Sensitized near-infrared luminescence of lanthanide complexes by energy transfer from a ruthenium antenna

Abstract The luminescent ruthenium tetrapyrido [3, 2- a :2′, 3″- c :3″, 2″- h :2‴, 3‴- j ] phenazine(tpphz) complex acts as a potential bridging ligand with a vacant diimine site, and is used as ‘metallo ligand’ to make heterodinuclear d–f complexes by attachment of a {Ln(dik) 3 } fragment (dik = tta (trifluoro theonyl acetone)) at the vacant site. When Ln = Nd, Yb or Er, the lanthanide centre has low-energy f–f excited states capable of accepting energy from the 3 MLCT excited state of the Ru(II) centre. Luminescence quenching of the 3 MLCT Ru(II) center affords sensitized Ln(III) based luminescence in the near-IR region. Nd(III) is found to be the most effective quencher for the 3 MLCT luminescence of the ruthenium component because of the high density of f–f excited states of the appropriate energy, which makes it a more efficient energy-acceptor compared to the Er and Yb complexes.