Synthesis of two lanthanide clusters Ln^(Ⅲ)_(4)(Gd_(4) and Dy_(4)) with [2×2] square grid shape:Magnetocaloric effect and slow magnetic relaxation behaviors  

作　　者：Chunying Xu Zhilei Wu Chenjuan Fan Lili Yan Wenmin Wang Baoming Ji 

机构地区：[1]Henan Key Laboratory of Function-Oriented Porous Materials.College of Chemistry and Chemical Engineering,Luoyang Normal University,Luoyang 471934,China [2]College of Chemistry and Environmental Science,Hebei University,Baoding 071002,China [3]Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),Nankai University.Tianjin 300071,China

出　　处：《Journal of Rare Earths》2021年第9期1082-1088,共7页稀土学报（英文版）

基　　金：Project supported by the National Natural Science Foundation of China (21372112,21701039);the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (201802099)。

摘　　要：Two isostructural tetranuclear lanthanide clusters named [Ln_(4)(L)_(4)(CH_(3) O)_(4)]·CH_(3) OH(Ln=Gd(Ⅲ) for 1,Dy(Ⅲ) for 2,H_(2) L=N’-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl) picolinohydrazide) were successfully isolated by using a polydentate Schiff based ligand and Ln(Ⅲ) nitrate salts.The structures of 1 and 2 were characterized by X-ray structural analyses,they are held by four double deprotonated ligands L2-.In them all the lanthanide ions are eight-coordinated and distributed over four vertices of a parallelogram,presenting a Ln4 cluster with a strict [2 × 2] square grid pattern.The details of magnetic analysis show that 1 displays weak anti-ferromagnetic exchange between neighboring Gd(Ⅲ) ions through carboxylate oxygen and methanol oxygen ligand atoms.Furthermore,1 exhibits significant magnetocaloric effect with the maximum entropy change-ΔSm value of 28.5 J/(kg K) for ΔH=7.0 T at 2.0 K.For compound 2,remarkable slow magnetic relaxation behaviors are observed in the presence of zero magnetic field with τ0=1.02 × 10^(-6) s and energy barrier ΔE/kB=43.24 K.

关 键 词：Lanthanide clusters [2×2]square grid Anti-ferromagnetic couplings Magnetocaloric effect Slow magnetic relaxation Rare earths 

分 类 号：O641.4[理学—物理化学]