A new rhodamine-based colorimetric cyanide chemosensor: convenient detecting procedure and high sensitivity and selectivity.

By applying an indirect strategy, a new rhodamine-based dye (I) was successfully developed as a colorimetric chemosensor for the sensitive detection of cyanide. In the presence of copper ions, the colorless solution of compound I changed to magenta; however, upon the addition of trace cyanide, the magenta color faded to colorless immediately, with a detection limit as low as 0.013 ppm (DeltaA = 0.054), much lower than the Maximum Contaminant Level for cyanide in drinking water (0.20 ppm) set by the US Environmental Protection Agency. Other anions, including Cl(-), I(-), IO(3)(-), SO(4)(2-), NO(2)(-), Br(-), H(2)PO(4)(-), F(-), SCN(-), HSO(4)(-), and ClO(4)(-), had nearly no influence on the probing behavior of dye I toward cyanide.