A selective, sensitive probe for mercury(II) ions based on oxazine-thione

A selective, sensitive probe for Hg(II) ions, 7-(diethylamino)-3-methyl-2H-benzo[b][1,4] oxazine-2-thione (1), is developed. Compound 1 behaves as a ratiometric probe, exhibiting a large blue shift of 100 nm in its absorption spectra upon exposure to Hg(II) ions. The dramatic color change of the solution made ‘naked-eye’ detection of Hg(II) ions possible. Emission spectra of 1 displayed a selective enhancement in intensity in the presence of Hg(II) ions. ESI+-MS analysis indicated that Hg2+-induced desulfurization caused the large absorption response.