Recognition of Al3+ and Zn2+ using a single Schiff-base in aqueous media

A naphthalene derivative 2-hydroxy-α-naphthaldehyde-(2′-methylquinoline-4′-formyl) hydrazone (HL) as a fluorescent chemosensor for Al3+/Zn2+ in ethanol and water (9:1, v/v) has been designed and synthesized. The receptor shows a large fluorescence enhancement at 509 nm and 543 nm in the present of Al3+ and Zn2+, respectively. The excited-state intramolecular proton transfer (ESIPT) process, coupled with photoinduced electron transfer (PET) process are proposed to explain the observed spectral response.