2021 Fiscal Year Research-status Report
3D spatial imaging of chirality using nuclear magnetic resonance (NMR)
| Project/Area Number |
19K05229
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
Labuta Jan 国立研究開発法人物質・材料研究機構, 国際ナノアーキテクトニクス研究拠点, 主任研究員 (00720690)
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| Project Period (FY) |
2019-04-01 – 2023-03-31
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| Keywords | Porphyrin / Chirality / Phase Separation / pH-responsivness / NMR / Chemical kinetics / Singlet oxygen |
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| Outline of Annual Research Achievements |
In FY2021, we have investigated chirality transfer and determination of enantiomeric excess (ee) in host-guest systems. The host (an ee-detector) was mainly a porphyrin-type unit in an organic solvent. Based on our previous experiences, the ee-detection in aqueous solutions is challenging. Therefore, we have also prepared a water-soluble porphyrin molecule. This molecule has a star shape with a central tetraphenylporphyrin (TPP) unit having four poly(N-isopropylacrylamide) (PNIPAM) arms. We have investigated physical properties of these molecules, including phase separation (LCST type behaviour), pH responsiveness, formation of 1D supramolecular polymers, etc. We have also investigated the kinetics of meso-chiral interconversion in overcrowded alkene rotor molecule (FDF), which is tunable by solvent properties. We have shown that FDF in various solvents has uneven populations of meso and chiral form in a slow exchange mode at room temperature. Moreover, FDF in aromatic solvents preferentially adopts a meso-form, whereas in non-aromatic solvents, a chiral form is preferred. This effect is attributed to solvophobic interactions between solvent molecules and peripheral hexyl chains of FDF, as revealed by extensive molecular dynamics (MD) simulations. These findings have connections in various fields of organic chemistry, such as the design of artificial molecular machines based on sterically crowded alkenes, solvent properties scales, enantioenrichment reactions, and asymmetric or stereoselective reactions.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
The final stage of the research plan is behind schedule due to the postponement of the 3D NMR measurements at the collaborating institution (Charles University, Czech Republic) due to the travel restrictions caused by the covid-19 situation. Therefore, the budget for these essential measurements was transferred to next year (FY2022), and the project was extended for one more year.
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| Strategy for Future Research Activity |
In FY2022, we plan to perform 3D NMR experiments at the state-of-art NMR facility located at Charles University, Prague, Czech Republic. Various NMR experiments involving the detection of chirality, solvent/temperature responsiveness, and generation of contrast in NMR imaging measurements will be tested in detail. Obtained data will be subject to advanced processing in order to generate 2D or 3D maps (images) of chirality distribution. The data processing computer codes for reliable image generation will also be developed. Obtained results will be published in peer-reviewed journals.
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| Causes of Carryover |
Due to the travel restrictions caused by the covid-19 situation, the 3D NMR measurements at the collaborating institution (Charles University, Czech Republic) were suspended. The budget was transferred to next year and will be used to perform these essential experiments in FY2022.
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Research Products
(8 results)
