Assembly And Magnetic Behavior Modulation Of Low Dimensional Rare Earth Molecule-Based Magnets

Rare earth-nitronyl nitroxide complexes with4f and2p spin carriers are fascinating to molecule-based magnets. Twenty-seven rare earth radical-based complexes have been constructed from five unpresented nitronyl nitroxides. The magnet-behavior and slow magnetic relaxation modulated by corresponding structures have been investigated.1. Two families of monomeric and one-dimensional (1D) RE-radical complexes have been synthesized by NIT-5-ThienPh. Three1D molecule-based magnets are formed through linking paramagnetic monomers as building blocks, and the transformation between the monomer and polymer exampled by the DyⅢ complexes is chemically controllable and reversible, indicating that actions inter-and intra1D chains are important for magnet-behaviors. A useful synthetic strategy is proposed to tune the magnetic behaviors including the slow magnetic relaxation and long-range magnetic ordering in chain-like compounds by varing metal ions.2. Further research on the position-isomer ligand of NIT-4-ThienPh provides an opportunity to tune magnet-behaviors. Two series of isomeric monomer and chain-like complexes, respectively, have been synthesized, confirming that actions intra1D chain play an important role toward slow magnetic relaxation.In comparison with the1D magnets based on NIT-5-ThienPh, NIT-4-ThienPh ligated TbⅢ complex exhibits higher blocking temperature, the DyⅢ complex shows an enhanced coercive field, and the HoⅢ complex reveals slow magnetic relaxation instead of long-range ordering.3.Various OD molecules are obtained based on the ligands of NIT-biThien/NIT-Thiazole including the first unchelated mononuclear two-spin with slow magnetic relaxation through metal-radical approach, which provides a way to study the magneto-structural relationship. Four DyⅢ dinuclear clusters ligated by NIT-PyNO are synthesized, magneto-structural relationship study of which indicates that the slow magnetic relaxation of dimer can be tuned to ON or OFF state modulated by the packing mode and ligand field. In this thesis, the area of1D rare earth molecule-based magnets is expanded, the magnetic behaviors of which are modulated by the metal ions, exchange interactions and position-isomer ligand; the research on OD rare earth radical-based complexes is investigated, the slow magnetic relaxations of which are tuned to ON/OFF state by local coordination field and intermolecular interactions.The design for the improvement of molecule-based magnets on theoretical and experimental proof is developed.