A highly selective and sensitive fluorescence turn-on probe for Ag+ in aqueous solution and live cells

A naphthalimide-based fluorescent probe, NPQ, that contains a novel receptor was successfully developed. NPQ exhibited turn-on fluorescence and excellent selectivity toward Ag+ in the presence of various other metal ions in aqueous solution. A series of control compounds were designed and synthesized in order to explore the photoinduced electron transfer (PET) quenching mechanism of NPQ and binding mode of NPQ with Ag+. Moreover, with the NPQ-Ag+ complex, I- was easily selectively recognized by a marked fluorescence quenching. The live cell imaging experiments demonstrate that NPQ can be used as a fluorescent probe for monitoring Ag+ in living cells.