A class of wavelength-tunable near-infrared aza-BODIPY dyes and their application for sensing mercury ion

We present the design, synthesis, photophysical properties and application for sensing mercury ion, of a series of excellent near infrared fluorescent aza-boron-dipyrromethene (aza-BODIPY) dyes. The introduction of different aromatic substituents to the aza-BODIPY core induced red-shifted absorption and emission wavelengths due to the extension of the π-system. In addition, "turn-off" fluorescence responses and solution color changes selectively toward mercury ion have also been realized. The Hg ²⁺-induced fluorescence quenching may be assigned to the energy or electron transfer from emissive aza-BODIPY core to Hg²⁺.