A Highly Selective Colorimetric and Fluorescent Probe for Cu2+ and Hg2+ Ions Based on a Distyryl BODIPY with Two Bis(1,2,3-triazole)amino Receptors

A new distyryl boron dipyrromethene (BODIPY) with two bis(1,2,3-triazole)amino substituents has been prepared by typical Knoevenagel condensation followed by click reaction. The compound selectively binds to Cu2+ and Hg2+ ions in CH3CN/H2O (1:1 v/v) to give remarkably blueshifted electronic absorption and fluorescence bands as a result of inhibition of the intramolecular charge-transfer process upon binding to these metal ions. The color changes can be easily seen by the naked eye. The binding stoichiometry between this probe and Cu2+ ions has been determined to be 1:2 by a Job plot of the fluorescence data with a binding constant of ((6.2 +/- 0.6)x109)?M-2. The corresponding value for Hg2+ ions is about sixfold smaller.