Aggregation induced emission based “turn-off” fluorescent chemosensor for selective and swift sensing of mercury (II) ions in water.

An Anthracene based fluorescent probe, 1-(Anthracen-2-yliminomethyl)-napthalen-2-ol (AIN), was synthesized via simple one-pot reaction from inexpensive reagents. Intriguingly, it exhibited novel AIE characteristics in H 2 O-THF mixtures at high water content. Size and growth process of particles in different volume percentage of water and THF mixtures were investigated using TRPL, DLS, SEM and optical microscope. The fluorescent aggregates exhibited distinct Hg 2+ -selective “on-off” type fluorescence switching upon binding. Additionally, the fluorescence quenching showed a linear correlation in the Hg 2+ concentration range from 0.3 to 3.6 μM and the limit of detection was estimated as low as ∼3 ppb. The drastic decrease in emission intensity of AIN aggregates was observed in the presence of mercury ions via a complex interplay through the ground state complexation between AIN and Hg 2+ ions and external heavy atom induced perturbation by Hg 2+ ions to the excited states of the AIN. A large Stern–Volmer quenching constant was estimated to be 2.54 × 10 5  M −1 . The proposed analytical system with clear AIE characteristics demonstrates a potential outlook for the on-site visual detection of Hg 2+ in paper strips. Finally, the sensory probe was also applied to determine the concentration of Hg 2+ in real water samples to demonstrate its practical applications. [ABSTRACT FROM AUTHOR]