Construction of a family of Ln 3 clusters using multidentate Schiff base and β-diketonate ligands: fluorescence properties, magnetocaloric effect and slow magnetic relaxation

• Published in: New journal of chemistry 2020-06, Vol.44 (22), p.9230-9237
• Main Authors: Wang, Wen-Min, Gao, Yu, Yue, Rong-Xin, Qiao, Na, Wang, Dan-Tong, Shi, Ying, Zhang, Huan, Cui, Jian-Zhong
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/D0NJ01172J

A family of μ-O acylhydrazone -bridged Ln 3 clusters, [Ln 3 (dbm) 5 (HL) 2 ]· x [solvent] (Ln = Nd ( 1 ), Sm ( 2 ), Gd ( 3 ), Tb ( 4 ), Dy ( 5 ), Ho ( 6 ), and Er ( 7 ), H 3 L = N ′-(2-hydroxybenzylidene)-6-(hydroxymethyl)picolinohydrazide, and Hdbm = dibenzoylmethane), was successfully obtained by using a multidentate hydrazone ligand and lanthanide β-diketone salts via a solvothermal method. The seven Ln 3 clusters were characterized by performing infrared spectroscopy (IR), elemental analysis (EA), thermogravimetric analysis (TGA), UV-Vis spectroscopy and single-crystal X-ray diffraction. Structural analyses showed clusters 1–7 to be isostructural and to mainly contain three Ln( iii ) ions connected through four μ-O hydrazone bridges. The magnetism investigations indicated showed cluster 3 displaying cryogenic magnetic refrigeration with a −Δ S m of 20.60 J K −1 kg −1 ( T = 2.0 K, Δ H = 7.0 T); while cluster 5 showed slow magnetic relaxation with a Δ E / k B of 20.47 K and τ 0 of 1.4 × 10 −8 s. Moreover, solid-state fluorescence analyses showed clusters 2 , 4 and 5 displaying the characteristic lanthanum luminescence at room temperature.