Two indole chalcone derivatives as chemosensor for cyanide anions

Two bromine substituted indole chalcone derivatives were synthesized via typical condensation reaction between 2-(hydroxyl)-4-bromine acetophenone and 3-indolealdehyde ( 1 ) or N-ethyl-3-indolealdehyde ( 2 ) in good yields. Their recognition properties for cyanide anions were investigated. The results indicate that the compounds exhibit quick and obvious color and fluorescence turn-on changes to cyanide anions with color changes from yellow to red ( 1 ) or from light yellow to deep yellow ( 2 ). Mechanism studies suggest that hydrogen bonding reaction between cyanide anions and N H moiety of compound 1 occurs, which leads to the red shift of absorption spectra and the deepening of color. To compound 2 , bonding mechanism is typical Michael reaction mechanism.