A H2O-induced fluorescence turn-on diarylethene derivative and its fluorescent sensing Al3

•A photoswitchable AIE system with an application in sensing Al3+ was constructed.•The water-induced fluorescence turn-on based on AIE and ESIPT was explored.•The turn-on fluorescent sensing Al3+ based on PET and ESIPT was studied. A diarylethene derivative has been synthesized by attaching a photochromic core to a pyrazine moiety through an aroylhydrazone linker. The compound showed weak excited state intramolecular proton transfer (ESIPT) based fluorescence in a series of polar solvents such as CH3CN, THF, DMSO, CH3CH2OH, CH3OH and their binary mixtures with water. However, when the water fraction in solutions was above 70%, a strong orange ESIPT emission at ~ 580 nm was found, which originated molecules aggregate and ESIPT. The active ESIPT process remains in the solid state, which exhibited orange fluorescence under 365 nm light illumination. The diarylethene derivative has been found to show fluorescence ‘‘turn-on’’ sensing Al3+ in CH3CN with the detection limit of 16.6 nM. Al3+ enhanced the fluorescence with 30 nm blue shifts and the fluorescence can be ON and OFF through interaction with Al3+ and EDTA. Moreover, the Al3+ in several water samples was detected using the sensor with high accuracy.