2020 Fiscal Year Research-status Report
Reactions of Super Reductants and Oxidants Explored by Ultrafast Spectroscopy
| Project/Area Number |
19K21127
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| Research Institution | Osaka University |
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Principal Investigator |
LU CHAO 大阪大学, 産業科学研究所, 助教 (90828112)
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | Excited Ions / Electron Transfer / Laser Flash Phtolysis / Physical Chemistry / Photochemistry |
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| Outline of Annual Research Achievements |
Fullerenes have become essential organic functional materials in a broad range of fields, including organic field-effect transistors, organic photovoltaics, and organic light-emitting diodes, etc., resulting from their high electron affinities and excellent electron transport properties. On the other hand, in organic optoelectronics and nanotechnology, origins of mobile charges play significant roles. Particularly, the information on the specific e.g. divalent ions of fullerenes is of great importance when taking into account of the roles of charge carriers in related n-type organic conductors, although the focused investigation is exceedingly scarce.
With the stepwise addition of trimethylhydroquinone dianion, a near-IR absorption band was clearly confirmed at approximately 1100 nm, which can be attributed to the generation of C60 radical anion. Interestingly, with a further increase of reductant, the 1100 nm peak decreased in intensity whereas a new signal at approximately 950 nm showed a rise. This phenomenon can be attributed to the generation of C60 dianion. Essentially the same phenomenon with the confirmation of C70 dianion was observed. The analogical generation of C60 and C70 dianions can be explained by a stepwise chemical reduction strategy.
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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
In this research project, the unprecedented properties and various charge transfer processes caused by excited radical ions/excited divalent ions as the super reductants and super oxidants are planned to be explored. The purposes of this research project are the clarification of excited-state dynamics and reaction mechanisms of excited radical ions/excited divalent ions and the exploration of their application for various redox systems to establish a new science field of super reductants and super oxidants.
In the current study, the reduction of fullerenes by trimethylhydroquinone dianion occurred via stepwise electron transfer from trimethylhydroquinone dianion to C60 and C70. A reliable method that selectively generates the C60 and C70 dianions was thus established for the subsequent femtosecond laser measurement of their excited states.
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| Strategy for Future Research Activity |
Characteristics of the excited states of excited divalent ions will be clarified compared with those of the corresponding excited mono radical anions or cations by using the femtosecond transient spectroscopy. Based on the detected dynamics and redox potentials, molecular systems for studying the charge transfer from excited divalent ions as the newly developed super redox agents will also be designed.
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| Causes of Carryover |
I need to prolong the period of my research project because I have recently moved my position with the research place. I need more time to adapt to the new environment and carry out my research. Usage plan will be mainly focused on the excited states of excited divalent ions compared with those of the corresponding excited mono radical anions or cations by using the femtosecond laser measurement.
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