Bright Circularly Polarized Electrochemiluminescence from Heterobinuclear Ir ^III –Au ^I Enantiomers

Abstract The development of efficient circularly polarized electrochemiluminescence (CP‐ECL) probes is still at its infancy and examples are still very limited. Yet, their achievement would enable gathering a readout that carries privileged information on the probe's chiral environment by monitoring luminescence polarization bias with high signal‐to‐noise ratio. Notwithstanding, this is a highly challenging task and requires judicious chemical engineering of chiral ECL‐active emitters. Herein, we aim at expanding the palette of CP‐ECL luminophores by presenting a novel class of enantiopure heterobinuclear Ir(III)–Au(I) complexes, which are investigated thoroughly by means of chemical, structural, and (chiro‐)optical techniques. The ground and excited state properties are also elucidated by using density functional theory (DFT) approaches including spin‐orbital coupling (SOC) perturbation. The chiral‐at‐metal complexes display luminescence with a polarization bias of the emitted light that is function of the helical arrangement of the coordination sphere around the Ir(III) center. Overall, the photo‐ and electro‐active complexes unraveled in this work combine unparallelly high photoluminescence quantum yield in the orange region, excellent circularly polarized luminescence (CPL) brightness up to 4.5 M −1 cm −1 with a notable ECL activity. Finally, these features provide emitters with CP‐ECL efficiency that encompass remarkably by a factor 3.5 that of the well‐known benchmark tris ‐(2,2′‐bipyridyl)ruthenium(II).