A dipicolylamine-appended cyclometalated iridium(III) complex: Synthesis, characterization and metal ions recognition

A new phosphorescent dye (complex 1) containing iridium cyclometalated complex as fluorophore and di(2-picolyl)amine (DPA), connected to the 4,4′-positions of the bipyridine unit through >CO, as recognition group was synthesized and characterized. The UV–Vis absorption and luminescence properties of 1 were investigated with heavy-metal ions as well as Zn2+, Cd2+, Co2+, Ni2+, Ag+, Fe2+, Mn2+, Hg2+, Pb2+ and Cu2+. The emission intensities of complex 1 were strongly quenched by the addition of Cu2+, Zn2+ and Hg2+. The binding constants (Ks) and stoichiometry of complex 1 were calculated from luminescence titration data, with values of Ks = 3.09 × 105 M−1 (Cu2+), 5.75 × 104 M−1 (Zn2+) and 1.90 × 104 M−1 (Hg2+), respectively. Therefore, 1 exhibited high selectivity and efficient signaling behavior to Cu2+ over Zn(II), Hg(II) and other metal ions.