A dendrimer consisting of a pyrene core and a 9-phenylcarbazole periphery as a multi-functional fluorescent probe for iodide, iron(III) and mercury(II).

A dendrimer (termed G2) containing pyrene as the core and 9-phenylcarbazole (PCZ) on the periphery is shown to be a multi-functional fluorescent probe for iodide, iron(III) and mercury(II). It serves as the fluorometric/colorimetric dual-channel probe for these ions. As a fluorometric probe, the fluorescence of G2 is quenched both by iodide and iron(III). After that, the fluorescence of G2 which has been added iodide will recover when added mercury(II); as a colorimetric probe, the color of G2 solution can turn to yellow only by iodide which will change from yellow to colorless again when adding mercury(II). The color change is sensitive and observed visually at 0.1 mM for iodide. G2 also is an electroactive precursor for preparation of fluorescent films via electropolymerization. The resulting films can be used as the fluorescent films to sense the ions. This is attributed to the presence of a large specific surface, highly cross-linked microstructures and enhanced π conjugation. The electropolymerized film has blue fluorescence with excitation/emission maxima at 365/460 nm. The limits of detection (LOD) of G2 for iodide, iron(III) and mercury(II) were calculated to be 9.3, 37.1 and 22.0 nM in solution and 5.1, 12.0 and 6.1 nM in films, respectively. The linear range is from 2 to 10 μM for G2 electropolymerized films. The detection range is from 2 to 400 μM for iron(III) and mercury(II). The detection range is from 2 to 130 μM for iodide. For a third application, G2 displays compelling sensing performance in environmental systems and in living roundworms. Graphical abstractAs schematic presentation, after adding iodide, the fluorescence of G2 is quenched and the color changes to yellow. When adding Hg2+ to G2-iodide, the fluorescence and color of G2 recover. Iron(III) can also quench G2, but the color does not change.