Highly selective fluorescent probe for sequential recognition of copper(II) and iodide ions

A new highly selective fluorescent probe based on 2-(2′-aminolphenyl)-4-hydroxymethylthiazole (1) was developed for the detection of copper and iodide ions in ethanol. Probe 1 selectively detected Cu2+ through a “switch off” response, showing a good association constant (Ka = 1.43 × 105 M−1) and binding with Cu2+ ions in a 1:1 stoichiometry. An in situ generated 1-Cu2+ (1:1) ensemble detected I− ions sequentially through a “switch on” response. The “switch off” response occurred with selective complexation of Cu2+ ions due to intramolecular charge transfer (ICT). An ensemble of 1 and copper(II) showed higher selectivity towards iodide than towards any other anions due to the reduction of Cu2+ to Cu+ by I− and subsequent complexation with 1.