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 fluorescent probe DS with a coupled system of FRET and ICT effects was designed and firstly synthesized.•DS can specifically recognize Al3+ in a fluorescence-enhanced and blue-shifted manner.•The recognition of Al3+ by DS possesses high selectivity, fast response and low detection limit.•Good results in test strip testing, mung bean sprout imaging, and actual water samples were achieved. 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. [Display omitted] A more flexible long-chain bis(salamo)-like fluorescent probe DS with a unique coupling system of FRET and ICT effects was designed and synthesized. DS has been proven to specifically recognize aluminum ion through fluorescence enhancement and blue shift, with high sensitivity, selectivity, and fast response. The recognition mechanism was determined and verified based on spectral characterization, HR-MS analysis as well as ESP analysis and DFT calculations. Finally, good results were obtained in practical applications, which are expected to gain applications in environmental detection and other fields.