A novel BODIPY-based colorimetric and fluorometric dual-mode chemosensor for Hg2+ and Cu2+

A novel BODIPY-based colorimetric fluorescent sensor with bis[2-(phenylseleno)ethyl]amine as binding site (Se-1) for Hg2+ and Cu2+ has been developed. Se-1 shows high selectivity and sensitivity toward Hg2+ and Cu2+ over alkali and transition metal ions. Se-1shows a significant red-shift in the absorption spectra from 525 to 571 nm for Hg2+ and 590 nm for Cu2+, which induces color changes from pink to purple and blue. Upon excitation at 570 nm, Se-1 upon interaction with Hg2+ ions displays a 5-fold fluorescence enhancement with a 2 nm blue-shift, while Se-1 with Cu2+ exhibits a 13-fold fluorescence enhancement and red-shifts from 595 to 610 nm. The binding mode of Se-1 with Hg2+ or Cu2+ has been investigated by Job's plot, ESI and 1H NMR experiments. The absorption and fluorescence of the Se-1-Hg2+ complex can be reversibly restored to that of the uncomplexed ligand by using EDTA or cysteine, however, the sensing processing of Se-1 in response to Cu2+ ions cannot.