Cu2+-selective fluorescent probe based on the hydrolysis of semicarbazide derivative of 2-(2-aminophenyl)benzothiazole

A new Cu2+-selective reaction-based fluorescent probe 1 based on the semicarbazide-bearing derivative of 2-(2aminophenyl)benzothiazole has been developed. Designed probe 1 exhibited turn-on-type fluorescence signaling behavior that was more prominent toward Cu2+ ions than to other environmentally relevant metal ions. The signaling of probe 1 was due to the Cu2+-induced hydrolysis of semicarbazide moiety to form its strongly fluorescent parent dye. Cu2+ signaling of probe 1 was not influenced by the presence of commonly encountered metal ions, and the detection limit was 1.71 x 10(-8) M (1.1 ppb). As a practical application, the determination of Cu2+ in simulated semiconductor wastewater was conducted using a smartphone as a portable signal detection tool. For the color test analysis, enhanced reproducibility of Cu2+-sensing was realized using the grayscale image rather than the red, green, or blue channel image.