Synthesis and properties of an AIE fluorescent probe for Cu2+ detection based on ESIPT system

The excessive accumulation of Cu2+ in the human body and the natural environment will endanger human health and break the balance of the ecosystem. Therefore, the development of a low-cost and rapid method to detect Cu2+ is of great significance to protect human health and the environment. In this study, we used electron-rich triphenylamine as the electron donor and AIE active core, coupled with the electron acceptor imine nitrogen, and further connected to the ESIPT active salicylaldimine unit, detection based on the ESIPT system a new AIE fluorescent probe 5-(diethylamino)-2-((E)-(((E)-4-(diphenylamino)benzylidene)hydrazono)methyl)phenol (DDP) was synthesized. DDP has strong fluorescence and can coordinate specifically with Cu2+ to form a copper complex and cause fluorescence quenching, thereby achieving the purpose of detecting Cu2+. The EDTA titration experiment was carried out on the DDP-Cu2+ solution, and the experimental results proved that the combination of DDP and Cu2+ is reversible. The interaction between DDP and Cu2+ rapidly forms a copper complex, which is approximately completed within 6 s. The detection limit of the probe is as low as 5.7 x 10(-8) M and it shows good stability in a weakly alkaline and weakly acidic environment, which provides necessary conditions for the detection of Cu2+ in a living environment. It is applied to the detection of Cu2+ in river water and lake water, showing a good linear relationship, indicating that DDP has the ability to detect Cu2+ in real water samples. Therefore, DDP is expected to become an effective tool for detecting Cu2+ in the environment and organisms.