Recyclable fluorescent chemodosimeters based on 8-hydroxyquinoline derivatives for highly sensitive and selective detection of mercury(II) in aqueous media and test strips.

Four novel highly selective 8-hydroxyquinoline-based fluorescent chemodosimeters (1-4) were synthesized for the rapid analysis of Hg2+ in aqueous solution and on paper strips, which probably attributed to the excited state intramolecular proton transfer (ESIPT) process. Chemodosimeter 1 was evaluated as a Hg2+ -ratiometric fluorescent sensor while others (2, 3 and 4) displayed fluorescence turn-on response for Hg2+ among the various survey metal ions. We demonstrated that chemodosimeters (1-4) could recognized Hg2+ ions based on a 1:1 stoichiometric binding event with fast detection time. More importantly, the detection limits for Hg2+ could reach at 10-9  M level except chemodosimeter 1 (4.05 × 10-8  M). In addition, it was found that chemodosimeters (1-4) were recycled efficiently because the Hg2+ induced emission spectra were reversed after adding NaBH4 . Finally, these four sensors were successfully applied for fabrication of simple device test strips for rapid and on-site detection of Hg2+ ions.