Slow magnetic relaxation in condensed versus dispersed dysprosium(III) mononuclear complexes

Goulven Cosquer, Fabrice Pointillart, Stéphane Golhen, Olivier Cador, Lahcène Ouahab

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81 Citations (Scopus)


Reaction of the ligands 4,5-bis(propylthio)tetrathiafulvalene-2-(2-pyridyl) benzimidazole (L1) and 4,5-bis(propylthio)tetrathiafulvalene-2-(2- pyridyl)-3-(2-pyridinylmethyl)benzimidazole (L2) with Dy(hfac) 3×2 H2O (hfac=1,1,1,5,5,5-hexafluoroacetylacetonate) gave mononuclear complexes [Dy(hfac)3(L1)] (1) and [Dy(hfac)3(L2)] (2). In both compounds the Dy III ion is surrounded by six oxygen and two nitrogen atoms. Complex 1 displays single-ion magnet (SIM) behaviour only in solution (Δ=12(1) K and τ0=1.9(4)×10-6 s), while complex 2 is a SIM in both solution (Δ=15(2) K and τ0=1.5(3)×10 -6 s) and solid state (Δ=17(2) K and τ0=9.5(2) ×10-6 s). The SIM behaviour is obtained if the hydrogen bond is broken by dissolution (1 in solution) or by alkylation (2). Multiple relaxation processes were identified for 2 with two competing processes: a fast one in zero field and a slow one for fields higher than 500 Oe. The two processes coexist for intermediate applied magnetic field. Magnetic-dilution and frozen-solution measurements led to the conclusion that the origin of these multiple relaxation processes is not due to the property of a single molecule.

Original languageEnglish
Pages (from-to)7895-7903
Number of pages9
JournalChemistry - A European Journal
Issue number24
Publication statusPublished - 2013 Jun 10


  • hydrogen bonds
  • lanthanides
  • relaxation processes
  • single-ion magnets
  • thiafulvalenes

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry


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