A Disulfide-Linked Naphthalimide Dimer for Hg(II) Detection in Aqueous Solution

A disulfide linked naphthalimide dimer probe was designed for mercury ion (Hg²⁺) 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 Hg²⁺ in comparison to other metal ions via a turn-on and reversible response to Hg²⁺ in neutral buffer solution. More importantly, the probe demonstrated a linear response for Hg²⁺ 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 Hg²⁺, 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 Hg²⁺ in environmental and biological samples.