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Structural Tailoring Effects on the Magnetic Behavior of Symmetric and Asymmetric Cubane-Type Ni complexes
작성자 작성일 2013-06-05 조회수 1166
Chemistry – An Asian Journal Volume 8, Issue 6, pages 1152–1159, June 2013

  • Structural Tailoring Effects on the Magnetic Behavior of Symmetric and Asymmetric Cubane-Type Ni complexes (Alexey N. Ponomaryov, Namseok Kim, Jaewon Hwang, Prof. Hiroyuki Nojiri, Dr. Johan van Tol, Dr. Andrew Ozarowski, Jena Park, Prof. Zeehoon Jang, Byoungjin Suh, Prof. Sungho Yoon(교신저자), Prof. Kwang-Yong Choi) Chemistry – An Asian Journal  Volume 8, Issue 6, pages 1152–1159, June 2013


     

     

    Using two kinds of carboxylate ligands with small but significant differences in steric size, symmetric and asymmetric FeII and NiII cubanes have been synthesized in a controlled fashion. Fast sweeping pulsed field measurements showed magnetization hysteresis loops for two cubane-type molecular complexes, [Ni4(μ-OMe)4(O2CAr4F-Ph)4(HOMe)8] and [Ni4(μ-OMe)4(O2CArTol)4(HOMe)6], thus suggesting single-molecule magnet behavior. To differentiate the magnetic properties between the symmetric and asymmetric cubanes, detailed electron paramagnetic resonance (EPR) measurements were performed. From the EPR data, taken at various frequencies and temperatures, zero-field splitting parameters D, E, and other higher-order parameters for both cubane samples were extracted. Compared to the symmetric Ni-cubane, the asymmetric one shows an increase in the D and E values by about 20%, thereby suggesting structural engineering effects on the magnetic properties. By using the magnetic parameters determined by EPR, a static magnetization curve at 2K and a temperature dependence of the magnetic susceptibility were simulated. A good agreement between theoretical and experimental data confirms the validity of the values obtained from EPR measurements

     



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