Naphthalimide derived fluorescent probes with turn-on response for Au3+ and the application for biological visualization

• Two high performance probes were simply synthesized with turn-on response.
• The Probe 1 worked best under physiological conditions with high sensitivity.
• Excellent biocompatibility facilitated Probe 2 to achieve bioimaging of Au3+.
• Both probes displayed rapid response for Au3+ with low detection limit.

The 4−N,N-dimethyl-1,8-naphthalimide based fluorescent probes have been explored for selective detection of Au3+. Both probes show a pronounced fluorescence enhancement response to Au3+. Hydroxy is introduced as ligand of Au3+ for Probe 1 and the newly designed Probe 2 contains an alkyne moiety to recognize Au3+ through an irreversible C≡C bond hydrolysis reaction. Probe 1 exhibits higher performance such as faster response, lower detection limit of 0.050 μM and the better responsive effect in 99.5% water system compared with most of probes published. The Probe 2 displays high stability to pH, suitable water solubility, wider linear range (0–100 μM) to Au3+, and live-cells imaging with low cytotoxicity.