upon addition of CN−, the OH signal of HNA disappeared completely, indicating
the presence of hydrogen bonds between CN− and naphthol OH protons. In contrast, other H signals on the naphthaldehyde rings shifted upfield due to the increasing of electron density around them. As a contrast, there was no new peaks observed, which excluded the nucleophilic addition of cyanide to the imine. More interestingly, upon addition of some water to the system of HNA with 50 equiv. of CN− in acetonitrile/water solvents (from 0 to 1:9, v/v), the emission intensity of 504 nm did not decrease instead to increase gradually. As shown in