A highly specific red‐emitting fluorescent probe for monitoring of Cu²⁺ in living cells and zebrafish

Abstract A novel seminaphthorhodafluor‐based fluorescent probe was designed and prepared. It exhibited an outstanding off–on fluorescence response (about 45‐fold enhancement) to Cu 2+ because the structure changed from a spirocyclic form to a ring‐open state. It showed satisfactory detection performances for Cu 2+ with fast response speed, high selectivity and anti‐interference, and a low detection limit (22.9 nM) due to its long emission wavelength and off–on fluorescence response mode. This probe was also satisfactorily applied for the monitoring of Cu 2+ in living cells and zebrafish.