In this report, we have synthesized a coumarin-functionalized salicylidene receptor, DTC and evaluated its metal ion recognition characteristics by using UV–visible, fluorescence spectroscopy and ESI-MS techniques. It is observed that the receptor acts as a chemodosimeter to detect Al3+ ion selectively amongst various interfering cations. It shows a detection limit of 0.94 ppb (parts per billion) which is superior over the salicylidene-based receptors reported earlier and is far below the detection limit of aluminium ions in drinking water as recommended by WHO. The receptor (DTC) undergoes the hydrolytic cleavage only upon interaction with Al3+ ions even in the presence of other competitive ions and elicits a distinct visual colour change from yellow to colourless accompanied by the quenching of green fluorescent signal at 520 nm in the receptor solution. The mechanism of interaction of Al3+ with DTC has been evaluated from UV–visible and fluorescence studies along with ESI-MS analysis and further corroborated by quantum mechanical calculations.
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