A fluorescent probe for specific dual recognition of Ni and pH.

Nickel ion (Ni) and pH play an important role in environment and living organisms. A fluorescent probe "naphthalimide- s-triazine" (NCNS) for targeted dual detection of Ni and pH was synthesized. As a result, NCNS exhibits excellent optical properties: a much larger Stokes shift (140 nm), eminent changes of fluorescence intensity and significant red-shift both for Ni and pH. As for the detection of Ni, the selectivity is high and the anti-interference is strong. NCNS can fluorescently detect Ni in a wider pH range from 4.0 to 10.5. It provides a much lower limit of detection (LOD, 20.03 nM), a rapid response time (150 s) and six times reversibility, showing the high sensitivity. Particularly, NCNS can be applied to fluorescently detect Ni in actual water samples and HA-VSMC imaging. In the detection of pH, the probe generates a ratiometric fluorescence in a wide pH range (3.0 ∼ 12.3). NCNS has been successfully made test paper both for Ni and pH. The mechanisms of the double recognition are verified by the density functional theory (DFT) calculations and the nuclear magnetic resonance (NMR) titration experiments.