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 Hg 2+ 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 Hg 2+ -ratiometric fluorescent sensor while others ( 2 , 3 and 4 ) displayed fluorescence turn-on response for Hg 2+ among the various survey metal ions . We demonstrated that chemodosimeters ( 1 – 4 ) could recognized Hg 2+ ions based on a 1:1 stoichiometric binding event with fast detection time. More importantly, the detection limits for Hg 2+ 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 Hg 2+ induced emission spectra were reversed after adding NaBH 4 . Finally, these four sensors were successfully applied for fabrication of simple device test strips for rapid and on-site detection of Hg 2+ ions.