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

摘要

Three new dinuclear lanthanide compounds, [Ln(hfac)(2)L](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 mu(2)-0 bridging 8-hydroxyquinoline Schiff base ligands. Magnetic measurements indicate that 1 displays cryogenic magnetic refrigeration properties with maximum -Delta S-m value of 19.94 J K-1 kg(-1) at 2 K and 7 T; whereas 2 shows slow magnetic relaxation with energy barriers of 15.3 K and tau(0) = 3.34 x 10(-6) s. Additionally, solid-state photoluminescence property reveals that 2 displays the characteristic Tbm luminescence at room temperature. (C) 2017 Elsevier Ltd. All rights reserved.