To validate the selectivity of sensor HNA in aqueous solution, fluorescence
spectral change of HNA upon addition of various anions in CH3CN with 5% H2O were measured (see Supplementary data,Fig. S5). Upon addition of various anions mentioned above to the CH3CN with 5% H2O solution of HNA, only CN− induced a dramatic fluorescence enhancement. Although HNA could not be used to etect CN− in 100% H2O, the possibility of HNA to be used in CH3CN with 5% H2O implies that HNA is strong enough to use the sensing mechanism to detect CN− also in more polar environments.In order to know more about the interactions between HNA and
CN−, fluorescence titration was carried out. When there is no CN−,HNA showed very week fluorescence intensity with emission band centered at 462 nm