Near-infrared (NIR) emitting Nd/Yb(iii) complexes sensitized by MLCT states of Ru(ii)/Ir(iii) metalloligands in the visible light region.

Four Ru(ii)/Ir(iii) metalloligands have been designed and synthesized from polypyridine and bibenzimidazole (BiBzIm) organic ligands, which show strong visible light absorption via metal-to-ligand charge transfer (MLCT) transitions. Nd/Yb(iii) complexes were further assembled from these Ru(ii)/Ir(iii) metalloligands, and Ln(iii)-centered NIR emissions can be efficiently sensitized by ³MLCT states of the metalloligands in the visible-light region. The energy transfer rates for the complexes are generally in the order Nd ＞ Yb, which is due to the better matching between ³MLCT states of Ru(ii)/Ir(iii) metalloligands and densely distributed excited states of Nd(iii) ions. Long decayed lifetimes on a μs scale and high quantum yields up to 1% are obtained in these lanthanide complexes, suggesting that the Ru(ii)/Ir(iii) metalloligands can serve as a good visible light harvesting antenna to efficiently sensitize Ln(iii)-based NIR luminescence. [ABSTRACT FROM AUTHOR]