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

Abstract

A new colorimetric 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 THF 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 μM using the fluorescence spectral changes, which were far lower than the WHO guideline of 1.9 μM. Moreover, 1-based test strips could successfully detect CN⁻ in water solutions.