A colorimetric and ratiometric turn-on BODIPY-based fluorescent probe for double-channel detection of Cu2+ and Hg2+

A colorimetric and turn-on fluorescent chemosensor (RS1) for the detection of Hg2+ and Cu2+ based on BODIPY has been synthesized. RS1 selectively binds with Hg2+ and Cu2+ ions in CH3CN among various metal ions. RS1 shows a significant red-shift in absorption spectra from 522 nm to 581 nm for Hg2+ and 600 nm for Cu2+, which induces naked-eye color changes from pink to purple and blue. Upon excitation at 520 nm, RS1 upon interaction with Hg2+ ions shows the increase of the ratio of fluorescent intensities (I589/I576) from 0.84 to 1.87, while RS1 with Cu2+ exhibits a huge increase of I610/I576 from 0.72 to 7.87. The binding stoichiometries of RS1 with Hg2+ or Cu2+ have been determined to be 1:1 by Jobʹs plot and ESI. The binding of RS1 with Hg2+ is chemically reversible, while the sensing processing of RS1 in response to Cu2+ ions is irreversible.