2-Amino-1,3-propanediol Ligand System For High-spin Mixed Valencemanganese Cluster:Preparation And Magnetic Characterization

The magnetic material is extremely important in the modern society, it is related toall aspects of information technology, automation, country defense, and nationaleconomy. The mechanism of magnetization of the conventional magnetic material iscaused due to its internal magnetic domain. Magnetic domain occur spontaneously inmagnetic material within a structural unit which has random directions of magneticmoments. When the external magnetic field is increased to a certain extent, all themagnetic moments of the magnetic domains are in the same direction, the material hasreached a magnetic saturation.In recent years, the development of a new molecular level magnetic materialsSMMs is being attended. Different from classic magnets mechanism, single-moleculemagnet generate magnetic relaxation phenomena from spin ground state and themagnetic anisotropy of the clusters. SMMs can be defined as: under the appliedmagnetic field are magnetized, and in the removal of the applied magnetic field thereis a certain residual magnetism; it must be the nature of the single molecule, namelythe state spin values and the anisotropy determined, and not caused by intermolecularinteractions or the long-range order. There are several typical magnetic properties ofsingle-molecule magnets:(1) Below the critical temperature, the macro magnetmagnetic hysteresis performed.(2)The intermolecular interaction is weak, can beapproximated as a zero-dimensional system.(3) Below the critical temperature, whenthe external magnetic field is removed, the magnetic attenuation is very slow.SMMsas molecular-level material, it keep the classic magnets similar macroscopic magneticproperties, which makes the development of single-molecule magnets have extremelybroad application prospects.In nearly two decades, many single-molecule magnet compounds weresynthesized, which attracted our attention to the synthesis is the high-spin mixedvalence manganese metal clusters. Study of the structural features of such substances,and directed synthesis of compounds of a similar nature has become the focus of ourstudy.The second chapter of the papers discussed in detail by changing the manganesesource,we successfully synthesis four manganese clusters using the2-amino-1,3-propanediol ligand.We make a detailed characterization and study of the structures of the four compounds, synthetic condition, and magnetic properties. Revealing the factthat different coordinating anion, by the influence of the weak chemical bond, haschanged the structure of the compound. It is worth noting that, the compound3has arare structure that Mn3structural units are connected to form a chain through sharedbivalent manganese atoms inclusive compound in1,3-propanediol ligand system. Bycomparison of compound2and compound3, illustrate the point of view that thereaction kinetics and thermodynamic competition exists in the self-assembly processof coordination chemistry.The third chapter discussed in detail by chemical modification of2-amino-1,3-propanediol, we successfully synthesised a one-dimensional chain, two-dimensionalmesh, two-dimensional tubular three compounds. For Compound5, the larger steric-hindrance of the ligand cause no greater space to accommodate more atom or a ligandin the ligand structure, resulting a linear Bridged Br ion. Through2-amino-1,3-propanediol benzene sulfonyl modification, we synthesis compound6which has atwo-dimensional mesh structure.Trough methylbenzenesulfonyl modification of,2-amino-1,3–propanediol, we synthesis compound7which has a two-dimensionaltubular structure. Comparing compound6and7, the two ligands’ minor differences-methylation or not determines whether the product is curled into a tubular shape. Ifthe layered structure is stacked in the compound7, the π-π interaction can not reachthe maximum, so that the compound curl into a tubular shape. It can be concluded that,instead of physical pressure differential chemical interactions can change the structureof a compound similar to the same as the macroscopic world. The tubular structure isfinally generated or not depending on the layer structure of the arrangement and theinterlayer forces.