Chalcone derivatives as fluorescence turn-on chemosensors for cyanide anions

Three o-hydroxy chalcone derivatives 1–3 with carbazolyl (1), pyrene (2) and 4-nitrobenzene (3) as terminal group have been synthesized. Their crystal structures, photophysical properties in CH3CN and recognition properties for cyanide anions have also been examined. The research indicates that the stronger electroaffinity of the chalcone derivativeʹs β-unit is beneficial to Michael reaction and can improve the response rate of the compound to cyanide anions. These compounds are found to be able to recognize cyanide anions with fluorescence turn-on response. Especially, compound 3 with strong electron accepting group exhibits remarkable response to cyanide anions in CH3CNH2O (1:1, v/v) solution with a ca. 40-fold intensity enhancement.