in environmental and biological samples.