Reaction-based colorimetric signaling of Cu2+ ions by oxidative coupling of phenols with 4-aminoantipyrine

A new Cu2+ -selective chromogenic probe system based on the oxidative coupling of phenols with 4-aminoantipyrine was developed. Cu2+ 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 Cu2+ ions was not interfered by the presence of representative metal ions except for Al3+ ions. The possible interference from Al3+ ions was successfully removed by using fluoride ions as a masking agent. The phenol-4-aminoantipyrine probe system showed chromogenic Cu2+ signaling by prominent color change from colorless to pink with a detection limit of 8.5 x 10(-7) M. The signaling of Cu2+ ions in practical samples using tap water and simulated semiconductor wastewater was also tested. (C) 2014 Elsevier B.V. All rights reserved.