Single fluorescent chemosensor for multiple targets: sequential detection of Al3+ and pyrophosphate and selective detection of F- in near-perfect aqueous solution

A simple and easily fabricated chemosensor (1), based on 2-furoic hydrazide and diethylaminosalicylaldehyde moieties, was devised and synthesized. Sensor 1 showed selective changes in fluorescence behavior toward three analytes in near-perfect aqueous solution. Al3+ and F- recognized by fluorescence enhancement of 1 and their limits of detection (0.19 mu M for Al3+ and 1.9 mu M for F-) were markedly low compared to World Health Organization guidelines (7.4 mu M for Al3+ and 79 mu M for F-) for drinking water. Furthermore, sensor 1 was used to quantify Al3+ and F- in real water samples and image Al3+ in living cells. Interestingly, the resulting 1-Al3+ complex could be used to discriminate pyrophosphate (PPi) over competing anions, including phosphate-based anions, by decreased fluorescence. Sensing mechanisms of 1 toward Al3+, PPi, and F- were proposed based on photophysical studies and theoretical calculations.