‘Naked-eye’ quinoline-based ‘reactive’ sensor for recognition of Hg 2+ ion in aqueous solution

A new ‘naked-eye’ quinoline-based ‘reactive’ ratiometric fluorescent probe was prepared. The reactive stoichiometry of the probe with Hg2+ ion was 2:1. The probe exhibited high selectivity towards Hg2+ ion to other metal ions with a 410-fold increase in absorbance intensity ratio (A402/A340) in aqueous solution over a wide-range pH value (2–12), accompanied by a resonance color change from colorless to pale yellow visible to naked-eye.