Thesis or Dissertation Study on the Structures and Magnetic Properties of Ground High-Spin 3d Homonuclear and 3d-4f Heteronuclear Complexes

井田, 由美  ,  イダ, ユミ  ,  Ida, Yumi

pp.1 - 115 , 2016-03-25 , The University of Electro-Communications
Description
This doctor thesis is written about the structural and magnetic study on the complexes related to single-molecule magnets (SMMs). SMMs have been attractive molecules due to their potential applications for information storage and quantum computing at the molecular level. Large magnetic moment and strong uniaxial magnetic anisotropy are required for SMMs. The author succeeded to prepare some novel compounds and precisely determined the magnetic parameters by means of magnetizations, magnetic susceptibilities, and electron paramagnetic resonance (EPR) techniques.The author studied the structure and magnetic properties of a novel nickel(II) trinuclear complex as well as two known related compounds. They possess the ground high-spin state and a uniaxial magnetic anisotropy, which are favorable for SMMs. However, they also showed intermolecular antiferromagnetic couplings through the weak halogen...halogen contacts. One of these complexes was characterized as a pseudo one-dimensional antiferromagnetic chain, and another as a ground antiferromagnet. The magnetic hysteresis was observed at the metamagnetic-like magnetization jump and not at zero field. The author concluded that the compounds were potential SMMs with considerable intermolecular antiferromagnetic interaction.For a heterospin 4f-3d system, the author et al. synthesized three new complexes involving one dysprosium(III) and two copper(II) ion as a magnetically interacting unit. The structural analysis of them clarified double oxygen bridges between the Dy and Cu ions. The magnetic study revealed the presence of Dy?Cu ferromagnetic interactions together with the SMM behavior.From the high-frequency EPR study the author found that the copper signal was biased owing to the exchange interaction from the dysprosium ion. The exchange coupling parameters were precisely determined from these exchange biases. To investigate magneto-structure relation, two additional data were taken from the literature, and the author attempted to draw a few plots of the exchange parameter as a function of geometrical parameters. Meaningful correlations were found when the Dy?O?Cu angle and Dy?O???O?Cu dihedral angle were applied. Though it is only empirical, such a magneto-structure relation has been proposed in Dy?Cu systems for the first time.In conclusion, the magnetic properties of the Ni3 and DyCu2 complexes were studied in detail in connection with the crystal structures. The present results would assist comprehension of SMMs and accelerate development of novel SMMs.
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