2018 Fiscal Year Research-status Report
Switching of Orbital Angular Momentum Using the Dynamic Bond
| Project/Area Number |
18K14244
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| Research Institution | Kyushu University |
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Principal Investigator |
SU SHENGQUN 九州大学, 先導物質化学研究所, 特任助教 (90817496)
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Keywords | dynamic bond / orbital angular momentum / coordination number |
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| Outline of Annual Research Achievements |
The purpose of this research project is controlling the orbital angular momentum contribution using the dynamic bond to realize a large magnetic change. The dynamic bond could switch the coordination number and bring abrupt changes in the ligand field. After we tried a series of polyoxoions with multiple coordination modes as anions, now we have obtained a cobalt(II) complex that exhibits 10-11% change of the magnetization with the changing of coordination numbers from six to seven, which is attained by switching between bonding and dissociation of the coordination bond Co-O. The nitrate ion acts as the donor of the dynamic bond in response to the temperature. In the easy axis, the magnetic change is about 20% in the easy axis. The change of magnetization can only be explained as a result of the modulation of the orbital angular momentum. The ab initio calculations indicated that the magnetic changes come from the contribution of the unquenched orbital angular momentum. It is the largest change reported in here from the contribution of the orbital angular momentum. Structural analysis and theoretical calculations further confirm that the dynamic bond is the crucial structure responsible for the magnetic change, which further suggests that using the dynamic bond is an effective way to tune the orbital angular momentum as expected.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
For a long time, our group mainly focused on developing molecular switches based on coordination complexes, especially spin-crossover compounds involving transition metal ions (3d4-3d7 transition metal complexes). A series of spin-crossover complexes (mono- and multi-nuclear) responsive to temperature or light have been synthesized, characterized, and well-studied. We can make full use of those multidentate ligands and methods of synthesis. This should be the main reason for the smooth progress of this research. In addition, we have a good grasp of the related magnetic characterizations, magnetic theories and the magnetic-structure relationship of metal complexes. Convenient test conditions, such as H-NMR, single-crystal x-ray diffraction and magnetic measurement instruments are also important.
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| Strategy for Future Research Activity |
Although we have obtained a complex with magnetic switching as expected, the evidence of the contribution of the orbital angular momentum on the magnetic changes is mainly dependent on the theoretical calculations. To further understand magnetic variations and verify calculation results, the other characterizations, such as, HF-EPR and XMCD, which are the most effective methods to characterizing the contribution of the orbital angular momentum, are necessary. These measurements may take a lot of time because we need to work with other research institutions with related test conditions. In addition, can we develop more such kind of compounds? We plan to try more strategies including different polyoxoions and mutidentate N-containing ligands to get more target complexes.
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