Transition metal complexes as a new class of photosensitizers for near-infrared lanthanide luminescence

In this paper, we report the near-infrared lanthanide luminescence of neodymium(III) and ytterbium(III) sensitized by energy transfer from the triplet excited state of a transition metal complex. In the present systems, polydentate neodymium(III) and ytterbium(III) complexes have been functionalized with the transition metal complexes ruthenium-tris(bipyridine) or ferrocene as the light harvesting units. Ruthenium-tris(bipyridine) and ferrocene have suitable triplet state energies for energy transfer to neodymium(III) and ytterbium(III), and have absorption bands in the visible part of the electromagnetic spectrum. The energy transfer process in the ruthenium-tris(bipyridine) complexes could be studied in detail because the donating state of the antenna (the 3MLCT state) is luminescent.