Bisindole anchored mesoporous silica nanoparticles for cyanide sensing in aqueous media.

For CN(-) recognition, a series of bisindolyl compounds 1-3 were prepared, and their chromodosimetric color changes toward anions were investigated. Nucleophilic addition of the cyanide ion to the meso position of the bisindolyl group gave rise to breaking of the double bond conjugation, thereby inducing spectroscopic changes in the compound. Mesoporous silica nanoparticles 3 also gave color changes from deep orange to yellow in response to the cyanide ion.