title: Unprecedented sensitization of visible and near-infrared lanthanide luminescence by using a tetrathiafulvalene-based chromophore.
abstract: Ligand L was synthesized and then coordinated to [Ln(hfac)3]⋅2 H2O (Ln(III)=Tb, Dy, Er; hfac(-)=1,1,1,5,5,5-hexafluoroacetylacetonate anion) and [Ln(tta)3]⋅2 H2O (Ln(III)=Eu, Gd, Tb, Dy, Er, Yb; tta(-)=2-thenoyltrifluoroacetonate) to give two families of dinuclear complexes [Ln2(hfac)6(L)]⋅C6H14 and [Ln2(tta)6(L)]⋅2 CH2Cl2. Irradiation of the ligand at 37,040 cm(-1) and 29,410 cm(-1) leads to tetrathiafulvalene-centered and 2,6-di(pyrazol-1-yl)-4-pyridine-centered fluorescence, respectively. The ligand acts as an organic chromophore for the sensitization of the infrared Er(III) (6535 cm(-1)) and Yb(III) (10,200 cm(-1)) luminescence. The energies of the singlet and triplet states of L are high enough to guarantee an efficient sensitization of the visible Eu(III) luminescence (17,300-14,100 cm(-1)). The Eu(III) luminescence decay can be nicely fitted by a monoexponential function that allows a lifetime estimation of (0.49±0.01) ms. Finally, the magnetic and luminescence properties of [Yb2(hfac)6(L)]⋅C6H14 were correlated, which allowed the determination of the crystal field splitting of the (2)F(7/2) multiplet state with M(J)=±1/2 as ground states.
authors.affiliation: Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1, 263 Avenue du Général Leclerc 35042 Rennes Cedex (France).
authors.forename: Min
authors.initials: M
authors.lastname: Feng
authors.forename: Fabrice
authors.initials: F
authors.lastname: Pointillart
authors.forename: Boris
authors.initials: B
authors.lastname: Le Guennic
authors.forename: Bertrand
authors.initials: B
authors.lastname: Lefeuvre
authors.forename: Stéphane
authors.initials: S
authors.lastname: Golhen
authors.forename: Olivier
authors.initials: O
authors.lastname: Cador
authors.forename: Olivier
authors.initials: O
authors.lastname: Maury
authors.forename: Lahcène
authors.initials: L
authors.lastname: Ouahab
keywords: chromophores; lanthanides; luminescence; magnetic properties; sulfur-containing heterocycles