Sensitized near-infrared luminescence from Nd(III), Yb(III) and Er(III) complexes by energy-transfer from ruthenium 1,3-Bis([1,10]phenanthroline-[5,6-d]-imidazol-2 -yl)benzene.

The luminescent ruthenium 1,3 -bis([1,10]phenanthroline-[5,6 -d]- imidazol-2 -yl)benzene (bpibH2) complex, a potentially useful bridging ligand with a vacant diimine site, has been used as 'metallo ligand' to make heterodinuclear d-f complexes by attachment of a {Ln(dik)3} fragment (dik = 1,3-diketonate) 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, there is quenching in the (3)MLCT luminescence of the Ru(II) centre, that affords sensitized lanthanide(III) based luminescence in the near-IR region. Nd(III) was found to be the most effective at quenching the (3)MLCT luminescence of the ruthenium component because of the high density of f-f excited states of the appropriate energy which make it as effective energy-acceptor compared to Er and Yb complexes.