Spontaneous detection of F and viscosity using a multifunctional tetraphenylethene-lepidine probe: Exploring environmental applications.

Excessive fluoride ions (F) in drinking water and food is harmful for human health and the environment. Therefore, a fluorescent probe tetraphenylethylene-quinoline (P-1) is developed with multiple sensing properties for the sequential detection of tert-butyldiphenylsilyl chloride (TBDS), F, and viscosity. Sensor P-1 first recognized TBDS and then observed an intramolecular charge transfer process, which produced an intermediate sensor P-2 in addition to fluorescence quenching at 576 nm. Following this, P-2 revealed a concentration-related quantitative analysis by tracking F and reproducing sensor P-1 reversibly with the fluorescence amplification at 496 nm when the SiN bond of P-2 was broken. A comparable sensing mechanism was noted in monitoring F and viscosity through a synthetically developed P-2 sensor. The characterizations (nuclear magnetic resonance-NMR, high resolution-mass-HR-MS, and high-performance liquid chromatography-HPLC) and density functional theory (DFT) confirmed the sensing mechanism of sensors P-1 and P-2. The proposed method was used to measure the viscosity of living cells and to measure F in food, water, and living cell samples. According to research results, quantitative emission characteristics versus F can offer insights into designing effective molecular probes with beneficial applications in healthcare and the environment.