Structures, luminescence properties, magnetocaloric effect and slow magnetic relaxation of three Ln (III) complexes based on 8‑hydroxyquinoline Schiff-base ligand

Abstract

Three new dinuclear lanthanide compounds, [Ln(hfac)2L]2 (Ln(III)=Gd (1), Tb (2) and Er (3), hfac=hexafluoroacetylacetonate and HL=2-[(4-ethylphenyl)imino]methyl-8-hydroxyquinoline), have been synthesized and characterized by elemental analysis, IR, PXRD and single crystal X-ray diffraction. The X-ray structural analysis exhibit that 1–3 are phenoxo-O-bridged dinuclear complexes and central Ln(III) ions are eight-coordinated with two bidentate hfac− and two μ2-O bridging 8-hydroxyquinoline Schiff base ligands. Magnetic measurements indicate that 1 displays cryogenic magnetic refrigeration properties with maximum −ΔSm value of 19.94JK−1kg−1 at 2K and 7T; whereas 2 shows slow magnetic relaxation with energy barriers of 15.3K and τ0=3.34×10−6s. Additionally, solid-state photoluminescence property reveals that 2 displays the characteristic TbIII luminescence at room temperature.