Synthesis of Highly Sensitive Fluorescent Probe Based on Tetrasubstituted Imidazole and Its Application for Selective Detection of Ag+ Ion in Aqueous Media

A small molecule fluorescent probe, 4-[2-(4-chlorophenyl)-4,5-diphenyl-1 H -imidazol-1-yl]aniline(L) for detecting Ag + ion was gently synthesized via one-pot multi-component reaction catalyzed by H 3 [PW 12 O 40 ] under solvent-free microwave irradiation. When the concentration of Ag+ ion changed from 0 to 8.0×10 −6 mol/L in the solution of H 2 O/CH 3 OH(19:1, volume ratio), the fluorescence emission spectrum was blue-shifted and accompanied by a gradual increase in fluorescence intensity with a low detection limit of 3.0×10 −11 mol/L. Moreover, UV-Vis absorption titration experiment demonstrated a 1:1 stoichiometric ratio and an association constant of (9.95±0.44)×10 5 L/mol between probe L and Ag + ion, and thus their complexation mechanism was also proposed and verified. More importantly, this fluorescent probe was remarkably specific for Ag + ion under the interference of other metal ions and exhibited a wide pH application range of 4.0―8.0. Additionally, preliminary application of this probe was also carried out and satisfactory results were shown.