Cyclometalated Ir(III) Complex as a Metalloligand and a Selective Cu(II) Sensor: Synthesis and Structural Characterization of a Heterometallic Tetranuclear Ir(III)/Cu(II) Complex

[Image: see text] A cyclometalated Ir(III) complex, [Ir(ppy)(2)(LH)] (2) [LH(2) = 1,2-bis(pyridine-2-carboxamido)benzene; ppyH = 2-phenylpyridine] was synthesized and structurally characterized. [Ir(ppy)(2)(LH)] contains free donor sites and functions as a metalloligand. Accordingly, it interacts with a Cu(II) salt to afford the heterometallic tetranuclear complex, [{Ir(ppy)(2)(L)}(2){Cu(2)Cl(2)}] (3). In the latter, a Cu(2)Cl(2) dimer bridges the two cyclometalated Ir(III) units, resulting in a Ir(III)–Cu(II)–Cu(II)–Ir(III) motif. 2 also functions as a selective and reversible sensor for Cu(2+), as revealed by quenching of its emission and subsequent revival of the luminescence signal upon addition of EDTA.