Tetrahydro[5]helicene thioimide-based fluorescent and chromogenic chemodosimeter for highly selective and sensitive detection of Hg2+

A highly selective and sensitive fluorescent ‘turn-on’ and chromogenic chemodosimeter based on tetrahydro[5]helicene thioimide has been developed. The chemodosimeter showed not only 200-fold enhancement of the fluorescent intensity in aqueous acetonitrile, but also marked color change of the solution from maroon to yellow-green solution upon the addition of Hg2+ ion. The detection limit of the chemodosimeter for Hg2+ was estimated to be 5.0 × 10−7 M. The response mechanism was resulted from the Hg2+-induced desulfurization of the thioimide to its imide precursor.