Design And Research Of Tricyano-bridged Trinuclear And Hexanuclear Molecule-based Magnets

In the new era, with the rapid development of information technology, the demand of recording devices with high density increasingly strong.The traditional inorganic magnetic materials can’t Keep pace with the times because of their size limits. The magnetic behaviors of molecule-based magnets lie compelety on molecule level that break the nano-superparamanetic limit, and the information storage density of molecule-based magnets can be increased a number of magnitudes. Therefore, molecule-based magnets have attracted significant attentions. molecule-based magnets are composed of paramagnetic metal ions and diamagnetic ligands, it is possible to tune the magnetic behaviors by chemical modification. Furthermore, it is easy to introduce new functional groups to couple with magnetism. cyano-bridged heterometallic molecular assemblies with reduced dimensionality, such as single molecule magnets and single-chain magnets, have been favored by many chemists and physicists during last decades, and it becomes the most typical representative of molecule-based magnets. Among the cyanide-based molecular precursors, we note the tricyanometalate can link various metal ions and leads to various structural architectures ran gin g from discrete polynuclear complexes to one-dimensional chains, two-dimensional and three-dimensional assemblies. Some of them are promising SMMs or SCMs. Transition metal ions apear larger magnetic moment and large spin ground state which are beneficial for the constructin g of single molecule magnets. In addition, the ligand field of total N chelating ligands is moderate so that the number of spin electrons out of metal center can be chan ged by external stimuli. Therefore, if we can make use of the unsarurated coordination sites of transition metal center with tri-chelating ligands to bridge the cyano-metal precursors through cyanide, we may get some heterometallic molecule-based magnetics that exhibit spin cross over. Moreover, we may get SMMs with SCO. Based on this strategy, we carried out the work in the following two aspects in this paper.1. Design and synthesis two kind tridentate ligands 2,6-bis(Pyrazol-3-yl)pyridine and 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine5 react with transition metal ions NiⅡ,CoⅡ,CuⅡ and thiocyanate to form some compounds with unsaturated coordination sites. React these compounds with PzTp, Tp*, Tp to replace the thiocyanate, then we got four compounds 1,2, 3and 4 with trinuclear. Magnetic tests showed that 1,2 display strong ferromagnetic couple interactions,3 appeared intense antiferromagnetic coupling, while 4 exhibited ferromagnetic interaction.2. Design and synthesis tridentate ligands 2,6-bis(N-pyrazolyl)pyridine, react with transition metal ions CoⅡ, NiⅡ and thiocyanate to form two compounds with unsaturated coordination sites. React these compounds with PzTp to replace the thiocynate, then we got two compounds 5 and 6 with hexanuclear.2,6-bis(3,5-dimethyl-N-pyrazolyI)pyridine, CoⅡ, NiⅡ and thiocyanate were reacted to get two complexes. React these complexes with Tp to replace the thiocynate, then got two cyano-brid ged extended square-type hexanuclear complex 7 and 8. Magnetic tests showed that all these four complexes display strong ferromagnetic couple interactions.