TPPO辅助配位形成的3d-4f氰基桥连YbFe和YbCo配合物的合成及单分子磁性对比研究  

Synthesis and comparative single-molecule magnetic research of cyano-bridged 3d-4f YbFe and YbCo compounds formed by TPPO assisted coordination

作　　者：刘贝 龚慧文 方玥懿 谷依 朱文华[1] LIU Bei;GONG Huiwen;FANG Yueyi;GU Yi;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）》2023年第2期262-269,共8页Journal of Hubei University：Natural Science

基　　金：湖北省教育厅重点项目(D20211003)资助。

摘　　要：近年来,越来越多的单分子磁体(SMMs)体系被探索出来,尤其关于DyⅢ、HoⅢ、ErⅢ等稀土离子组装而成的SMMs的研究取得了阶段性的进展,但目前对YbⅢ的系统性和比较性的研究较少.基于此,为探究YbⅢ配合物的组成和结构对磁弛豫性能的影响,本研究合成并表征了两种氰基桥连3d-4f一维链状配合物{[Yb(TPPO)4][Fe(CN)6]}(H2O)(简写为1YbFe,其中TPPO为三-(N,N-四亚甲基)磷酰胺)和{[Yb(TPPO)4][Co(CN)6]}(H2O)(简写为2YbCo).粉末X线衍射表明两种化合物均有较高的纯度,单晶X射线衍射结果显示两种化合物局部配位几何结构均为八面体(Oh)构型.磁性研究证明零场下配合物1YbFe和2YbCo存在量子隧穿(QTM)效应,交流磁化率不表现出频率依赖性.在外加2 kOe直流场下,QTM效应被抑制.当温度降低至7 K以下时,化合物1YbFe的交流磁化率虚部χ″表现出明显的频率依赖性,在f=1000 Hz下,在温度为3 K处出现峰值.化合物2YbCo的虚部χ″在温度为4 K(f=1000 Hz)和3 K(f=100 Hz)处出现易于分辨的峰值,也表现出明显的频率依赖性.经对比研究表明,直流场诱导产生的磁弛豫现象主要来源于稀土YbⅢ离子.在相同交流场频率下,化合物2YbCo的虚部峰值温度高于1YbFe,应归因于抗磁性CoⅢ取代顺磁性[FeⅢ]LS时减弱了对稀土YbⅢ离子的横向涨落场.In recent years,more and more single-molecule magnets(SMMs)systems have been explored.In particular,the researches on SMMs assembled from rare earth ions such as DyⅢ,HoⅢ,and ErⅢhave made phased progress.However,there are few systematic and comparative studies on YbⅢat present.With this in mind,in order to explore the effect of the structure and composition of YbIIIcompounds on the magnetic relaxation properties,two cyano-bridged 3d-4f one-dimensional chain compounds{[Yb(TPPO)4][Fe(CN)6]}(H2O)(1YbFe)and{[Yb(TPPO)4][Co(CN)6]}(H2O)(2YbCo)were synthesized and characterized in this paper.Powder X-ray diffractions indicated that the samples of the two compounds had high purity.Single-crystal X-ray diffractions results showed that the local coordination geometry of YbⅢions in the two compounds was octahedral(Oh)configuration.Magnetic studies had proven that quantum tunneling of the magnetization(QTM)dominated under zero field for compounds 1YbFe and 2YbCo,and the AC(alternating current)susceptibilities showed no frequency dependence.The QTM effect was suppressed under a 2 kOe external DC(direct current)field.When the temperature dropped below 7 K,the imaginary partχ″of AC susceptibilities of compound 1YbFe exhibited obvious frequency dependence,with a peak temperature of 3 K at f=1000 Hz.The imaginary partχ″of the compound 2YbCo had easily distinguishable peaks at temperatures of 4 K(f=1000 Hz)and 3 K(f=100 Hz),showing also clear frequency dependence.The comparative study shows that the field-induced magnetic relaxation mainly comes from YbⅢions.At each same frequency,theχ″peak temperature for 2YbCo is higher than that for 1YbFe,which should be attributed to the weakening of the transverse fluctuation field of YbⅢions when diamagnetic CoⅢreplaces paramagnetic[FeⅢ]LS.

关 键 词：YbⅢ化合物 3d-4f异金属链结构 晶体结构 单分子磁体 

分 类 号：O641.4[理学—物理化学]