Syntheses,Structures,and Sensitized Lanthanide Luminescence by Pt - Ln (Ln=Eu,Nd,Yb) Energy Transfer for Heteronuclear PtLn2 and Pt2Ln4 Complexes with a Terpyridyl-Functionalized Alkynyl Ligand

摘要

Reaction of Pt(dppm-P,P')Cl2 (dppm=1,2-bis(diphenylphosphino)methane) with HC ident to CPhtpy (HC ident to CPhtpy=4'-(4-ethynylphenyl)-2,2':6',2"-terpyridine) in the presence of copper(I) iodide and diisopropylamine induced isolation of mononuclear complex cis-Pt(dppm-P,P)(C ident to CPhtpy)2 (1),which can be converted into face-to-face diplatinum-(II) species Pt2(mu-dppm)2(C ident to CPhtpy)4 (5) when equivalent dppm is added.Incorporating 1 or 5 to Ln(hfac)3(H2O)2 (Hhfac=hexafluoroacetylacetone) gave PtLn2 (Ln=Nd (2),Eu (3),Yb (4)) or Pt2Ln4 (Ln=Nd (6),Eu (7),Gd (8),Yb (9)) adducts with the lanthanide centers chelated by terdentate terpyridyl in the bridging C ident to CPhtpy.The structures of 1,6,7,and 9 were determined by X-ray crystallography.Upon excitation at lambda_(ex)=360-450 nm (2-4) or 360-500 nm (6-9),where the Pt~(II) alkynyl antenna chromophores absorb strongly but the model complexes Ln(hfac)3(HC ident to CPhtpy) lack obvious absorption in this region,these PtLn2 and Pt2Ln4 (Ln=Nd,Eu,Yb) species exhibit bandlike lanthanide luminescence that is typical of the corresponding Ln~(3+) ions,demonstrating unambiguously that efficient Pt->Ln energy transfer occurs indeed from the Pt~(II) alkynyl antenna chromophores to the lanthanide centers across the bridging C ident to CPhtpy with intramolecular P···Ln distances being ca.14.2 A.The Pt -> Ln energy transfer rate (k_(ET)) is 6.07 x 10~7 s~(-1) for Pt2Nd4 (6) and 2.12 x 105 s~(-1) for Pt2Yb4 (9) species.