A colorimetric and fluorescent probe containing diketopyrrolopyrrole and 1,3-indanedione for cyanide detection based on exciplex signaling mechanism

A new fluorescent probe 1 comprising diketopyrrolopyrrole and indanedione-based Michael receptor, which recognized cyanide anion with high selectivity was designed and synthesized. Addition of CN− aqueous solution to 1 in THF resulted in a rapid color change from purple to yellow together with a large blue shift from 553 to 480 nm, while other anions did not induce any significant color change. Furthermore, the Michael addition of cyanide to 1 elicited 3.11 and 6.13-fold PL enhancements at 484 and 572 nm, respectively, which constituted the fluorescence signature for cyanide detection. The mechanism of exciplex formation was proposed for this interesting observation. The detection limits were 0.36 μM using the fluorescence spectra changes, which was far lower than the WHO guideline of 1.9 μM. The results indicated 1 can act as dual-channel, high selective, immediacy and sensitive optical probe for CN−.