Structures, luminescence and magnetic properties of four phenoxo-O bridged Ln2 compounds: Distinct single-molecule magnets behaviors were observed in two Tb2 compounds

Abstract

Four new dinuclear lanthanide compounds, [Ln(hfac)2L]2 (Ln(III)=Eu (1) and Tb (2)) and [Ln(tfac)2L]2·(C7H16)x (Ln(III)=Tb (3), Yb (4), HL=2-[[(4-iodophenyl)imino]methyl]-8-hydroxyquinoline, hfac=hexafluoroacetylacetonate, tfac=trifluoroacetylacetonate), have been synthesized, structurally and magnetically characterized. The X-ray structural analysis exhibit that 1–4 are phenoxo-O-bridged dinuclear compounds and central Ln(III) ions are eight-coordinated with two bidentate hfac− and two μ2-O bridging 8-hydroxyquinoline Schiff base ligands. Magnetic measurements indicated that slow magnetic relaxation behaviors were observed in 2 under 0dc field, with an optimized dc field of 2000Oe for 2, the quantum tunneling of the magnetization was suppressed with ΔE/kB of 6.72K. However, no evident ac magnetic signals were observed in 3 under 0dc field. The distinct single-molecule magnets behaviors are mainly due to the slight different coordination environments around central TbIII ions of 2 and 3.