A new highly selective and turn-on fluorescence probe for detection of cyanide

A new compound was conveniently synthesized via the condensation of 2-hydroxy-1,3,5-benzenetricarbaldehyde (1) with 1-methyl-2,3,3-trimethyl-3H-indolium (2) in ethanol. Its recognition ability was firstly carried out in DMSO. After addition of all kinds of anions, only CN− can induce a turn on fluorescence accompanying a blue-green fluorescence color. The mechanism is based on nucleophilic addition reaction of cyanide anion with the polarized CN bond of the indolium group blocking the π-conjugation between indolium and 2-hydroxy-1,3,5-benzenetricarbaldehyde, which was proved by H NMR and ESI-MS. In addition, the detection was completed with 2 min and the detection limit was found to be 45 nmol/L.