A simple but highly sensitive and selective colorimetric and fluorescent probe for Cu²⁺ in aqueous media

In this paper, CN-DPA was prepared as an effective colorimetric and fluorescent probe for copper ions (Cu²⁺) in aqueous solution. It exhibits good sensitivity and selectivity for Cu²⁺ over other metal ions both in aqueous solution and on a simple colorimetric paper-made test kit. Upon addition of Cu²⁺, a remarkable color change from purple to colorless was easily observed by the naked eye, and a fluorescence quenching was also determined. Furthermore, CN-DPA can be used to quantitatively detect Cu²⁺. The linear range was 0-5 μM determined by absorption spectrometry. All these selective and sensitive results indicate that CN-DPA could meet the selective requirements for biomedical and environmental application and be sensitive enough to detect Cu²⁺ in environmental water samples, even in drinking water, which has a limit of 20 μM defined by the U.S. Environmental Protection Agency.