2013 Fiscal Year Annual Research Report
巨大有機分子の光化学物性を扱うための励起状態分子動力学法の開発
| Project/Area Number |
12F02333
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| Research Institution | Nagoya University |
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Principal Investigator |
IRLE Stephan 名古屋大学, トランスフォーマティブ生命分子研究所, 教授
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| Co-Investigator(Kenkyū-buntansha) |
KOWALCZYK Timothy D. 名古屋大学, トランスフォーマティブ生命分子研究所, 外国人特別研究員
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| Keywords | Excited states / DFTB / Organic electronics / COF / Fullerenes / Intermolecular interactions |
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| Research Abstract |
We employed simulations based on density functional theory (DFT) and density functional tight binding (DFTB) to characterize structural and electronic properties of self-assembling organic molecular architectures of several varieties. In a flexible organic chromophore developed by collaborators in the Yamaguchi group, we identified a correlation between calculated excited state redshifts and experimental fluorescence wavelgenths, supporting the hypothesis of excimer formation in the excited state. We also showed through periodic DFTB simulations that small intercalating molecules can effectively tune the band gap in covalent organic frameworks.
Furthermore, direct dynamics simulations of C_2 loss in C_<62> and C_<72> fullerenes support the proposed size-down synthesis mechanism as the final step of C_<60> and C_<70> fullerene formation. We also studied the effect of intermolecular stacking on aromaticity in porphyrinoid complexes to demonstrate that the stability of a formally antiaromatic, recently synthesized Ni(II) norcorrole is due to a reduction in antiaromaticity upon stacking, rather than a metal-metal bonding effect. Finally, to develop a fuller understanding of how intermolecular interactions alter excited state properties in organic molecules, we developed and implemented a new strategy called △DFTB to rapidly evaluate excited state energies and forces.
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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
Regarding both the method development and application sides of this project, we have completed most of our intended research goals and reported on several of the projects at international conferences thanks to support from the Grant-in-Aid. We changed the focus of method development from constrained DFTB to ADFTB ; however, these techniques both extend the arsenal of methods for excited states in DFTB, so the ultimate goal of that research topic was still achieved. Three manuscripts describing work carried out during H25 were published earlier this year, and additional manuscripts are in preparation.
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| Strategy for Future Research Activity |
We will complete manuscripts describing the antiaromatic stacking and excimer formation projects later this year. I will follow through with the ongoing extensions of the work as I establish an independent laboratory at Western Washington University in the USA. I also intend to report on the work carried out during my time in Japan at the American Conference of Theoretical Chemistry in July. One important way in which I hope to extend this research in the future is to interface the △ADFTB approach with rare-event simulation techniques to probe the photostability of organic chromophores from first principles.
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Research Products
(3 results)
