Selective sensing of PPi by fluorogenic Al(III)-probe complex in aqueous medium.

A newly designed Schiff base probe JN has been synthesized. It is highly selective and sensitive towards Al in nearly 100% aqueous medium by exhibiting a dramatic "turn-on" fluorescence response at 495 nm (λ = 450 nm). The sensing mechanism of JN towards Al ions was proposed as the combination of PET, ICT, ESIPT, and CHEF processes according to spectra studies and theory calculations. The in situ generated mononuclear Al(III) complex JN-Al could sequentially detect PPi ions by turn-off fluorescence response. The selectivity and sensitivity of the JN-Al complex towards PPi ions are based on demetalization process. Interestingly, the fact that Al can bind with 1, 2, or 3 PPi has been revealed by HRMS study. The probes JN and JN-Al complexes were able to capture Al and PPi ions, respectively, as demonstrated by fluorescence imaging of the adult zebrafish and onion inner epidermal cells samples.