Construction And Magnetic Properties Of Tricyano-Bridged Low-Dimensional Molecule-Based Magnets

Single-molecule magnets and single-chain magnets, a kind of potential high-density information storage material, have been well investigated from more and more researchers in information storage, switch material, and so on. However, it is still a challenge to synthesize single-molecule magnets and single-chain magnets. This paper meets the requirements of strong magnetic anisotropy through choosing some large and negative zero field splitting constants of metal ions, meets the requirements of weak intermolecular magnetic coupling through choosing different building units and long or block auxiliary ligand to separate the molecules, and meets the requirements of large spin state or strong intrachain magnetic interactions through maintain intramolecular ferromagnetic coupling. By regulating auxiliary ligand, building units and metal ions, this thesis studies the difference of molecule-based magnets behavior under the control of different auxiliary ligands, and the correlations between magnetic properties and structure of these material in this process, explore the method of constructing single-molecule and single-chain magnets. The main results are as following.(1) Twenty-one cyano-bridged polynuclear compounds were synthesized by the versatile tricyanometalate [Fe(L)(CN)3]-(L= Tp, pzTp, Tp*) or tetracyanometalate building blocks [Fe(bpy)(CN)4]-to react with divalent transition metal ions (Cu(1-5,19), Mn(6,7), Ni(8, 10-13), Co(9,14-17,20), Fe(18,21)) in the presence of monodentate or bidentate auxiliary ligand, including eleven trinuclear compounds (1-11), seven tetranuclear compounds (12-18) and three hexanuclear compounds (19-21). The regulation of single-molecule magnet behavior is is realized by adjusting metal ion, steric hindrance and the intramolecular ferromagnetic interaction. In addition, the regulation of light and heat to magnetic properties is realized by the introduction of spin unit.(2) Ten cyano-bridged one-dimensional compounds were synthesized by the versatile tricyanometalate [Fe(L)(CN)3]-(L= Tp, pzTp, Tp*) or tetracyanometalate building blocks [Fe(bpy)(CN)4]- to react with divalent transition metal ions (Co(22,23,27,28), Cu(24,25), Mn(26,30), Fe(29), Ni(31)) in the presence of different auxiliary ligand or coordinated solvent molecules, consisting of two single zigzag chain (22,23), six double zigzag chains (24-29), one tubular coordination polymer (30) and one linear compound (31), and their structures and magnetic properties were characterized. The transformation from the coexistence of metamagnetism and single-chain magnet behavior to single-chain magnet behavior.is realized by modifying the chain framework and the relative strength of interchain and intrachain interactions, which provide new ideas to develop single-chain magnets.(3) Seven cyano-bridged two-dimensional compounds were constructed by the versatile tricyanometalate [Fe(L)(CN)3]-(L=Tp, pzTp) or tetracyanometalate building blocks [Fe(bpy)(CN)4]-to react with divalent transition metal ions (Cu(32),Mn(33,36), Co(34,35), Fe(37), Ni(38)) in the presence of auxiliary ligand (N-methylimidazole, 4,4'-bis(imidazolyl)biphenyl) or coordinated solvent molecules. The transformation from antiferromagnetic, ferrimagnetic to spin-glass behavior is realized by modifying the framework, and retain the properties of one-dimensional magnets.