1,8-naphthalimide modified [12]aneN₃ compounds as selective and sensitive probes for Cu²⁺ ions and ATP in aqueous solution and living cells.

A new fluorescent probe 1 featuring one 1,8-naphthalimide and two [12]aneN3 units was synthesized. In the presence of Cu(2+) ions, the fluorescence emission of 1 was quenched by a factor of 127-fold and no interference by other metal ions was observed under physiological conditions. By means of titration and a Job's plot it was established that 1 forms a complex with Cu(2+) ions in a 1:2 ratio. The fluorescence of the 1-Cu(2+) complex was recovered by the addition of Adenosine-5'-triphosphate (ATP) in aqueous solution. Due to its low cytotoxicity, good water solubility, and high sensitivity, probe 1 was successfully applied in the sequential recognition of Cu(2+) and ATP in aqueous solution and HeLa cells. The highly selective and sensitive ability of 1-Cu(2+) complex to detect ATP even enables its bio-analytical applications in real-time imaging in living cells.