A simple and effective fluorescent chemosensor for the cascade recognition of Zn2+ and H2PO4− ions in protic media

The chiral Schiff base N -(2-hydroxy-1-naphthyl)methylidene-( S )-α-phenylethylamine ( 1 ) was designed and synthesized as a fluorescent chemosensor based on the photoinduced electron transfer (PET) and C N isomerization mechanisms. The receptor exhibited a highly selective switch-on fluorescence response toward Zn 2+ and especially avoided the interference of Cd 2+ when the detection was conducted in unbuffered methanol solution. Furthermore, the in situ generated 1 ·Zn II -complex could be employed for the specific recognition of H 2 PO 4 − by fluorescence turn-off signaling through a ligand displacement process.