title: Multiple magnetic relaxation processes, magnetocaloric effect and fluorescence properties of rhombus-shaped tetranuclear rare earth complexes.
abstract: 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.
authors.affiliation: Department of Chemistry, Tianjin University, Tianjin 300072, People's Republic of China. cuijianzhong@tju.edu.cn.
authors.forename: Hong-Ling
authors.initials: HL
authors.lastname: Gao
authors.affiliation: Department of Chemistry, Tianjin University, Tianjin 300072, People's Republic of China. cuijianzhong@tju.edu.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, Tianjin University, Tianjin 300072, People's Republic of China. cuijianzhong@tju.edu.cn.
authors.forename: Shuang
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Chemistry, Tianjin University, Tianjin 300072, People's Republic of China. cuijianzhong@tju.edu.cn.
authors.forename: Hai-Yun
authors.initials: HY
authors.lastname: Shen
authors.affiliation: Department of Chemistry, Tianjin University, Tianjin 300072, People's Republic of China. cuijianzhong@tju.edu.cn.
authors.forename: Wen-Min
authors.initials: WM
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Tianjin University, Tianjin 300072, People's Republic of China. cuijianzhong@tju.edu.cn.
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Cui