A Highly Selective Fluorescent Probe for Hg(2+) Based on a 1,8-Naphthalimide Derivative

[Image: see text] Hg(2+) has a significant hazardous impact on the environment and ecosystem. There is a great demand for new methods with high selectivity and sensitivity to determine mercury in life systems and environments. In this paper, a novel turn-on Hg(2+) fluorescent probe has been reported with a naphthalimide group. The Hg(2+) fluorescent probe was designed by the inspiration of the well-known specific Hg(2+)-triggered thioacetal deprotection reaction. A 1,2-dithioalkyl group was chosen as the specific recognition site of Hg(2+). The probe showed weak fluorescence without Hg(2+), and the color of the solution was light yellow. In the presence of Hg(2+), the probe reacted specifically with the mercury ion to produce an aldehyde and emitted strong fluorescence, and the color of the solution also turned light green, thus realizing the monitoring of the mercury ion. The Hg(2+) fluorescent probe showed outstanding sensitivity and selectivity toward Hg(2+). Furthermore, the Hg(2+) fluorescent probe could work in a wide pH range. The linear relationship between the fluorescence intensity at 510 nm and the concentration of Hg(2+) was obtained in a range of Hg(2+) concentration from 2.5 × 10(–7) to 1.0 × 10(–5) M. The detection limit was found to be 4.0 × 10(–8) M for Hg(2+). Furthermore, with little cell toxicity, the probe was successfully applied to the confocal image of Hg(2+) in PC-12 cells.