A symmetric pseudo salen based turn-on fluorescent probe for sensitive detection and visual analysis of zinc ion

A turn-on fluorescence probe for zinc ion has been synthesized, which contains a symmetric pseudo salen moiety as zinc recognition site. The multidentate salen ligand chelates with zinc ions, and generates the rigidity of the zinc complex, which subsequently results in a dramatic fluorescence enhancement of the probe. Mass spectral and spectroscopic results reveal that the reaction proceeds rapidly in a 1 to 1 stoichiometric manner to form a clean zinc complex. We have demonstrated that the fluorescence probe not only has high selectivity for zinc ion over other biological relevant ions but also shows high sensitivity for zinc ion with a detection limit of 83 nM. A fluorescence test paper has been developed by incorporating the probe on a polyamide fiber paper. The fluorescence color of the test paper became bright green-yellow under UV lamp when water sample containing zinc ions was dropped on it, suggesting its potential application in the measurement of zinc ions.