SYNTHESIS, LUMINESCENCE, AND EXCITED-STATE COMPLEXES OF THE TRIS(1,10-PHENANTHROLINE)IRIDIUM(III) AND BIS(TERPYRIDINE)IRIDIUM(III) CATIONS

We report the synthesis and luminescence properties of Ir(phen)33+ and Ir(terp)23+ (phen = 1,10-phenanthroline and terp = 2,6-bis(2-pyridyl)pyridine). Their emissions are assigned to predominantly π-π* phosphorescences. A novel excited-state complex is proposed to form between Ir(phen) 33+ and Ir(terp)23+ and HgCl2. Although HgCl2 is normally a quencher, it can greatly enhance the lifetimes and luminescence efficiencies of the Ir(phen)33+ and Ir(terp)23+—up to an order of magnitude. The changes arise from alteration of the radiative and nonradiative rate constants in the excited-state complex. The effect of temperature, solvent, oxygen, and inert ions on the interactions of HgCl2 with the excited complexes is explored. A simple associative model accurately reproduces all lifetime and intensity changes. A rationale based on the well-known affinity of HgCl2 for aromatic molecules is proposed. © 1990, American Chemical Society. All rights reserved.