A new colorimetric and fluorescent probe based on Rhodamine B hydrazone derivatives for cyanide and Cu2+ in aqueous media and its application in real life.

A simple selective colorimetric and fluorimetric chemosensor RD based on Rhodamine B hydrazone derivatives was designed and synthesized, which showed both colorimetric and fluorescence responses for cyanide and Cu2+ in aqueous solution with specific selectivity and high sensitivity. In the presence of cyanide, the sensor exhibited a visible color change from colorless to pale yellow by naked-eyes and rapidly produced a strong yellow fluorescence in aqueous solution. The detection limit on fluorescence response of RD sensor to CN- is down to 3.54×10-7M. In addition, compared to other metal ions such as Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Cr3+, Zn2+ and Mg2+ in aqueous solutions, RD could show both colorimetric and fluorescence responses rapidly for Cu2+. Notably, this sensor can be used as a molecular switch controlled by CN- and H+ cyclically. Test strips based on RD were fabricated that could be used as a convenient and efficient CN- and Cu2+ test kits. RD could detect cyanide in germinated potato, bitter almond and tap water. This chemosensor enabled detection of two ions, which do not need to rely on two different sensors.