Luminescence and Single-Molecule-Magnet Behaviour in Lanthanide Coordination Complexes Involving Benzothiazole-Based Tetrathiafulvalene Ligands

Abstract

The two ligands 4-[6-(1,3-benzothiazol-2-yl)pyridin-3-yl]-4′,5′-bis(methylthio)tetrathiafulvene (L1) and 4-[6-(1,3-benzothiazol-2-yl)pyridin-3-yl]-4′,5′-(ethylenedithio)tetrathiafulvene (L2) were developed, and six new lanthanide coordination complexes, namely, [Ln2(hfac)6(L1)2]·C6H14·xCH2Cl2 [Ln = Dy and x = 0.25 (1); Ln = Yb and x = 0.30 (2); hfac– = 1,1,1,5,5,5-hexafluoroacetylacetonate], [Ln(hfac)3(L2)] [Ln = Dy (3), Yb (4)] and [Ln(tta)3(L1)] [Ln = Yb (5), Er (6); tta– = 2-thenoyltrifluoroacetylacetonate], were characterized by single-crystal X-ray diffraction. Compounds 1–6 were identified as mononuclear complexes, and the crystal packing depends on the natures of the ancillary and tetrathiafulvalene-based ligands. The two dysprosium derivatives, 1 and 3, displayed single-molecule-magnet behaviour in zero applied magnetic field. Although the near-infrared luminescence of 2 and 4 is almost undetectable, the change of ancillary ligand switched on the YbIII (5) and ErIII (6) luminescence.