Sensitization of Lanthanide Luminescence in Heterotrinuclear PtLn₂(Ln = Eu, Nd, Yb) Complexes with Terpyridyl-Functionalized Alkynyl by Energy Transfer from a Platinum(II) Alkynyl Chromophore

The preparation and characterization of the mononuclear complexes cis -Pt(dppe)(C⋮CPhtpy) 2 ( 1 ) and cis -Pt(dppp)(C⋮CPhtpy) 2 ( 5 ) (dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, HC⋮CPhtpy = 4‘-(4-ethynylphenyl)-2,2‘:6‘,2‘ ‘-terpyridine) and the corresponding PtLn 2 (Ln = Eu, Nd, Yb) heterotrinuclear complexes by incorporating the precursor 1 or 5 with Ln(hfac) 3 (H 2 O) 2 are described. 1 and 5 exhibit intense, long-lived room-temperature phosphorescence, originating probably from an admixture of 3 ILCT (π → π*(C⋮Cphtpy)) and 3 MLCT (d(Pt) → π*(C⋮CPhtpy)) triplet states, which qualifies them as favorable energy donors to facilitate Pt → Ln energy transfer in the corresponding PtLn 2 heterotrinuclear complexes. As anticipated, sensitized lanthanide luminescence in PtLn 2 heterotrinuclear complexes is attained through efficient energy transfer from Pt II alkynyl chromophore based 3 MLCT and 3 ILCT triplet states.