title: Luminescence and single-molecule magnet behavior in lanthanide complexes involving a tetrathiafulvalene-fused dipyridophenazine ligand.
abstract: The reaction between the TTF-fused dipyrido[3,2-a:2',3'-c]phenazine (dppz) ligand (L) and 1 equiv of Ln(hfac)3·2H2O (hfac(-) = 1,1,1,5,5,5-hexafluoroacetyacetonate) or 1 equiv of Ln(tta)3·2H2O (tta(-) = 2-thenoyltrifluoroacetonate) (Ln(III) = Dy(III) or Yb(III)) metallic precursors leads to four mononuclear complexes of formula [Ln(hfac)3(L)]·C6H14 (Ln(III) = Dy(III) (1), Yb(III) (2)) and [Ln(tta)3(L)]·C6H14 (Ln(III) = Dy(III) (3), Yb(III) (4)), respectively. Their X-ray structures reveal that the Ln(III) ion is coordinated to the bischelating nitrogenated coordination site and adopts a D4d coordination environment. The dynamic magnetic measurements show a slow relaxation of the Dy(III) magnetization for 1 and 3 with parameters highlighting a slower relaxation for 3 than for 1 (τ0 = 4.14(±1.36) × 10(-6) and 1.32(±0.07) × 10(-6) s with Δ = 39(±3) and 63.7(±0.7) K). This behavior as well as the orientation of the associated magnetic anisotropy axes have been rationalized on the basis of both crystal field splitting parameters and ab initio SA-CASSCF/RASSI-SO calculations. Irradiation of the lowest-energy HOMO → LUMO ILCT absorption band induces a (2)F5/2 → (2)F7/2 Yb-centered emission for 2 and 4. For these Yb(III) compounds, Stevens operators method has been used to fit the thermal variation of the magnetic susceptibilities, and the resulting MJ splittings have been correlated with the emission lines.
authors.affiliation: †Institut des Sciences Chimiques de Rennes UMR 6226 CNRS-Université de Rennes 1, 35042 Rennes Cedex, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Pointillart
authors.affiliation: †Institut des Sciences Chimiques de Rennes UMR 6226 CNRS-Université de Rennes 1, 35042 Rennes Cedex, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Jung
authors.affiliation: †Institut des Sciences Chimiques de Rennes UMR 6226 CNRS-Université de Rennes 1, 35042 Rennes Cedex, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Berraud-Pache
authors.affiliation: †Institut des Sciences Chimiques de Rennes UMR 6226 CNRS-Université de Rennes 1, 35042 Rennes Cedex, France.
authors.forename: Boris
authors.initials: B
authors.lastname: Le Guennic
authors.affiliation: †Institut des Sciences Chimiques de Rennes UMR 6226 CNRS-Université de Rennes 1, 35042 Rennes Cedex, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Dorcet
authors.affiliation: †Institut des Sciences Chimiques de Rennes UMR 6226 CNRS-Université de Rennes 1, 35042 Rennes Cedex, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Golhen
authors.affiliation: †Institut des Sciences Chimiques de Rennes UMR 6226 CNRS-Université de Rennes 1, 35042 Rennes Cedex, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Cador
authors.affiliation: §Laboratoire de Chimie, l'ENS-LYON-UMR 5182, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Maury
authors.affiliation: ∥Institut Lumière Matière, UMR 5306 CNRS-Université de Lyon 1, 10 rue Ada Byron, 69622 Villeurbanne Cedex, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Guyot
authors.affiliation: ‡Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
authors.forename: Silvio
authors.initials: S
authors.lastname: Decurtins
authors.affiliation: ‡Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
authors.forename: Shi-Xia
authors.initials: SX
authors.lastname: Liu
authors.affiliation: †Institut des Sciences Chimiques de Rennes UMR 6226 CNRS-Université de Rennes 1, 35042 Rennes Cedex, France.
authors.forename: Lahcène
authors.initials: L
authors.lastname: Ouahab