脲基有机配体与硫氰根协同构建的五角双锥型Dy^(Ⅲ)单离子磁体的磁性研究  

Magnetic study of pentagonal bipyramidal Dy^(Ⅲ)single-ion magnets co-constructed by urea-based organic ligands and thiocyanate

作　　者：谷依 赵曼芸 董晓燕 黄宁宁 边青燕 黄云燕 朱文华[1] GU Yi;ZHAO Manyun;DONG Xiaoyan;HUANG Ningning;BIAN Qingyan;HUANG Yunyan;ZHU Wenhua(College of Chemistry and Chemical Engineering,Hubei University,Wuhan 430062,China)

机构地区：[1]湖北大学化学化工学院,湖北武汉430062

出　　处：《湖北大学学报（自然科学版）》2024年第6期864-871,共8页Journal of Hubei University：Natural Science

基　　金：国家自然科学基金(22271082);湖北省教育厅重点项目(D20211003);湖北高校省级教学研究项目(2022204)资助。

摘　　要：Dy^(Ⅲ)离子具有大的基态自旋值,是获取大磁弛豫能垒单分子磁体(SMMs)非常有潜力的稀土离子之一,而SCN-属于典型的无机含氰基短桥配体,具有空间位阻较小、配位能力较强等特点,可以作为阴离子构筑单分子磁体。基于此,本文中使用脲类有机配体TMU(1.1.3.3-四甲基脲)和DMPU(N,N-二甲基丙烯基脲),与DyCl_(3)·6H_(2)O和KSCN反应,通过溶剂挥发法,成功得到了2例新的稀土配合物[Dy(TMU)_(3)(SCN)_(3)(H_(2)O)][Dy(TMU)_(3)(SCN)_(3)(H_(2)O)](简称1Dy)和Dy(DMPU)_(4)(SCN)_(3)(简称2Dy)。单晶X射线衍射实验结果表明:配合物1Dy的中心Dy^(Ⅲ)离子与3个TMU中的氧原子、3个SCN-离子中的氮原子以及1个水分子中的氧原子进行配位,构成了趋于理想的五角双锥(D 5h)配位几何构型。配合物2Dy的中心Dy^(Ⅲ)离子与4个DMPU的氧原子和3个SCN-中的氮原子进行配位,构成了轴向略微拉长的D 5h配位几何构型。对于具有扁圆形电子密度的Dy^(Ⅲ)自由离子而言,电子密度大的配体分布在赤道面位置会抑制以Dy^(Ⅲ)离子为中心离子的单离子磁体(SIMs)的磁各向异性。磁性研究表明,配合物1Dy和2Dy在零场下其交流磁化率不表现出频率依赖性,而是存在很强的量子隧穿(QTM)效应。Dy^(Ⅲ)ion has a large ground state spin value,and is one of the most promising rare earth ions for obtaining single-molecule magnets(SMMs)with a large magnetic relaxation energy barrier.SCN-is a typical inorganic cyano-containing short bridge ligand with small steric hindrance and strong coordination ability,which can be used as an anion to construct single molecule magnets.In this paper,two new rare earth complexes[Dy(TMU)_(3)(SCN)_(3)(H_(2)O)][Dy(TMU)_(3)(SCN)_(3)(H_(2)O)](referred to as 1Dy)and Dy(DMPU)_(4)(SCN)_(3)(referred to as 2Dy)were successfully obtained through solvent evaporation method,utilizing the urea-based organic ligand TMU and DMPU to react with DyCl_(3)·6H_(2)O and KSCN.The results of single crystal X-ray diffraction experiments show that the central Dy^(Ⅲ)ion of complex 1Dy coordinates with oxygen atoms in three TMU molecules,nitrogen atoms in the three SCN-ions and the oxygen atom in one water molecule,form an ideal pentagonal bipyramidal(D 5h)coordination geometry.The central Dy^(Ⅲ)ion of complex 2Dy coordinates with oxygen atoms in four DMPU ligands and nitrogen atoms in three SCN-anions to form an axially slightly elongated D 5h coordination geometry.For Dy^(Ⅲ)free-ions with a oblate-shaped electron density,the distribution of ligands with high electron density at the equatorial plane suppresses the magnetic anisotropy of single-ion(SIMs)magnets with a Dy^(Ⅲ)ion as the central ion.Magnetic studies show that the ac magnetic susceptibility of the complexes 1Dy and 2Dy don’t exhibit frequency dependence under a zero dc field,but exhibite strong quantum tunneling(QTM)effects.

关 键 词：单分子磁体 五角双锥 磁弛豫 量子隧穿 

分 类 号：O641[理学—物理化学]