A highly selective fluorescent sensor for Al³⁺ and the use of the resulting complex as a secondary sensor for PPi in aqueous media: its applicability in live cell imaging

An easy-to-make salicylimine (L) bearing an "O-N-O"-coordination site was used as a highly selective fluorescent sensor for Al(3+) and PPi in aqueous solution. Sensor L showed a significant fluorescence enhancement in the presence of Al(3+) over other competitive metal ions. It works based on the Al(3+)-induced formation of a 1 : 1 L-Al(3+) complex, producing a chelation-enhanced fluorescence effect, the fluorescence quantum yield reached 0.59. This L-Al(3+) ensemble is a subsequent fluorescent sensor for PPi due to the strong attraction between Al(3+) and PPi, it can selectively discriminate PPi overcoming the interference of the biological competitors including PO4(3-), ADP and ATP at physiological pH. L and L-Al(3+) exhibit high sensitivity and selectivity for Al(3+) and PPi, the detection limits were found to be as low as 2.94 × 10(-8) M and 2.74 × 10(-7) M, respectively. It was further confirmed that sensor L had potential practical applications through mapping of Al(3+) in live cells.