A simple fluorescent iodide ion sensor was fabricated. Ag+ was found to specifically induce the aggregation of perylene–3, 4, 9, 10–tetracarboxylate tetrapotassium salt (PTK) in water, simultaneously, fluorescence of PTK was quenched. The resultant PTK–Ag+ aggregates showed a "turn–on" fluorescence response for halide ion, especially I-, and excellent selectivity toward possible interfering anions, contain sulfide.
