Reaction-based colorimetric signaling of Cu(2+) ions by oxidative coupling of phenols with 4-aminoantipyrine

A new Cu(2+)-selective chromogenic probe system based on the oxidative coupling of Phenols with 4-aminoantipyrine was developed. Cu(2+) ions promoted facile coupling of Phenols with 4-aminoantipyrine to yield quinoneimine dyes. Signaling with a number of Phenols having no para-substituent, such as o-cresol and m-cresol, as well as p-chlorophenol having para substituent that could be expelled during the oxidation process was possible. The signaling of Cu(2+) ions was not interfered by the presence of representative metal ions except for Al(3+) ions. The possible interference from Al(3+) ions was successfully removed by using fluoride ions as a masking agent. The phenol-4-aminoantipyrine probe system showed chromogenic Cu(2+) signaling by prominent color change from colorless to pink with a detection limit of 8.5×10(-7) M. The signaling of Cu(2+) ions in practical samples using tap water and simulated semiconductor wastewater was also tested.