A more flexible long-chain bis(salamo)-like fluorescent probe based on FRET and ICT effects for the identification of aluminum ion in the environment and plants

A more flexible long-chain bis(salamo)-like fluorescent probe DS was designed and synthesized. The unique coupling systems of FRET and ICT effects were designed for DS, which was demonstrated to be capable of detecting aluminum ion through the FRET effect, changing the fluorescence of the solution from green to bright blue (55 nm blue-shift) with good selectivity and fast response, and detecting Al3+ over a wide pH range. The recognition mechanism was determined based on spectral characterization, in the sense that the coordination of Al3+ with the probe DS molecule turned on the intramolecular FRET and ICT processes. ESP analysis and DFT calculations validated the binding sites and fluorescence recognition mechanism. Finally, good results have been achieved in practical applications. The test paper experiment confirmed that DS can be prepared into portable Al3+ test paper, the fluorescence imaging experiment of mung bean sprouts showed that DS can be used for the fluorescence imaging of Al3+ in plants, and the environmental water samples test proved that various ions in the actual water samples hardly interfere with the identification of Al3+, and it is expected to be applied in the environmental testing and other fields.