2017 Fiscal Year Annual Research Report
Development of porous magnets with electron donor/acceptor metal–organic frameworks
| Project/Area Number |
17J02497
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| Research Institution | Tohoku University |
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Principal Investigator |
張 俊 東北大学, 理学研究科, 特別研究員(DC1)
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| Project Period (FY) |
2017-04-26 – 2020-03-31
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| Keywords | magnetic sponge / Curie temperature (Tc) / electronic state |
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| Outline of Annual Research Achievements |
A reversible magnetic change induced by guest molecules is desirable in the fields of both metal-organic frameworks/porous coordination polymers(MOFs/PCPs) and molecule-based magnets. The magnetic sponge behavior via electronic state modulations was achieved in a new D2A-type-layered magnet,[{Ru2(O2CPh-2,3,5-Cl3)4}2(TCNQMe2)]-4DCM (1; 2,3,5-Cl3PhCO2－ = 2,3,5-trichlorobenzoate; TCNQMe2 = 2,5-dimethyl-7,7,8,8-tetracyanoquinodimethane, DCM = dichloromethane), where [Ru2(O2CPh-2,3,5-Cl3)4] ([Ru2II,II]) is an electron-donor (D) and TCNQMe2 is an electron-acceptor (A). Compound 1 had a 1e-I state. Strong intra-layer antiferromagnetic couplings between [Ru2] and TCNQMe2, as well as ferromagnetic interlayer interactions, induced long-range ferrimagnetic ordering at Tc = 101 K. Interstitial DCM molecules were located between layers, and these were gradually eliminated under vacuum at 80 °C to form a solvent-free compound (1-dry) without loss of crystallinity. The electronic state of 1-dry thermally fluctuated and eventually provided a charge-disproportionate disordered state, 1.5e-I. The Tc in 1-dry was 34 K. A large Tc variation with about 70 K was switchable; switching was achieved by charge state modulations accompanied with subtle structural modifications in solvation/desolvation treatments.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
My research plan is to realize deliberate control of the physical properties such as magnetism and electrical conductivity via guest molecule sorption. Last year, the first compound 1 was synthesized. It showed large Tc variation with about 70 K, which was achieved by charge state modulations accompanied with subtle structural modifications in solvation/desolvation treatments. This is just one example of magnetic sponges, for which the magnetic properties were tuned by solvation/desolvation. Additionally, other compounds were also be prepared. The magnetic phase could be controlled by solvent or a simple, ubiquitous gas such as O2, N2, and CO2. This work is now under way.
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| Strategy for Future Research Activity |
Electronic-state-sensitive, porous materials are a new class of functional porous materials. Previously, we found examples of magnetic sponges, for which the magnetic properties were tuned by charge state modulations accompanied with subtle structural modifications in solvation/ desolvation treatments. Next, we'd like to focus the guest molecule on a simple, ubiquitous gas such as O2, N2, and CO2 to control the magnetic phase. Because gas molecules are relatively small compared with solvent. So, they are easy to handle. And MOFs always show gate-opening behavior for different gas molecules, which is propitious to adjust physical properties. Besides, the paramagnetic O2 could adjust the inter-layer magnetic interaction in two-dimensional frameworks.
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