Sequential colorimetric recognition of Cu2+ and CN− by asymmetric coumarin-conjugated naphthol groups in aqueous solution

• A new cumarin-containing naphthol-based sensor 1 was synthesized.
• This sensor could sequentially detect Cu2+ and CN− through naked-eye in aqueous solution.
• It could be used as a practical and viable colorimetric test kit for detecting Cu2+ in aqueous solution.

A new chemo-sensor (E)-4-((2-((2-hydroxynaphthalen-1-yl)methylene)amino)phenyl-amino)-3-nitro-2H-chromen-2-one (1) based on the combination of 2-hydroxy-1-naphthaldehyde and precursor 4-((2-aminophenyl)amino)-3-nitro-2H-chromen-2-one was designed and synthesized as a selective colorimetric sensor for Cu2+. 1 exhibited a color change from yellow to orange in the presence of Cu2+ in aqueous solution and the resulting 1-Cu2+ complex sensed cyanide through naked eye. Moreover, 1 could be used as a practical, visible colorimetric test strip for Cu2+ in aqueous environment. These results demonstrate a new type of the sequential recognition of Cu2+ and CN− by a convenient, easy and colorimetric method.

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