对叔丁基杯[8]芳烃修饰的[Ln~Ⅲ6Co~Ⅱ8]（Ln=Sm,Gd,Dy）核簇化合物的合成、结构与磁性研究

Syntheses, structures and magnetic properties of [LnⅢ6CoⅡ8] （Ln = Sm, Gd, Dy） clusters capped by p.tert-butylcalix[8]arenes

本文以对叔丁基杯[8]芳烃(H8C8A)为配体,在溶剂热条件下制得了三个十四核的3d-4f化合物[LnIII6CoII8(C8A)2(O)2(OH)4(CO3)2(HCOO)2(CH3COO)4(DMF)m(H2O)n]·pDMF·qH2O(其中DMF=N,N′-二甲基甲酰胺;1:Ln=Sm,m=8,n=6,p=1,q=5;2和3:Ln=Gd(2)或Dy(3),m=10,n=4,p=0,q=7).X射线单晶测试表明,化合物结构中,杯[8]芳烃呈双锥式构型,每个锥式空腔下缘结合一个稀土离子,两个钴离子位于双锥的连接处,形成一个Ln2Co2-C8A四核单元,两个四核单元通过两个稀土离子连接形成环状结构,加上另外四个配位的钴离子,形成Ln6Co8核簇.磁性研究表明:化合物2在?H为7T,温度为4K时熵变值为14.83Jkg?1K?1,化合物3在低温下表现出频率依赖特性.

Three compounds, [LnⅢ6CoⅡ8（CSA）2（O）2（OH）4（CO3）2（HCOO）2（CH3COO）4（DMF）m（H20）n]·pDMF·qH2O （H8C8A = p-tert-butylcalix[8]arene; DMF = N,N＇-dimethylformide; 1： Ln = Sm, m = 8, n = 6, p = 1, q = 5; 2, 3： Ln = Gd（2） or Dy（3）, m = 10, n = 4, p = 0, q = 7）, were obtained by solvothermal method and characterized by singlecrystal X-ray diffraction, element analysis, and so on. Structure analysis reveals the C8A molecule adopts a double cone conformation which bonds two lanthanide cations and two cobalt cations to form a Ln2Co2-C8A subunit. A Ln6Co8 cluster forms by bridging two such subunits with two other lanthanide ions and bonding four other cobalt ions. Magnetic measurement indicates that the entropy change of compound 2 is of 14.83 J kg·K^-1 when AH is 7 T at 4 K and 3 exhibits the slow relaxation behavior at the low temperature.