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

A cyclometalated Ir­(III) complex,
[Ir­(ppy)2(LH)] (2) [LH2 = 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{Cu2Cl2}] (3).
In the latter, a Cu2Cl2 dimer bridges the two
cyclometalated Ir­(III) units, resulting in a IrIII–CuII–CuII–IrIII motif. 2 also functions as a selective and reversible sensor for
Cu2+, as revealed by quenching of its emission and subsequent
revival of the luminescence signal upon addition of EDTA.