Wang Wen-Min, Zhang Hong-Xia, Wang Shi-Yu, Shen Hai-Yun, Gao Hong-Ling, Cui Jian-Zhong, Zhao Bin
Department of Chemistry, Tianjin University , Tianjin 300072, People's Republic of China.
College of Chemistry, Key Laboratory of Advanced Energy Material Chemistry, MOE, TKL of Metal and Molecule Based Material Chemistry, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University , Tianjin 300071, People's Republic of China.
Inorg Chem. 2015 Nov 16;54(22):10610-22. doi: 10.1021/acs.inorgchem.5b01404. Epub 2015 Oct 30.
New dinuclear lanthanide(III) complexes based on an 8-hydroxyquinoline Schiff base derivative and β-diketonate ligands, [Ln2(hfac)4(L)2] (Ln(III) = Gd (1), Tb (2), Dy (3), Ho (4), Er (5)), [Ln2(tfac)4(L)2] (Ln(III) = Gd (6), Tb (7), Dy (8), Ho (9)), and [Dy(bfac)4(L)2·C7H16] (10) (L = 2-[[(4-fluorophenyl)imino] methyl]-8-hydroxyquinoline, hfac = hexafluoroacetylacetonate, tfac = trifluoroacetylacetonate, and bfac = benzoyltrifluoroacetone), have been synthesized. The single-crystal X-ray diffraction data show that complexes 1-10 are phenoxo-O-bridged dinuclear complexes; each eight-coordinated center Ln(III) ion is in a slightly distorted dodecahedral geometry with two bidentate β-diketonate coligands and two μ2-O bridging 8-hydroxyquinoline Schiff base derivative ligands. The magnetic study reveals that 1 and 6 display cryogenic magnetic refrigeration properties, whereas complexes 3, 8, and 10 show different SMM behaviors with energy barriers of 6.77 K for 3, 19.83 K for 8, and 25.65 K for 10. Meanwhile, slow magnetic relaxation was observed in 7, while no out-of-phase alternating-current signals were found for 2. The different dynamic magnetic behaviors of two Tb2 complexes and the three Dy2 complexes mainly derive from the tiny crystal structure changes around the Ln(III) ions. It is also proved that the β-diketonate coligands can play an important role in modulating magnetic dynamics of the lanthanide 8-hydroxyquinoline Schiff base derivative system.
基于8-羟基喹啉席夫碱衍生物和β-二酮配体合成了新型双核镧系(III)配合物，[Ln2(hfac)4(L)2]（Ln(III)=Gd (1)、Tb (2)、Dy (3)、Ho (4)、Er (5)）、[Ln2(tfac)4(L)2]（Ln(III)=Gd (6)、Tb (7)、Dy (8)、Ho (9)）和[Dy(bfac)4(L)2·C7H16] (10)（L = 2-[[(4-氟苯基)亚氨基]甲基]-8-羟基喹啉，hfac = 六氟乙酰丙酮，tfac = 三氟乙酰丙酮，bfac = 苯甲酰三氟丙酮）。单晶X射线衍射数据表明，配合物1-10为苯氧-O-桥联双核配合物；每个八配位中心Ln(III)离子处于略微扭曲的十二面体几何构型，带有两个双齿β-二酮辅助配体和两个μ2-O桥联8-羟基喹啉席夫碱衍生物配体。磁性研究表明，1和6表现出低温磁制冷性能，而配合物3、8和10表现出不同的单分子磁体行为，其能垒分别为3的6.77 K、8的19.83 K和10的25.65 K。同时，在7中观察到缓慢的磁弛豫，而在2中未发现异相交流信号。两种Tb2配合物和三种Dy2配合物不同的动态磁行为主要源于Ln(III)离子周围微小的晶体结构变化。还证明了β-二酮辅助配体在调节镧系8-羟基喹啉席夫碱衍生物体系的磁动力学方面可以发挥重要作用。
