Fast and Reversible “Turn on” Fluorescent Sensors Based on Bisphenol-a for Zn2+ in Aqueous Solution

Two novel bisphenol-A derivatives (R1 and R2) linked pyrene and napthylthiazole moieties were synthesized via condensation reaction, and positively applied for the selective recognition of Zn2+ ion in EtOH/H2O. Their optical properties were observed by using UV-vis and fluorescence measurements. R1 and R2 exhibited high selectivity and sensitivity towards Zn2+ over other metal ions. This fluorescence selectivity may be owing to inhibited excited-state intramolecular proton transfer (ESIPT) and photoinduced electron transfer (PET). The fluorescence titration analysis indicated detection limits of R1 and R2 for Zn2+ at 17.5 nM and 0.94 μM, respectively. Moreover, R1 and R2 were successfully applied to the detection of Zn2+ with different concentrations in water samples.