Yang En-Cui, Liu Zhong-Yi, Zhang Lei, Yang Na, Zhao Xiao-Jun
Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, College of Chemistry, Tianjin Normal University, Tianjin 300387, P. R. China.
Dalton Trans. 2016 May 10;45(19):8134-41. doi: 10.1039/c6dt00010j.
Disc-like Co core-derived (4,4)- and (3,6)-connected layers, {[Co7(C2H5OH)1.5(H2O)0.5(Hdatrz)2(μ3-OH)4(ip)5]·2.5H2O·C2H5OH}n () and [Co7(H2O)4(ade)2(μ3-OH)6(sip)2]n () (Hdatrz = 3,5-diamino-1,2,4-triazole, ade(-) = adeninate, ip(2-) = isophthalate and sip(3-) = 5-sulfoisophthalate) were solvothermally generated and structurally and magnetically characterized. The effect of magnetic anisotropy and exchange coupling from the local Co cores on the resulting magnetism properties are discussed. A crystallographically asymmetric Co core in exhibited an unusual single-molecule magnet (SMM)-like response under zero dc field resulting from strong anisotropy generated by two different types of Co(II) polyhedra and highly anisotropic exchange interactions. By contrast, a highly symmetric Co disc in belonging to the C2h point group showed only strong ferromagnetic exchange, to lead to an overall ST = 7/2 spin ground-state at low temperature. Thus, the interplay of magnetic anisotropy and exchange coupling has a great and complicated influence on the overall magnetic phenomena, which should be fully considered for the design and preparation of new Co(II)-SMMs.
盘状Co核衍生的(4,4)-和(3,6)-连接层，{[Co7(C2H5OH)1.5(H2O)0.5(Hdatrz)2(μ3-OH)4(ip)5]·2.5H2O·C2H5OH}n () 和 [Co7(H2O)4(ade)2(μ3-OH)6(sip)2]n () (Hdatrz = 3,5-二氨基-1,2,4-三唑，ade(-)=腺嘌呤，ip(2-)=间苯二甲酸酯，sip(3-)=5-磺基间苯二甲酸酯) 通过溶剂热法制备，并进行了结构和磁性表征。讨论了局部Co核的磁各向异性和交换耦合对所得磁性的影响。中晶体学不对称的Co核在零直流场下表现出异常的类单分子磁体(SMM)响应，这是由两种不同类型的Co(II)多面体产生的强各向异性和高度各向异性的交换相互作用导致的。相比之下，属于C2h点群的高度对称的Co盘仅显示出强铁磁交换，在低温下导致整体ST = 7/2自旋基态。因此，磁各向异性和交换耦合的相互作用对整体磁现象有很大且复杂的影响，在设计和制备新型Co(II)-SMMs时应充分考虑这一点。
