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

•Cu2+-selective probe based on oxidative coupling of phenols with 4-aminoantipyrine was devised.•“Naked-eye” detection of Cu2+ was possible via color change from colorless to pink.•Applicability in tap water and semiconductor wastewater was also investigated.•Detection limit of the probe system for Cu2+ in aqueous acetonitrile was 8.5×10−7 M.

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 8.5×10−7 M. The signaling of Cu2+ ions in practical samples using tap water and simulated semiconductor wastewater was also tested.

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