An easy-to-synthesize multi-photoresponse smart sensor for fast detecting Zn2+ and quantifying Fe3+ based on the enol/keto binding mode
A readily available 4-diethylaminosalicylaldazine-modified fluorene Schiff base (EASA-F) has been designed and synthesized through one step reaction. The EASA-F exhibits the fast fluorescent OFF-ON response to Zn2+ and OFF-ON-OFF behavior to Fe3+ in aqueous acetonitrile, synchronously accompanied the diverse absorption-ratiometric as well as naked-eye colorimetric changes, which can be attributed to the inhibition of C=N isomerization and ESIPT processes in addition to ICT mechanism due to different binding mode between enol-keto species and Zn2+/Fe3+. Moreover, the multi-optical responses for EASA-F to Zn2+/Fe3+ are reversible with EDTA as a chelating ligand. These, together with the dual-optical changes from the metal displacement of EASA-F-Zn2+ by Fe3+, endow the single molecule EASA-F as a real-time versatile sensor for sensitively detecting Zn2+ and accurately quantifying Fe3+.