A colorimetric probe based on diketopyrrolopyrrole and tert-butyl cyanoacetate for cyanide detection

A new calorimetric probe 1 comprising a diketopyrrolopyrrole-based Michael receptor, which recognized cyanide anions with high selectivity, was designed and synthesized. Addition of CN- aqueous solution to 1 in THE resulted in a rapid color change from pink to light yellow together with a large blue shift from 530 to 487 nm, while other anions did not induce any significant color change. Furthermore, Michael addition of cyanide to 1 elicited 94% fluorescence quenching at 640 nm accompanied by appearance of a weak new emission at 560 nm, which constituted the fluorescence signature for cyanide detection. The detection limits were determined to be 0.75 mu M using the fluorescence spectral changes, which were far lower than the WHO guideline of 1.9 mu M. Moreover, 1-based test strips could successfully detect CN- in water solutions.