A highly selective and sensitive fluorescent 'turn-on' chemosensor for Al3+ based on CN isomerisation mechanism with nanomolar detection

A new Schiff base 1 was synthesised by direct condensation of 4-tert-butyl-2-aminophenol with an equimolar amount of 4-(diethylamino)-2-hydroxybenzaldehyde and characterised by single crystal XRD. The chemosensing ability of 1 in ethanol was evaluated towards various metal ions prepared in H2O. Sensor 1 showed a high sensitivity and selectivity for Al3+ through a significant 'turn-on' fluorescence response at 490 nm over the other tested metal ions with a detection limit down to 99.5 nM. The 1:1 binding stoichiometry between 1 and Al3+ was established using Job's plot, and the proposed complex structure was calculated by applying the DFT method.