Selective chemosensor capable of sensing both CN⁻ and Zn²⁺: Its application to zebrafish

We reported a novel naphthol-based chemosensor AIN ((E)-1-(((5-methylisoxazol-3-yl)imino)methyl)naphthalen-2-ol) for CN⁻ and Zn²⁺, which comprises of imine as a chromophore and naphthol group as a fluorophore. Chemosensor AIN, in a near-perfect aqueous solution, selectively responds to CN⁻ with colorimetric and fluorescent alterations whereas it responds to Zn²⁺ in dimethylformamide with a fluorescent change. A notable color transition from yellow to colorless was shown for AIN in the presence of cyanide via a nucleophilic addition process, while Zn²⁺ was sensed through π → π* transition with a unique fluorescence enhancement. We characterized the sensing properties of AIN toward CN⁻ and Zn²⁺ with the application of photophysical experiments and theoretical calculation. Moreover, AIN with the great photostability and low biotoxicity demonstrated fluorescent bio-imaging of CN⁻ in live zebrafish.