| Project/Area Number |
17350073
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Functional materials chemistry
|
|---|
| Research Institution | Osaka City University |
|---|
Principal Investigator |
SHIOMI Daisuke Osaka City University, Graduate School of Science, Associate Professor, 大学院理学研究科, 助教授 (40260799)
|
|---|
| Project Period (FY) |
2005 – 2006
|
| Project Status |
Completed (Fiscal Year 2006)
|
| Budget Amount *help |
¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 2006: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2005: ¥4,500,000 (Direct Cost: ¥4,500,000)
|
|---|
| Keywords | molecule-based magnet / organic magnet / radical / ferrimagnet / nitronyl nitroxide / magnetic susceptibility / electron spin resonance / ESR / EPR |
|---|
| Research Abstract |
Construction of genuinely organic molecule-based ferrimagnets as an exotic magnetic material has been a challenging issue in materials science and spin chemistry during last decades. A practical difficulty in constructing organic molecule-based ferrimagnetics is co-crystallization of two kinds of molecules with different spin quantum numbers S's, e.g., S=1 and S=1/2. We propose a supramolecular approach to the co-crystallization. Noncovalent bonding such as hydrogen bonding and coulombic interaction between ionic charges can be a driving force for crystallization of open-shell molecules with differing S's, e.g., biradical (S=1) and monoradical (S=1/2).
We have designed and synthesized nitronyl-and imino-nitroxide biradicals with pyridine and aniline substituents as S=1 components for the supramolecular ferrimagnets. The neutral biradicals of 2,6- and 3,5-substituted pyridines and anilines were synthesized. The cationic biradicals were prepared by N-methylation of the neutral precursors. The molecular ground states of of the neutral biradicals and the salts with closed-shell anions were found to be triplet (S=1) from magnetic susceptibility measurements. Therefore, both the neutral biradicals and the cations serve as building blocks for organic supramolecular ferrimagnets.
One of the the neutral biradicals, the 3,5-pyridine derivative of nitronyl nitroxide was found to co-crystallize with p-benzoic acid substituted monoradical. The hydrogen-bonded complex undergoes an antiferromagnetic phase transition at 5 K. The nature and the origin of the phase transition have been clrified on the basis the X-ray crystal structure and magnetic susceptibility measurements on aligned single crystals.
|
