This paper reports the synthesis of carbon-centered Au(I)-Ag(I) clusters with high phosphorescence quantum yields using N-heterocyclic carbene ligands. A heterometallic cluster [(C)(Au-L)6Ag2]4+, where L denotes benzimidazolylidene-based carbene ligands, shows a high phosphorescence quantum yield (Φ = 0.88). Theoretical calculations suggest that the carbene ligands enhance radiative decay and suppress non-radiative pathways. These clusters are taken up by cells, emit phosphorescence, and translocate to specific organelles, enabling ligand-specific, organelle-selective phosphorescence imaging.
