Highly Sensitive 'on-off' Pyrene Based AIEgen for Selective Sensing of Copper (II) Ions in Aqueous Media.

A Fluorescent chemosensor based on pyrene scaffold, 5-diethylamino-2-(pyren-1-yliminomethyl)-phenol (PDS) is synthesized using condensation method. It displays novel aggregation-induced emission (AIE) phenomena in its aggregated/solid state. The AIE characteristic of PDS is studied in CH 3 CN/H 2 O mixtures at different volume percentage of water and morphology of the aggregated particles are investigated by DLS and optical fluorescence microscopic study. The probe is aggregated into ordered one-dimensional (1-D) rod like microcrystals and exhibit high efficiency of solid-state emission with green colour. By taking advantage of its interesting AIE feature, the aggregated hydrosol has been utilized as 'off-on' type fluorescence switching chemosensor with superb selectivity and sensitivity towards Cu 2+ ions and the limit of detection (LOD) was calculated as low as 6.3 µM. A high Stern-Volmer quenching constant was estimated to be 2.88 × 10 5  M -1 . The proposed chemosensor with AIE feature reveals a prospective view for the on-site visual recognition of Cu 2+ ions in fluorescent paper strips and the synthesized probe is also exploited to find out the concentration of Cu 2+ ions in real water samples.