Multiple magnetic relaxation processes, magnetocaloric effect and fluorescence properties of rhombus-shaped tetranuclear rare earth complexes

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 45; no. 1; pp. 253 - 264
• Main Authors: Gao, Hong-Ling, Jiang, Li, Liu, Shuang, Shen, Hai-Yun, Wang, Wen-Min, Cui, Jian-Zhong
• Format: Journal Article
• Language: English
• Published: England 07.01.2016
• Subjects: Dysprosium; Emission; Fluorescence; Ligands; Magnetic properties; Magnetic relaxation; Rare earth metals; Wavelengths
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt03790e

Seven new tetranuclear rare earth (RE) complexes [RE4(acac)4L6(μ3-OH)2] (HL = 5-(4-fluorobenzylidene)-8-hydroxylquinoline; acac = acetylacetonate; RE = Y (1), Eu (2), Gd (3), Tb (4), Dy (5), Tm (6) and Lu (7)) have been synthesized and completely characterized. Complex exhibits multiple zero-field slow magnetic relaxation processes typical of Single Molecule Magnets (SMMs). Two distinct slow magnetic relaxation processes, with effective energy barriers of Ueff = 48 K for the slow relaxation (SR) process and Ueff = 121 K for the fast relaxation (FR) process, are mainly attributed to the presence of two crystallographically independent Dy(III) sites. The magnetocaloric effect (MCE) was detected as -ΔSm(T) = 20.8 J kg(-1) K(-1) for complex . The fluorescence properties of complexes 1, 2, 4, 5 and 7 were also investigated. Complexes 2, 4 and 5 show the characteristic peaks for their corresponding RE(III) center, while complexes 1 and 7 show similar emission peaks to the Schiff base ligand when they are excited at the appropriate wavelength.