Visualization of Zn2+ Ions in Live Zebrafish Using a Luminescent Iridium(III) Chemosensor

A novel luminescent cydometalated iridium(III) complex-based chemosensor (1) bearing a zinc-specific receptor, tris(2-pyridylmethyl)amine, and the 3-pheny1-1H-pyrazole ligand has been designed and synthesized. Upon the addition of Zn2+ ions to a solution of iridium(III) complex 1, a pronounced luminescence color change from blue to green can be observed, which may be attributed to the suppression of photoinduced electron transfer upon complexation of complex 1 with Zn2+ ions. The interaction of iridium(III) complex 1 with Zn2+ ions was investigated by UV-vis absorption titration, emission titration, and H-1 NMR titration. Furthermore, the iridium(III) complex 1 exhibited good selectivity for Zn2+ over 13 other common metal ions, including K+, Ag+, Na+, Ni2+, Fe3+, Hg2+, Cd2+, Mg2+, Cu2+, Mn2+, Co2+, and Pb2+ ions. The practical application of the iridium(III) complex 1 in visualizing intracellular Zn2+ distribution in live zebrafish was also demonstrated.