An easy-to-synthesize multi-photoresponse smart sensor for rapidly detecting Zn2+ and quantifying Fe3+ based on the enol/keto binding mode

摘要

A readily available 4-diethylaminosalicylaldazine-modified fluorene Schiff base (EASA-F) was designed and synthesized through a one-step reaction. EASA-F exhibited a fast fluorescence OFF-ON response to Zn2+ and an OFF-ON-OFF behavior to Fe3+ in aqueous acetonitrile. This was synchronously accompanied by diverse absorption-ratiometric changes and colorimetric changes that were observable by the naked eye; these changes were attributed to the inhibition of C & xe001;N isomerization and ESIPT processes in addition to the ICT mechanism that resulted from the different binding modes between the enol-keto species and Zn2+/Fe3+. Moreover, the multi-optical responses of EASA-F to Zn2+/Fe3+ were reversible with EDTA as the chelating ligand. These findings combined with the dual-optical changes from the metal displacement of EASA-F-Zn2+ by Fe3+ make the single-molecule EASA-F a real-time versatile sensor for sensitively detecting Zn2+ and accurately quantifying Fe3+.