Structures, magnetic refrigeration and single molecule-magnet behavior of five rhombus-shaped tetranuclear Ln()-based clusters

• Published in: New journal of chemistry Vol. 44; no. 25; pp. 1266 - 1274
• Main Authors: Wang, Wen-Min, Huai, Lei, Wang, Xi-Wen, Jiang, Kai-Jun, Shen, Hai-Yun, Gao, Hong-Ling, Fang, Ming, Cui, Jian-Zhong
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 07.07.2020
• Subjects: Acetylacetone; Clusters; Crystallography; Gadolinium; Hydroxyquinoline; Imines; Lanthanum; Luminescence; Magnetic induction; Magnetic permeability; Magnetic properties; Magnetic relaxation; Optical properties; Refrigeration; Room temperature
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d0nj01969k

A series of coplanar tetranuclear Ln( iii )-based clusters, namely [Ln 4 (acac) 4 (L) 6 (μ 3 -OH) 2 ]·[solvent] (Ln = Eu ( 1 ), Gd ( 2 ), Tb ( 3 ), Dy ( 4 ) and Er ( 5 )), have been synthesized by using an 8-hydroxyquinoline Schiff base ligand (HL = 5-(2-thenylidene)-8-hydroxylquinoline) and acetylacetone. Their structures and magnetic properties have been completely characterized. The structure determination shows that clusters 1-5 are isostructural with a rhombus-shaped Ln 4 core. The magnetic studies reveal that the Gd 4 cluster ( 2 ) displays cryogenic magnetocaloric effects with a maximum −Δ S m value of 22.09 J kg −1 K −1 at 2.5 K and Δ H = 7.0 T; while ac susceptibility measurements show that single molecule-magnet behavior is exhibited by the Dy 4 cluster ( 4 ) with the anisotropic barrier (Δ E / k B ) of 75.01 K. Interestingly, more than one maximal out-of-phase ac signals ( χ ′′) were observed in 4 , suggesting the operation of multiple magnetic relaxation processes in 4 . In addition, the solid state luminescence properties reveal that clusters 1 , 3 , and 4 display the characteristic lanthanum luminescence at room temperature. The rhombus-shaped Gd 4 cluster displays a magnetic refrigeration property, and the Dy 4 cluster shows remarkable SMM behavior.