Research activity information

• Jul. 2023 ACS The Journal of Physical Chemistry Letters Poster Award, Time-Resolved EPR Study on Conformational Changes in Triplet-Triplet Dissociation and Annihilation after Intramolecular Singlet Fission

  Ryota Kusumoto


• Nov. 2022 神戸大学, 学長表彰(財務貢献者), 学長表彰(財務貢献者)

  小堀康博

  財務貢献者

  Others


• Nov. 2021 神戸大学, 学長表彰, 財務貢献者

  小堀康博

  財務貢献

  Others


• Sep. 2019 光化学協会, 第33回光化学協会賞, 電子スピン分極イメージング法の開発による光エネルギー変換機構の解明

  小堀 康博

  小堀康博氏は、植物光合成による光エネルギー変換過程の根源的な仕組みを理解し、超高効率な人工光合成や有機太陽電池に代表される光を入力としたエネルギー変換デバイスの設計指針を得ることを目的とし、時間分解電子スピン共鳴法を用い、I：常磁性サイト間の電子的相互作用メカニズム、II：光電荷分離および一重項励起子分裂による中間体の電子状態、立体構造および運動性を明らかにする実験的手法を確立した。結晶生成が困難であるにもかかわらず、次世代のクリーンエネルギー創出に向け分子機構の解明が必要な様々な反応系で、反応初期過程の仕組みをオングストローム領域の三次元映像化によって明らかにする画期的な実験的方法論を開発した。1) 植物PSIIタンパク質や太陽電池において生成する初期電荷分離状態の不対電子軌道を特定し、2) 中間体分子の距離および位置と分子配向を高い空間分解能にて画像化し、3)不対電子軌道間の重なり、トラップ深さと運動性を特徴付けた。高等植物が光合成による水分解を可能にした初期電荷分離過程における分子論的進化の仕組みが初めて明らかとなった。さらに一重項分裂による多重励起子生成機構の解明を行った。連結二量体の一重項分裂で生成する強相関五重項多重励起子生成の置換位置依存性を見いだし、スピン変換による再結合抑制効果を示した。種々の系で強相関五重項生成過程を調べ、励起子拡散のエントロピー効果によるスピン副準位選択性と多重励起子立体配向を世界に先駆け示すと共に、分子内多重励起子量子ダイナミクスの分子運動効果を特徴づけた。これらの業績は、光化学協会賞に値するものとして認められた。


• Sep. 2019 分子科学会, 第4回分子科学国際学術賞, 電子スピン分極イメージング法による光エネルギー変換機構の解明

  小堀 康博

  分子科学研究分野において量ではなく質的に優れた研究業績をあげ、国際的に高く評価されている研究者として高い水準の研究業績をあげ、国を超える分子科学の発展に大きな貢献を果たした功績が認められ、小堀教授が分子科学会｛会員数1506名(2019年)｝より第4回分子科学国際学術賞を授与されました。小堀教授は生体や太陽電池の様々な系で生成する励起子･電荷による光エネルギー変換機構の詳細を明らかにしました。次世代エネルギー源の分子設計に極めて重要な独創的成果を挙げたことが国際的にも評価され受賞につながりました。 2013年より本学理学研究科化学専攻教授に着任し、光合成タンパク質や太陽電池を対象とする励起子･光電荷分離構造解析と電子スピン分極イメージング法の開発を進めました。2017年に中間体分子の距離および位置と分子配向を高い空間分解能にて画像化し、さらに電子軌道の重なりや運動性を特徴付けたことにより、高等植物が光合成による水分解を可能にした初期電荷分離過程における分子論的進化の仕組みを示しました。さらに近年では、一重項励起子分裂による多重励起子生成機構の解明でも顕著な研究業績を次々と挙げています。これらは太陽電池の超高効率化に道を拓く多重励起子生成機構(DOI: doi.org/10.1073/pnas.1820932116他)や量子コンピューティングの先端領域(DOI:10.1021/jacs.8b13155他)で国際的に大きな影響を与えています。これらの成果は超高効率な人工光合成や有機太陽電池などの光エネルギー変換デバイスの開発に大きな契機をもたらすものです。


• Nov. 2017 電子スピンサイエンス学会, 第56回電子スピンサイエンス学会年会(SEST2017) 優秀ポスター賞2, アフリカツメガエル由来クリプトクロムに生成する光電荷分離状態の電子的相互作用

  濱田 実里, KOBORI YASUHIRO

  Japan society


• Oct. 2017 化学フェスタ実行委員会, 最優秀ポスター発表賞（CSJ 化学フェスタ賞）, 時間分解EPR 法による室温リン光発光性有機包接結晶の励起三重項状態の電子構造

  江間 文俊, KOBORI YASUHIRO

  Japan society


• Sep. 2017 光化学協会, 2017年光化学討論会 優秀学生発表賞（ポスター）2, Time-Resolved EPR Study on Photoinduced Charge-Transfer Trap State in Thiophene-Thiazolothiazole Copolymer Film

  山本 雄大, KOBORI YASUHIRO

  International society


• Nov. 2016 一般社団法人 電子スピンサイエンス学会, 第55回電子スピンサイエンス学会年会 優秀発表賞, 時間分解EPR 法による有機包接室温強リン光発光結晶の励起三重項状態の電子構造

  江間 文俊, KOBORI YASUHIRO

  Japan society


• Sep. 2016 光化学協会, 2016年光化学討論会 優秀学生発表賞(ポスター発表), 時間分解電子スピン共鳴法によるチオフェンーチアゾロチアゾールコポリマー：PCBM有機薄膜における電荷分離状態の立体構造とダイナミクス

  阿児 拓海, KOBORI YASUHIRO

  International society


• Aug. 2016 Organizing Committee of Asia-Pacific EPR/ESR Symposium 2016, The 2016 APES AWARD for best talk among young scientists, Electronic Structure of the Excited Triplet State of Hexaphyrins with twisted Mobious Conformation as Studied by TR EPR

  Fumitoshi Ema, Yasuhiro Kobori

  International society


• Jun. 2016 AWEST2016, 2016 The International EPR (ESR) Society Poster Award, Time-domain EPR observations of changes in protein binding structures induced by the amyloid fibrillation of human insulin

  Tomoka ABE, Yasuhiro KOBORI

  International society


• Nov. 2014 The Society of Electron Spin Science and Technology (SEST), SEST Student Research Award of APES-IES-SEST2014, Time-resolved EPR study on the Electronic Structure of the Excited Triplet State of [26] and [28] Hexaphyrins

  江間 文俊, KOBORI YASUHIRO

  International society


• Nov. 2014 International EPR/ESR Society, International EPR/ESR Society Poster Award of APES-IES-SEST2014, Time-resolved EPR study on the Electronic Structure of the Excited Triplet State of [26] and [28] Hexaphyrins

  江間 文俊, KOBORI YASUHIRO

  International society


• Oct. 2014 International Meeting on Spins in Organic Semiconductors, Poster Award of 5th International Meeting on Spin in Organic Semiconductors, Morphology effect of the geometry of the photoinduced charge-separated states in RR-P3HT:PCBM blend films studied by time-resolved EPR

  三浦 拓, KOBORI YASUHIRO

  International society


• May 2014 科学技術振興機構さきがけ「太陽光と光電変換機能」研究領域, 科学技術振興機構さきがけ「太陽光と光電変換機能」領域 総括賞, 第10回領域会議 発表

  KOBORI YASUHIRO

  Japan society


• Aug. 2009 公益信託分子科学研究奨励森野基金, 公益信託分子科学研究奨励森野基金研究助成, 時間分解磁気共鳴分光法を用いた人工光合成およびタンパク質の機能の解明

  KOBORI YASUHIRO

  Publisher


• Nov. 2006 電子スピンサイエンス学会, 電子スピンサイエンス学会奨励賞, 光電荷分離状態の電子スピン間相互作用機構の解明

  KOBORI YASUHIRO

  Japan society

• Anisotropic activations controlling doublet-quartet spin conversion of linked chromophore-radical molecular qubits in fluid

  Yasuhiro Kobori, Yuya Kokado, Kevin Lars Kopp, Tsubasa Okamoto, Masaaki Fuki

  Feb. 2025, Journal of Chemical Physics, 162(5) (5), 054505-1 - 054505-10, English

  [Refereed]

  Scientific journal


• Triazolium-Catalyzed Metal-Free Photochemical Reduction of CO₂ into Formate

  Weibin Xie, Masaaki Fuki, Ayana Sukegawa, Kenji Okunaka, Masahiko Hayashi, Yasuhiro Kobori, Ryosuke Matsubara

  American Chemical Society (ACS), Nov. 2024, ACS Sustainable Chemistry & Engineering, 12(47) (47), 17328 - 17335

  Scientific journal


• Macrocyclic Parallel Dimer Showing Quantum Coherence of Quintet Multiexcitons at Room Temperature

  Wataru Ishii, Masaaki Fuki, Eman M. Bu Ali, Shunsuke Sato, Bhavesh Parmar, Akio Yamauchi, Catherine Helenna Mulyadi, Masanori Uji, Samara Medina Rivero, Go Watanabe, Jenny Clark, Yasuhiro Kobori, Nobuhiro Yanai

  Corresponding, American Chemical Society (ACS), Sep. 2024, Journal of the American Chemical Society, 146(37) (37), 25527 - 25535

  [Refereed]

  Scientific journal


• Nonfullerene Acceptors Bearing Spiro-Substituted Bithiophene Units in Organic Solar Cells: Tuning the Frontier Molecular Orbital Distribution to Reduce Exciton Binding Energy.

  Kai Wang, Seihou Jinnai, Takumi Urakami, Hirofumi Sato, Masahiro Higashi, Sota Tsujimura, Yasuhiro Kobori, Rintaro Adachi, Akira Yamakata, Yutaka Ie

  The development of nonfullerene acceptors (NFAs), represented by ITIC, has contributed to improving the power conversion efficiency (PCE) of organic solar cells (OSCs). Although tuning the electronic structures to reduce the exciton binding energy (Eb) is considered to promote photocharge generation, a rational molecular design for NFAs has not been established. In this study, we designed and developed two ITIC-based NFAs bearing spiro-substituted bithiophene or biphenyl units (named SpiroT-DCI and SpiroF-DCI) to tune the frontier molecular orbital (FMO) distribution of NFAs. While the highest occupied molecular orbitals (HOMOs) of SpiroF-DCI and ITIC are delocalized in the main π-conjugated framework, the HOMO of SpiroT-DCI is distributed on the bithiophene unit. Reflecting this difference, SpiroT-DCI exhibits a smaller Eb than either SpiroF-DCI or ITIC, and exhibits greater external quantum efficiency in single-component OSCs. Furthermore, SpiroT-DCI shows improved PCEs for bulk-heterojunction OSCs with a donor of PBDB-T, compared with that of either SpiroT-DCI or ITIC. Time-resolved spectroscopy measurements show that the photo-induced intermolecular charge separation is effective even in pristine SpiroT-DCI films. This study highlights the introduction of spiro-substituted bithiophene units that are effective in tuning the FMOs of ITIC, which is desirable for reducing the Eb and improving the PCE in OSCs.

  Aug. 2024, Angewandte Chemie (International ed. in English), e202412691, English, International magazine

  [Refereed]

  Scientific journal


• End-to-End Bent Perylene Bisimide Cyclophanes by Double Sulfur Extrusion

  Yuki Tanaka, Keita Tajima, Ryota Kusumoto, Yasuhiro Kobori, Norihito Fukui, Hiroshi Shinokubo

  Corresponding, American Chemical Society (ACS), May 2024, Journal of the American Chemical Society, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Efficient Spin Interconversion by Molecular Conformation Dynamics of a Triplet Pair for Photon Up-Conversion in an Amorphous Solid

  Tsubasa Okamoto, Seiichiro Izawa, Masahiro Hiramoto, Yasuhiro Kobori

  American Chemical Society (ACS), Mar. 2024, The Journal of Physical Chemistry Letters, 15(11) (11), 2966 - 2975

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Double Hydrogen Atom Transfer Strategy for Catalytic Acceptorless Dehydrogenation of Cycloalkanes

  Rahul Jagtap, Yuki Nishioka, Stephen Geddis, Yu Irie, Fuki Masaaki, Yasuhiro Kobori, Rintaro Adachi, Akira Yamakata, Harunobu Mitsunuma, Motomu Kanai

  The advancement of an effective hydrogen liberation tech-nology from liquid organic hydrogen carriers (LOHCs), such as cyclohexane and methylcyclohexane (MCH), holds significance in realizing a hydrogen-centric society. However, the attainment of homogeneous catalytic acceptorless dehydrogenation (CAD) characterized by elevated selectivity for thorough aromatization under mild conditions remains unrealized. In this study, a catalyst system, facilitated by a double hydrogen atom transfer (HAT) processes, has been devised for the CAD of inert cycloalkanes at ambient temperature under visible light irradiation. Through the synergistic utilization of tetrabutylammonium chloride (TBACl) and thiophosphoric acid (TPA) HAT catalysts, successful CAD with comprehensive aromatization has been accomplished with high functional group tolerance.

  American Chemical Society (ACS), Feb. 2024


• The Effect of Torsional Motion on the Quintet Multiexciton Formation through Intramolecular Singlet Fission in Ferrocene-Bridged Pentacene Dimers.

  Ryo Hayasaka, Hayato Sakai, Masaaki Fuki, Tsubasa Okamoto, Ramsha Khan, Masahiro Higashi, Nikolai V Tkachenko, Yasuhiro Kobori, Taku Hasobe

  A series of ferrocene (Fc)-bridged pentacene (Pc)-dimers [Fc-Ph(2,n)-(Pc)2: n shows the number of phenylene spacers] were synthesized to examine the tortional motion effect of Fc-terminated phenylene linkers on the strongly coupled quintet multiexciton (5TT) formation through intramolecular singlet fission (ISF). Fc-Ph(2,4)-(Pc)2 has the relatively small electronic coupling and large conformational flexibility according to spectroscopic and theoretical analyses. Fc-Ph(2,4)-(Pc)2 exhibits high-yield 5TT together with quantitative singlet TT (1TT) generation through ISF. This demonstrates much more efficient ISF than those of the other less flexible Pc-dimers. The activation entropy in 1TT spin conversion of Fc-Ph(2,4)-(Pc)2 is larger than those of the other systems due to the larger conformational flexibility, associated with the torsional motion of the linkers. The torsional motion of linkers in 1TT is attributable to weakened metal-ligand bonding in the Fc due to hybridization of hole level of Pc to Fc in 1TT unpaired orbitals.

  Corresponding, Jan. 2024, Angewandte Chemie (International ed. in English), 63(8) (8), e202315747, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Room-temperature quantum coherence of entangled multiexcitons in a metal-organic framework.

  Akio Yamauchi, Kentaro Tanaka, Masaaki Fuki, Saiya Fujiwara, Nobuo Kimizuka, Tomohiro Ryu, Masaki Saigo, Ken Onda, Ryota Kusumoto, Nami Ueno, Harumi Sato, Yasuhiro Kobori, Kiyoshi Miyata, Nobuhiro Yanai

  Singlet fission (SF) can generate an exchange-coupled quintet triplet pair state 5TT, which could lead to the realization of quantum computing and quantum sensing using entangled multiple qubits even at room temperature. However, the observation of the quantum coherence of 5TT has been limited to cryogenic temperatures, and the fundamental question is what kind of material design will enable its room-temperature quantum coherence. Here we show that the quantum coherence of SF-derived 5TT in a chromophore-integrated metal-organic framework (MOF) can be over hundred nanoseconds at room temperature. The subtle motion of the chromophores in the MOF leads to the enough fluctuation of the exchange interaction necessary for 5TT generation, but at the same time does not cause severe 5TT decoherence. Furthermore, the phase and amplitude of quantum beating can be controlled by molecular motion, opening the way to room-temperature molecular quantum computing based on multiple quantum gate control.

  Corresponding, American Chemical Society (ACS), Jan. 2024, Science advances, 10(1) (1), eadi3147, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Boosting charge separation in organic photovoltaics: unveiling dipole moment variations in excited non-fullerene acceptor layers

  Akira Yamakata, Kosaku Kato, Takumi Urakami, Sota Tsujimura, Kasumi Murayama, Masahiro Higashi, Hirofumi Sato, Yasuhiro Kobori, Tomokazu Umeyama, Hiroshi Imahori

  Neat ITIC films are found to facilitate charge transfer, dissociation, and free carrier formation without the need for donor layers. This process, driven by V-type molecular stacking, significantly boosts organic photovoltaic efficiency.

  Royal Society of Chemistry (RSC), 2024, Chemical Science, 15(32) (32), 12686 - 12694

  Scientific journal


• Visible-light-induced Direct C–H Alkylation of Polycyclic Aromatic Hydrocarbons with Alkylsulfones

  Masakazu Nambo, Motoo Ohtsuka, Koushik Ghosh, Jacky C.-H. Yim, Hikaru Sotome, Tsubasa Okamoto, Kayo Suda, Yasuhiro Kobori, Daisuke Yokogawa, Hiroshi Miyasaka, Cathleen Crudden

  Polycyclic aromatic hydrocarbons (PAHs) are fragments of graphene that have attracted considerable attention as a new class of carbon-based materials. The functionalization of edge positions in PAHs is important to...

  Royal Society of Chemistry (RSC), 2024, Chemical Science, 15(27) (27), 10592 - 10599, English, International magazine

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Photoisomerization of "Partially Embedded Dihydropyridazine" with a Helical Structure.

  Kazuteru Usui, Ami Amano, Kasumi Murayama, Miho Sasaya, Ryota Kusumoto, Tomohiro Umeno, Satsuki Murase, Naoko Iizuka, Shota Matsumoto, Yasufumi Fuchi, Kazuyuki Takahashi, Masatoshi Kawahata, Yasuhiro Kobori, Satoru Karasawa

  Invited for the cover of this issue are the groups of Kazuteru Usui and Satoru Karasawa at Showa Pharmaceutical University and Yasuhiro Kobori of Kobe University. The image depicts chirality control of helical compounds through cycles of photocleavage and recombination under sunlight with a "Jack and the Beanstalk" motif. Read the full text of the article at 10.1002/chem.202302413.

  Corresponding, Nov. 2023, Chemistry (Weinheim an der Bergstrasse, Germany), 29(62) (62), e202303311, English, International magazine

  [Refereed]

  Scientific journal


• Biomimetic design of an α-ketoacylphosphonium-based light-activated oxygenation auxiliary.

  Ryoto Oya, Kenji Ota, Masaaki Fuki, Yasuhiro Kobori, Masahiro Higashi, Kazunori Nagao, Hirohisa Ohmiya

  The biomimetic design of a transition metal complex based on the iron(iv)-oxo porphyrin π-cation radical species in cytochrome P450 enzymes has been studied extensively. Herein, we translate the functions of this iron(iv)-oxo porphyrin π-cation radical species to an α-ketoacyl phosphonium species comprised of non-metal atoms and utilize it as a light-activated oxygenation auxiliary for ortho-selective oxygenation of anilines. Visible light irradiation converts the α-ketoacyl phosphonium species to the excited state, which acts as a transiently generated oxidant. The intramolecular nature of the process ensures high regioselectivity and chemoselectivity. The auxiliary is easily removable. A one-pot protocol is also described.

  Oct. 2023, Chemical science, 14(38) (38), 10488 - 10493, English, International magazine

  Scientific journal


• Metal-free reduction of CO2 to formate using a photochemical organohydride-catalyst recycling strategy.

  Weibin Xie, Jiasheng Xu, Ubaidah Md Idros, Jouji Katsuhira, Masaaki Fuki, Masahiko Hayashi, Masahiro Yamanaka, Yasuhiro Kobori, Ryosuke Matsubara

  Increasing levels of CO2 in the atmosphere is a problem that must be urgently resolved if the rise in current global temperatures is to be slowed. Chemically reducing CO2 into compounds that are useful as energy sources and carbon-based materials could be helpful in this regard. However, for the CO2 reduction reaction (CO2RR) to be operational on a global scale, the catalyst system must: use only renewable energy, be built from abundantly available elements and not require high-energy reactants. Although light is an attractive renewable energy source, most existing CO2RR methods use electricity and many of the catalysts used are based on rare heavy metals. Here we present a transition-metal-free catalyst system that uses an organohydride catalyst based on benzimidazoline for the CO2RR that can be regenerated using a carbazole photosensitizer and visible light. The system is capable of producing formate with a turnover number exceeding 8,000 and generates no other reduced products (such as H2 and CO).

  Corresponding, Mar. 2023, Nature chemistry, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Nonpolymer Organic Solar Cells: Microscopic Phonon Control to Suppress Nonradiative Voltage Loss via Charge-Separated State.

  Takaaki Nagatomo, Ajendra K Vats, Kyohei Matsuo, Shinya Oyama, Naoya Okamoto, Mitsuharu Suzuki, Tomoyuki Koganezawa, Masaaki Fuki, Sadahiro Masuo, Kaoru Ohta, Hiroko Yamada, Yasuhiro Kobori

  Recent remarkable developments on nonfullerene solar cells have reached a photoelectric conversion efficiency (PCE) of 18% by tuning the band energy levels in small molecular acceptors. In this regard, understanding the impact of small donor molecules on nonpolymer solar cells is essential. Here, we systematically investigated mechanisms of solar cell performance using diketopyrrolopyrrole (DPP)-tetrabenzoporphyrin (BP) conjugates of C4-DPP-H2BP and C4-DPP-ZnBP, where C4 represents the butyl group substituted at the DPP unit as small p-type molecules, while an acceptor of [6,6]-phenyl-C61-buthylic acid methyl ester is employed. We clarified the microscopic origins of the photocarrier caused by phonon-assisted one-dimensional (1D) electron-hole dissociations at the donor-acceptor interface. Using a time-resolved electron paramagnetic resonance, we have characterized controlled charge-recombination by manipulating disorders in π-π donor stacking. This ensures carrier transport through stacking molecular conformations to suppress nonradiative voltage loss capturing specific interfacial radical pairs separated by 1.8 nm in bulk-heterojunction solar cells. We show that, while disordered lattice motions by the π-π stackings via zinc ligation are essential to enhance the entropy for charge dissociations at the interface, too much ordered crystallinity causes the backscattering phonon to reduce the open-circuit voltage by geminate charge-recombination.

  Mar. 2023, ACS physical chemistry Au, 3(2) (2), 207 - 221, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Dynamics and mechanism of radical formation in a highly sensitive oxime photoinitiator as revealed by time-resolved absorption and EPR measurements

  Kaori Sameshima, Tomomi Kawakami, Hikaru Sotome, Masaaki Fuki, Yasuhiro Kobori, Hiroshi Miyasaka

  Elsevier BV, Mar. 2023, Journal of Photochemistry and Photobiology A: Chemistry, 437, 114479 - 114479, English

  [Refereed]

  Scientific journal


• Singlet fission as a polarized spin generator for dynamic nuclear polarization

  Yusuke Kawashima, Tomoyuki Hamachi, Akio Yamauchi, Koki Nishimura, Yuma Nakashima, Saiya Fujiwara, Nobuo Kimizuka, Tomohiro Ryu, Tetsu Tamura, Masaki Saigo, Ken Onda, Shunsuke Sato, Yasuhiro Kobori, Kenichiro Tateishi, Tomohiro Uesaka, Go Watanabe, Kiyoshi Miyata, Nobuhiro Yanai

  Abstract Singlet fission (SF), converting a singlet excited state into a spin-correlated triplet-pair state, is an effective way to generate a spin quintet state in organic materials. Although its application to photovoltaics as an exciton multiplier has been extensively studied, the use of its unique spin degree of freedom has been largely unexplored. Here, we demonstrate that the spin polarization of the quintet multiexcitons generated by SF improves the sensitivity of magnetic resonance of water molecules through dynamic nuclear polarization (DNP). We form supramolecular assemblies of a few pentacene chromophores and use SF-born quintet spins to achieve DNP of water-glycerol, the most basic biological matrix, as evidenced by the dependence of nuclear polarization enhancement on magnetic field and microwave power. Our demonstration opens a use of SF as a polarized spin generator in bio-quantum technology.

  Springer Science and Business Media LLC, Mar. 2023, Nature Communications, 14(1) (1), 1056, English

  [Refereed]

  Scientific journal


• Thermodynamic Control of Intramolecular Singlet Fission and Exciton Transport in Linear Tetracene Oligomers

  Shunta Nakamura, Hayato Sakai, Masaaki Fuki, Rikuto Ooie, Fumitaka Ishiwari, Akinori Saeki, Nikolai V. Tkachenko, Yasuhiro Kobori, Taku Hasobe

  Corresponding, Wiley, Jan. 2023, Angewandte Chemie International Edition, 62(8) (8), e202217704, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Caging and photo-triggered uncaging of singlet oxygen by excited state engineering of electron donor–acceptor-linked molecular sensors

  Devika Sasikumar, Yuta Takano, Hanjun Zhao, Reiko Kohara, Morihiko Hamada, Yasuhiro Kobori, Vasudevanpillai Biju

  Abstract Singlet oxygen (¹O₂), one of the most sought-after species in oxidative chemical reactions and photodynamic cancer therapy, is activated and neutralized in the atmosphere and living cells. It is essential to see "when" and "where" ¹O₂ is produced and delivered to understand and utilize it. There is an increasing demand for molecular sensor tools to capture, store, and supply ¹O₂, controlled by light and engineered singlet and triplet states, indicating the ¹O₂-capturing-releasing state. Here, we demonstrate the outstanding potential of an aminocoumarin-methylanthracene-based electron donor–acceptor molecule (1). Spectroscopic measurements confirm the formation of an endoperoxide (1-O₂) which is not strongly fluorescent and remarkably different from previously reported ¹O₂ sensor molecules. Moreover, the photoexcitation on the dye in 1-O₂ triggers fluorescence enhancement by the oxidative rearrangement and a competing ¹O₂ release. The unique ability of 1 will pave the way for the spatially and temporally controlled utilization of ¹O₂ in various areas such as chemical reactions and phototherapies.

  Springer Science and Business Media LLC, Dec. 2022, Scientific Reports, 12(1) (1), 11371, English

  [Refereed]

  Scientific journal


• Diphenyldihydropentalenediones: Wide Singlet–Triplet Energy Gap Compounds Possessing the Planarly Fixed Diene Subunit

  Tomoki Nagaoka, Yasunori Matsui, Masaaki Fuki, Takuya Ogaki, Eisuke Ohta, Yasuhiro Kobori, Hiroshi Ikeda

  American Chemical Society ({ACS}), Nov. 2022, ACS Omega, 7(44) (44), 40364 - 40373, English

  Scientific journal


• Photochromism of colloidal ZnO nanocrystal powders under ambient conditions

  Hiroki Ito, Daisuke Yoshioka, Morihiko Hamada, Tsubasa Okamoto, Yasuhiro Kobori, Yoichi Kobayashi

  Springer Science and Business Media LLC, Jul. 2022, Photochemical and Photobiological Sciences, 21, 1781 - 1791, English

  [Refereed][Invited]

  Scientific journal


• Microscopic Structures, Dynamics, and Spin Configuration of the Charge Carriers in Organic Photovoltaic Solar Cells Studied by Advanced Time-Resolved Spectroscopic Methods

  Kaoru Ohta, Keisuke Tominaga, Tadaaki Ikoma, Yasuhiro Kobori, Hiroko Yamada

  Corresponding, American Chemical Society ({ACS}), Jun. 2022, Langmuir, 38, 1781 - 1791, English

  [Refereed][Invited]

  Scientific journal


• Effects of the rigid and sterically bulky structure of non-fused nonfullerene acceptors on transient photon-to-current dynamics

  Seihou Jinnai, Kasumi Murayama, Keisuke Nagai, Megumi Mineshita, Kosaku Kato, Azusa Muraoka, Akira Yamakata, Akinori Saeki, Yasuhiro Kobori, Yutaka Ie

  Non-fused electron-accepting π-conjugated compounds have been investigated recently for application to nonfullerene acceptors (NFAs) in organic solar cells (OSCs).

  Corresponding, Royal Society of Chemistry (RSC), Jun. 2022, Journal of Materials Chemistry A, 10(37) (37), 20035 - 20047, English

  [Refereed][Invited]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Diphenyldihydropentalenediones: Potential Singlet Fission Materials with High Triplet Energy Levels

  Tomoki Nagaoka, Yasunori Matsui, Masaaki Fuki, Takuya Ogaki, Eisuke Ohta, Yasuhiro Kobori, Hiroshi Ikeda

  Apr. 2022


• Identification of a Self-Photosensitizing Hydrogen Atom Transfer Organocatalyst System

  Hiromu Fuse, Yu Irie, Masaaki Fuki, Yasuhiro Kobori, Kosaku Kato, Akira Yamakata, Masahiro Higashi, Harunobu Mitsunuma, Motomu Kanai

  We developed organocatalyst systems to promote the cleavage of stable C-H bonds, such as formyl, α-hydroxy, and benzylic C-H bonds, through a hydrogen atom transfer (HAT) process without the use of exogenous photosensitizers. An electronically tuned thiophosphoric acid, 7,7'-OMe-TPA, was assembled with substrate or co-catalyst N-heteroaromatics through hydrogen bonding and π-π interactions to form electron donor-acceptor (EDA) complexes. Photoirradiation of the EDA complex induced stepwise, sequential single-electron transfer (SET) processes to generate a HAT-active thiyl radical. The first SET was from the electron-rich naphthyl group of 7,7'-OMe-TPA to the protonated N-heteroaromatics and the second proton-coupled SET (PCET) from the thiophosphoric acid moiety of 7,7'-OMe-TPA to the resulting naphthyl radical cation. Spectroscopic studies and theoretical calculations characterized the stepwise SET process mediated by short-lived intermediates. This organocatalytic HAT system was applied to four different carbon-hydrogen (C-H) functionalization reactions, hydroxyalkylation and alkylation of N-heteroaromatics, acceptorless dehydrogenation of alcohols, and benzylation of imines, with high functional group tolerance.

  Mar. 2022, J. Am. Chem. Soc., 144(14) (14), 6566 - 6574, English, International magazine

  [Refereed]

  Scientific journal


• Molecular Design Strategy for High-Yield and Long-Lived Individual Doubled Triplet Excitons through Intramolecular Singlet Fission

  Taku Hasobe, Shunta Nakamura, Nikolai V. Tkachenko, Yasuhiro Kobori

  Multi-exciton generation of organic chromophores, i.e., singlet fission (SF), is highly promising for photoenergy conversion such as photocatalysis and photovoltaics. Among the reported high-yield SF systems, many systems possess only short-lived triplet excited states derived from correlated triplet pair intermediates, but not individual doubled triplet excitons. However, high-yield and long-lived individual triplet exciton generation is favorable for achieving efficient photoenergy conversion. In this Focus Review, we discuss the molecular design strategy for high-yield and long-lived individual triplet exciton generation through intramolecular SF utilizing a series of acene derivatives such as hexacene, pentacene, and tetracene. In addition to clarifying the structural and vibronic characters required for high-yield individual triplet exciton generation, specific examples of the photoenergy conversion far exceeding 100% quantum yields of subsequent electron-transfer products and singlet oxygen generation are presented.

  American Chemical Society (ACS), Dec. 2021, ACS Energy Letters, 7(1) (1), 390 - 400, English

  [Refereed][Invited]

  Scientific journal


• Organic photostimulated luminescence associated with persistent spin-correlated radical pairs

  Manabu Sakurai, Ryota Kabe, Masaaki Fuki, Zesen Lin, Kazuya Jinnai, Yasuhiro Kobori, Chihaya Adachi, Takashi Tachikawa

  Photostimulated luminescence allows energy or data to be stored and released using electromagnetic waves as both the input and output, and has attracted considerable interest in the fields of biomedical and information technologies. However, this phenomenon is mostly limited to solid inorganic materials. Here, we report photostimulated luminescence from purely organic blend films, composed of electron donor, acceptor, and trap/emitter molecules. Charges in the films are accumulated as radical ions by ultraviolet light irradiation and then extracted by near-infrared light irradiation. Even after storage in the dark for one week they produce visible light with good repeatability, color tunability, and are responsive to weak external magnetic fields. These findings might broadly impact existing applications and provide new prospects for innovative flexible devices.

  Springer Science and Business Media LLC, Dec. 2021, Communications Materials, 2(1) (1), English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Orientations and water dynamics of photoinduced secondary charge-separated states for magnetoreception by cryptochrome

  Misato Hamada, Tatsuya Iwata, Masaaki Fuki, Hideki Kandori, Stefan Weber, Yasuhiro Kobori

  In the biological magnetic compass, blue-light photoreceptor protein of cryptochrome is thought to conduct the sensing of the Earth’s magnetic field by photoinduced sequential long-range charge-separation (CS) through a cascade of tryptophan residues, W_A(H), W_B(H) and W_C(H). Mechanism of generating the weak-field sensitive radical pair (RP) is poorly understood because geometries, electronic couplings and their modulations by molecular motion have not been investigated in the secondary CS states generated prior to the terminal RP states. In this study, water dynamics control of the electronic coupling is revealed to be a key concept for sensing the direction of weak magnetic field. Geometry and exchange coupling (singlet–triplet energy gap: 2J) of photoinduced secondary CS states composed of flavin adenine dinucleotide radical anion (FAD^−•) and radical cation W_B(H)^+• in the cryptochrome DASH from Xenopus laevis were clarified by time-resolved electron paramagnetic resonance. We found a time-dependent energetic disorder in 2J and was interpreted by a trap CS state capturing one reorientated water molecule at 120 K. Enhanced electron-tunneling by water-libration was revealed for the terminal charge-separation event at elevated temperature. This highlights importance of optimizing the electronic coupling for regulation of the anisotropic RP yield on the possible magnetic compass senses.

  Springer Science and Business Media LLC, Dec. 2021, Communications Chemistry, 4(1) (1), English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Synergetic Role of Conformational Flexibility and Electronic Coupling for Quantitative Intramolecular Singlet Fission

  Shunta Nakamura, Hayato Sakai, Hiroki Nagashima, Masaaki Fuki, Kakeru Onishi, Ramsha Khan, Yasuhiro Kobori, Nikolai V. Tkachenko, Taku Hasobe

  We present a novel design concept of molecular dimers for quantitative individual triplet yield (φT) through intramolecular singlet fission. We synthesized a series of tetracene (Tc) dimers bridged by different phenylene-based linkers, focusing on the conformational flexibility in addition to the electronic coupling. In transient absorption measurements, a 4,4′-biphenyl-bridged Tc dimer with weaker electronic coupling and larger conformational flexibility exhibited the quantitative φT: 196 ± 12% at high excitation energy. Moreover, decoupled spins associated with conformational change were directly characterized by time-resolved electron paramagnetic resonance. Strong interplay of the geometry change and electronic localization was revealed on the triplet pair dissociation through magnitudes of spin-spin exchange couplings. Thus, a synergetic role of conformational flexibility and electronic coupling in quantitative φT was clarified.

  Corresponding, American Chemical Society (ACS), Aug. 2021, The Journal of Physical Chemistry C, 125(33) (33), 18287 - 18296, English

  [Refereed]

  Scientific journal


• Manipulation of Charge-Transfer States by Molecular Design: Perspective from “Dynamic Exciton”

  Hiroshi Imahori, Yasuhiro Kobori, Hironori Kaji

  Corresponding, American Chemical Society (ACS), Jul. 2021, Accounts of Materials Research, 2(7) (7), 501 - 514, English

  [Refereed][Invited]

  Scientific journal


• Enthalpy-Entropy Compensation Effect for Triplet Pair Dissociation of Intramolecular Singlet Fission in Phenylene Spacer-Bridged Hexacene Dimers.

  Shunta Nakamura, Hayato Sakai, Masaaki Fuki, Yasuhiro Kobori, Nikolai V Tkachenko, Taku Hasobe

  Hexacene (Hc) is highly promising for singlet fission (SF). However, the number of SFs in Hc is extremely limited. As far as Hc dimers in solution are concerned, there is no report on the observation of the dissociation process from a correlated triplet pair (TT) to an individual one. The emphasis in this study is on the first observation of the quantitative TT generation together with the orientation-dependent photophysical discussions for TT dissociation using para- and meta-phenyl-bridged Hc dimers. Moreover, the activation enthalpies of Hc dimers in TT dissociation are smaller than those of pentacene (Pc) dimers, whereas the relative entropic contributions for Gibbs free energy of activation are much larger than the enthalpic ones in both Hc and Pc dimers. This implies that the vibrational motions are responsible for the intramolecular conformation changes associated with the TT dissociation. Consequently, "enthalpy-entropy compensation" has a large impact on the rate constants and quantum yields.

  Corresponding, Jul. 2021, The journal of physical chemistry letters, 12(28) (28), 6457 - 6463, English, International magazine

  [Refereed]

  Scientific journal


• Fast T-Type Photochromism of Colloidal Cu-Doped ZnS Nanocrystals

  Yulian Han, Morihiko Hamada, I-Ya Chang, Kim Hyeon-Deuk, Yasuhiro Kobori, Yoichi Kobayashi

  This paper reports on durable and nearly temperature-independent (at 298-328 K) T-type photochromism of colloidal Cu-doped ZnS nanocrystals (NCs). The color of Cu-doped ZnS NC powder changes from pale yellow to dark gray by UV light irradiation, and the color changes back to pale yellow on a time scale of several tens of seconds to minutes after stopping the light irradiation, while the decoloration reaction is accelerated to submillisecond in solutions. This decoloration reaction is much faster than those of conventional inorganic photochromic materials. The origin of the reversible photoinduced coloration is revealed to be a strong optical transition involving a delocalized surface hole which survives over a minute after escaping from intraparticle carrier recombination due to electron-hopping dissociation. ZnS NCs can be easily prepared in a water-mediated one-pot synthesis and are less toxic. Therefore, they are promising for large-scale photochromic applications such as windows and building materials in addition to conventional photochromic applications. Moreover, the present study demonstrates the importance of excited carrier dynamics and trap depths, resulting in coloration over minutes not only for photochromic nanomaterials but also for various advanced photofunctional materials, such as long persistent luminescent materials and photocatalytic nanomaterials.

  Corresponding, American Chemical Society (ACS), Feb. 2021, Journal of the American Chemical Society, 143(5) (5), 2239 - 2249, English, International magazine

  [Refereed]

  Scientific journal


• Geometries and Terahertz Motions Driving Quintet Multiexcitons and Ultimate Triplet-Triplet Dissociations via the Intramolecular Singlet Fissions.

  Yasuhiro Kobori, Masaaki Fuki, Shunta Nakamura, Taku Hasobe

  Importance of vibronic effects has been highlighted for the singlet-fission (SF) that converts one high-energy singlet exciton into doubled triplet excitons, as strongly coupled multiexcitons. However, molecular mechanisms of spin conversion processes and ultimate decouplings in the multiexcitons are poorly understood. We have analyzed geometries and exchange couplings (singlet-quintet energy gaps: 6J) of the photoinduced multiexcitons in the pentacene dimers bridged by a phenylene at ortho and meta positions [denoted as o-(Pc)2 and m-(Pc)2] by simulations of the time-resolved electron paramagnetic resonance spectra. We clarified that terahertz molecular conformation dynamics play roles on the spin conversion from the singlet strongly coupled multiexcitons 1(TT) to the quintet multiexcitons 5(TT) and on the intramolecular decouplings in the 6J to form spin correlated triplet pairs (T+T). The strongly coupled 5(TT) multiexcitons are revealed to possess entirely planar conformations stabilized by mutually delocalized spin distributions, while the intramolecular decoupled spin-correlated triplet pairs generated at 1 μs are also stabilized by distorted conformations resulting in two separately localized biradical characters.

  Corresponding, Oct. 2020, The journal of physical chemistry. B, 124(42) (42), 9411 - 9419, English, International magazine

  [Refereed][Invited]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Unraveling Hidden Correlations between Molecular Diffusivity and Reactivity in Ruthenium Complex-Modified Mesoporous Silica

  Tatsuya Watase, Minoru Sohmiya, Zhujun Zhang, Yasuhiro Kobori, Takashi Tachikawa

  American Chemical Society (ACS), Oct. 2020, The Journal of Physical Chemistry C, 124(39) (39), 21502 - 21511, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Organic Photostimulated Luminescence

  Manabu Sakurai, Ryota Kabe, Masaaki Fuki, Zesen Lin, Kazuya Jinnai, Yasuhiro Kobori, Chihaya Adachi, Takashi Tachikawa

  Photostimulated luminescence, which allows energy or data to be stored and released using electromagnetic waves as both the input and output, has attracted considerable interest in the fields of biomedical and informatics technologies, but this phenomenon is mostly limited to solid inorganic materials. Here, we report photostimulated luminescence from purely organic blend films composed of electron donor, acceptor, and trap/emitter molecules. In the films, charges are accumulated as radical ions by ultraviolet light irradiation and then extracted by near infrared light irradiation to produce visible light. Films are capable of multiple cycles (>10 times) of organic photostimulated luminescence, which was still observable from films left in the dark at room temperature for one week after excitation, and emission color could be varied by changing the trap/emitter molecules. These findings will broadly impact existing applications and provide new prospects for innovative flexible devices.

  American Chemical Society (ACS), Sep. 2020, English

  [Refereed]


• TiO2 superstructures with oriented nanospaces: a strategy for efficient and selective photocatalysis

  Yuta Murakami, Takashi Kamegawa, Yasuhiro Kobori, Takashi Tachikawa

  Feb. 2020, Nanoscale, 12, 6420 - 6428, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Electron spin polarization generated by transport of singlet and quintet multiexcitons to spin-correlated triplet pairs during singlet fissions

  Saki Matsuda, Shinya Oyama, Yasuhiro Kobori

  Singlet fission (SF) is expected to exceed the Shockley-Queisser theoretical limit of efficiency of organic solar cells. Transport of spin-entanglement in the triplet-triplet pair state via one singlet exciton is a promising phenomenon for several energy conversion applications including quantum information science. However, direct observation of electron spin polarization by transport of entangled spin-states has not been presented. In this study, time-resolved electron paramagnetic resonance has been utilized to observe the transportation of singlet and quintet characters generating correlated triplet-triplet (T + T) exciton-pair states by probing the electron spin polarization (ESP) generated in thin films of 6,13-bis(triisopropylsilylethynyl)pentacene. We have clearly demonstrated that the ESP detected at the resonance field positions of individual triplet excitons is dependent on the morphology and on the detection delay time after laser flash to cause SF. ESP was clearly explained by quantum superposition of singlet-triplet-quintet wavefunctions via picosecond triplet-exciton dissociation as the electron spin polarization transfer from strongly exchange-coupled singlet and quintet TT states to weakly-coupled spin-correlated triplet pair states. Although the coherent superposition of spin eigenstates was not directly detected, the present interpretation of the spin correlation of the separated T + T exciton pair may pave new avenues not only for elucidating the vibronic role in the de-coupling between two excitons but also for scalable quantum information processing using quick T + T dissociation via one-photon excitation.

  Feb. 2020, Chemical Science, 11(11) (11), 2934 - 2942, English, International magazine

  [Refereed][Invited]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Structural Dynamics of Lipid Bilayer Membranes Explored by Magnetic Field Effect Based Fluorescence Microscopy.

  Manabu Sakurai, Yasuhiro Kobori, Takashi Tachikawa

  Lipid bilayer membranes are known to exist as heterogeneous and dynamic structures where the molecules are always moving and fluctuating under physiological conditions. Magnetic field effects (MFEs) studied herein are phenomena in which the exciplex emission from an electron donor-acceptor dyad increases or decreases by applying an external magnetic field. The characteristic dependence of MFEs on the viscosity and polarity of the surrounding medium has been applied to investigate the local environments around the probe molecule. In this study, a novel MFE-based fluorescence microscopy technique was developed to explore the structural dynamics of lipid bilayer membranes. The vesicle formation during the membrane deformation was selectively visualized through the MFEs, thus allowing the extraction of information on the cellular dynamics at high temporal and spatial resolutions. This highly versatile and powerful technique is applicable to a wide range of areas, such as biology and material science.

  Dec. 2019, The journal of physical chemistry. B, 123(50) (50), 10896 - 10902, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Electrostatic Interaction with Anionic Polymer Activates Berberine

  Kazutaka Hirakawa, Mariko Yamada, Shigetoshi Okazaki, Morihiko Hamada, Yasuhiro Kobori

  Dec. 2019, Electrostatic Interaction with Anionic Polymer Activates Berberine, 40, 4 - 7, English

  [Refereed]

  Scientific journal


• Controlled Orientations of Neighboring Tetracene Units by Mixed Self-Assembled Monolayers on Gold Nanoclusters for High-Yield and Long-Lived Triplet Excited States through Singlet Fission

  Toshiyuki Saegusa, Hayato Sakai, Hiroki Nagashima, Yasuhiro Kobori, Nikolai V. Tkachenko, Taku Hasobe

  Copyright © 2019 American Chemical Society. Although tetracene (Tc) is well-known as a good candidate for singlet fission (SF), the number of high-yield and long-lived triplet excited states through SF is extremely limited because of the relative acceleration of the reverse triplet-triplet annihilation (TTA) considering the energy matching between a singlet and two triplet states. Systematic control of electronic interactions between two neighboring units using conventional covalent linkages and molecular assembly methods to optimize these kinetic processes is quite difficult because of the complicated synthesis and random orientations. In this study, we propose a novel supramolecular strategy utilizing mixed self-assembled monolayers (SAMs) with two different chain lengths. Specifically, mixed Tc-SAMs on gold nanoclusters, which are prepared using Tc-modified heterodisulfides with two different chain lengths, attain high-yield SF (φSF ≈ 90%) and individual triplet yields (φ? ≈ 160%). The obtained φSF is the highest value among Tc derivatives in homogeneous solution to the best of our knowledge.

  Corresponding, Sep. 2019, J. Am. Chem. Soc., 141(37) (37), 14720 - 14727, English

  [Refereed]

  Scientific journal


• Exergonic Intramolecular Singlet Fission of an Adamantane-Linked Tetracene Dyad via Twin Quintet Multiexcitons

  Yasunori Matsui, Shuhei Kawaoka, Hiroki Nagashima, Tatsuo Nakagawa, Naoki Okamura, Takuya Ogaki, Eisuke Ohta, Seiji Akimoto, Ayana Sato-Tomita, Shigeyuki Yagi, Yasuhiro Kobori, Hiroshi Ikeda

  © 2019 American Chemical Society. An adamantane-linked tetracene dyad (Tc-Ad-Tc) undergoes exergonic intramolecular singlet fission (SF), producing long-lived (τ = 175 μs) and high-energy (2 × 1.03 eV) multiexciton. Time-resolved absorption, fluorescence decay, and electron paramagnetic resonance (EPR) spectroscopic analysis revealed that the long-lived triplet species is generated in this system via a correlated triplet pair having singlet and quintet characteristics. Time-resolved EPR analysis revealed formation of syn and anti conformers in the quintet, i.e., 5(3Tc-Ad-3Tc)*. The quintet generation requires small conformational motion to induce singlet-quintet spin relaxation. The presence of aliphatic linkages, like the rigid adamantane group, may enable effective conservation of intrinsic high S1 and T1 levels of the original monomers, moderate bridge-mediated σ-πinteraction leading to exergonic intramolecular SF involving 1Tc*-Ad-Tc → 1(3Tc-Ad-3Tc)*, and prevention of undesirable triplet-triplet annihilation, finally result in long-lived and high-energy multiexciton.

  Corresponding, Aug. 2019, Journal of Physical Chemistry C, 123(31) (31), 18813 - 18823, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Photosensitizing Activity of Berberine-Cyclodextrin Inclusion Complexes

  Kazutaka Hirakawa, Akiko Kitagawa, Shigetoshi Okazaki, Fumitoshi Ema, Yasuhiro Kobori

  Aug. 2019, Photomedicine and Photobiology, 40, 7 - 10, English

  [Refereed]

  Scientific journal


• Transient Electron Spin Polarization Imaging of Heterogeneous Charge-Separation Geometries at Bulk-Heterojunction Interfaces in Organic Solar Cells

  Yasuhiro Kobori, Takumi Ako, Shinya Oyama, Takashi Tachikawa, Kazuhiro Marumoto

  Despite the importance of elucidating photoinduced charge-generation mechanisms for the development of efficient organic solar cells (OSC), it has been quite difficult to characterize molecular geometries, electronic couplings, and charge mobilities in the initial photoinduced charge-separated (CS) states for the heterogeneous molecular environments in bulk-heterojunction interfaces between electron donor-acceptor domains in the photoactive layers. In this study, we employed a time-resolved electron paramagnetic resonance method to characterize two kinds of electron spin polarizations (ESPs) of the photoinduced CS states as different geometries, exchange couplings, and spin-relaxation times of spin-correlated radical pairs in OSC blend films composed of regioregular poly(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl-C-61-butyric acid methyl ester by applying polarized light excitations (magnetophotoselection) with respect to an external magnetic field direction at a cryogenic temperature. From this, we performed analysis of mapping the ESPs to space directions to obtain image views of the molecular geometries in mobile and trapped CS states. We propose that the heterogeneities in the interfacial charge generations may be correlated with high- and low-frequency phonon modes leading to the mobile and weakly trapped charge pairs, respectively, denoting the great significance of such molecular motions for the efficient photocarriers overcoming the interfacial electrostatic binding potential.

  Corresponding, AMER CHEMICAL SOC, Jun. 2019, JOURNAL OF PHYSICAL CHEMISTRY C, 123(22) (22), 13472 - 13481, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Charge Carrier Dynamics in Sr-Doped NaTaO3 Photocatalysts Revealed by Deep Ultraviolet Single-Particle Microspectroscopy

  Seigo Mizutani, Izuru Karimata, Longjie An, Takamasa Sato, Yasuhiro Kobori, Hiroshi Onishi, Takashi Tachikawa

  Among various metal oxides, sodium tantalate (NaTaO3) is one of the best semiconductors for achieving efficient photocatalytic water splitting. However, the primary mechanism responsible for increasing the reaction rate up to an order of magnitude by specific metal doping and surface modification with co-catalysts has not been elucidated yet. In order to clarify the underlying mechanism, we explored the structure-dependent photoluminescence (PL) of pristine and Sr-doped NaTaO3 crystals at the (near) single-particle level using a time-resolved deep ultraviolet fluorescence microscope. Combined with transmission electron microscope techniques, the PL characteristics of individual particles were directly linked to the dopant concentrations in each particle, allowing us to unravel the complex effects of Sr-doping on the charge carrier dynamics. Furthermore, we investigated the photocatalytic reduction reaction for a single Sr-doped NaTaO3 particle to gain critical information related to dopant-driven electron migration, which is a key process for efficient photocatalysis.

  AMER CHEMICAL SOC, May 2019, JOURNAL OF PHYSICAL CHEMISTRY C, 123(20) (20), 12592 - 12598, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Long-lived Triplet Excitons Formed by Exergonic Intramolecular Singlet Fission of an Adamantane-linked Tetracene Dyad

  Yasunori Matsui, Shuhei Kawaoka, Hiroki Nagashima, Tatsuo Nakagawa, Naoki Okamura, Takuya Ogaki, Eisuke Ohta, Seiji Akimoto, Shigeyuki Yagi, Yasuhiro Kobori, Hiroshi Ikeda

  American Chemical Society ({ACS}), Mar. 2019


• Mechanistic Insights into Photochemical Reactions on CH3NH3PbBr3 Perovskite Nanoparticles from Single-Particle Photoluminescence Spectroscopy

  Kimura Yuki, Karimata Izuru, Kobori Yasuhiro, Tachikawa Takashi

  Metal halide perovskites have attracted considerable attention in applications such as photovoltaic cells and light-emitting diodes. The performance and durability of perovskite devices are significantly dependent on the nature of structural defects, but the underlying mechanisms of structure-related photochemical reactions are not yet fully elucidated. This study demonstrates that the photoluminescence (PL) from individual perovskite nanoparticles (NPs) can be utilized to resolve the different trapping pathways of the photogenerated charges, and hence, obtain a correlation between the pathways. PL deactivation and activation were observed and mainly attributed to nonradiative Auger recombination by the trapped charges and the passivation of surface traps by oxygen, respectively. Single-particle spectroelectrochemical techniques were further employed to explore the possible origin of the effective charge trap states and the reversibility of redox events under electrical bias. Consequently, this study unravels the complex effects of the structural defects on the charge carrier dynamics in perovskites.

  Wiley‐VCH Verlag, Mar. 2019, ChemNanoMat, 5(3) (3), 340 - 345, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Quantitative Sequential Photoenergy Conversion Process from Singlet Fission to Intermolecular Two-Electron Transfers Utilizing Tetracene Dimer

  Shunta Nakamura, Hayato Sakai, Hiroki Nagashima, Yasuhiro Kobori, Nikolai V. Tkachenko, Taku Hasobe

  Corresponding, American Chemical Society (ACS), Nov. 2018, ACS Energy Lett., 2019((4)) ((4)), 26 - 31, English

  [Refereed]

  Scientific journal


• Several Orders of Magnitude Difference in Charge-Transfer Kinetics Induced by Localized Trapped Charges on Mixed-Halide Perovskites.

  Izuru Karimata, Kaoru Ohta, Yasuhiro Kobori, Takashi Tachikawa

  Partial halide substitution in organolead halide perovskites MAPbX3 (MA = CH3NH3+, X = Cl-, Br-, or I-) leads to semiconductor heterostructures with precisely tuned band-gap energies, which facilitates efficient charge extraction or separation for high-performance solar cells and optoelectronic devices. In this study, partially iodide-substituted MAPbBr3 perovskites were prepared through a halide-exchange reaction in the liquid phase, and in situ space- and time-resolved photoluminescence profiles were acquired by means of confocal microscopy. The rates of charge transfer from the bulk MAPbBr3 to the surface MAPbBr3- xI x domains, which are widely distributed over a single crystal, were found to greatly depend on the excitation-power density. In particular, an abnormally slow charge-transfer process, lasting a few nanoseconds, was observed at higher excitation density. To explain the dependence of this rate on the excitation density, and its correlation with the charge-trapping rate in the bulk MAPbBr3, we propose a plausible mechanism in which trap filling associated with surface-trapped holes induces band bending within the space charge region. This band bending modulates carrier dynamics near the surface, thereby leading to efficient charge extraction from the bulk. To validate the mechanism, the carrier dynamics was numerically simulated using a diffusion model that includes the effect of the localized electric field. Our findings provide significantly deeper insight into the carrier dynamics within heterostructured perovskites with nanoscale heterogeneities, and a robust route for manipulating the photogenerated charges in various types of perovskite devices.

  Oct. 2018, ACS applied materials & interfaces, 10(43) (43), 37057 - 37066, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Singlet-Fission-Born Quintet State: Sublevel Selections and Trapping by Multiexciton Thermodynamics

  Hiroki Nagashima, Shuhei Kawaoka, AKIMOTO SEIJI, TACHIKAWA TAKASHI, Yasunori Matsui, Hiroshi Ikeda, KOBORI YASUHIRO

  Corresponding, Sep. 2018, The Journal of Physical Chemistry Letters, 9(19) (19), 5855–5861, English

  [Refereed]

  Scientific journal


• Multiexciton Dynamics Depending on Intramolecular Orientations in Pentacene Dimers: Recombination and Dissociation of Correlated Triplet Pairs

  Hayato Sakai, Ryutaro Inaya, Hiroki Nagashima, Shunta Nakamura, Yasuhiro Kobori, Nikolai V. Tkachenko, Taku Hasobe

  Pentacene dimers bridged by a phenylene at ortho and meta positions [denoted as o-(Pc)2 and m-(Pc)2] were synthesized to examine intramolecular orientation-dependent multiexciton dynamics, especially focusing on singlet fission (SF) and recombination from correlated triplet pairs . Absorption and electrochemical measurements indicated strong intramolecular couplings of o-(Pc)2 relative to m-(Pc)2. Femtosecond and nanosecond TA measurements successfully demonstrated efficient SF in both dimers. In contrast, the dissociation process from the (TT) to the individual triplets was clearly observed in m-(Pc)2, which is in sharp contrast to a major recombination process in o-(Pc)2. Time-resolved electron spin resonance (TR-ESR) measurements demonstrated that the recombination and dissociation proceed from the quintet state of 5(TT) in m-(Pc)2. The rate constant of the SF was 2 orders of magnitude greater in o-(Pc)2 than that in m-(Pc)2 and was rationalized by enhanced electronic coupling between adjacent HOMOs of the Pc units.

  Corresponding, American Chemical Society, Jun. 2018, Journal of Physical Chemistry Letters, 9(12) (12), 3354 - 3360, English

  [Refereed]

  Scientific journal


• Charge-Transfer Character Drives Möbius Antiaromaticity in the Excited Triplet State of Twisted [28]Hexaphyrin.

  Fumitoshi Ema, Mana Tanabe, Shohei Saito, Tomoki Yoneda, Kenji Sugisaki, Takashi Tachikawa, Seiji Akimoto, Seigo Yamauchi, Kazunobu Sato, Atsuhiro Osuka, Takeji Takui, Yasuhiro Kobori

  Möbius aromatic molecules have attracted great attention as new functional materials because of their π-orbital cyclic conjugations lying along the twisted Möbius topology. To elucidate the electronic character of the lowest excited triplet (T1) state of a Möbius aromatic [28]hexaphyrin, we employed a time-resolved electron paramagnetic resonance (TREPR) method with applied magnetophotoselection measurements at 77 K. Analyses of the EPR parameters have revealed that the T1 state possesses intramolecular charge-transfer (CT) character together with local excitation character residing at one side in the Möbius strip ring. We have also demonstrated that the CT character between orthogonal unpaired orbitals triggers quick triplet deactivation by spin-orbit coupling. This deactivation can be an important barometer to represent the "antiaromaticity" because of a connection between the orthogonal CT character and instability by a weakened spin-spin exchange coupling in the T1 state.

  Corresponding, May 2018, The journal of physical chemistry letters, 9(10) (10), 2685 - 2690, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• UVA- and visible light-mediated generation of carbon radicals from organochlorides using non-metal photocatalyst

  R. Matsubara, T. Yabuta, U. Md Idros, M. Hayashi, F. Ema, Y. Kobori, K. Sakata

  2018, J. Org. Chem., 83, 9381 - 9390, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Identifying triplet pathways in dilute pentacene films

  D. Lubert-Perquel, E. Salvadori, M. Dyson, P. N. Stavrinou, R. Montis, H. Nagashima, Y. Kobori, S. Heutz, C. W. M. Kay

  Building efficient triplet-harvesting layers for photovoltaic applications requires a deep understanding of the microscopic properties of the components involved and their dynamics. Singlet fission is a particularly appealing mechanism as it generates two excitons from a single photon. However, the pathways of the coupled triplets into free species, and their dependence on the intermolecular geometry, has not been fully explored. In this work, we produce highly ordered dilute pentacene films with distinct parallel and herringbone dimers and aggregates. Using electron paramagnetic resonance spectroscopy, we provide compelling evidence for the formation of distinct quintet excitons in ambient conditions, with intrinsically distinctive electronic and kinetic properties. We find that the ability of quintets to separate into free triplets is promoted in the parallel dimers and this provides molecular design rules to control the triplets, favouring either enhanced photovoltaic efficiency (parallel) or strongly bound pairs that could be exploited for logic applications (herringbone).

  2018, Nature Communications, 9(1) (1), 4222 - 4222, English, International magazine

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Multiple Quintets via Singlet Fission in Ordered Films at Room Temperature

  D. V. Lubert-Perquel, E. Salvadori, M. Dyson, P. N. Stavrinou, R. Montis, H. Nagashima, Y. Kobori, S. Heutz, C. W. M. Kay

  Jan. 2018, arXiv:1801.00603, English

  [Refereed]

  Scientific journal


• Time-Resolved EPR Study on Singlet-Fission Induced Quintet Generation and Subsequent Triplet Dissociation in TIPS-Phenyl-Tetracene Aggregates

  Hiroki Nagashima, Shuhei Kawaoka, Yasunori Matsui, Takashi Tachikawa, Hiroshi Ikeda, Yasuhiro Kobori

  The singlet fission (SF) is expected to be powerful tool for exceeding the theoretical limit of the power conversion efficiency on the organic solar cells. However, little is known on the intermolecular SF mechanism in the solid state. In the present study, we have investigated intermolecular SF in 2-phenyl-6,11-bis(triisopropylsilylethynyl)tetracene (TIPS-Ph-Tc) in frozen solutions using a time-resolved electron paramagnetic resonance measurement at a low temperature. SF-born quintet states (Q) and subsequent dissociations into two triplet states (T + T) were detected for a diluted solute concentration of 10(-4) M in dichloromethane. The microsecond triplet dissociation was found to occur due to the amorphous morphology in the frozen aggregate, suggesting that Q is generated as a trapped state. Furthermore, it was also suggested that the T + T dissociation follows the Q generation due to a T-T repulsion, whose energy were determined by the negative exchange couplings in the triplet pairs, (TT).

  Corresponding, TECHNICAL ASSOC PHOTOPOLYMERS,JAPAN, 2018, JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY, 31(2) (2), 163 - 167, English

  [Refereed]

  Scientific journal


• Direct Observation of Charge Collection at Nanometer-​Scale Iodide-​Rich Perovskites during Halide Exchange Reaction on CH3NH3PbBr3

  Izuru Karimata, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  Organolead halide perovskites MAPbX3 (MA = CH3NH3+, X = Cl-, Br-, or I-) are known to undergo reversible halide exchange reactions, enabling bandgap tuning over the visible light region. Using single-particle photoluminescence (PL) imaging for in situ observation, we have studied the structure-dependent charge dynamics during halide exchange with iodide ions on an MAPbBr3 crystal. In particular, we optically detected nanometer-scale iodide-rich domains (i.e., MAPbBrI2) and found that their lifetimes of several tens of milliseconds are limited by reaction with diffusing vacancies. Furthermore, it was discovered that these domains effectively collect the charge carriers from the bulk crystal, thus resulting in amplified spontaneous emission (ASE) under continuous-wave laser irradiation. Our findings will provide direction for development of perovskite heterostructures with enhanced charge utilization.

  Mar. 2017, Journal of Physical Chemistry Letters, 8(8) (8), 1724 - 1728, English, International magazine

  [Refereed]

  Scientific journal


• Regulated electron tunneling of photoinduced primary charge-​separated state in the photosystem II reaction center

  Masashi Hasegawa, Hiroki Nagashima, Reina Minobe, TACHIKAWA TAKASHI, Hiroyuki Mino, KOBORI YASUHIRO

  In initial events of the photosynthesis by higher plants, the photosystem II (PSII) generates photoinduced primary charge-separated (CS) state composed of reduced pheophytin (PheoD1-•) and oxidized special pair (P+•) in chlorophyll a (Chla) PD1/PD2 in the D1/D2 heterodimer, ultimately leading to the water oxidation at the oxygen-evolving Mn4CaO5 cluster by P+•. To understand the mechanism of the efficient generation of initially localized CS state (PD1+• PheoD1-•), we have characterized cofactor geometries and electronic coupling of the photoinduced primary CS state in quinone prereduced membrane of PSII from spinach using the time-resolved electron paramagnetic resonance method. It has been revealed that the electronic coupling between the charges is significantly weak in the CS state separated by 1.5 nm, showing the importance of regulated cofactor-cofactor electronic interaction between a vinyl substituent in PheoD1 and an accessory chlorophyll to inhibit the energy-wasting charge recombination after the primary electron-transfer processes.

  Corresponding, Feb. 2017, The Journal of Physical Chemistry Letters, 8(6) (6), 1179 - 1184, English, International magazine

  [Refereed]

  Scientific journal


• Switching of the pi-electronic conjugations in the reduction of a dithienylethene-fused p-benzoquinone

  Eiji Saito, Takumi Ako, Yasuhiro Kobori, Akihiko Tsuda

  The electron accepting character of a dithienylethene-fused p-benzoquinone derivative is significantly reduced upon ring-closing isomerization. Visible light unlocks the pi-electronic conjugation of the quinone so it can be utilized for a light-driven oxidation reaction.

  ROYAL SOC CHEMISTRY, 2017, RSC ADVANCES, 7(5) (5), 2403 - 2406, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Topotactic Epitaxy of SrTiO3 Mesocrystal Superstructures with Anisotropic Construction for Efficient Overall Water Splitting

  Peng Zhang, Tomoya Ochi, Mamoru Fujitsuka, Yasuhiro Kobori, Tetsuro Majima, Takashi Tachikawa

  The higher-order structures of semiconductor-based photocatalysts play crucial roles in their physicochemical properties for efficient light-to-energy conversion. A novel perovskite SrTiO3 mesocrystal superstructure with well-defined orientation of assembled cubic nanocrystals was synthesized by topotactic epitaxy from TiO2 mesocrystals through a facile hydrothermal treatment. The SrTiO3 mesocrystal exhibits three times the efficiency for the hydrogen evolution of conventional disordered systems in alkaline aqueous solution. It also exhibits a high quantum yield of 6.7 % at 360 nm in overall water splitting and even good durability up to 1 day. Temporal and spatial spectroscopic observations revealed that the synergy of the efficient electron flow along the internal nanocube network and efficient collection at the larger external cubes produces remarkably long-lived charges for enhanced photocatalysis.

  Wiley-VCH Verlag, 2017, Angewandte Chemie - International Edition, 56(19) (19), 5299 - 5303, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Time-Resolved EPR Study on Photoinduced Charge-Transfer Trap State in Thiophene-Thiazolothiazole Copolymer Film

  Yuta Yamamoto, Takumi Ako, Takashi Tachikawa, Itaru Osaka, Yasuhiro Kobori

  To shed a light on fundamental optoelectronic properties of conjugated polymer films applicable to the organic photovoltaics (OPV), field-effect transistors (FET) and light-emitting diodes (LED), we have characterized interspin separation and exchange coupling of interchain charge-transfer (CT) states in a pristine film of thiophene thiazolothiazole copolymer by using the time-resolved EPR method. It has been indicated that the CT state is generated at the disordered regions of the polymer films as deep trap sites via the singlet-exciton diffusion in polymer amorphous phase. These characteristics of the trapped charges may limit the device performances in the OPV, FET and LED applications and thus are informative for the device developments.

  Corresponding, TECHNICAL ASSOC PHOTOPOLYMERS,JAPAN, 2017, JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY, 30(5) (5), 551 - 555, English

  [Refereed][Invited]

  Scientific journal


• Self-Assembled Molecular Gear: A 4:1 Complex of Rh(III)Cl Tetraarylporphyrin and Tetra(p-pyridyl)cavitand

  Munechika Nakamura, Kazuki Kishimoto, Yasuhiro Kobori, Tomoka Abe, Kenji Yoza, Kenji Kobayashi

  The components of a 4:1 mixture of Rh(III)Cl tetrakis(4-methylphenyl)porphyrin 1 and a bowl-shaped tetra(4-pyridyl)cavitand 4 self-assemble into a 4:1 complex, 1(4)center dot 4 via Rh-pyridyl axial coordination bonds. The single crystal X-ray diffraction analysis and variable-temperature (VT) H-1 NMR study of 1(4)center dot 4 indicated that 1(4)center dot 4 behaves as a quadruple interlocking gear with an inner space; wherein (i) four subunits-1 are gear wheels and four p-pyridyl groups in subunit-4 are axes of gear wheels; (ii) one subunit-1 and two adjacent subunits-1 interlock with one another cooperatively, and (iii) four subunits-1 in 1(4)center dot 4 rotate quickly at 298 K on the NMR. time scale. Together, the extremely strong porphyrin-Rh-pyridyl axial coordination bond, the rigidity of the methylene-bridge cavitand as a scaffold of the pyridyl axes, and the cruciform arrangement of the interdigitating p-tolyl groups as the teeth moiety of the gear wheels in the assembling 1(4)-unit make 1(4)center dot 4 function as a quadruple interlocking gear in solution. The gear function of 1(4)center dot 4 was also supported by the rotation behaviors of other 4:1 complexes: 2(4)center dot 4 and 3(4)center dot 4 obtained from Rh(III)Cl tetrakis[4-(4-methylphenyl)phenyl]porphyrin 2 or Rh(III)Cl tetrakis(3,5-dialkoxyphenyl)porphyrin 3 and 4 also served as quadruple interlocking gears, whereas 1(4)center dot 5 obtained from 1 and tetrakis[4-(4-pyridyl)phenyl]cavitand 5 did not behave as a gear. The results of activation parameters (Delta H double dagger, Delta S double dagger, and Delta G double dagger) obtained from Eyring plots based on line-shape analysis of the VT H-1 NMR spectra of 1(4)center dot 4, 2(4)center dot 4, and 3(4)center dot 4 also support the interlocking rotation (geared coupled rotation) mechanism.

  Corresponding, AMER CHEMICAL SOC, Sep. 2016, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 138(38) (38), 12564 - 12577, English, International magazine

  [Refereed]

  Scientific journal


• Photoinduced Charge-Transfer State of 4-Carbazolyl-3-(trifluoromethyl)benzoic Acid: Photophysical Property and Application to Reduction of Carbon-Halogen Bonds as a Sensitizer

  Ryosuke Matsubara, Toshiyuki Shimada, Yasuhiro Kobori, Tatsushi Yabuta, Toshiyuki Osakai, Masahiko Hayashi

  The photoinduced persistent intramolecular charge-transfer state of 4-carbazolyl-3-(trifluoromethyl)benzoic acid was confirmed. It showed a higher catalytic activity in terms of yield and selectivity in the photochemical reduction of alkyl halides compared to the parent carbazole. Even unactivated primary alkyl bromides could be reduced by this photocatalyst. The high catalytic activity is rationalized by considering the slower backward single-electron transfer owing to the spatial separation of the donor and acceptor subunits.

  WILEY-V C H VERLAG GMBH, Jul. 2016, CHEMISTRY-AN ASIAN JOURNAL, 11(14) (14), 2006 - 2010, English, International magazine

  [Refereed]

  Scientific journal


• Time Resolved EPR Study on the Photoinduced Long-Range Charge-Separated State in Protein: Electron Tunneling Mediated by Arginine Residue in Human Serum Albumin

  Masaaki Fuki, Hisao Murai, Takashi Tachikawa, Yasuhiro Kobori

  To elucidate how local molecular conformations play a role on electronic couplings for the long-range photoinduced charge-separated (CS) states in protein systems, we have analyzed time-resolved electron paramagnetic resonance (TREPR) spectra by polarized laser irradiations of 9,10-anthraquinone-1-sulfonate (AQ1S-) bound to human serum albumin (HSA). Analyses of the magnetophotoselection effects on the EPR spectra and a docking simulation clarified the molecular geometry and the electronic coupling of the long-range CS states of AQ1S•2--tryptophan214 radical cation (W214•+) separated by 1.2 nm. The ligand of AQ1S- has been demonstrated to be bound to the drug site I in HSA. Molecular conformations of the binding region were estimated by the docking simulations, indicating that an arginine218 (R218+) residue bound to AQ1S•2- mediates the long-range electron-transfer. The energetics of triad states of AQ1S•2--R218+-W214•+ and AQ1S--R218•-W214•+ have been computed on the basis of the density functional molecular orbital calculations, providing the clear evidence for the long-range electronic couplings of the CS states in terms of the superexchange tunneling model through the arginine residue.

  Corresponding, American Chemical Society, May 2016, Journal of Physical Chemistry B, 120(19) (19), 4365 - 4372, English, International magazine

  [Refereed]

  Scientific journal


• Geometries, Electronic Couplings, and Hole Dissociation Dynamics of Photoinduced Electron-Hole Pairs in Polyhexylthiophene-Fullerene Dyads Rigidly Linked by Oligophenylenes

  Taku Miura, Ran Tao, Sho Shibata, Tomokazu Umeyama, Takashi Tachikawa, Hiroshi Imahori, Yasuhiro Kobori

  To shed a light on fundamental molecular functions of photoinduced charge conductions by organic photovoltaic materials, it is important to directly observe molecular geometries of the intermediate charges just after the photoinduced electron-transfer reactions. However, highly inhomogeneous molecular environments at the bulk heteojunction interfaces in the photoactive layers have prevented us from understanding the mechanism of the charge conductions. We have herein investigated orbital geometries, electronic couplings, and hole-dissociation dynamics of photo induced charge-separated (CS) states in a series of poly(3-hexylthiophene) fullerene linked dyads bridged by rigid oligo-p-phenylene spacers by using time-resolved EPR spectroscopy. It has been revealed that one-dimensional intramolecular hole-dissociations exothermically take place from localized holes in initial CS states, following bridge-mediated, photoinduced charge separations via triplet exciton diffusions in the conjugated polymer-backbones. This molecular wire property of the photoinduced charges in solution at room temperature demonstrates the potential utility of the covalently bridged polymer molecules applied for the molecular devices.

  Corresponding, AMER CHEMICAL SOC, May 2016, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 138(18) (18), 5879 - 5885, English, International magazine

  [Refereed]

  Scientific journal


• Crystal-Face-Dependent Charge Dynamics on a BiVO4 Photocatalyst Revealed by Single-Particle Spectroelectrochemistry

  T. Tachikawa, T. Ochi, Y. Kobori

  Feb. 2016, ACS Catal., 6(4) (4), 2250 - 2256, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Remarkable Dependence of the Final Charge Separation Efficiency on the Donor-Acceptor Interaction in Photoinduced Electron Transfer

  Tomohiro Higashino, Tomoki Yamada, Masanori Yamamoto, Akihiro Furube, Nikolai V. Tkachenko, Taku Miura, Yasuhiro Kobori, Ryota Jono, Koichi Yamashita, Hiroshi Imahori

  The unprecedented dependence of final charge separation efficiency as a function of donor-acceptor interaction in covalently-linked molecules with a rectilinear rigid oligo-p-xylene bridge has been observed. Optimization of the donor-acceptor electronic coupling remarkably inhibits the undesirable rapid decay of the singlet charge-separated state to the ground state, yielding the final long-lived, triplet charge-separated state with circa 100% efficiency. This finding is extremely useful for the rational design of artificial photosynthesis and organic photovoltaic cells toward efficient solar energy conversion.

  Corresponding, WILEY-V C H VERLAG GMBH, Jan. 2016, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 55(2) (2), 629 - 633, English

  [Refereed]

  Scientific journal


• Morphology Effect on Geometry of Photoinduced Charge-Separated State in P3HT:PCBM Blend Films as Studied by Time-Resolved EPR Spectroscopy

  Taku Miura, Takashi Tachikawa, Yasuhiro Kobori

  Corresponding, TECHNICAL ASSOC PHOTOPOLYMERS,JAPAN, 2016, JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY, 29(4) (4), 561 - 564, English

  [Refereed]

  Scientific journal


• Surface Charge Trapping in Organolead Halide Perovskites Explored by Single-Particle Photoluminescence Imaging

  Takashi Tachikawa, Izuru Karimata, Yasuhiro Kobori

  Organometal halide perovskites have attracted considerable attention because of their striking electrical and optical properties that are desirable for application in solar cells and optoelectronic devices; however, the structure-related dynamics of photogenerated charges are almost always masked by ensemble averaging in conventional spectroscopic methods, making it difficult to clarify the underlying mechanism. Here we investigate the photoluminescence characteristics of CH3NH3PbBr3 perovskite nanoparticles using single-particle spectroscopy combined with electron microscopy. The in situ analysis of light and Lewis-base-induced surface passivation revealed that the photoluminescence quenching and blinking phenomena of single CH3NH3PbBr3 nanoparticles are most probably caused by charge trapping at surface states, where the number of effective trapping sites was estimated to be 1-4 per particle.

  AMER CHEMICAL SOC, Aug. 2015, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 6(16) (16), 3195 - 3201, English

  [Refereed]

  Scientific journal


• Time-Resolved Electron Paramagnetic Resonance Study on Cofactor Geometries and Electronic Couplings after Primary Charge Separations in the Photosynthetic Reaction Center

  Yasuhiro Kobori, Nina Ponomarenko, James R. Norris

  To elucidate how cofactor geometries after photoinduced primary charge-separations influence electronic couplings (V-CR) for primary charge-recombination (CR) processes in the photosynthetic reaction center, we have analyzed time-resolved electron paramagnetic resonance (TREPR) spectra both of the primary charge-separated (CS) state (P+center dot HA-center dot) and its charge-recombined triplet state (P-3*) of the special pair in Rhodobacter sphaeroides R26. To determine the CS-state geometry, quantum mechanical modeling has been performed on the spin polarization of the P-3* generated by the spin dynamics due to the anisotropies of the hyperfine and the spinspin dipolar interactions in the primary CS state. From transverse magnetizations of the primary CS state, we have also determined the V-CR value leading to the singlet excited state (P-1*) of the special pair. The above analyses have revealed that while the primary charge separation does not largely modulate the cofactor conformations, it leads to significant enhancement in the V-CR of the singlet recombination processes with respect to the triplet CR. This enhanced coupling is demonstrated by the larger orbital overlap between P-1* and an electron-accepting orbital of chlorophyll (B-A) than between P-3* and B-A, caused by the charge-transfer electronic character of P-1* in which the electron is locally distributed at a side of the bacteriochlorophyll (P-M) situated in close proximity to B-A.

  AMER CHEMICAL SOC, Apr. 2015, JOURNAL OF PHYSICAL CHEMISTRY C, 119(15) (15), 8078 - 8088, English

  [Refereed]

  Scientific journal


• Overcoming Coulombic Traps: Geometry and Electronic Characterizations of Light-Induced Separated Spins at the Bulk Heterojunction Interface

  Yasuhiro Kobori, Taku Miura

  Recent progress is overviewed on experimental elucidations of fundamental molecular functions of the light energy conversions by the photoactive layers of the organic photovoltalic (OPV) cells by means of the time-resolved electron paramagnetic resonance spectroscopy. Positions and orientations of the unpaired electrons and electronic coupling matrix elements are clarified in photoinduced, primary charge-separated (CS) states. Connections between the molecular geometries and the electronic couplings have been characterized for the initial CS states to elucidate how the structure, orbital delocalization, and molecular libration play roles on exothermic carrier dissociation via a vibrationally relaxed charge-transfer complex with prevention of the energy-wasting charge recombination. Superior functions to biological molecules are presented for the efficient photocurrent generations induced by orbital delocalization and by shallow trap depths at polymer-stacking domains. The above structural and electronic characteristics of the primary electron hole pairs are essential to evaluations, designs, and developments of the efficient solar cells using organic molecules.

  AMER CHEMICAL SOC, Jan. 2015, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 6(1) (1), 113 - 123, English

  [Refereed]

  Scientific journal


• Time-Resolved Electron Paramagnetic Resonance Study on Long-Range Interfacial Electronic Coupling in Organic Photovoltaic Interface

  KOBORI YASUHIRO, MIURA TAKU

  Time-resolved electron paramagnetic resonance (TREPR) spectroscopy has been utilized at T = 77 K to characterize geometries and electronic couplings (V_CR) of transient charge-separated (CS) states in photoactive layers in organic thin film solar cells fabricated by spin-coating of mixed solutions of polyalkylthiophenes (RR-P3AT) and [6, 6]-C₆₁-butyric acid methyl ester (PCBM). Electron-hole distance of the interfacial transient CS states has been revealed to be modulated by alkyl side-chain number in P3AT. This result is explained by a coupling of a hole dissociation to polymer librations by the side-chains. From an exponential decay of V_CR with respect to the CS distance, an attenuation factor (β_e) of the decay has been determined to be β_e＝0.2 Å⁻¹. Such a long-range tunneling feature is explained by generations of shallowly trapped, delocalized electron-hole pairs by the dissociations of the hole toward π-stacking directions at the organic photovoltaic interface.

  Corresponding, The Surface Science Society of Japan, Nov. 2014, e-J. Surf. Sci. Nanotech., 35(11) (11), 621 - 626, English

  [Refereed][Invited]

  Scientific journal


• Time-Resolved EPR Study of Electron-Hole Dissociations Influenced by Alkyl Side Chains at the Photovoltaic Polyalkylthiophene:PCBM Interface

  Taku Miura, Motoko Aikawa, Yasuhiro Kobori

  Nanosecond time-resolved electron paramagnetic resonance (TREPR) spectroscopy has been utilized at T = 77 K to characterize alkyl side-chain effects on geometries and on the electronic couplings (V-CR) of transient charge-separated (CS) states in the photoactive layers fabricated by the spin-coating of mixed solutions of regioregular polyalkylthiophenes (RR-P3AT) and [6,6]-C-61-butyric acid methyl ester (PCBM). By increasing the alkyl side-chain number from 6 to 12 in P3AT, a highly distant and long-lived CS state has been obtained. This result is explained by a coupling of the hole dissociation to the polymer librations by the side-chains. From an exponential decay of V-CR with respect to the CS distance, the attenuation factor (beta(e)) has been determined to be beta(e) = 0.2 angstrom(-1). Such a long-range tunneling feature is explained by the generations of the shallowly trapped, delocalized electron-hole pairs by the dissociation of the hole toward pi-stacking directions at the organic photovoltaic interface.

  Corresponding, AMER CHEMICAL SOC, Jan. 2014, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 5(1) (1), 30 - 35, English

  [Refereed]

  Scientific journal


• Initial Molecular Photocurrent: Nanostructure and Motion of Weakly Bound Charge-Separated State in Organic Photovoltaic Interface

  Yasuhiro Kobori, Ryohei Noji, Shuhei Tsuganezawa

  To elucidate mechanism of the efficient photocarrier generation by the photoactive bulkheterojunction layers of the organic photovoltaic (OPV) devices, we have employed the time-resolved electron paramagnetic resonance method on solid blends composed of [6,6]-C-61-butyric acid methyl ester (PCBM) and of poly(3-hexylthiophene-2,5-diyl) (P3HT) with different regioregularities. The photoinduced charge-separated (CS) states have been detected at the boundary regions between the P3HT and PCBM domains at T = 77 K. We have characterized molecular geometries, electronic couplings, and molecular motions of the long-range CS states. From the CS structure, it is indicated that the pentagonal or hexagonal aromatic rings of the buckyball in PCBM directly face the aromatic plane of the pi-stacked P3HT surfaces. It has been concluded that the distant CS states are produced via fast hole-delocalization process from the contact charge-transfer (CT) states. Such hole dynamics is explained by a coupling of the hole to librations of chains in the conjugated polymer. It has been concluded that both the enthalpy stabilization and the enhancement of the entropy occur through the orbital delocalization by the electron-phonon coupling, overcoming the initial CT binding to generate the molecular photocurrent.

  Corresponding, AMER CHEMICAL SOC, Jan. 2013, JOURNAL OF PHYSICAL CHEMISTRY C, 117(4) (4), 1589 - 1599, English

  [Refereed]

  Scientific journal


• Structure and dynamics of photogenerated triplet radical ion pairs in DNA hairpin conjugates with anthraquinone end caps

  Raanan Carmieli, Amanda L. Smeigh, Sarah M. Mickley Conron, Arun K. Thazhathveetil, Masaaki Fuki, Yasuhiro Kobori, Frederick D. Lewis, Michael R. Wasielewski

  A series of DNA hairpins (AqGn) possessing a tethered anthraquinone (Aq) end-capping group were synthesized in which the distance between the Aq and a guanine-cytosine (G-C) base pair was systematically varied by changing the number (n - 1) of adenine-thymine (A-T) base pairs between them. The photophysics and photochemistry of these hairpins were investigated using nanosecond transient absorption and time-resolved electron paramagnetic resonance (TREPR) spectroscopy. Upon photoexcitation, 1*Aq undergoes rapid intersystem crossing to yield 3*Aq, which is capable of oxidizing purine nucleobases resulting in the formation of 3(Aq -•Gn +•). All 3(Aq -•Gn +•) radical ion pairs exhibit asymmetric TREPR spectra with an electron spin polarization phase pattern of absorption and enhanced emission (A/E) due to their different triplet spin sublevel populations, which are derived from the corresponding non-Boltzmann spin sublevel populations of the 3*Aq precursor. The TREPR spectra of the 3(Aq -•Gn +•) radical ion pairs depend strongly on their spin-spin dipolar interaction and weakly on their spin-spin exchange coupling. The anisotropy of 3(Aq -•Gn +•) makes it possible to determine that the π systems of Aq -• and G +• within the radical ion pair are parallel to one another. Charge recombination of the long-lived 3(Aq -•Gn +•) radical ion pair displays an unusual bimodal distance dependence that results from a change in the rate-determining step for charge recombination from radical pair intersystem crossing for n < 4 to coherent superexchange for n > 4. © 2012 American Chemical Society.

  Corresponding, Jul. 2012, Journal of the American Chemical Society, 134(27) (27), 11251 - 11260, English

  [Refereed]

  Scientific journal


• Protein-Ligand Structure and Electronic Coupling of Photoinduced Charge-Separated State: 9,10-Anthraquinone-1-sulfonate Bound to Human Serum Albumin

  Yasuhiro Kobori, Masaaki Fuki

  To elucidate how the protein ligand docking structure affects electronic interactions in the electron-transfer process, we have analyzed time-resolved electron paramagnetic resonance spectra of photoinduced charge-separated (CS) states generated by light excitation of 9,10-anthraquinone-1-sulfonate (AQ1S(-)) bound to human serum albumin at a hydrophobic drug-binding region. The spectra have been explained in terms of the triplet triplet electron spin polarization transfer model to determine both the geometries and the exchange couplings of the CS states of AQ1S(2-center dot) - histidine-242 radical cation (H242(+center dot)) and AQ1S(2-center dot)tryptophan-214 radical cation (W214(+center dot)). For the CS state of the former, it has been revealed that, due to the orthogonal relationship between the singly occupied molecular orbitals of AQ1S(2-center dot) and H242(+center dot), the electronic coupling (5.4 cm(-1)) is very weak, contributing to the prevention of energy-wasting charge recombination, even at a contact edge-to-edge separation.

  Corresponding, AMER CHEMICAL SOC, Oct. 2011, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 133(42) (42), 16770 - 16773, English

  [Refereed]

  Scientific journal


• Conversion of Cobalt(II) Porphyrin into a Helical Cobalt(III) Complex of Acyclic Pentapyrrole

  Katsunori Yamanishi, Masamichi Miyazawa, Takeshi Yairi, Shintaro Sakai, Naoko Nishina, Yasuhiro Kobori, Mitsuru Kondo, Fumio Uchida

  WILEY-BLACKWELL, 2011, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 50(29) (29), 6583 - 6586, English

  [Refereed]

  Scientific journal


• Electron Spin Polarization Transfer to the Charge-Separated State from Locally Excited Triplet Configuration. Theory and Its Application to Characterization of Geometry and Electronic Coupling in the Electron Donor-Acceptor System

  Yasuhiro Kobori, Masaaki Fuki, Hisao Murai

  We present a theoretical model of analysis of the time-resolved electron paramagnetic resonance (TREPR) spectrum of the charge-separated (CS) state generated by the photoinduced electron transfer (ET) reaction via the locally excited triplet state in an electron donor acceptor (D-A) system with a fixed molecular orientation We show, by the stochastic-Liouville equation, that chemically induced dynamic electron polarization (CIDEP) of the triplet mechanism is explained by lack of transfer of quantum coherence terms in the primary triplet spin state, resulting in net emissive or absorptive electron spin polarization (ESP) which is dependent on anisotropy of the singlet-triplet intersystem crossing in the precursor excited state This disappearance of the coherence is clearly shown to occur when the photoinduced ET rate is smaller than the angular frequency of the Zeeman splitting the transferred coherence terms are averaged to be zero due to effective quantum oscillations during the time that the chemical reaction proceeds The above theory has been applied to elucidate the molecular geometries and spin spin exchange interactions (2J) of the CS states for both folded and extended conformers by computer simulations of TREPR spectra of the zinc porphyrin-fullerene dyad (ZnP-C(60)) bridged by diphenyldisilane On the extended conformation, the electronic coupling is estimated from the 2J value It has been revealed that the coupling term is smaller than the reported electronic interactions of the porphyrin-C(60) systems bridged by diphenylamide spacers The difference in the electronic couplings has been explained by the difference in the LUMO levels of the bridge moieties that mediate the superexchange coupling for the long-range ET reaction

  Corresponding, AMER CHEMICAL SOC, Nov. 2010, JOURNAL OF PHYSICAL CHEMISTRY B, 114(45) (45), 14621 - 14630, English

  [Refereed][Invited]

  Scientific journal


• On Electron Spin Polarization Created in the Excited Triplet State of Accessory Chlorophyll via Photoinduced Charge-Recombination of the Photosystem II Reaction Center

  Shusuke Katagiri, Yasuhiro Kobori

  We present a theoretical approach to investigate the electron spin polarization (ESP) of the excited triplet state that has been detected using the time-resolved electron paramagnetic resonance (TREPR) method in the photosystem II center of the plants. We show, using the stochastic Liouville equation, that the ESP pattern created in the accessory chlorophyll (Chl(accD1)) which reside near the P(D1) chlorophyll of the active branch is explained by one-step, concerted double electron transfer model, initiating from the singlet-triplet conversion of the light-induced charge-separated state composed of P(D1) radical cation and pheophytin radical anion. We also considered the sequential ESP transfer model via the triplet charge-recombination (CR) and the triplet-triplet energy transfer processes. It has been clearly shown that the ESP created in the (3)Chl(accD1)* is dependent on the rate constant (k (TT)) of the triplet-triplet energy transfer from the intermediate triplet state created by the CR. Also we show that the relative orientation of the principal axes of the spin dipolar interaction in the intermediate triplet state ((3)P(D1)*, as an example) may play a role in the ESP pattern, when the k (TT) is smaller than the angular frequency of the Zeeman energy. We have theoretically shown that the TREPR measurement of the ESP is very powerful to investigate the primary chemical process and to characterize the intermediate as a signature of the stepwise ESP transfer.

  Corresponding, SPRINGER WIEN, Jan. 2010, APPLIED MAGNETIC RESONANCE, 37(1-4) (1-4), 177 - 189, English

  [Refereed][Invited]

  Scientific journal


• Encapsulated-guest rotation in a self-assembled heterocapsule directed toward a supramolecular gyroscope

  Hitomi Kitagawa, Yasuhiro Kobori, Masamichi Yamanaka, Kenji Yoza, Kenji Kobayashi

  The self-assembled heterocapsule 1(.)2, which is formed by the hydrogen bonds of tetra(4-pyridyl)-cavitand 1 and tetrakis(4-hydroxyphenyl)-cavitand 2, encapsulates 1 molecule of guests such as 1,4-diacetoxybenzene 3a, 1,4-diacetoxy-2,5-dimethylbenzene 3b, 1,4-diacetoxy-2,5-dialkoxybenzenes (3c, OCH(3); 3d, OC(2)H(5); 3e, OC(3)H(7); 3f, OC(4)H(9); 3g, OC(5)H(11); 3h, OC(6)H(13); 3i, OC(8)H(17)), 1,4-diacetoxy-2,5-difluorobenzene 4a, and 1,4-diacetoxy-2,3-difluorobenzene 4b. The X-ray crystallographic analysis of 3c@(1(.)2) showed that the acetoxy groups at the 1,4- positions of 3c are oriented toward the 2 aromatic cavity ends of 1(.)2 and that 3c can rotate along the long axis of 1(.)2. Thus, the 1(.)2 (stator) with the encapsulation guest ( rotator) behaves as a supramolecular gyroscope. A variable temperature (VT) (1)H NMR study in CDCl(3) showed that 3a, 3b, 4a, and 4b within 1(.)2 rotate rapidly even at 218 K, whereas guest rotation is almost inhibited for 3h and 3i even at 323 K. In this respect, 4b with a large dipole moment is a good candidate for the rotator of 1(.)2. For 3c-3g, the enthalpic (Delta H(double dagger)) and entropic (Delta S(double dagger)) contributions to the free energy of activation (Delta G(double dagger)) for the guest-rotational steric barriers within 1(.)2 were obtained from Eyring plots based on line-shape analysis of the VT (1)H NMR spectra. The value of Delta G(double dagger) increased in the order 3c < 3d < 3e < 3f < 3g. Thus, the elongation of the alkoxy chains at the 2,5-positions of 3 puts the brakes on guest rotation within 1(.)2.

  NATL ACAD SCIENCES, Jun. 2009, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 106(26) (26), 10444 - 10448, English

  [Refereed]

  Scientific journal


• Time-Resolved EPR Characterization of a Folded Conformation of Photoinduced Charge-Separated State in Porphyrin-Fullerene Dyad Bridged by Diphenyldisilane

  Yasuhiro Kobori, Yuki Shibano, Tsubasa Endo, Hayato Tsuji, Hisao Murai, Kohei Tamao

  For development of the molecular solar-energy conversion systems, it is crucial to investigate how both the molecular geometry and electronic structure of electron donor-bridge-acceptor (D-B-A) molecules contribute to the electronic coupling for the charge-separation (CS) and charge-recombination (CR) processes. In a D-B-A system of a porphyrin-fullerene dyad (ZnP-C(60)) bridged by a diphenyldisilane spacer, we have characterized one specific folded molecular conformation in the CS state among several existing conformations using the time-resolved electron paramagnetic resonance (TREPR) method at low temperature. To determine the molecular conformation and spin-spin exchange coupling of the CS state, we have considered (1) the electron spin polarization transfer from the excited triplet state of the C(60) moiety to the CS state and (2) the sublevel-selective spin relaxations and CR in the CS state. In the CS state of this conformation, although the ZnP cation and C(60) anion radicals are in close proximity, direct overlap between their singly occupied molecular orbitals is small, resulting in detection of the long-lived CS state which has a totally different conformation from the optically detected, charge-transfer (CT) complex. It has been demonstrated that, among several folded and extended molecular conformations created by the flexibility of the -Si-Si- bridge, the EPR conformation can play a role on the prevention of the energy-wasting CR.

  Corresponding, AMER CHEMICAL SOC, Feb. 2009, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 131(5) (5), 1624 - +, English

  [Refereed]

  Scientific journal


• 2SA1-02 Analysis of reaction intermadiate-protein interaction by time-resolved EPR(2SA1 Electron Spin Resonance on Biophysics -The Next Generation-,The 47th Annual Meeting of the Biophysical Society of Japan)

  Kobori Yasuhiro

  The Biophysical Society of Japan General Incorporated Association, 2009, Seibutsu Butsuri, 49, S10, English


• Magnetophotoselection in the Spin-Polarized Triplet State Radical-Ion Pair Formed in the Photo-Induced Solvent-Mediated Electron Transfer Reaction from N,N-Diethylaniline to Xanthone in Viscous Solution

  Asako Ishigaki, Yasuhiro Kobori, Hisao Murai

  The triplet state radical-ion pair (RIP) formed in the photolysis of xanthone (Xn) and N,N-diethylaniline (DEA) in a highly viscous mixtures of 2-propanol and cyclohexanol was studied by time-resolved ESR. As the viscosity of the mixed solution increases, the spectrum reveals a magnetic dipole-dipole interaction in the triplet state of the RIP. Immediately after laser photolysis, the spin-polarized RIP spectrum exhibits magnetophotoselection (MPS). This suggests that the electron transfer (ET) reaction is faster than the longitudinal relaxation of the excited triplet state of Xn ((3)Xn*) or much faster than the tumbling motion of (3)Xn*. The former mechanism is likely under the conditions employed. Indeed, a huge RIP-cored aggregation is quickly formed with solvent molecules which obstruct the free revolution of the RIP. The MPS spectra also indicate that only the molecules closely located react by the solvent-mediated ET.

  AMER CHEMICAL SOC, Jan. 2009, JOURNAL OF PHYSICAL CHEMISTRY A, 113(4) (4), 633 - 638, English

  [Refereed]

  Scientific journal


• 1D radical motion in protein pocket: Proton-coupled electron transfer in human serum albumin

  Y Kobori, Norris, JR

  AMER CHEMICAL SOC, Jan. 2006, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 128(1) (1), 4 - 5, English

  [Refereed]

  Scientific journal


• Time-resolved detection of melanin free radicals quenching reactive oxygen species

  BLL Seagle, KA Rezai, EM Gasyna, Y Kobori, KA Rezaei, Norris, JR

  AMER CHEMICAL SOC, Aug. 2005, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 127(32) (32), 11220 - 11221, English

  [Refereed]

  Scientific journal


• Primary charge-recombination in an artificial photosynthetic reaction center

  Y Kobori, S Yamauchi, S Tero-Kubota, H Imahori, S Fukuzumi, Norris, JR

  AMER CHEMICAL SOC, Aug. 2005, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 230(25) (25), U2941 - U2941, English

  [Refereed]

  Scientific journal


• Primary charge-recombination in an artificial photosynthetic reaction center

  Y Kobori, S Yamauchi, K Akiyama, S Tero-Kubota, H Imahori, S Fukuzumi, JR Norris

  NATL ACAD SCIENCES, Jul. 2005, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 102(29) (29), 10017 - 10022, English

  Scientific journal


• Melanin photoprotection in the human retinal pigment epithelium and its correlation with light-induced cell apoptosis

  BLL Seagle, KA Rezai, Y Kobori, EM Gasyna, KA Rezaei, Norris, JR

  Time-resolved electron paramagnetic resonance (TREPR) spectroscopy was used to study melanin free radicals in human retinal pigment epithelium (RPE) cells and tyrosine-derived synthetic melanin. TREPR signal traces from RPE cells reveal in vivo light-induced melanin free radical photochemistry in more detail than previously known. Electron spin polarization reflecting a non-Boltzmann population within the energy levels of the spin system is observed in RPE cells as the result of the triplet state photoproduction and subsequent disappearance of free radicals in the melanin polymer. In a set of RPE cells cultured from individual sources, differences in optical absorption, continuous wave EPR spectra, and TREPR signals were correlated with apoptosis assays performed by flow cytometry. Continuous wave EPR spectra of RPE cells and TREPR of acidified synthetic melanin suggest that increased melanin aggregation provides an increase in photoprotection in the RPE cells that are relatively less susceptible to blue light-induced apoptosis.

  NATL ACAD SCIENCES, Jun. 2005, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 102(25) (25), 8978 - 8983, English

  [Refereed]

  Scientific journal


• Aspects of the electron transfer reaction rate for systems accompanying a chemical equilibrium change

  T Yago, Y Kobori, K Akiyama, S Tero-Kubota

  In photoinduced electron-transfer systems accompanying chemical equilibrium changes, such as the formation/dissociation of a noncovalent-bonded complex, the calculation method of the charge separation and recombination reaction rates have been derived based on a simple model, in which the formation /dissociation of noncovalent bonding during the electron-transfer reaction is treated as a change of the chemical equilibrium. The effects of the formation /dissociation of noncovalent bonding on the driving forces and the reorganization energies were calculated using the chemical equilibrium constants for the reactant and product states. It has been demonstrated that the formation/dissociation of noncovalent bonding affects the electron-transfer reaction rates not only by stabilizing the charge- separated state, but also by increasing the reorganization energy.

  CHEMICAL SOC JAPAN, Nov. 2004, BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 77(11) (11), 1997 - 2001, English

  [Refereed]

  Scientific journal


• Superexchange electron tunneling mediated by solvent molecules: Pulsed electron paramagnetic resonance study on electronic coupling in solvent-separated radical ion pairs

  Y Kobori, T Yago, K Akiyama, S Tero-Kubota, H Sato, F Hirata, Norris, JR

  Nanosecond pulsed electron paramagnetic resonance spectroscopy is applied to characterize exponential decay constants (beta) of the squared electronic coupling matrix element (V-DA(2)) in transient, solvent-separated radical ion pairs (RIP) composed of quinone anions and several cation radicals in aprotic liquid solutions of N,N-dimethylformamide, DMSO, and benzonitrile. The distance dependence of singlet-triplet energy splitting (2J) is shown to be described by beta in V-DA for charge-recombination processes. We show that the radical pair mechanism (RPM) electron spin polarization (P-RPM) is quite sensitive to beta. The beta value is characterized by using the stochastic Liouville equation to fit the experimental P-RPM values. The beta values (from 0.8 to 1.0 Angstrom(-1)) manifest that V-DA is governed by the superexchange mechanism mediated by the intervening solvent molecules from a result that the beta increases with increasing the tunneling energy gap (DeltaG(eff)) for solvent oxidation or reduction in several intermolecular electron-transfer systems. We propose a simple three-dimensional model of V-DA, in which the through-solvent tunneling pathways are exponentially increased with the increase in the intermolecular distance in bulk, condensed media. This model explains the DeltaG(eff) dependence of beta, including the data previously reported on the charge-transfer reactions both in liquid and frozen (77 K) solutions. Effective solvent-solvent coupling is estimated to be v(B) approximate to 850 cm(-1) at a mean nearest-neighbor distance of 5.7 Angstrom. This relatively large magnitude of v(B) may agree with dynamical amplifications of the effective coupling by low-frequency motions of the mediators as reported in charge-transfer reactions in biological systems.

  AMER CHEMICAL SOC, Jul. 2004, JOURNAL OF PHYSICAL CHEMISTRY B, 108(29) (29), 10226 - 10240, English

  [Refereed]

  Scientific journal


• Unusually large dynamic electron polarization in an O-2((1)Delta(g))-2,2,6,6-tetramethylpiperidine-1-oxyl radical system

  M Mitsui, K Takeda, Y Kobori, A Kawai, K Obi

  Net absorptive (Abs) chemically induced dynamic electron polarization (CIDEP) is observed in the system of the lowest excited singlet molecular oxygen O-2((1)Delta(g)) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical in benzene by means of the time-resolved ESR (TR-ESR) spectroscopy. As a result of (1) the analysis of CIDEP time profiles by the modified Bloch and kinetic equations and (2) the quenching of CIDEP by triethylamine, it is confirmed that the Abs CIDEP is created through the interaction of O-2((1)Delta(g)) with TEMPO. The creation of Abs CIDEP is reasonably interpreted in terms of the radical-triplet pair mechanism (RTPM) of the O-2((3)Sigma(g)(-))-TEMPO pair with doublet precursor. The absolute magnitude of net Abs CIDEP created on TEMPO is experimentally estimated to be 340 +/- 40 in the unit of Boltzmann polarization. To our knowledge, this is one of the largest magnitudes of CIDEP measured so far by the TR-ESR method. Based upon the RTPM theory, the origin of this unusually large CIDEP is attributed to the large spin relaxation effect via the electron spin dipole-dipole interaction of O-2((3)Sigma(g)(-)) formed in the quenching process of O-2((1)Delta(g)) by TEMPO. As a result of the discussion about the large CIDEP in O-2((1)Delta(g)) quenching by TEMPO, it is proposed that the quenching takes place through the enhanced intersystem crossing accompanied with strong electron exchange interaction between an oxygen molecule and a TEMPO radical.

  AMER CHEMICAL SOC, Feb. 2004, JOURNAL OF PHYSICAL CHEMISTRY A, 108(7) (7), 1120 - 1126, English

  [Refereed]

  Scientific journal


• Theoretical Study on Electronic and Solvent Reorganization Associated with a Charging Process of Organic Compounds. 2. A New Decomposition Procedure into Electrostatic and Nonelectrostatic Responses

  H. Sato, Y. Kobori, S. Tero-Kubota, F. Hirata

  2004, J. Phys. Chem. B, 108(31) (31), 10709 - 11715, English

  [Refereed]

  Scientific journal


• Superexchange Electron Tunneling Mediated by Solvent Molecules: Pulsed Electron Paramagnetic Resonance Study on Electronic Coupling in Solvent-Separated Radical Ion Pairs

  Y. Kobori, T. Yago, K. Akiyama, S. Tero-Kubota, H. Sato, F. Hirata, J. R. Norris

  2004, J. Phys. Chem. B, 108(31) (31), 10709 - 11715, English

  [Refereed]

  Scientific journal


• Quenching mechanism of excited coronene by a nitroxide radical studied by probing dynamic electron polarization

  M Mitsui, Y Kobori, A Kawai, K Obi

  By use of the time-resolved electron spin resonance (TR-ESR) method, quenching mechanisms of S-1 and T-1 coronene by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical were investigated by probing absorptive (abs) and emissive (em) chemically induced dynamic electron polarizations (CIDEP), which are generated by interactions of S-1 and T-1 coronene with TEMPO radicals, respectively. Absolute magnitudes of abs and em CIDEPs created on TEMPO radicals in the coronene-TEMPO system in benzene were determined as 1.8 and 2.2, respectively, in the units of Boltzmann polarization by utilizing Bloch and kinetic equations. This result is evaluated by a theoretical model that describes the magnitude of CIDEP created in the radical-triplet (RT) system, and it is clarified that exchange interaction of the T-1 coronene-TEMPO pair is much larger than the Zeeman energy and the em CIDEP is dominantly generated in the level-crossing regions. This means that quenching of T-1 coronene by TEMPO in benzene occurs through an electron-exchange interaction in an RT encounter complex. A ratio of em to abs CIDEP magnitudes was determined to be 1.2. The difference between the magnitudes of abs and em CIDEPs implies that the mean reaction distance of S, quenching is about 1-2 Angstrom longer than that of T-1 quenching. This result suggests that an S-1-T-1 enhanced intersystem crossing occurs through both charge transfer and exchange mechanisms while T-1 quenching occurs only through exchange mechanism.

  AMER CHEMICAL SOC, Jan. 2004, JOURNAL OF PHYSICAL CHEMISTRY A, 108(4) (4), 524 - 531, English

  [Refereed]

  Scientific journal


• Control of the sign of exchange interactions in solvent-separated radical ion pairs

  S Tero-Kubota, K Zikihara, T Yago, Y Kobori, K Akiyama

  The chemically induced dynamic electron polarization spectra generated by the laser photolysis of several donor-acceptor systems have been studied to verify the solvent effects on the exchange interaction in solvent-separated radical ion pairs. It has been shown that the sign of the exchange interaction depends on the polarity of solvents. The individual reorganization energies have been determined for several solvent-separated radical ion pair systems.

  SPRINGER WIEN, 2004, APPLIED MAGNETIC RESONANCE, 26(1-2) (1-2), 145 - 154, English

  [Refereed]

  Scientific journal


• Reorganization energy induced by noncovalent bonding interaction in electron transfer reactions

  T Yago, Y Kobori, K Akiyama, S Tero-Kubota

  A simple model is proposed to calculate a component of the electron-transfer reorganization energy derived from the reversible process of noncovalnt bond formation/dissociation between the reactant and hydrogen bonding donor or ligand. In the model, the reorganization of the formation/dissociation of the noncovalent-bonded complex is estimated by considering the chemical equilibrium change during the electron-transfer reaction. The effects of the hydrogen bonding and the ligand binding on the reorganization energies are calculated for the one-electron reduction processes of quinones, flavin, and the hem-fragment of cytochrome c based on the formation/dissociation constants of the noncovalent-bonded complexes in the liquid phase.

  AMER CHEMICAL SOC, Dec. 2003, JOURNAL OF PHYSICAL CHEMISTRY B, 107(48) (48), 13255 - 13257, English

  [Refereed]

  Scientific journal


• Time-resolved EPR study on reorganization energies for charge recombination reactions in the systems involving hydrogen bonding

  T Yago, Y Kobori, K Akiyama, S Tero-Kubota

  Hydrogen bonding effects on reorganization energies (lambda) in the photoinduced electron donor-acceptor system of duroquinone (DQ)-1,2,4-trimethoxybenzene (TMB) in benzonitrile have been investigated by time-resolved EPR and cyclic voltammetry measurements. The solvent reorganization energies (lambda(S)) determined for the radical ion pair systems involving the hydrogen-bonded complexes are larger by similar to0.2 eV than those calculated from the Marcus continuum dielectric model. The present results suggest that dissociation of the DQ anion-alcohol hydrogen-bonded complex results in the new component of As for the charge recombination reaction in polar solvents. (C) 2003 Elsevier Science B.V. All rights reserved.

  ELSEVIER SCIENCE BV, Feb. 2003, CHEMICAL PHYSICS LETTERS, 369(1-2) (1-2), 49 - 54, English

  [Refereed]

  Scientific journal


• Theoretical Study of Electronic and Solvent Reorganization Associated with a Charging Process of Organic Compounds. I. Molecular and Atomic Level Description of Solvent Reorganization

  H. Sato, Y. Kobori, S. Tero-Kubota, F. Hirata

  2003, J. Chem. Phys., 119(5) (5), 2753 - 2760, English

  [Refereed]

  Scientific journal


• Long-Range Jump versus Stepwise Hops: Magnetic Field Effects on the Charge-Transfer Fluorescence from Photoconductive Polymer Films

  F. Ito, T. Ikoma, K. Akiyama, Y. Kobori, S. Tero-Kubota

  2003, J. Am. Chem. Soc., 125(16) (16), 4722 - 4723, English

  [Refereed]

  Scientific journal


• Diffusion-model analysis of effective CIDEP distance in solvent-separated radical-ion pair

  Y Kobori, T Yago, S Tero-Kubota

  The radical pair mechanism (RPM) of chemically induced dynamic electron polarization (CIDEP) is theoretically analyzed to determine what intermolecular separations (r(eff)) effectively contribute to the CIDEP generated from diffusive, separated radical-ion pairs (RIP) in terms of the charge-transfer interaction in the singlet-triplet energy splitting (J) by taking into account the distance-dependent electronic coupling and reorganization energy. The diffusion-model analysis reveals that the hyperfine-dependent RPM polarization (P-RPM) phase is varied with the driving force (-DeltaG(CR)) for the charge-recombination (CR) process and that the boundary -DeltaG(CR) between the opposite phases coincides well with the total reorganization energy around the diffusible separation distance, r(eff) = 1.2 nm, between the ion radicals. For the first time, the r(eff) is well described by the exponent parameter 66) in the distance-dependent electronic coupling, suggesting that the RPM CIDEP detection can be applied to characterize the electronic coupling in individual solvent-separated RIP systems. It has been concluded that, in contrast to the spin exchange interaction of the neutral radical pairs, the characteristic long-range charge-transfer interaction enables us to utilize the simple diffusion-model analysis to successfully evaluate the r(eff) and the P-RPM, in homogeneous liquid polar solvents.

  SPRINGER WIEN, 2003, APPLIED MAGNETIC RESONANCE, 23(3-4) (3-4), 269 - 287, English

  [Refereed]

  Scientific journal


• Time-resolved EPR study on reorganization energies for charge recombination processes in nanometer-separated radical ion pairs

  Tomoaki Yago, Yasuhiro Kobori, Kimio Akiyama, Shozo Tero-Kubota

  The reorganization energies for the intermolecular charge recombination processes have been determined for the electron donor-acceptor systems involving the quinones and methoxy aromatic molecules by time-resolved EPR and cyclic voltammetry measurements in polar solvents. We have carefully examined what distance between the donor and acceptor molecules is effective for the radical pair mechanism (RPM) chemically induced dynamic electron polarization (CIDEP) detection using the stochastic Liouville equation on the basis of the charge transfer (CT) interaction mechanism in the singlet-triplet energy splitting (2J) in radical ion pairs. The RPM CIDEP shows that the signs of the J are inverted from positive to negative with decreasing temperature. The results are interpreted by the CT interaction mechanism. With the observations of the J ∼ 0 condition, the individual values of the total and solvent reorganization energies (λs) are determined for several 1.2 nm separated donor-acceptor systems. The individual λs values ranging from 1.27 to 1.39 eV in the present donor-acceptor systems agree with those calculated from the Marcus continuum dielectric model at 1.2 nm donor-acceptor separation within the deviation of ∼0.1 eV. In the dimethoxynaphthalene (DMN)-duroquinone (DQ) system, the solvent reorganization around the methoxy groups is dominated due to the localization of the electron spin density in the DMN cation radical.

  Oct. 2002, Journal of Physical Chemistry B, 106(39) (39), 10074 - 10081, English

  [Refereed]

  Scientific journal


• Time-resolved EPR study on reorganization energies for charge recombination processes in nanometer-separated radical ion pairs

  T Yago, Y Kobori, K Akiyama, S Tero-Kubota

  The reorganization energies for the intermolecular charge recombination processes have been determined for the electron donor-acceptor systems involving the quinones and methoxy aromatic molecules by time-resolved EPR and cyclic voltammetry measurements in polar solvents. We have carefully examined what distance between the donor and acceptor molecules is effective for the radical pair mechanism (RPM) chemically induced dynamic electron polarization (CIDEP) detection using the stochastic Liouville equation on the basis of the charge transfer (CT) interaction mechanism in the singlet-triplet energy splitting (2J) in radical ion pairs. The RPM CIDEP shows that the signs of the J are inverted from positive to negative with decreasing temperature. The results are interpreted by the CT interaction mechanism, With the observations of the J 0 condition, the individual values of the total and solvent reorganization energies (As) are determined for several 1.2 nm separated donor-acceptor systems. ne individual As values ranging from 1.27 to 1.39 eV in the present donor-acceptor systems agree with those calculated from the Marcus continuum dielectric model at 1.2 nm donor-acceptor separation within the deviation of similar to0.1 eV. In the dimethoxynaphthalene (DMN)duroquinone (DQ) system, the solvent reorganization around the methoxy groups is dominated due to the localization of the electron spin density in the DMN cation radical.

  AMER CHEMICAL SOC, Oct. 2002, JOURNAL OF PHYSICAL CHEMISTRY B, 106(39) (39), 10074 - 10081, English

  [Refereed]

  Scientific journal


• Spin dynamics and zero-field splitting constants of the triplet exciplex generated by photoinduced electron transfer reaction between erythrosin B and duroquinone

  T Tachikawa, Y Kobori, K Akiyama, A Katsuki, UE Steiner, S Tero-Kubota

  The spin dynamics of the duroquinone anion radical generated by photoinduced electron transfer reactions from triplet erythrosin B to duroquinone has been studied by using transient absorption and pulsed FT-EPR spectroscopy. Triplet exciplex formation as the reaction intermediate is verified by the observation of spin-orbit coupling induced electron spin polarization. The kinetic parameters for exciplex formation and the intrinsic enhancement factors of electron spin polarization are determined in various alcoholic solvents. The zero-field splitting constants of the triplet exciplex are determined by the analysis of the solvent viscosity dependence of the enhancement factors of the electron spin polarization. (C) 2002 Elsevier Science B.V. All rights reserved.

  ELSEVIER SCIENCE BV, Jul. 2002, CHEMICAL PHYSICS LETTERS, 360(1-2) (1-2), 13 - 21, English

  [Refereed]

  Scientific journal


• Solvent effects on the intrinsic enhancement factors of the triplet exciplex generated by photoinduced electron transfer reaction between eosin Y and duroquinone

  T Tachikawa, Y Kobori, K Akiyama, A Katsuki, Y Usui, UE Steiner, S Tero-Kubota

  The spin dynamics of the duroquinone anion radical (DQ(.)) generated by photoinduced electron transfer reactions from triplet eosin Y ((EY2)-E-3) to DQ have been studied by using transient absorption and pulsed EPR spectroscopy. Unusual net-absorptive electron spin polarization plus net-emissive polarization were observed, suggesting the production of the triplet exciplex or contact radical pair as the reaction intermediate. The kinetic parameters and intrinsic enhancement factors of the electron spin polarization were determined in various alcoholic solvents. The net-absorptive electron spin polarization was also observed in ethanol-water mixed solvents. The solvent effects on the radical yield are analysed on the basis of a stochastic Liouville equation established for the magnetic field effects on the radical yield. The zero-field splitting constants of the triplet exciplex are estimated from the solvent viscosity dependence of the enhancement factors due to spin-orbit coupling induced depopulation of the reaction intermediate.

  TAYLOR & FRANCIS LTD, May 2002, MOLECULAR PHYSICS, 100(9) (9), 1413 - 1420, English

  [Refereed]

  Scientific journal


• Determination of electron-transfer reorganization energy in nanometer-separated radical ion pair by time-resolved EPR spectroscopy

  Y Kobori, T Yago, K Akiyama, S Tero-Kubota

  AMER CHEMICAL SOC, Oct. 2001, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 123(39) (39), 9722 - 9723, English

  [Refereed]

  Scientific journal


• Spin-Orbit Coupling Induced Electron Polarization in Photoinduced Electron Transfer Reactions

  S. Tero-Kubota, A. Katsuki, Y. Kobori

  2001, J. Photochem. Photobiol. C, 2(1) (1), 17 - 33, English

  [Refereed]

  Scientific journal


• Magnetic field effects on the triplet exciplex dynamics in the duroquinone-N, N-dimethylaniline derivative systems

  S Sasaki, Y Kobori, K Akiyama, S Tero-Kubota

  Magnetic field effects (MFEs) on the radical yield in the photoinduced electron transfer reaction from the p-halogen derivatives (4XDMA) of N,N-dimethylaniline to the excited trip]et state of duroquinone (DQ) have been investigated in alcoholic solutions at room temperature. In I-propanol and I-butanol solutions, the radical yields decreased as the magnetic field increased and became nearly constant at 1-1.8 T in the DQ-4BrDMA and DQ-4IDMA systems, suggesting that the spin-orbit coupling interaction due to the heavy atoms governs the radical yield. On the other hand, in the methanol solution MFE due to a radical pair mechanism was observed. We concluded that the key intermediate to determine the radical yield is the triplet exciplex or contact radical ion pair in the l-propanol and l-butanol solutions, while it is the solvent-separated radical ion pair in the methanol solution.

  SPRINGER, 2001, RESEARCH ON CHEMICAL INTERMEDIATES, 27(1-2) (1-2), 155 - 164, English

  [Refereed]

  Scientific journal


• Magnetic Field and Spin Effects from Sequential p-Type and d-Type Triplet Mechanisms

  A. Katsuki, Y. Kobori, S. Tero-Kubota, S. Milikisyants, H. Paul, U. E. Steiner

  2001, Mol. Phys., 100(8) (8), 1245 - 1259, English

  [Refereed]

  Scientific journal


• Theoretical analysis of singlet-triplet energy splitting generated by charge-transfer interaction in electron donor-acceptor radical pair systems

  Y Kobori, K Akiyama, S Tero-Kubota

  A theoretical analysis was performed for a prediction of the singlet-triplet energy splitting (J) of electron donor-acceptor radical pairs on the basis of the electron transfer reaction theory. It has been strongly indicated that charge-transfer interaction dominates the J in condensed phase photoinduced electron transfer systems. (C) 2000 American Institute of Physics. [S0021-9606(00)51226-4].

  AMER INST PHYSICS, Jul. 2000, JOURNAL OF CHEMICAL PHYSICS, 113(2) (2), 465 - 468, English

  [Refereed]

  Scientific journal


• Chemically induced dynamic electron polarization study on the mechanism of exchange interaction in radical ion pairs generated by photoinduced electron transfer reactions

  Y Kobori, S Sekiguchi, K Akiyama, S Tero-Kubota

  Photoinduced electron transfer reactions were studied by using the continuous wave time-resolved electron paramagnetic resonance and Fourier-transformed electron paramagnetic resonance spectroscopy in polar solvents. The chemically induced dynamic electron polarization was investigated in both singlet and triplet precursor intermolecular electron transfer systems. The signs of the exchange interaction, which are defined by the energy differences between the singlet and tripler radical ion pairs, depended on the free energy changes for the charge recombination processes. The results are interpreted in terms of the mechanism that the spin selective stabilization and destabilization are caused by the perturbation through the electronic coupling from the ground state and the locally excited triplet state of the donor-acceptor pair at the equilibrium nuclear coordinate. in the singlet precursor electron transfer systems, the positive exchange interaction resulted from the selective tripler stabilization in the radical ion pair, when the ion pair state crossed with the locally excited triplet state at the normal region. In the triplet precursor electron transfer systems, the negative exchange interaction resulted from the selective singlet stabilization when the ion pair state crossed with the singlet ground state at the normal region. When the free energy change is larger than about 1.8 eV, the positive exchange interaction resulted from the spin-selective destabilization in the singlet ion pair, since the level crossing occurs at the inverted region.

  AMER CHEMICAL SOC, Jul. 1999, JOURNAL OF PHYSICAL CHEMISTRY A, 103(28) (28), 5416 - 5424, English

  [Refereed]

  Scientific journal


• Intrinsic enhancement factors of the spin-orbit coupling mechanism polarization in the duroquinone-N,N-dimethylaniline derivative systems

  S Sasaki, Y Kobori, K Akiyama, S Tero-Kubota

  Dynamics of the electron spin polarization of the quinone anion radical generated from the photoinduced electron transfer between duroquinone (DQ) and N,N-dimethylaniline (DMA) as well as its p-halogen substituents (4XDMA) has been investigated by using transient absorption and FTEPR spectroscopies. The radical yield decreased with increasing atomic number of the halogen in the donor. The intrinsic enhancement factors of net absorptive polarization due to the spin-orbit coupling mechanism (SOCM) of V-SOCM = 2, 17, and 25 were determined in the unit of thermal equilibrium polarization at room temperature for the DQ-4ClDMA, DQ-4BrDMA, and DQ-4IDMA systems, respectively. The net absorptive spin polarization observed has been discussed in terms of SOC interaction of the triplet contact radical ion pair (CRIP) state with the ground state, which is coupled with the singlet GRIP states in the solvent coordinate.

  AMER CHEMICAL SOC, Oct. 1998, JOURNAL OF PHYSICAL CHEMISTRY A, 102(42) (42), 8078 - 8083, English

  [Refereed]

  Scientific journal


• Exchange interaction in radical-triplet pairs: Evidences for CIDEP generation by level crossings in triplet-doublet interactions

  Y Kobori, K Takeda, K Tsuji, A Kawai, K Obi

  Chemically induced dynamic electron polarization (CIDEP) generated through interaction of the excited triplet state of 1-chloronaphthalene, benzophenone, benzil, and Buckminsterfullerene (C-60) with 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) radical was investigated by using time-resolved ESR spectroscopy. We carefully examined what factors affect the CIDEP intensities. By comparing CIDEP intensities of TEMPO in the 1-chloronaphthalene, benzophenone, and benzil systems with that obtained in the C-60-TEMPO system, the absolute magnitude of net emissive polarization was determined to be -2,2, -6.9, and -8.0, respectively, in the units of Boltzmann polarization. In the 1-chloronaphthalene-TEMPO system, the viscosity effect on the magnitude of net polarization was studied by changing the temperature (226-275 K) in 2-propanol, The emissive polarization was concluded to result from the state mixing between quartet and doublet manifolds in a radical-triplet pair induced by the zero-field splitting interaction of the counter triplet molecule. The magnitude of net polarization is much larger than the polarization calculated with the reported theory that the CIDEP is predominantly generated in the region where the exchange interaction is smaller than the Zeeman energy. Our experimental results are quantitatively explained by the theory that the CIDEP is generated predominantly in the regions where the quartet and doublet levels cross. We propose a theoretical treatment to calculate the magnitude of net polarization generated by the level crossings in the radical-triplet pair mechanism under highly viscous conditions and perform a numerical analysis of the net RTPM polarization with the stochastic-liouville equation. The viscosity dependence of the net polarization indicates that the back transition from the doublet to quartet states sufficiently occurs in the level-crossing region under highly viscous conditions. The estimated large exchange interaction suggests that the quenching of the excited triplet molecules by TEMPO proceeds via the electron exchange interaction.

  AMER CHEMICAL SOC, Jul. 1998, JOURNAL OF PHYSICAL CHEMISTRY A, 102(27) (27), 5160 - 5170, English

  [Refereed]

  Scientific journal


• Marcus free energy dependence of the sign of exchange interactions in radical ion pairs generated by photoinduced electron transfer reactions

  S Sekiguchi, Y Kobori, K Akiyama, S Tero-Kubota

  AMER CHEMICAL SOC, Feb. 1998, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 120(6) (6), 1325 - 1326, English

  [Refereed]

  Scientific journal


• CIDEP Studies on the Signs of Exchange Interactions in Radical Ion Pairs Generated by Photoinduced Electron Transfer Reactions

  KOBORI YASUHIRO

  1998, Proceedings of the Joint 29th AMPERE-13th ISMAR. International Conference on Magnetic Resonance and Related Phenomena, Berlin, vol. II, 929, English

  [Refereed]

  International conference proceedings


• CIDEP in radical-singlet molecular oxygen system

  A Kawai, M Mitsui, Y Kobori, K Obi

  Net absorptive CIDEP generation has been demonstrated on singlet molecular oxygen and 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxyl (OTEMPO) radical system in benzene. CIDEP generation was reasonably explained in terms of the radical-triplet pair mechanism of triplet molecular oxygen-OTEMPO pair with doublet precursor. Several excited molecule-OTEMPO systems have been investigated if this CIDEP generation contributes to their CIDEP spectra. Surprisingly strong CIDEP was produced even in the presence of trace amount of dissolved oxygen, which suggests the importance of complete degassing for CIDEP studies in general systems.

  SPRINGER VERLAG, 1997, APPLIED MAGNETIC RESONANCE, 12(4) (4), 405 - 410, English

  [Refereed]

  Scientific journal


• The first observation of CIDEP generated through the interaction between an excited singlet oxygen molecule and a free radical

  M Mitsui, K Takeda, Y Kobori, A Kawai, K Obi

  Chemically induced dynamic electron polarization (CIDEP) generated through the interaction between the lowest excited singlet oxygen molecule and 2,2,6,6,-tetramethylpiperidinyl-1-oxyl (TEMPO) radical was observed by the time-resolved ESR technique. Excited singlet oxygen molecules were produced by the triplet sensitizer through energy transfer. Absorptive electron spin polarization was generated on the free radical in the excited singlet oxygen molecule - free radical system, in which the CIDEP generation was interpreted by the radical-triplet pair mechanism with doublet precursor (DP-RTPM). The CIDEP time profile was successfully analyzed by using the Bloch equations. Quenching of O-1(2) by beta-carotene provides further evidence for DP-RTPM in the O-1(2)-TEMPO system.

  ELSEVIER SCIENCE BV, Nov. 1996, CHEMICAL PHYSICS LETTERS, 262(1-2) (1-2), 125 - 130, English

  [Refereed]

  Scientific journal


• Time-resolved ESR studies on ketyl type radical-amine complexes

  A Kawai, A Aoki, Y Kobori, K Obi

  Time-resolved (TR) ESR spectra were measured for alpha-hydroxybenzyl-amine (alpha-HB) and alpha-hydroxydiphenylmethyl-amine complexes. Hyperfine coupling constants (hfcc) of the complexes were determined, and considerable increase in hfcc was recognized on the hydrogen of hydroxy group of both radical complexes, which suggests that the complexes are produced through the hydrogen bond formation between hydroxy group df the radical and amino group of amines. Complex formation constants were determined for various alpha-HB-amine complexes by monitoring TR-ESR signals of the complexes against amine concentrations. It has been noticed that the degree of hydrogen substitution on nitrogen atom of aliphatic amine roughly determines the complex formation constant: complexes with primary amines show the largest value of the complex formation constant while tertiary amines show the smallest value. This result is interpreted based on the structure of the amine.

  AMER CHEMICAL SOC, Jun. 1996, JOURNAL OF PHYSICAL CHEMISTRY, 100(24) (24), 10021 - 10026, English

  [Refereed]

  Scientific journal


• Absolute magnitude of spin polarization in the radical-triplet pair mechanism: CIDEP generation by level crossings in a triplet-doublet interaction

  Y Kobori, M Mitsui, A Kawai, K Obi

  Chemically induced dynamic electron polarization (CIDEP) generated through the interaction of the excited tripler state of benzophenone with the 2,2,6,6,-tetramethyl-1-piperidinyloxyl (TEMPO) radical was investigated by time-resolved ESR spectroscopy in benzene solution. We carefully examined what factors control the CIDEP intensities. By comparing the CIDEP intensity of TEMPO obtained in the triplet benzophenone-TEMPO system with the intensity in the C-60-TEMPO system, the absolute magnitude of net emissive polarization was determined to be -6.9 in the unit of Boltzmann polarization. The emissive polarization is attributed to state mixing between a quarter and a doublet in the radical-tripler pair induced by the zero-field splitting interaction of the counter triplet molecule. Our result is quantitatively explained by the theory that the net CIDEP is generated predominantly in regions where the quarter and doubler levels cross. This indicates that the quenching of the excited triplet benzophenone by TEMPO in benzene can proceed via an electron-exchange interaction.

  ELSEVIER SCIENCE BV, Apr. 1996, CHEMICAL PHYSICS LETTERS, 252(5-6) (5-6), 355 - 361, English

  [Refereed]

  Scientific journal


• DIRECT OBSERVATION OF CIDEP GENERATED THROUGH ENHANCED INTERSYSTEM CROSSING

  Y KOBORI, A KAWAI, K OBI

  The concentration dependence of free radicals (TEMPO) of enhanced absorptive chemically induced dynamic electron polarization (CIDEP) spectra was studied quantitatively to clarify the mechanism of CIDEP generation in excited singlet state-radical systems. It was experimentally demonstrated that the CIDEP intensity on the free radical was in proportion to the concentration of the spin-polarized free radical. The rate constant of the CIDEP generation was determined to be (6.3 +/- 0.2) X 10(9) M(-1) s(-1) from the Stern-Volmer plots of CIDEP intensity in the coronene-TEMPO system in benzene. The absorptive CIDEP spectra were attributed to the free radicals which enhanced the S-1-T-1 intersystem crossing and were interpreted by introducing the stochastic-Liouville equation into the radical-triplet pair mechanism with doublet precursor.

  AMER CHEMICAL SOC, Jun. 1994, JOURNAL OF PHYSICAL CHEMISTRY, 98(26) (26), 6425 - 6429, English

  [Refereed]

  Scientific journal


• TIME-RESOLVED ESR-SPECTRA OF THE ALPHA-HYDROXYBENZYL AMINE COMPLEX

  A KAWAI, Y KOBORI, K OBI

  Time-resolved ESR spectra of the alpha-hydroxybenzyl radical were measured in benzene and 2-propanol solutions by the photodissociation of benzoin. The hyperfine structure (hfs) of alpha-hydroxybenzyl depends on the solvents. In a benzene solution containing triethylamine, two species with different hyperfine structure appeared simultaneously. As the ratio of intensity for the two species depends on the concentration of triethylamine, one of them is assigned to the bare alpha-hydroxybenzyl and the other to the 1:1 complex of alpha-hydroxybenzyl and triethylamine. The equilibrium constant of complex formation was estimated to be about 450 M-1 from the analysis of CIDEP intensities.

  ELSEVIER SCIENCE BV, Nov. 1993, CHEMICAL PHYSICS LETTERS, 215(1-3) (1-3), 203 - 208, English

  [Refereed]

  Scientific journal

• 光受容クリプトクロムによる磁気コンパス機構：タンパク質結合水のゆらぎの役割

  小堀康博

  Lead, ニュー・サイエンス社, Mar. 2023, 細胞, 55(3) (3), 45 - 47, Japanese, Domestic magazine

  [Invited]

  Report scientific journal


• 光受容クリプトクロムによる磁気コンパス機構：タンパク質結合水のゆらぎの役割

  小堀康博

  Lead, 北隆館, Mar. 2023, アグリバイオ, 7(4) (4), 77 - 80

  [Invited]


• Electron Spin Polarization Imaging Method Applied for Elucidating Photon-to-Energy Conversion Mechanism in Organic Thin Film Solar Cells

  Yasuhiro Kobori

  Lead, 光化学協会誌誌, Dec. 2019, 光化学協会誌, 50(3) (3), 177 - 184, Japanese, Domestic magazine

  [Refereed][Invited]

  Introduction scientific journal


• 研究室訪問「神戸着任から新規な中間体磁気イメージング法の開発まで」

  小堀康博

  電子スピンサイエンス学会, Oct. 2017, 電子スピンサイエンス, Japanese, Domestic magazine

  [Refereed][Invited]

  Introduction scientific journal


• 有機半導体界面の光電荷解離機構

  小堀康博

  電子スピンサイエンス学会, Oct. 2016, 電子スピンサイエンス, Japanese, Domestic magazine

  [Refereed][Invited]

  Report scientific journal


• タンパク質の光エネルギー変換機構：光電荷分離のダイナミクスと構造解析の最前線

  KOBORI Yasuhiro

  光化学協会, Dec. 2012, 光化学協会誌「光化学」, 43(3) (3), 134 - 141, Japanese, Domestic magazine

  [Refereed][Invited]

  Introduction scientific journal

• 量子生命科学ハンドブック (瀬藤;光利;荒牧, 修平)

  小堀康博

  Contributor, エヌ・ティー・エス, Mar. 2024, 83-93, Japanese, ISBN: 9784860438821

  [Refereed]

  Textbook


• 化学便覧 基礎編 改訂6版

  小堀康博

  Contributor, 15.4 電子スピン共鳴スペクトル, 丸善出版(株), Mar. 2021


• Roles of orbitals and molecular motions on the light-energy conversions studied by 3D visualization of electron spin polarization

  Yasuhiro Kobori

  Single work, 解説, 月刊「化学」(化学同人), Mar. 2020, Japanese

  Textbook


• 「電子スピンコヒーレンスによる有機太陽電池基板の電子伝達機能の解明」in: 「太陽光と光電変換機能-分野融合から生まれる次世代太陽電池-」

  KOBORI YASUHIRO

  Single work, シーエムシー出版, Feb. 2016, Japanese

  Scholarly book


• 「有機薄膜太陽電池の電子伝達機構：光合成反応中心との比較」光合成研究と産業応用最前線

  KOBORI YASUHIRO, MIURA TAKU

  Others, 株式会社エヌ･ティー･エス, Dec. 2014, Japanese

  Scholarly book


• Translation of sections of 2.22-2.40 and of 3.12-3.27 in “Principle of Moderen Molecular Photochemistry: An Introduction” by N.J. Turro, V. Ramamurthy, J. C. Scaiano,

  KOBORI YASUHIRO, YAMAUCHI SEIGO

  Joint translation, 丸善, Jul. 2013, Japanese

  Textbook


• タンパク質による光エネルギー変換機構：レーザー励起時間分解電子スピン共鳴法を用いた立体構造解析

  KOBORI YASUHIRO

  Single work, 光技術コンタクト, Mar. 2012, Japanese, 植物の光合成やDNAの修復など、さまざまな生命活動でタンパク質は、光を利用して電子伝達を行う中間体分子を効率よく生み出し、エネルギー生産へとつなぐ重要な役割を持つ。光エネルギー変換初期過程では、光の吸収によって電子軌道エネルギーが励起された生体分子が、その近傍の分子に電子あるいは正孔のどちらかを与える。このため生成する中間体分子は、軌道に収容される電子対の内の1つの電子が不足した状態（ラジカル）であり、磁性を持つ。ある励起分子が近傍の分子に電子1個を与えると、両分子が不対電子を持つ状態（電荷分離状態）になる。このような光電荷分離状態は不安定であり、電子あるいは正孔を戻して元の安定な状態に戻ろうとするはずであるが、これではエネルギー変換にはならない。生命が高い効率で光エネルギー変換を行うために、タンパク質は光照射直後に生成した中間体分子の位置や向きを巧

  Scholarly book

• Spin conversion mechanism for efficient photon up-conversion in amorphous rubrene

  Tsubasa OKAMOTO, Yasuhiro Kobori

  9th Kanto Spin Chemistry Meeting, Mar. 2024, English

  Oral presentation


• Quantum decoherence in triplet-radical linked system

  Yasuhiro Kobori

  9th Kanto Spin Chemistry Meeting, Mar. 2024, English

  Oral presentation


• ゆらぎによる励起子ペアのスピン偏極

  小堀康博

  第2回DNP研究会, Mar. 2024, Japanese

  [Invited]

  Invited oral presentation


• パルスEPR法によるスピン相関三重項対のスピン量子コヒーレンス観測

  小堀康博, 婦木正明, 羽曾部卓

  日本化学会第104春季年会(2024), Mar. 2024, Japanese

  Oral presentation


• 時間分解電子スピン共鳴法とパルス電子スピン共鳴法による非フラーレン型有機薄膜太陽電池の界面電荷分離状態の解析

  村山加純, 小堀康博

  日本化学会第104春季年会(2024), Mar. 2024, Japanese

  Oral presentation


• Molecular conformation dynamics effect in singlet-fissions

  Yasuhiro Kobori

  The 9th International Symposium on Dynamic Exciton, Nov. 2023, English

  [Invited]

  Invited oral presentation


• Spin-state dynamics and anisotropies in organic solar cells using transient EPR

  Yasuhiro Kobori

  The 8th International Symposium on Dynamic Exciton, Nov. 2023, English

  [Invited]

  Invited oral presentation


• 三重項ー三重項消滅を用いた光アップコンバージョンの時間分解EPR法による観測：分子内三重項励起子ホッピングの寄与

  東晃輔, 小堀康博

  第62回電子スピンサイエンス学会年会, Nov. 2023, Japanese

  Poster presentation


• 非フラーレン型アクセプターを用いた有機薄膜太陽電池光活性層の初期電荷分離構造：時間分解EPR法による解析

  辻村颯太, 小堀康博

  第62回電子スピンサイエンス学会年会, Nov. 2023, Japanese

  Poster presentation


• 三重項-三重項消滅型光アップコンバータにおける励起子ダイナミクスの時間分解EPRによる解析

  岡本翔, 小堀康博

  第62回電子スピンサイエンス学会年会, Nov. 2023, Japanese

  Oral presentation


• フェロセンで連結したペンタセンダイマーにおける一重項分裂で生成する多重励起子

  婦木正明, 小堀康博

  第62回電子スピンサイエンス学会年会, Nov. 2023, Japanese

  Poster presentation


• 熱活性化遅延蛍光に至る薄膜中三重項励起子の低振動運動:時間分解EPRによる観測

  小堀康博

  第62回電子スピンサイエンス学会, Nov. 2023, Japanese

  Oral presentation


• Photoinduced spin entanglement and decoherence in functionality of complex molecular systems

  Yasuhiro Kobori

  第73回錯体化学討論会, Sep. 2023, English

  [Invited]

  Invited oral presentation


• 分子内一重項励起子分裂に伴う構造変化と三重項消滅: 時間分解EPRと過渡吸収による解析

  楠本遼太, 羽曾部卓, 小堀康博

  第17回分子科学討論会2023, Sep. 2023, Japanese

  Oral presentation


• Observation of photon upconversion by triplet-triplet annihilation using time-resolved EPR: Contribution of intramolecular triplet exciton rotation

  東晃輔, 小堀康博

  2023年光化学討論会, Sep. 2023, English

  Poster presentation


• Elucidation of Initial Charge Separation Structure in ITIC-Based Organic Thin Film Solar Cell Studied by Time-Resolved EPR

  辻村颯太, 小堀康博

  2023年光化学討論会, Sep. 2023, English

  Poster presentation


• 三重項－三重項消滅を用いた液体光アップコンバータに生成する電子スピン分極の時間発展

  岡本翔, 小堀康博

  2023年光化学討論会, Sep. 2023, Japanese

  Oral presentation


• フェロセンで連結したペンタセンダイマーにおける一重項分裂で生成する三重項励起子

  婦木正明, 小堀康博

  2023年光化学討論会, Sep. 2023, Japanese

  Poster presentation


• 光エネルギー変換への鍵となる分子配向と低周波振動:時間分解EPRによる観測

  小堀康博

  2023年光化学討論会, Sep. 2023, Japanese

  [Invited]

  Invited oral presentation


• Time-Resolved EPR Study on Conformational Changes in Triplet-Triplet Dissociation and Annihilation after Intramolecular Singlet Fission

  Ryota Kusumoto, Taku Hasobe, Yasuhiro Kobori

  The 31st International Conference on Photochemistry, Jul. 2023, English

  Poster presentation


• Time-resolved EPR study of electron spin polarization in an efficient triplet-triplet annihilation upconversion system

  Tsubasa OKAMOTO, Yasuhiro Kobori

  The 31st International Conference on Photochemistry, Jul. 2023, English

  Poster presentation


• Impact of Non-fullerene Acceptor Steric Structure on Photoinduced Charge-Separation in Bulkheterojunction Film Studied by Time-resolved EPR

  Kasumi Murayama, Yasuhiro Kobori

  The 31st International Conference on Photochemistry, Jul. 2023, English

  Poster presentation


• Key conformation dynamics for light-induced energy conversions: Transient EPR study

  Yasuhiro Kobori

  The 31st International Conference on Photochemistry, Jul. 2023, English

  [Invited]

  Invited oral presentation


• 有機薄膜太陽電池における電荷輸送機構への非フラーレンアクセプターの立体構造の効果

  村山加純, 小堀康博

  高知化学シンポジウム2023, Jul. 2023, Japanese

  Poster presentation


• 分子内一重項励起子分裂で生成する三重項励起子対の構造変化と三重項消滅 時間分解EPRと過渡吸収による解析

  楠本遼太, 羽曾部卓, 小堀康博

  高知化学シンポジウム2023, Jul. 2023, Japanese

  Poster presentation


• Non-Polymer Organic Solar Cells: Microscopic Phonon Control to Suppress Non-Radiative Voltage Loss via Charge-Separated State

  Yasuhiro Kobori

  ECS Meeting, May 2023, English

  [Invited]

  Invited oral presentation


• Water Dynamics Control of Charge Separation for Magnetoreception by Cryptochrome

  Yasuhiro Kobori

  Gordon Research Conference, Quantum Biology, Mar. 2023, English, Galveston, TX, United States, International conference

  [Invited]

  Invited oral presentation


• 電子スピン共鳴法を用いた液体光アップコンバータに生成する三重項励起子のダイナミクス解析

  岡本翔, 小堀康博

  日本化学会第103春季年会(2023), Mar. 2023, Japanese, 東京理科大学, Domestic conference

  Poster presentation


• 分子ゆらぎが起こす低分子有機太陽電池の電圧損失:時間分解 EPR 法による長距離電荷再結合機構

  小堀康博, 長友敬晃, Ajendra Kumar Va, 松尾恭平, 尾山真也, 岡本直也, 鈴木充朗, 小金澤智之, 婦木正明, 増尾貞弘, 太田薫, 山田容子

  第61回電子スピンサイエンス学会, Dec. 2022, Japanese, 熊本市民会館, Domestic conference

  Oral presentation


• ESRによる非フラーレン型有機薄膜太陽電池における電荷輸送機構の解析

  村山加純, 小堀康博

  第61回電子スピンサイエンス学会年会, Dec. 2022, Japanese, 熊本市民会館, Domestic conference

  Oral presentation


• 分子内一重項励起子分裂で生成する多重励起子の低温での構造変化とその機構:時間分解ESR法を用いた解析

  楠本 遼太, 中村 俊太, 婦木 正明, 羽曾部 卓, 小堀 康博

  第61回電子スピンサイエンス学会年会, Dec. 2022, Japanese, 熊本市民会館, Domestic conference

  Oral presentation


• 9,10-ジフェニルアントラセンにおける三重項―三重項消滅過程の電子スピン分極

  岡本翔, 小堀康博

  第61回電子スピンサイエンス学会年会, Dec. 2022, Japanese, 熊本市民会館, Domestic conference

  Poster presentation


• テトラセン分子ワイヤーにおける一重項分裂で生成した多重励起子と解離状態

  婦木 正明, 中村 俊太, 酒井 隼人, 羽曾部 卓, 小堀 康博

  第61回電子スピンサイエンス学会年会, Dec. 2022, Japanese, 熊本市民会館, Domestic conference

  Oral presentation


• Spin-Entanglement Transport during Singlet Fissions

  Yasuhiro Kobori

  Asia Pacific EPR/ESR Symposium, Nov. 2022, English, Web上での発表, China, International conference

  [Invited]

  Invited oral presentation


• Conformation Change of Exciton Pairs: Spin-Entanglement Transport during Singlet Fissions Studied by Time-Resolved EPR

  Yasuhiro Kobori

  Spin Chemistry Meeting, Sep. 2022, English, Northwestern Univ. Evanston, IL, United States, International conference

  Oral presentation


• Non-Fullerene Organic Photovoltaic: Effect of Introducing Spirofluorene Substituent to Acceptor on the Photoinduced Charge Separation Structure

  村山加純, 陣内青萌, 家裕隆, 小堀康博

  光化学討論会2022, Sep. 2022, Japanese, 京都大学桂キャンパス, Domestic conference

  Poster presentation


• 分子内一重項励起子分裂で生成する多重励起子の低温領域での構造変化:時間分解EPR法による解析

  楠本 遼太, 中村 俊太, 婦木 正明, 羽曾部 卓, 小堀 康博

  光化学討論会2022, Sep. 2022, Japanese, 京都大学桂キャンパス, Domestic conference

  Poster presentation


• Spin Dynamics of Triplet-Triplet Annihilation in a Photon Upconversion System Using 9,10-diphenylanthracene

  岡本翔, 小堀康博

  光化学討論会2022, Sep. 2022, Japanese


• テトラセン分子ワイヤーにおける一重項分裂で生成した三重項状態

  婦木 正明, 中村 俊太, 酒井 隼人, 羽曾部 卓, 小堀 康博

  2022年光化学討論会, Sep. 2022, Japanese, 京都大学桂キャンパス, Domestic conference

  Poster presentation


• 金属有機構造体の励起子分裂による多重励起子のスピン量子操作

  小堀 康博, 婦木 正明, 田中 健太郎, 山内 朗生, 君塚 信夫, 笠 僚宏, 恩田 健, 宮田 潔志, 楊井 伸浩

  光化学討論会2022, Sep. 2022, Japanese, 京都大学桂キャンパス, Domestic conference

  Oral presentation


• Exciton Dynamics on Triplet-Triplet Annihilation Upconversion in Organic Semiconductors Revealed by Time-Resolved EPR

  Tsubasa Okamoto, Seiichiro Izawa, Masahiro Hiramoto, Yasuhiro Kobori

  61st Rocky Mountain Conference on Magnetic Resonance, Jul. 2022, English, Denver, Colorado, United States, International conference

  Oral presentation


• Conformations of Exciton Pairs Associated with Spin-Entanglement Transports during Singlet Fissions

  Yasuhiro Kobori

  ECS Meeting, May 2022, English, Vancouver, CA, Canada, International conference, Co-authored internationally

  [Invited]

  Invited oral presentation


• 時間分解電子スピン共鳴法による非フラーレン型太陽電池材料の界面電荷分離構造解析

  村山加純, 陣内 青萌, 家 裕隆, 小堀康博

  日本化学会第102春季年会(2022), Mar. 2022, Japanese, Web上での発表, Domestic conference

  Oral presentation


• 分子内一重項励起子分裂で生成する多重励起子の構造変化:時間分解ＥＰＲ法による解析

  楠本遼太,中村 俊太,婦木 正明,羽曾部 卓,小堀康博

  日本化学会第102春季年会(2022), Mar. 2022, Japanese, Web上での発表, Domestic conference

  Oral presentation


• 時間分解EPR法による熱活性化遅延蛍光分子の励起状態の解析

  勝平譲治・日下部 悠・和田啓幹・菅野奈都子・Ren Yongxia・梶 弘典・小堀康博

  日本化学会第102春季年会(2022), Mar. 2022, Japanese, Web上での発表, Domestic conference

  Oral presentation


• 電子スピン分極の空間映像化による動的エキシトン機構解析

  小堀康博

  京都大学分子工学研究科特別講演会, Jan. 2022, Japanese, 京都大学分子工学研究科

  [Invited]

  Public discourse


• Heterogeneous charge-separation geometries at bulk-heterojunction interfaces in organic solar cell studied by transient EPR

  Yasuhiro Kobori

  Pacifichem2021, Dec. 2021, English, Web上での発表, International conference

  [Invited]

  Invited oral presentation


• Water dynamics control of the magnetic compass

  Yasuhiro Kobori

  7th Kanto Area Spin Chemistry Meeting (KASC 7), Dec. 2021, English, Web上での発表, Domestic conference

  [Invited]

  Invited oral presentation


• Spin-entanglement transport via singlet-fission as studied by transient EPR

  Yasuhiro Kobori

  Pacifichem2021, Dec. 2021, English, Web上での発表, International conference

  [Invited]

  Invited oral presentation


• 動物の磁気コンパスにおける水和運動の役割: 光受容タンパク質の長距離電荷分離機構

  小堀康博

  第１５回物性科学領域横断研究会, Nov. 2021, Japanese, Web上での発表, Domestic conference

  [Invited]

  Invited oral presentation


• Vibronic Spins in Singlet Fissions

  Yasuhiro Kobori

  Modern Development of Magnetic Resonance, Nov. 2021, English, Web上での発表, International conference

  [Invited]

  Invited oral presentation


• Conformation change and electronic de-coupling via intramolecular singlet fissions

  Yasuhiro Kobori

  ICFPE2021, Oct. 2021, English, Web上での発表, International conference

  [Invited]

  Invited oral presentation


• 分子内励起子分裂に伴う立体構造変化と電子的デカップリング :電子スピン分極映像化による解析

  小堀康博

  第15回 分子科学討論会, Sep. 2021, Japanese, Web上での発表, Domestic conference

  Oral presentation


• 光合成光電荷分離のスピン量子コヒーレンスとデコヒーレンス

  小堀康博

  量子生命科学会第3回大会, Sep. 2021, Japanese, Web上での発表, Domestic conference

  [Invited]

  Invited oral presentation


• 時間分解EPR法による熱活性化遅延蛍光分子の励起状態の解析

  勝平譲治, 日下部 悠, 和田啓幹, 菅野奈都子, Ren Yongxia, 梶 弘典, 小堀康博

  2021年光化学討論会, Sep. 2021, Japanese, Web上での発表, Domestic conference

  Poster presentation


• 時間分解EPRによるビフェニル連結テトラセンダイマーの分子内励起子分裂機構の解明

  大西翔, 小堀康博

  2021年光化学討論会, Sep. 2021, Japanese, Web上での発表, Domestic conference

  Poster presentation


• ベンゾポルフィリン-ジケトピロロピロールをドナーとするバルクヘテロ接合界面の電荷移動と電荷解離:時間分解EPRによる解析

  長友 敬晃・婦木 正明・山田 容子・増尾 貞弘・小堀 康博

  2021年光化学討論会, Sep. 2021, Japanese, Web上での発表, Domestic conference

  Poster presentation


• 結晶性薄膜の一重項励起子分裂 : 活性化多重励起子の構造と解離に対する動的効果

  小堀康博

  光化学討論会2021, Sep. 2021, Japanese, Web上での発表, Domestic conference

  Oral presentation


• 電子スピン分極映像化による超高効率エネルギー変換機構の解明

  小堀康博

  第19回ESR夏の学校講演会, Sep. 2021, Japanese, Web上での発表, Domestic conference

  [Invited]

  Public discourse


• 「電子スピン分極映像化による超高効率光エネルギー変換機構の解明」

  小堀康博

  第一回広帯域極限電磁波生命理工連携研究会, Sep. 2021, Japanese, Web上での発表, Domestic conference

  [Invited]

  Nominated symposium


• Generation domain of quintet multiexcitons via singlet fission in organic thin films as studied by time-resolved EPR

  Takaaki Nagatomo, Yasuhiro Kobori

  ISMAR-APNMR2021, Aug. 2021, English, Web上での発表, International conference

  Poster presentation


• Vibronic Effect of Donor-Acceptor Interaction Determines Fate of Mutiexciton Spins Generated By Singlet Fission

  Yasuhiro Kobori

  ECS Meeting, Jun. 2021, English, Web上での発表, International conference

  [Invited]

  Invited oral presentation


• Conformation Changes in Intramolecular Multiexciton Spins

  Yasuhiro KOBORI

  6th Kanto Area Spin Chemistry Meeting, Dec. 2020, English, Web上での発表, International conference

  [Invited]

  Invited oral presentation


• 電子スピンの量子･動的効果で読み解く光エネルギー変換のしくみ

  小堀康博

  “光”機到来！Qコロキウム, Dec. 2020, Japanese, Web上での発表, Domestic conference

  [Invited]

  Public discourse


• 植物PSIIの電荷再結合に対する活性化パラメータの再評価

  尾崎恭佑, 長嶋宏樹, 三野広幸, 立川貴士, 小堀康博

  電子スピンサイエンス学会年会2020, Nov. 2020, Japanese, Web上での発表, Domestic conference

  Poster presentation


• 共有結合した二量体における一重項励起子分裂によって生成された五重項励起子の立体配置

  婦木正明, 鈴木悠大, 中村俊太, 酒井隼人, 羽曾部卓, 小堀康博

  電子スピンサイエンス学会年会2020, Nov. 2020, Japanese, Web上での発表, Domestic conference

  Poster presentation


• 分子内一重項分裂によるスピン相関三重項対生成に対する振電効果

  小堀康博, 婦木正明, 中村俊太, 羽曾部卓

  電子スピンサイエンス学会年会2020, Nov. 2020, Japanese, Web上での発表, Domestic conference

  Oral presentation


• Fast T-Type Photochromism of Colloidal Cu-Doped ZnS Nanocrystals

  Yoichi KOBAYASHI, Morihiko HAMADA, Yasuhiro KOBORI

  2020年光化学討論会, Sep. 2020, Japanese, Web上での発表, Domestic conference

  Oral presentation


• 有機薄膜中の一重項励起子分裂による五重項多重励起子の生成ドメイン

  長友 敬晃, 松田 紗季, 濱田 守彦, 小堀 康博

  2020年光化学討論会, Sep. 2020, Japanese, Web上での発表, Domestic conference

  Poster presentation


• 植物 PSII の初期光電荷分離による立体配置と電荷再結合に対する温度効果

  尾崎 恭佑, 長嶋 宏樹, 三野 広幸, 立川 貴士, 小堀 康博

  2020年光化学討論会, Sep. 2020, Japanese, Web上での発表, Domestic conference

  Poster presentation


• 共有結合した二量体における一重項分裂によって生成された五重項励起子の立体配置

  婦木 正明, 中村 俊太, 羽曾部 卓, 小堀 康博

  2020年光化学討論会, Sep. 2020, Japanese

  Oral presentation


• 有機薄膜中のシングレットフィッションによる多重励起子解離機構:時間分解 EPR 法を用いた解析

  松田 紗季, 婦木 正明, 小堀 康博

  2020年光化学討論会, Sep. 2020, Japanese, Web上での発表, Domestic conference

  Poster presentation


• Photon-to-Energy Conversion Mechanisms Revealed by Quantum Effects on Electron Spin Polarization

  Yasuhiro KOBORI

  JPA Award 2019 Award Lecture, Sep. 2020, Japanese, Web上での発表, Domestic conference

  [Invited]

  Invited oral presentation


• Electron Spin Polarization Transfers in Charge-Separation and in Singlet Fission

  Yasuhiro Kobori

  5th Kanto Area Spin Chemistry Meeting (4th KASC), Dec. 2019, English, Saitama Univ., Japan, International conference

  [Invited]

  Invited oral presentation


• TIPS ペンタセン薄膜の一重項分裂による室温での時間分解 EPR

  長友敬晃, 松田紗季, 濱田守彦, 小堀康博

  第58回電子スピンサイエンス学会年会（SEST2019）, Nov. 2019, Japanese, Domestic conference

  Poster presentation


• 時間分解 EPR 法を用いた P3HT:PC70BM ブレンド膜における 光誘起電荷ダイナミクスの解明

  尾山真也, 長嶋宏樹, 濱田守彦, 梅山有和, 立川貴士, 今堀博, 小堀康博

  第58回電子スピンサイエンス学会年会（SEST2019）, Nov. 2019, Japanese, Domestic conference

  Poster presentation


• 非フラーレンアクセプターを用いたブレンド膜の時間分解 EPR

  岡村芽衣水, 濱田守彦, 小堀康博

  第58回電子スピンサイエンス学会年会（SEST2019）, Nov. 2019, Japanese, Domestic conference

  Poster presentation


• 時間分解 EPR 法による一重項励起子分裂により生成した多重励起子解離機構の解明

  松田紗季, 尾山真也, 立川貴士, 小堀康博

  第58回電子スピンサイエンス学会年会（SEST2019）, Nov. 2019, Japanese, Domestic conference

  Poster presentation


• 偏光励起による五重項状態の効率的形成に関する研究

  長嶋宏樹, 松井康哲, 河岡秀平, 秋本誠志, 立川貴士, 池田浩, 小堀康博

  第58回電子スピンサイエンス学会年会（SEST2019）, Nov. 2019, Japanese, Domestic conference

  Poster presentation


• ハロゲン混合型有機無機ペロブスカイトにおける光誘起相分離

  坂本 萌里, 狩俣 出, 小堀 康博, 立川 貴士

  2019年光化学討論会, Sep. 2019, Japanese, Domestic conference

  Poster presentation


• 植物 PSII の初期光電荷分離による立体配置と電荷再結合に対する温度効果

  尾崎 恭佑, 長嶋 宏樹, 尾山 真也, 三野 広幸, 立川 貴士, 小堀 康博

  2019年光化学討論会, Sep. 2019, Japanese, Domestic conference

  Poster presentation


• イオンダイナミクスが誘起する有機鉛ペロブス カイトの単一粒子発光スイッチング

  狩俣 出, 小堀康博, 立川 貴士

  Sep. 2019

  Oral presentation


• 二色時間分解 EPR 測定法を用いた有機太陽電池 における電荷分離状態の観測

  濱田 守彦, 尾山 真也, 尾坂 格, 立川 貴士, 小堀 康博

  2019年光化学討論会, Sep. 2019, Japanese, Domestic conference

  Oral presentation


• Transport of Spin-Correlated Multiexciton via Singlet Fission

  Yasuhiro Kobori

  Wasielewski Symposium (Wazapalooza2019), Sep. 2019, English, Northweastern University, Evanston, USA, United States, International conference

  [Invited]

  Invited oral presentation


• Photoinduced charge recombination in P3HT:PC70BM blend film studied by TR-EPR

  ○Shinya Oyama, Hiroki Nagashima, Takashi Tachikawa, Yasuhiro Kobori

  16th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena, Aug. 2019, English, Saint Petersburg, Russia, International conference

  Poster presentation


• Molecular geometries and motions driving quintet multiexcitons via singlet fissions

  ○Yasuhiro Kobori, Hiroki Nagashima, Shuhei Kawaoka, Seiji Akimoto, Takashi Tachikawa, Yasunori Matsui, Hiroshi Ikeda

  16th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena, Aug. 2019, English, Saint Petersburg, Russia, International conference

  Oral presentation


• Mechanism of multiple multiexciton formation and triplet dissociation by singlet fission in thin films

  Saki Matsuda, Shinya Oyama, Takashi Tachikawa, Yasuhiro Kobori

  16th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena, Aug. 2019, English, Saint Petersburg, Russia, International conference

  Poster presentation


• Molecular Geometries and Motions Drive Quintet Multiexcitons via Singlet Fissions

  ○Yasuhiro Kobori, Hiroki Nagashima, Shuhei Kawaoka, Seiji Akimoto, Takashi Tachikawa, Yasunori Matsui, Hiroshi Ikeda

  6th Awaji International Workshop on “Electron Spin Science & Technology: Biological and Materials Science Oriented Applications” (6th AWEST 2019), Jun. 2019, English, Awaji Yumebutai International Conference Center, International conference

  Oral presentation


• Transient Electron Spin Polarization Imaging of Photoinduced Interfacial Charge Separation Geometries in Organic Photovoltaic Cell

  ○Yasuhiro Kobori, Takumi Ako, Takashi Tachikawa, Kazuhiro Marumoto

  235th ECS Meeting, May 2019, English, Dallas（USA）, International conference

  [Invited]

  Invited oral presentation


• Geometry and Dynamics of Quintet Multiexciton Studied By Time-Resolved EPR

  ○Yasuhiro Kobori, Hiroki Nagashima, Shuhei Kawaoka, Seiji Akimoto, Takashi Tachikawa, Yasunori Matsui, Hiroshi Ikeda

  235th ECS Meeting, May 2019, English, Dallas（USA）, International conference

  [Invited]

  Invited oral presentation


• Unveiling Primary Photo-Energy Conversion Mechanisms by Transient Electron Spin Polarization Imaging Spectroscopy

  Yasuhiro Kobori

  Colloquium in Department of Applied Chemistry, National Chiao Tung University, Apr. 2019, English, National Chiao Tung University(台湾), International conference

  [Invited]

  Invited oral presentation


• 有機鉛ハロゲン化物ペロブスカイトにおける発光挙動の単一粒子発光観測

  木村 優季, 狩俣 出, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conference

  Oral presentation


• 時間分解電子スピン共鳴法を用いた光エネルギー変換初期過程の観測

  KOBORI YASUHIRO

  第19回分子分光研究会, Mar. 2019, Japanese, 静岡大学 静岡キャンパス, Domestic conference

  [Invited]

  Invited oral presentation


• 酸化チタンメソ結晶の制御されたナノ空間を利用した選択的光触媒反応

  村上 雄太, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conference

  Oral presentation


• ルテニウム色素吸着メソポーラスシリカの単一粒子蛍光顕微鏡観測：細孔内拡散と光触媒活性の関係

  渡瀬 達也, 宗宮 穣, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conference

  Poster presentation


• ハロゲン混合型有機無機ペロブスカイトナノ粒子の単一粒子発光イメージング

  坂本 萌里, 狩俣 出, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conference

  Poster presentation


• ソフトクリスタルにおける刺激応答構造変化の蛍光顕微鏡観測

  山下 真帆, 永井 彩香, KOBORI YASUHIRO, 伊藤 傑, TACHIKAWA TAKASHI

  日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conference

  Poster presentation


• Three-Dimension Visualizations of Electron Spin Polarization for Elucidating Photo-Energy Conversion Mechanisms

  Yasuhiro Kobori

  6th OCU International Workshop on Quantum Chemistry/Quantum Chemical Calculations on Quantum Computers: Quantum Algorithms, Mar. 2019, English, OCU Media Center, Osaka City University, International conference

  [Invited]

  Invited oral presentation


• Single-Particle Photoluminescence Switching Induced by Ion Dynamics in Organic-Inorganic Perovskite Nanoparticles

  ○Izuru Karimata, Yasuhiro Kobori, Takashi Tachikawa

  日本化学会 第99春季年会 (2019), Mar. 2019, English, 甲南大学 岡本キャンパス, Domestic conference

  Oral presentation


• Observation of Quantitative Intermolecular Two-Electron Transfer Process through Highly Efficient Singlet Fission in Tetracene Dimer

  ○NAKAMURA, Shunta, SAKAI, Hayato, NAGASHIMA, Hiroki, KOBORI, Yasuhiro, TKACHENKO, Nikolai, HASOBE, Taku

  日本化学会 第99春季年会 (2019), Mar. 2019, English, 甲南大学 岡本キャンパス, Domestic conference

  Oral presentation


• Long-lived Triplet Excitons Formed by Intramolecular Singlet Fission of Adamantane-linked Tetracene Dyad

  ○MATSUI, Yasunori, KAWAOKA, Shuhei, NAGASHIMA, Hiroki, NAKAGAWA, Tatsuo, OKAMURA, Naoki, OHTA, Eisuke, YAGI, Shigeyuki, KOBORI, Yasuhiro, IKEDA, Hiroshi

  日本化学会 第99春季年会 (2019), Mar. 2019, English, 甲南大学 岡本キャンパス, Domestic conference

  Oral presentation


• Local Environment of Lipid Bilayer Membrane Monitored by Magnetic Field Effect-Based Fluorescence Imaging

  ○Manabu Sakurai, Yasuhiro Kobori, Takashi Tachikawa

  日本化学会 第99春季年会 (2019), Mar. 2019, English, 甲南大学 岡本キャンパス, Domestic conference

  Oral presentation


• Intramolecular Singlet Fission Behavior of Adamantane-linked Tetracene Dyad

  ○KAWAOKA, Shuhei, MATSUI, Yasunori, NAGASHIMA, Hiroki, NAKAGAWA, Tatsuo, OKAMURA, Naoki, OHTA, Eisuke, YAGI, Shigeyuki, KOBORI, Yasuhiro, IKEDA, Hiroshi

  日本化学会 第99春季年会 (2019), Mar. 2019, English, 甲南大学 岡本キャンパス, Domestic conference

  Poster presentation


• Cuをドープした水溶性ZnSナノ結晶の光物性とフォトクロミズム

  韓 玉蓮, 濱田 守彦, KOBORI YASUHIRO, 小林 洋一

  日本化学会 第99春季年会 (2019), Mar. 2019, Japanese, 甲南大学 岡本キャンパス, Domestic conference

  Oral presentation


• 部位特異的スピンラベルEPR分光法によるABCトランスポーター; BhuUVの構造変化測定

  大西 萌, KOBORI YASUHIRO, 城 宜嗣, 杉本 宏, TSUBAKI MOTONARI, KIMURA TETSUNARI

  神戸大学先端融合研究環境環ワークショップ『非共有結合系の分子科学：計測技術から探る生体分子科学の新展開』, Jan. 2019, Japanese, 神戸大学 六甲台キャンパス 理学部Z201, 205号室, Domestic conference

  Poster presentation


• 部位特異的スピンラベルEPR分光法によるABCトランスポーター;BhuUVの構造変化の実時間測定

  大西 萌, TSUBAKI MOTONARI, KOBORI YASUHIRO, KIMURA TETSUNARI

  神戸大学 研究基盤センター 若手フロンティア研究会2018, Dec. 2018, Japanese, 神戸大学百年記念館, Domestic conference

  Poster presentation


• Singlet-Fission-Born Quintet State: Sublevel Selections and Trapping by Entropy Enhancement in Disordered Aggregates

  Hiroki Nagashima, Shuhei Kawaoka, Seiji Akimot, Takashi Tachikawa, Yasunori Matsui, Hiroshi Ikeda, Yasuhiro Kobori

  10th Asian Photochemistry Conference (APC2018), Dec. 2018, English, Howard Civil Service Internationl House（Taipei）, International conference

  Oral presentation


• Single-Particle Emission Observation of Ruthenium Complex Supported on Mesoporous Silica

  Tatsuya Watase, Minoru Sohmiya, Yasuhiro Kobori, Takashi Tachikawa

  10th Asian Photochemistry Conference (APC2018), Dec. 2018, English, Howard Civil Service Internationl House（Taipei）, International conference

  Poster presentation


• Single-Particle Emission Observation of NaTaO3 Photocatalysts Using Deep Ultraviolet Fluorescence Microscope

  Seigo Mizutani, Yasuhiro Kobori, Takashi Tachikawa

  10th Asian Photochemistry Conference (APC2018), Dec. 2018, English, Howard Civil Service Internationl House（Taipei）, International conference

  Poster presentation


• Localized Trapped Charges Induce Slow Charge Transfer over a Few Nanoseconds on Heterostructured CH3NH3PbBr3-xIx

  ○Izuru Karimata, Kaoru Ohta, Yasuhiro Kobori, Takashi Tachikawa

  10th Asian Photochemistry Conference (APC2018), Dec. 2018, English, Howard Civil Service Internationl House（Taipei）, International conference

  Poster presentation


• Local Environment Mapping of Lipid Bilayer Membranes using Magnetic Field Effects

  ○Manabu Sakurai, Yasuhiro Kobori, Takashi Tachikawa

  10th Asian Photochemistry Conference (APC2018), Dec. 2018, English, Howard Civil Service Internationl House（Taipei）, International conference

  Oral presentation


• Development of Titanium Dioxide Mesocrystals for Highly Efficient and Selective Photocatalysis: Role of Oriented Nano-Space

  ○Yuta Murakami, Yasuhiro Kobori, Takashi Tachikawa

  10th Asian Photochemistry Conference (APC2018), Dec. 2018, English, Howard Civil Service Internationl House（Taipei）, International conference

  Poster presentation


• Development of Hierarchical Mesocrystals for Efficient Photocatalysis

  ○Takashi Tachikawa, Tomoya Ochi, Zhujun Zhang, Yasuhiro Kobori

  10th Asian Photochemistry Conference (APC2018), Dec. 2018, English, Howard Civil Service Internationl House（Taipei）, International conference

  Oral presentation


• 時間分解EPR法を用いたPC70BM薄膜中における励起子拡散の観測

  濱田 守彦, 長嶋 宏樹, 尾山 真也, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  第57回電子スピンサイエンス学会年会（SEST2018）, Nov. 2018, Japanese, 北海道大学, Domestic conference

  Oral presentation


• 時間分解EPR法を用いたP3HT:PC70BMブレンド膜に生成する光電荷分離状態の観測

  尾山 真也, 長嶋 宏樹, 濱田 守彦, 五十嵐 健翔, 梅山 有和, TACHIKAWA TAKASHI, 今堀 博, KOBORI YASUHIRO

  第57回電子スピンサイエンス学会年会（SEST2018）, Nov. 2018, Japanese, 北海道大学, Domestic conference

  Oral presentation


• 有機包接結晶における室温リン光発光性三重項電荷移動状態のゲスト分子依存性

  江間 文俊, 小野 利和, 久枝 良雄, 長嶋 宏樹, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Poster presentation


• 電子スピン共鳴によるSrドープNaTaO3光触媒の電子励起状態の研究

  佐藤 孝賢, KOBORI YASUHIRO, ONISHI HIROSHI

  第21回分子科学討論会2018, Sep. 2018, Japanese, 福岡国際会議場, Domestic conference

  Poster presentation


• 新規金属酸化物メソ結晶の開発と高効率・高選択的光触媒への応用

  村上 雄太, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Poster presentation


• 新規テトラセンダイアドで実現する分子内シングレットフィッション

  河岡 秀平, 松井 康哲, 長嶋 宏樹, 中川 達央, 岡村 奈生己, 太田 英輔, 八木 繁幸, KOBORI YASUHIRO, 池田 浩

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Poster presentation


• 時間分解EPR 法を用いたP3HT:PC70BM ブレンド膜に生成する光電荷分離状態の観測

  尾山 真也, 長嶋 宏樹, 濱田 守彦, 五十嵐 健翔, 梅山 有和, TACHIKAWA TAKASHI, 今堀 博, KOBORI YASUHIRO

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Poster presentation


• 時間分解EPRによる一重項分裂反応から生じた三重項励起子対のダイナミクスの解析

  長嶋 宏樹, 河岡 秀平, AKIMOTO SEIJI, TACHIKAWA TAKASHI, 松井 康哲, 池田 浩, KOBORI YASUHIRO

  第12回分子科学討論会2018, Sep. 2018, Japanese, 福岡国際会議場, Domestic conference

  Oral presentation


• 混合ハロゲン化物ペロブスカイトにおける電荷キャリアダイナミクス

  TACHIKAWA TAKASHI, 狩俣 出, OHTA KAORU, KOBORI YASUHIRO

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Oral presentation


• メソポーラスシリカ担持ルテニウム錯体の単一粒子発光観測：細孔内拡散と光触媒活性の関係

  渡瀬 達也, 宗宮 穣, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Poster presentation


• ハロゲン交換反応によるペロブスカイトナノ粒子のコアーシェル空間制御

  狩俣 出, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Poster presentation


• タンタル酸ナトリウム光触媒の発光特性と金属ドープ濃度の関係性

  水谷 晟吾, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Poster presentation


• クリプトクロムに生成する光電荷分離状態の立体構造の観測

  濱田 実里, KOBORI YASUHIRO, TACHIKAWA TAKASHI, 長嶋 宏樹, 神取 秀樹, 岩田 達也

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Poster presentation


• TREPR 法によるシングレットフィッションにおける五重項状態の生成機構

  長嶋 宏樹, 河岡 秀平, AKIMOTO SEIJI, TACHIKAWA TAKASHI, 松井 康哲, 池田 浩, KOBORI YASUHIRO

  2018年光化学討論会, Sep. 2018, Japanese, 関西学院大学・上ケ原キャンパス, Domestic conference

  Oral presentation


• Singlet-Fission-Born Quintet State: Sublevel Selections and Trapping by Multiexciton Thermodynamics

  Yasuhiro Kobori

  3rd International conference SPIN PHYSICS, SPIN CHEMISTRY and SPIN TECHNOLOGY, Sep. 2018, English, Novosibirsk (Russia), International conference

  [Invited]

  Invited oral presentation


• Real-time measurements of the conformational changes in ABC transporter; BhuUV, revealed by site-directed spin-labeling EPR spectroscopy

  ○Kizashi Onishi, Motonari Tsubaki, Yasuhiro Kobori, Tetsunari Kimura

  第56回日本生物物理学会年会, Sep. 2018, English, 岡山大学 津島キャンパス, Domestic conference

  Poster presentation


• AB18 - Electron Spin Polarization Imaging of Photoinduced Primary Charge-Separated States in PSII

  ○Yasuhiro Kobori, Hiroki Nagashima, Takashi Tachikawa, Hiroyuki Mino

  The third joint conference of the Asia-Pacific EPR/ESR Society and the International EPR (ESR) Society (IES), Sep. 2018, English, Brisbane, International conference

  Oral presentation


• 光合成初期反応の電子スピン画像解析

  KOBORI YASUHIRO

  第5回森野ディスカッション, Aug. 2018, Japanese, 東京大学理学部 小柴ホール, Domestic conference

  Invited oral presentation


• Correlated dynamics of photogenerated charges and ions in organolead mixed-halide perovskites

  ○Takashi Tachikawa, Izuru Karimata, Yasuhiro Kobori

  27th IUPAC International Symposium on Photochemistry, Jul. 2018, English, University College Dublin(Ireland), International conference

  Oral presentation


• Time-Resolved EPR Study on Singlet Fission and Subsequent Triplet Dissociation Dynamics

  Hiroki Nagashima, Shuhei Kawaoka, Seiji Akimoto, Takashi Tachikawa, Yasunori Matsui, Hiroshi Ikeda, ○Yasuhiro Kobori

  35th International Conference of Photopolymer Science and Technology(ICPST-35), Jun. 2018, English, 幕張メッセ国際会議場, International conference

  [Invited]

  Invited oral presentation


• Time Resolved EPR Study on Photoinduced Charge-Transfer Trap States in Thiophene-Thiazolothiazole Copolymers Films

  ○Yasuhiro Kobori, Yuta Yamamoto, Takumi Ako, Hiroki Nagashima, Takashi Tachikawa, Itaru Osaka

  233rd ECS MEETING, May 2018, English, Seattle, WA USA, International conference

  [Invited]

  Invited oral presentation


• NaTaO3光触媒に生成する光キャリアの運動と空間分布

  KOBORI YASUHIRO

  タンタル酸ナトリウム光触媒のダイナミズムに関する研究会2018, Feb. 2018, Japanese, 石川県白山市, Domestic conference

  Oral presentation


• Spin convrsion of the singlet-fission-bornmultiexciton in the amorphous aggregates

  Hiroki Nagashima, Shuhei Kawaoka, Seiji Akimoto, Takashi Tachikawa, Yasunori Matsui, Hiroshi Ikeda, Yasuhiro Kobori

  The third joint conference of the Asia-Pacific EPR/ESR Society and the International EPR (ESR) Society (IES), 2018, English, Brisbane, International conference

  Oral presentation


• Multiexciton dynamics in amorphous aggregates of singlet fission materials studied by time-Resolved EPR spectroscopy

  Hiroki Nagashima, Shuhei Kawaoka, Seiji Akimoto, Takashi Tachikawa, Yasunori Matsui, Hiroshi Ikeda, Yasuhiro Kobori

  10th Asian Photochemistry Conference (APC 2018), 2018, English, 台北, International conference

  Poster presentation


• 巨大分子の光機能解明と時間発展

  KOBORI YASUHIRO

  先端的ESR研究Workshop2017, Dec. 2017, Japanese, 弥彦温泉 四季の宿みのや (新潟県西蒲原郡弥彦村弥彦), Domestic conference

  Oral presentation


• 電子スピン分極イメージング法によるクリプトクロム光電荷分離状態の立体構造解析

  KOBORI YASUHIRO, 濱田 美里, 長嶋 宏樹, TACHIKAWA TAKASHI, 岩田 達也, 神取 秀樹, Till Biskup, Stefan Weber

  第56回電子スピンサイエンス学会年会（SEST2017）, Nov. 2017, Japanese, 東京工業大学, Domestic conference

  Oral presentation


• 時間分解EPR法による室温リン光発光性有機包接結晶の三重項電荷移動状態におけるゲスト分子依存性

  江間 文俊, 小野 利和, 福田 有貴, 久枝 良雄, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  第56回電子スピンサイエンス学会年会（SEST2017）, Nov. 2017, Japanese, 東京工業大学, Domestic conference

  Poster presentation


• 光誘起電子移動反応における磁場効果を利用した新規蛍光イメージング法の開発

  櫻井 学, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  第56回電子スピンサイエンス学会年会（SEST2017）, Nov. 2017, Japanese, 東京工業大学, Domestic conference

  Poster presentation


• 強磁場・テラヘルツ領域におけるヘミンの精密ESR分光

  OKAMOTO Tsubasa, OHMICHI Eiji, OKUBO Susumu, EMA Fumitoshi, KOBORI Yasuhiro, OHTA Hitoshi

  第56回電子スピンサイエンス学会年会（SEST2017), Nov. 2017, Japanese, 東京工業大学 大岡山キャンパス, Domestic conference

  Oral presentation


• ペンタセン・テトラセン誘導体における一重項分裂により生成した五重項状態の観測

  長嶋 宏樹, 松岡 秀平, 稲谷 隆太郎, AKIMOTO SEIJI, 松井 康哲, TACHIKAWA TAKASHI, 羽曽部 卓, 池田 浩, KOBORI YASUHIRO

  第56回電子スピンサイエンス学会年会（SEST2017）, Nov. 2017, Japanese, 東京工業大学, Domestic conference

  Oral presentation


• タンタル酸ナトリウム光触媒の発光挙動におけるドーピングの効果

  TACHIKAWA TAKASHI, 水谷 晟吾, KOBORI YASUHIRO

  第36回 固体・表面光化学討論会, Nov. 2017, Japanese, 滋賀県立大学, Domestic conference

  Oral presentation


• アフリカツメガエル由来クリプトクロムに生成する光電荷分離状態の電子的相互作用

  濱田 実里, 長嶋 宏樹, 神取 秀樹, 岩田 達也, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  第56回電子スピンサイエンス学会年会（SEST2017）, Nov. 2017, Japanese, 東京工業大学, Domestic conference

  Poster presentation


• TREPR法によるチオフェン-チアゾロチアゾールポリマー薄膜に生成する光誘起キャリアトラップ状態の観測

  山本 雄大, 阿児 拓海, 長嶋 宏樹, TACHIKAWA TAKASHI, 尾坂 格, KOBORI YASUHIRO

  第56回電子スピンサイエンス学会年会（SEST2017）, Nov. 2017, Japanese, 東京工業大学, Domestic conference

  Poster presentation


• Time-Resolved EPR Study on Photoinduced Charge-Transfer Trap States in Thiophene-Thiazolothiazole Copolymer Films

  Yasuhiro Kobori

  11th Japanese-Russian Workshop on “Open Shell Compounds and Molecular Spin Devices”, Nov. 2017, English, Awaji Yumebutai International Conference Center, International conference

  [Invited]

  Invited oral presentation


• PSII反応中心の光電荷分離と励起子生成に対する励起波長依存性

  見延 玲奈, 長谷川 将司, 長嶋 宏樹, TACHIKAWA TAKASHI, 三野 広幸, KOBORI YASUHIRO

  第56回電子スピンサイエンス学会年会（SEST2017）, Nov. 2017, Japanese, 東京工業大学, Domestic conference

  Poster presentation


• 有機無機ペロブスカイトのハロゲン交換反応における過渡種生成と電荷捕集のその場観測

  狩俣 出, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  第7回CSJ化学フェスタ2017, Oct. 2017, Japanese, タワーホール船堀, Domestic conference

  Poster presentation


• 有機金属ハロゲン化物ペロブスカイトにおける光反応挙動の単一粒子解析

  木村 優季, 狩俣 出, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  第7回CSJ化学フェスタ2017, Oct. 2017, Japanese, タワーホール船堀, Domestic conference

  Poster presentation


• 時間分解EPR法による室温リン光発光性有機包接結晶の励起三重項状態の電子構造

  江間 文俊, 小野 利和, 福田 有貴, 久枝 良雄, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  第7回CSJ化学フェスタ2017, Oct. 2017, Japanese, タワーホール船堀, Domestic conference

  Poster presentation


• 深紫外蛍光顕微鏡によるNaTaO3 光触媒の発光観測

  水谷 晟吾, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2017年光化学討論会, Sep. 2017, Japanese, 東北大学青葉山キャンパス, Domestic conference

  Poster presentation


• 時間分解EPR 法による室温リン光発光性有機包接結晶の励起三重項状態の電子構造

  江間 文俊, 小野 利和, 福田 有貴, 久枝 良雄, 長嶋 宏樹, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  2017年光化学討論会, Sep. 2017, Japanese, 東北大学青葉山キャンパス, Domestic conference

  Poster presentation


• Regulation of Initial Charge Separation in Photosynthetic Reaction Center detected by Transient EPR

  Hiroyuki Mino, Hiroyuki Tsukuno, Risa Mutoh, Hiroki Nagashima, Yasuhiro Kobori, Genji Kurisu, Hirozo Oh-oka

  第55回日本生物物理学会年会, Sep. 2017, Japanese, 熊本大学 黒髪北地区, Domestic conference

  Oral presentation


• The mechanism of efficient charge separation reaction in photosystem II of higher plants

  Hiroki Nagashima, Masashi Hasegawa, Reina Minobe, Hiroyuki Mino, Yasuhiro Kobori

  第55回日本生物物理学会年会, Sep. 2017, Japanese, 熊本大学 黒髪北地区, Domestic conference

  Poster presentation


• 顕微分光法を用いた二酸化チタンメソ結晶の光機能性評価

  村上 雄太, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2017年光化学討論会, Sep. 2017, Japanese, 東北大学青葉山キャンパス, Domestic conference

  Poster presentation


• Initial charge separated spin-polarized radical pair in reaction center of Heliobacterium modesticaldum

  Hiroyuki Mino, Hiroyuki Tsukuno, Risa Mutoh, Hiroki Nagashima, Yasuhiro Kobori, Genji Kurisu, Hirozo Oh-oka

  第55回日本生物物理学会年会, Sep. 2017, Japanese, 熊本大学 黒髪北地区, Domestic conference

  Poster presentation


• チタン酸ストロンチウムメソ結晶光触媒における特異な電荷移動挙動

  TACHIKAWA TAKASHI, 越智 友哉, KOBORI YASUHIRO

  2017年光化学討論会, Sep. 2017, English, 東北大学青葉山キャンパス, Domestic conference

  Oral presentation


• アフリカツメガエル由来クリプトクロムに生成する光電荷分離状態の電子的相互作用

  濱田 実里, KOBORI YASUHIRO, TACHIKAWA TAKASHI, 長嶋 宏樹, 神取 秀樹, 岩田 達也

  2017年光化学討論会, Sep. 2017, Japanese, 東北大学青葉山キャンパス, Domestic conference

  Poster presentation


• Time-Resolved EPR Study on Photoinduced Charge-Transfer Trap State in Thiophene-Thiazolothiazole Copolymer Film

  山本 雄大, 阿児 拓海, TACHIKAWA TAKASHI, 尾坂 格, KOBORI YASUHIRO

  2017年光化学討論会, Sep. 2017, English, 東北大学青葉山キャンパス, Domestic conference

  Poster presentation


• Time-resolved and pulsed electron paramagnetic resonance study on the singlet-fission materials

  長嶋 宏樹, 河岡 秀平, 松井 康哲, TACHIKAWA TAKASHI, 池田 浩, KOBORI YASUHIRO

  2017年光化学討論会, Sep. 2017, English, 東北大学青葉山キャンパス, Domestic conference

  Poster presentation


• SrドープNaTaO3光触媒の電子スピン共鳴による計測評価

  佐藤 孝賢, KOBORI YASUHIRO, ONISHI HIROSHI

  第11回分子科学討論会2017仙台, Sep. 2017, Japanese, 東北大学 川内北キャンパス, Domestic conference

  Poster presentation


• Slow Charge Transfer Process over a Few Nanoseconds in Heterostructured CH3NH3PbBr3-xIx

  狩俣 出, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2017年光化学討論会, Sep. 2017, English, 東北大学青葉山キャンパス, Domestic conference

  Poster presentation


• PSII 反応中心の光電荷分離と励起子生成に対する励起波長依存性

  見延 玲奈, 長谷川 将司, 長嶋 宏樹, TACHIKAWA TAKASHI, 三野 広幸, KOBORI YASUHIRO

  2017年光化学討論会, Sep. 2017, Japanese, 東北大学青葉山キャンパス, Domestic conference

  Poster presentation


• Electron tunneling route of photoinduced primary charge-separated state in the PSII studied by electron spin polarization imaging method

  KOBORI YASUHIRO, 長嶋 宏樹, 長谷川 将司, 見延 玲奈, TACHIKAWA TAKASHI, 三野 広幸

  2017年光化学討論会, Sep. 2017, English, 東北大学青葉山キャンパス, Domestic conference

  Oral presentation


• Electron spin polarization imaging of photoinduced primary charge-separated states in PSII

  Yasuhiro Kobori

  15th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena(SCM2017), Sep. 2017, English, Schluchsee, Germany, International conference

  [Invited]

  Invited oral presentation


• 時間分解電子スピン共鳴法による生体分子機能の解明

  KOBORI YASUHIRO

  第30回生物無機化学夏季セミナー, Aug. 2017, Japanese, 白子・サンライズオーツカ, Domestic conference

  Oral presentation


• 光合成初期反応の電子スピン画像解析

  KOBORI YASUHIRO

  第4回森野ディスカッション, Jul. 2017, Japanese, 東京大学理学部 小柴ホール, Domestic conference

  [Invited]

  Invited oral presentation


• シロキ基を有する室温リン光発性有機結晶の三重項状態に対する時間分解EPR観測

  江間 文俊, 鴫谷 亮祐, 清水 正毅, 三宅 祐輔, 田嶋 邦彦, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  第21回ESRフォーラム研究会2017 京都, Jul. 2017, Japanese, 京都工芸繊維大学, Domestic conference

  Poster presentation


• TREPR法によるチオフェン-チアゾロチアゾールポリマー簿膜に生成する光誘起キャリアトラップ状態の観測

  山本 雄大, 阿児 拓海, TACHIKAWA TAKASHI, 尾坂 格, KOBORI YASUHIRO

  第21回ESRフォーラム研究会2017 京都, Jul. 2017, Japanese, 京都工芸繊維大学, Domestic conference

  Poster presentation


• PSⅡ反応中心の光電荷分離と励起子生成に対する励起波長依存性

  見延 玲奈, 長谷川 将司, 長嶋 宏樹, TACHIKAWA TAKASHI, 三野 広幸, KOBORI YASUHIRO

  第21回ESRフォーラム研究会2017 京都, Jul. 2017, Japanese, 京都工芸繊維大学, Domestic conference

  Poster presentation


• チタン酸ストロウムメソ結晶の合成と水分解光触媒へ応用

  TACHIKAWA TAKASHI, Peng Zhang, 越智 友哉, 藤塚 守, KOBORI YASUHIRO, 真嶋 哲郎

  第36回光がかかわる触媒化学シンポジウム, Jun. 2017, Japanese, 近畿大学, Domestic conference

  Oral presentation


• Time-resolved EPR Study on Photoinduced Electron Spin Polarization and Dynamics of Radicals at Bilayer Interface

  Fumitoshi Ema(Yasuhiro Kobori, Zhebin Fu, Hisao Murai

  5th Awaji International Workshop on “Electron Spin Science & Technology: Biological and Materials Science Oriented Applications” (5th AWEST 2017), Jun. 2017, English, Awaji Yumebutai International Conference Center, International conference

  Poster presentation


• Time Resolved EPR Study on Photoinduced Charge-Separations in Thin Films of Thiophene-Thiazolothiazole Copolymers

  ○Yasuhiro Kobori, Yuta Yamamoto, Takumi Ako, Takashi Tachikawa, Itaru Osaka

  34th International Conference of Photopolymer Science and Technology, Jun. 2017, English, Makuhari Messe, International conference

  [Invited]

  Invited oral presentation


• Time-resolved EPR Study on Antiaromatic Excited Triplet State of [28]Hexaphyrin with Twisted Möbius Conformation

  ○Fumitoshi Ema, Shohei Saito, Atsuhiro Osuka, Mana Tanabe, Seigo Yamauchi, Kenji Sugisaki, Kazunobu Sato, Takeji Takui, Takashi Tachikawa, Yasuhiro Kobori

  5th Awaji International Workshop on “Electron Spin Science & Technology: Biological and Materials Science Oriented Applications” (5th AWEST 2017), Jun. 2017, English, Awaji Yumebutai International Conference Center, International conference

  Poster presentation


• Electron spin polarization imaging applied to primary charge separation in the PSII

  ○Yasuhiro Kobori, Masashi Hasegawa, Hiroki Nagashima, Reina Minobe, Takashi Tachikawa, Hiroyuki Mino

  5th Awaji International Workshop on “Electron Spin Science & Technology: Biological and Materials Science Oriented Applications” (5th AWEST 2017), Jun. 2017, English, Awaji Yumebutai International Conference Center, International conference

  [Invited]

  Invited oral presentation


• Time-Resolved EPR Study on Charge Dynamics of Electron-Hole Pairs in Lead Iodide Perovskite Thin Film

  ○Yasuhiro Kobori, Kosuke Miyazaki, Takashi Tachikawa, Yuhei Ogomi, Shuzi Hayase

  231st ECS Meeting, May 2017, English, New Orleans, LA, International conference

  [Invited]

  Invited oral presentation


• Geometries and Dynamics of Photoinduced Electron-Hole Pairs in Polyhexylthiophene-Fullerene Systems

  ○Yasuhiro Kobori, Taku Miura, Ran Tao, Tomokazu Umeyama, Sho Shibata, Takashi Tachikawa, Hiroshi Imahori

  231st ECS Meeting, May 2017, English, New Orleans, LA, International conference

  [Invited]

  Invited oral presentation


• 光誘起電子移動反応における磁場効果を利用した新規蛍光顕微鏡観察手法の開発

  櫻井 学, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  日本化学会 第97春季年会 (2017), Mar. 2017, Japanese, 慶應義塾大学 日吉キャンパス, Domestic conference

  Poster presentation


• Charge Carrier Dynamics of CH3NH3PbBr3-xIx with Hetero-Band Structures

  ○Izuru Karimata, Yasuhiro Kobori, Takashi Tachikawa

  日本化学会 第97春季年会 (2017), Mar. 2017, English, 慶應義塾大学 日吉キャンパス, Domestic conference

  Poster presentation


• 電子スピン分極イメージング法の開発によるPSII 電荷分離構造の三次元映像化

  KOBORI YASUHIRO

  分子研研究会－生体や物質機能の起源にせまる先端的電子スピン計測－, Dec. 2016, Japanese, 自然科学研究機構 分子科学研究所, Domestic conference

  [Invited]

  Invited oral presentation


• 時間分解EPR法による有機包接室温強リン光発光結晶の励起三重項状態の電子構造

  江間 文俊, 小野 利和, 福田 有貴, 久枝 良雄, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  第55回電子スピンサイエンス学会年会, Nov. 2016, Japanese, 大阪市立大学, Domestic conference

  Oral presentation


• 効率的な炭素ラジカルの生成を目指した有機分子触媒の開発

  薮田 達志, MATSUBARA RYOSUKE, HAYASHI MASAHIKO, KOBORI YASUHIRO

  第6回CSJ化学フェスタ2016, Nov. 2016, Japanese, タワーホール船堀, Domestic conference

  Poster presentation


• フォトクロミックキノンの光レドックス変換と化学反応への応用

  SAITO Eiji, AKO Takumi, KOBORI Yasuhiro, TSUDA Akihiko

  第6回 CSJ化学フェスタ 2016, Nov. 2016, Japanese, 公益社団法人日本化学会, 東京•タワーホール船堀, Domestic conference

  Poster presentation


• ねじれたメビウス構造を有するヘキサフィリンの励起三重項状態の電子構造

  江間 文俊, 齋藤 尚平, 大須賀 篤弘, 田辺 真奈, 山内 清語, 杉崎 研司, 佐藤 和信, 工位 武治, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  第6回CSJ化学フェスタ2016, Nov. 2016, Japanese, タワーホール船堀, Domestic conference

  Poster presentation


• Time resolved EPR study on orientations and electronic couplings of the primary charge-separated state in the PSII reaction center

  ○Reina Minobe, Masashi Hasegawa, Shusuke Katagiri, Takahiro Sakai, Hiroki Nagashima, Takashi Tachikawa, Hiroyuki Mino, Yasuhiro Kobori

  第54回日本生物物理学会年会, Nov. 2016, English, つくば国際会議場, Domestic conference

  Poster presentation


• Effects of amyloid fibrillations on geometries of human insulin as studied by time-resolved EPR spectroscopy

  ○Tomoka Abe, Takashi Tachikawa, Eri Chatani, Paul Zierep, Stefan Weber, Toshifumi Mori, Shinji Saito, Yasuhiro Kobori

  第54回日本生物物理学会年会, Nov. 2016, English, つくば国際会議場, Domestic conference

  Poster presentation


• 単一粒子顕微分光電気化学法によるSrTiO3メソ結晶の発光観測

  越智 友哉, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2016年光化学討論会, Sep. 2016, Japanese, 東京大学駒場第一キャンパス, Domestic conference

  Poster presentation


• 時間分解電子スピン共鳴法によるチオフェンーチアゾロチアゾールコポリマー：PCBM有機薄膜における電荷分離状態の立体構造とダイナミクス

  阿児 拓海, TACHIKAWA TAKASHI, 尾坂 格, KOBORI YASUHIRO

  2016年光化学討論会, Sep. 2016, Japanese, 東京大学駒場第一キャンパス, Domestic conference

  Poster presentation


• 時間分解EPR法による二分子膜界面におけるビタミンCの抗酸化反応機構と スピンダイナミクス

  江間 文俊, 付 哲斌, 村井 久雄, KOBORI YASUHIRO

  第10回分子科学討論会, Sep. 2016, Japanese, 神戸ファッションマート, Domestic conference

  Poster presentation


• 時間分解EPR法によるチオフェン-チアゾロチアゾールポリマー薄膜に生成する光電荷分離状態の観測

  山本 雄大, TACHIKAWA TAKASHI, 尾坂 格, KOBORI YASUHIRO

  2016年光化学討論会, Sep. 2016, Japanese, 東京大学駒場第一キャンパス, Domestic conference

  Poster presentation


• 時間分解EPR法によるPSII反応中心に生成する初期電荷分離構造の解析

  見延 玲奈, 長谷川 将司, 片桐 秀輔, 酒井 貴弘, 長嶋 宏樹, TACHIKAWA TAKASHI, 三野 広幸, KOBORI YASUHIRO

  第10回分子科学討論会, Sep. 2016, Japanese, 神戸ファッションマート, Domestic conference

  Poster presentation


• Long-range charge transfer and transient species formation during halide exchange reaction on an organolead halide perovskite crystal

  ○Izuru Karimata, Yasuhiro Kobori, Takashi Tachikawa

  2016年光化学討論会, Sep. 2016, English, 東京大学駒場第一キャンパス, Domestic conference

  Oral presentation


• Primary Charge-Separation Mechanism in the Photosynthetic Reaction Center Studied by Time-Resolved EPR Spectroscopy

  Yasuhiro Kobori

  2016 Electron Donor Acceptor Interactions Gordon Research Conference, Aug. 2016, English, Newport, USA, International conference

  [Invited]

  Invited oral presentation


• Electronic Structure of the Excited Triplet State of Hexaphyrins with twisted Mobious Conformation as Studied by TR EPR

  ○Fumitoshi Ema, Shohei Saito, Atsuhiro Osuka, Mana Tanabe, Seigo Yamauchi, Kenji Sugisaki, Kazunobu Sato, Takeji Takui, Takashi Tachikawa, Yasuhiro Kobori

  Asia-Pacific EPR/ESR Symposium 2016, Aug. 2016, English, Irkutsk city, Russia, International conference

  Oral presentation


• 有機包接室温強リン光発光結晶の三重項状態に対する時間分解 EPR 観測

  江間 文俊, 小野 利和, 福田 有貴, 久枝 良雄, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  第20回ESRフォーラム研究会 in 神戸, Jul. 2016, Japanese, 神戸大学 瀧川記念学術交流会館, Domestic conference

  Oral presentation


• 電⼦スピン共鳴法を⽤いたヒトインスリンのアミロイド線維化による構造変化の観測

  安倍知花, TACHIKAWA TAKASHI, CHATANI ERI, Till Biskup, Stefan Weber, KOBORI YASUHIRO

  第20回ESRフォーラム研究会 in 神戸, Jul. 2016, Japanese, 神戸大学 瀧川記念学術交流会館, Domestic conference

  Poster presentation


• 時間分解EPR 法によるチオフェンーチアゾロチアゾールコポリマー：PCBM有機薄膜に⽣成する光誘起キャリアのダイナミクス

  阿児 拓海, TACHIKAWA TAKASHI, 尾坂 格, KOBORI YASUHIRO

  第20回ESRフォーラム研究会 in 神戸, Jul. 2016, Japanese, 神戸大学 瀧川記念学術交流会館, Domestic conference

  Poster presentation


• 時間分解EPR 法によるチオフェン-チアゾロチアゾールポリマー薄膜に⽣成する光電荷分離状態の構造解析

  山本 雄大, TACHIKAWA TAKASHI, 尾坂 格, KOBORI YASUHIRO

  第20回ESRフォーラム研究会 in 神戸, Jul. 2016, Japanese, 神戸大学 瀧川記念学術交流会館, Domestic conference

  Poster presentation


• 時間分解EPR 法によるPSII 反応中⼼に⽣成する初期電荷分離構造解析

  見延 玲奈, 谷川 将司, 片桐 秀輔, 酒井 貴弘, ⻑嶋 宏樹, TACHIKAWA TAKASHI, 三野 広幸, KOBORI YASUHIRO

  第20回ESRフォーラム研究会 in 神戸, Jul. 2016, Japanese, 神戸大学 瀧川記念学術交流会館, Domestic conference

  Poster presentation


• 光誘起電⼦移動反応における磁場効果の蛍光顕微鏡観察⼿法の開発

  櫻井 学, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  第20回ESRフォーラム研究会 in 神戸, Jul. 2016, Japanese, 神戸大学 瀧川記念学術交流会館, Domestic conference

  Poster presentation


• 光によるキノンのレドックス変換

  SAITO Eiji, AKO Takumi, KOBORI Yasuhiro, TSUDA Akihiko

  第5回 JACI/GSCシンポジウム, Jun. 2016, Japanese, 公益社団法人 新化学技術推進協会, 神戸・ANAクラウンプラザ, Domestic conference

  Poster presentation


• Time-domain EPR observations of changes in protein binding structures induced by the amyloid fibrillation of human insulin

  ○Tomoka Abe, Takashi Tachikawa, Eri Chatani, Till Biskup, Stefan Weber, Yasuhiro Kobori

  4th Awaji International Workshop on “Electron Spin Science & Technology: Biological and Materials Science Oriented Applications”, Jun. 2016, English, Awaji Yumebutai International Conference Center, International conference

  Poster presentation


• Morphology Effect on the Geometry of the Photoinduced Charge-Separated State in P3HT:PCBM Brend Films as Studied by Time-Resolved EPR Spectroscopy

  Taku Miura, Takashi Tachikawa, ○Yasuhiro Kobori

  The 33rd International Conference of Photopolymer Science and Technology, Jun. 2016, English, Makuhari Messe, Chiba, International conference

  [Invited]

  Invited oral presentation


• Dynamics of Photoinduced Electron-Hole Pairs in Polyhexylthiophene-Fullerene Dyads Rigidly Linked by Oligophenylenes

  ○Yasuhiro Kobori, Taku Miura, Ran Tao, Sho Shibata, Tomokazu Umeyama, Takashi Tachikawa, Hiroshi Imahori

  4th Awaji International Workshop on “Electron Spin Science & Technology: Biological and Materials Science Oriented Applications”, Jun. 2016, English, Awaji Yumebutai International Conference Center, International conference

  [Invited]

  Invited oral presentation


• SINGLE-PARTICLE PHOTOLUMINESCENCE MEASUREMENTS REVEAL THE SURFACE CHARGE TRAPPING IN ORGANOLEAD BROMIDE PEROVSKITE

  ○Izuru Karimata, Takashi Tachikawa, Yasuhiro Kobori

  The XXVIth IUPAC Symposium on Photochemistry, Apr. 2016, English, Osaka City Central Public Hall, Osaka, Japan, International conference

  Poster presentation


• CRYSTAL-FACE-DEPENDENT CHARGE DYNAMICS ON A BiVO 4 PHOTOCATALYST STUDIED BY SINGLE-PARTICLE PHOTOELECTROCHEMISTRY

  ○Tomoya Ochi, Yasuhiro Kobori, Takashi Tachikawa

  The XXVIth IUPAC Symposium on Photochemistry, Apr. 2016, English, Osaka City Central Public Hall, Osaka, Japan, International conference

  Poster presentation


• 有機金属ハロゲン化物ペロブスカイトにおけるハロゲン交換反応の単一粒子分光

  狩俣 出, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  日本化学会第96春季年会(2016), Mar. 2016, Japanese, 同志社大学 京田辺キャンパス, Domestic conference

  Oral presentation


• 単一粒子顕微分光電気化学法によるBiVO4光触媒の結晶面依存キャリアダイナミクス観測

  越智 友哉, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  日本化学会第96春季年会(2016), Mar. 2016, Japanese, 同志社大学 京田辺キャンパス, Domestic conference

  Oral presentation


• 効率的な炭素ラジカルの生成を目指した有機分子触媒の開発

  薮田 達志, MATSUBARA RYOSUKE, 島田 聡之, HAYASHI MASAHIKO, KOBORI YASUHIRO

  日本化学会 第96春季年会 (2016), Mar. 2016, Japanese, 同志社大学 京田辺キャンパス, Domestic conference

  Oral presentation


• チオフェン−チアゾロチアゾールポリマー:PCBM有機薄膜における初期電荷分離機構

  阿児 拓海, 尾坂 格, TACHIKAWA Takashi, KOBORI Yasuhiro

  応用物理学会春期学術講演会, Mar. 2016, Japanese, 東京工業大学大岡山キャンパス, Domestic conference

  Oral presentation


• Synthesis and single-particle photoluminescence observation of hybrid organic-inorganic perovskite nanoparticles

  Izuru Karimata, Yasuhiro Kobori, Takashi Tachikawa

  Pacifichem 2015, Dec. 2015, English, Hawai, USA, International conference

  Oral presentation


• 有機薄膜太陽電池の光電流生成初期過程：界面電子-正孔対の立体構造と電子状態

  KOBORI Yasuhiro

  異分野融合ワークショップ「有機太陽電池開発の現状と展望」, Nov. 2015, English, Domestic conference

  [Invited]

  Invited oral presentation


• 時間分解ERR法によるチオフェン−チアゾロチアゾールポリマー：PCBM有機薄膜における光電荷分離ダイナミクス

  阿児 拓海, TACHIKAWA Takashi, 尾坂 格, KOBORI Yasuhiro

  第54回電子スピンサイエンス学会年会, Nov. 2015, Japanese, 朱鷺メッセ, Domestic conference

  Poster presentation


• 時間分解EPR法によるヘキサフィリン励起三重項状態の生成機構と電子状態の解明

  江間 文俊, 齋藤 尚平, 大須賀 篤弘, 田辺 真奈, 山内 清語, 杉崎 研司, 佐藤 和信, 工位 武治, TACHIKAWA Takashi, KOBORI Yasuhiro

  第54回電子スピンサイエンス学会年会, Nov. 2015, Japanese, 朱鷺メッセ, Domestic conference

  Oral presentation


• ペロブスカイト型太陽電池の光活性層界面に生成する光電荷分離状態の時間分解EPR

  宮崎 晃侑, 長谷川 将司, 尾込 裕平, TACHIKAWA Takashi, 早瀬 修二, KOBORI Yasuhiro

  第54回電子スピンサイエンス学会年会, Nov. 2015, Japanese, 朱鷺メッセ, Domestic conference

  Poster presentation


• 有機-無機ハイブリッド型ペロブスカイトの単一粒子発光観察

  狩俣 出, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2015年 光化学討論会, Sep. 2015, Japanese, 大阪市立大学 杉本キャンパス, Domestic conference

  Poster presentation


• 有機-無機ハイブリッド型ペロブスカイトナノ粒子の発光ブリンキング挙動

  TACHIKAWA TAKASHI, 狩俣 出, KOBORI YASUHIRO

  2015年 光化学討論会, Sep. 2015, Japanese, 大阪市立大学 杉本キャンパス, Domestic conference

  Oral presentation


• 時間分解EPR法を用いたアミロイド線維を形成するヒトインスリンにおけるアミノ酸残基局所構造の観測

  安倍 知花, TACHIKAWA TAKASHI, CHATANI ERI, KOBORI YASUHIRO

  2015年 光化学討論会, Sep. 2015, Japanese, 大阪市立大学 杉本キャンパス, Domestic conference

  Poster presentation


• Time-Resolved EPR Study on Geometry and Dynamics of the Primary Charge-Separated State in the Photosystem II Reaction Center of Spinach

  KOBORI YASUHIRO, 長谷川 将司, TACHIKAWA TAKASHI, 近藤 徹, 長島 宏樹, 酒井 貴弘, 三野 広幸

  第53回日本生物物理学会年会, Sep. 2015, Japanese, 金沢大学角間キャンパス, Domestic conference

  Oral presentation


• 時間分解EPR法によるチオフェンーチアゾロチアゾールポリマー:PCBM有機薄膜における初期電荷分離状態の観測

  阿児 拓海, TACHIKAWA TAKASHI, 尾坂 格, KOBORI YASUHIRO

  2015年 光化学討論会, Sep. 2015, Japanese, 大阪市立大学 杉本キャンパス, Domestic conference

  Poster presentation


• 蛍光プローブを用いたBiVO4光触媒のその場観察

  越智 友哉, KOBORI YASUHIRO, TACHIKAWA TAKASHI

  2015年 光化学討論会, Sep. 2015, Japanese, 大阪市立大学 杉本キャンパス, Domestic conference

  Poster presentation


• ホウレン草のPSII反応中心に生成する光電荷分離状態の時間分解EPR

  長谷川 将司, 酒井 貴弘, 長嶋 宏樹, TACHIKAWA TAKASHI, 三野 広幸, KOBORI YASUHIRO

  2015年 光化学討論会, Sep. 2015, Japanese, 大阪市立大学 杉本キャンパス, Domestic conference

  Poster presentation


• Primary Charge-Separation Mechanism in the Photosynthetic Reaction Center

  Yasuhiro Kobori

  International Workshop for Green Photonics, Sep. 2015, English, 奈良先端科学技術大学院大学, International conference

  [Invited]

  Invited oral presentation


• Time-resolved EPR on primary charge separation and recombination in the photosynthetic reaction center: Impact of electronic couplings

  Yasuhiro Kobori, Nina Ponomarenko, James R. Norris Jr

  AWEST2015, Jun. 2015, English, Awaji, Japan, International conference

  [Invited]

  Invited oral presentation


• Orbital Functionalities on the Primary Charge-Separations in the Organic Photovoltaic Solar Cell: A Transient Electron Paramagnetic Resonance Study

  Yasuhiro Kobori

  Colloquium at Freiburg Institute of Advanced Studies, Jun. 2015, English, International conference

  Public discourse


• 有機-無機ペロブスカイトナノ粒子の合成と単一粒子発光挙動

  TACHIKAWA TAKASHI, KARIMARA IZURU, KOBORI YASUHIRO

  ナノ学会第13回大会, May 2015, Japanese, 東北大学 片平さくらホール, Domestic conference

  Oral presentation


• 時間分解EPR法によるヘキサフィリン励起三重項状態の電子構造の解明

  江間 文俊, 齋藤 尚平, 大須賀 篤弘, 田辺 真奈, 山内 清語, 杉崎 研司, 佐藤 和信, 工位 武治, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  日本化学会第95春季年会2015, Mar. 2015, Japanese, 公益社団法人 日本化学会, 日本大学 理工学部船橋キャンパス, Domestic conference

  Oral presentation


• 時間分解EPR法によるP3HT:PCBM有機薄膜太陽電池の光電流生成機構の解明

  阿児 拓海, 三浦 拓, TACHIKAWA TAKASHI, 丸本 一弘, KOBORI YASUHIRO

  日本化学会第95春季年会2015, Mar. 2015, Japanese, 公益社団法人 日本化学会, 日本大学 理工学部船橋キャンパス, Domestic conference

  Oral presentation


• アミロイド線維化タンパク質-アントラキノンスルフォン酸イオン複合体の時間分解EPR

  安倍 知花, CHATANI ERI, TACHIKAWA TAKASHI, KOBORI YASUHIRO

  日本化学会第95春季年会2015, Mar. 2015, Japanese, 公益社団法人 日本化学会, 日本大学 理工学部船橋キャンパス, Domestic conference

  Oral presentation


• Time-resolved EPR study on cofactor geometries and electronic couplings after primary charge-separations in the photosynthetic reaction center

  Yasuhiro Kobori

  SCM 2015 - 14th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena, Mar. 2015, English, Kolkata, India, International conference

  [Invited]

  Invited oral presentation


• 時間分解EPR法による光合成反応中心の初期電荷分離構造と電子的相互作用の解析

  KOBORI YASUHIRO, Ponomarenko Nina, Norris James

  2014光化学討論会, Nov. 2014, Japanese, 北海道大学 札幌キャンパス, Domestic conference

  Oral presentation


• Time-resolved EPR study on the Electronic Structure of the Excited Triplet State of [26] and [28] Hexaphyrins

  Fumitoshi Ema, Atsuhiro Osuka, Mana Tanabe, Seigo Yamauchi, Takashi Tachikawa, Yasuhiro Kobori

  アジア太平洋EPR/ESR学会－国際EPR(ESR)学会－第53回電子スピンサイエンス学会年会合同国際会議（APES-IES-SEST2014), Nov. 2014, English, International conference

  Poster presentation


• Time resolved EPR study on photoinduced primary charge-separated state of the PSII reaction center from spinach

  Masashi Hasegawa, Masaki Tsushima, Takashi Tachikawa, Hiroyuki Mino, Yasuhiro Kobori

  アジア太平洋EPR/ESR学会－国際EPR(ESR)学会－第53回電子スピンサイエンス学会年会合同国際会議（APES-IES-SEST2014), Nov. 2014, English, International conference

  Poster presentation


• Time resolved EPR study on photoinduced intermediates in photoactive interface of the perovskite solar cell

  Kousuke Miyazaki, Taku Miura, Masasi Hasegawa, Yuhei Ogomi, Takashi Tachikawa, Shuji Hayase, Yasuhiro Kobori

  アジア太平洋EPR/ESR学会－国際EPR(ESR)学会－第53回電子スピンサイエンス学会年会合同国際会議（APES-IES-SEST2014), Nov. 2014, English, International conference

  Poster presentation


• Morphology effect on the geometry of the photoinduced charge-separated states in RR P3HT:PCBM blend films studied by time-resolved EPR

  Taku Miura, Takashi Tachikawa, Yasuhiro Kobori

  アジア太平洋EPR/ESR学会－国際EPR(ESR)学会－第53回電子スピンサイエンス学会年会合同国際会議（APES-IES-SEST2014), Nov. 2014, English, International conference

  Poster presentation


• Electron-hole dissociations and electronic coupling influenced by alkyl side chains in the photovoltaic Polyalkylthiophene:PCBM interface

  KOBORI YASUHIRO

  アジア太平洋EPR/ESR学会－国際EPR(ESR)学会－第53回電子スピンサイエンス学会年会合同国際会議（APES-IES-SEST2014), Nov. 2014, English, 東大寺総合文化センター, International conference

  [Invited]

  Invited oral presentation


• Electron-hole dissociation influenced by alkyl side chains in the photovoltaic polyalkylthiophene:PCBM interfaces

  Yasuhiro Kobori

  32nd Samahang Pisika ng Philipinas Physics Congress, Nov. 2014, English, フィリピン大学国立物理研究所, International conference

  Keynote oral presentation


• Effect of glycerol concentration on structure of photoinduced chargeseparated states in 9,10-anthraquinone-1-sulfonate-human serum albumin system

  Masaki Tsushima, Masaaki Fuki, Taku Miura, Takashi Tachikawa, Yasuhiro Kobori

  アジア太平洋EPR/ESR学会－国際EPR(ESR)学会－第53回電子スピンサイエンス学会年会合同国際会議（APES-IES-SEST2014), Nov. 2014, English, International conference

  Poster presentation


• Morphology effect on the geometry of the the photoinduced charge separated states in RR-P3HT:PCBM blend film studies by time-resolved EPR

  TAKU MIURA, KOBORI YASUHIRO

  5th International Meeting on Spin in Organic Semiconductors, Oct. 2014, English, Himeji, International conference

  Poster presentation


• Electron-hole dissociations influenced by alkyl side chains in the photovoltaic Polyalkylthiophene:PCBM interface

  KOBORI YASUHIRO

  32nd National Physics Congress of the Samahang Pisika ng Pilipinas, Oct. 2014, English, National Institute of Physics University of the Philippines, Quezon City, Philippines, International conference

  Keynote oral presentation


• 時間分解EPR法によるヘキサフィリン励起三重項状態の電子構造の解明

  江間 文俊, 大須賀 篤弘, 田辺 真奈, 山内 清語, 立川 貴志, KOBORI YASUHIRO

  2014年光化学討論会, Sep. 2014, Japanese, 北海道大学 札幌キャンパス, Domestic conference

  Poster presentation


• 光合成反応中心の初期電荷分離過程に伴う立体構造変化:時間分解EPR法による解析

  KOBORI YASUHIRO, Ponomarenko Nina, Norris JAMES

  第8回分子科学討論会, Sep. 2014, Japanese, 広島大学 東広島キャンパス, Domestic conference

  Oral presentation


• ポリヘキシルチオフェン－フラーレンをオリゴフェニレンで連結した分子P3HT-Phm-C60に生成する光誘起電荷分離状態の時間分解EPR法による解析

  三浦 拓, 陶 然, 梅山 有和, 立川 貴志, KOBORI YASUHIRO, 今堀 博

  2014年光化学討論会, Sep. 2014, Japanese, 北海道大学 札幌キャンパス, Domestic conference

  Poster presentation


• ホウレン草のPSII反応中心に生成する光電荷分離状態の時間分解EPR

  長谷川 将司, 三浦 拓, 立川 貴士, 三野 広幸, KOBORI YASUHIRO

  2014年光化学討論会, Sep. 2014, Japanese, 北海道大学 札幌キャンパス, Domestic conference

  Poster presentation


• ぺロブスカイト型太陽電池の光活性層界面に生成する光電荷分離状態の時間分解EPR

  宮崎 晃侑, 三浦 拓, 尾込 裕平, 立川 貴志, 早瀬 修二, KOBORI YASUHIRO

  2014年光化学討論会, Sep. 2014, Japanese, 北海道大学 札幌キャンパス, Domestic conference

  Poster presentation


• ヒト血清アルブミンーアントラキノン-1-スルホン酸イオン複合体の電荷分離構造に対するグリセロール添加効果

  対馬 正樹, 婦木 正明, 三浦 拓, 立川 貴志, KOBORI YASUHIRO

  2014年光化学討論会, Sep. 2014, Japanese, 北海道大学 札幌キャンパス, Domestic conference

  Poster presentation


• Electron-hole dissociations influenced by alkyl side chains in the photovoltaic Polyalkylthiophene:PCBM interface

  KOBORI YASUHIRO

  Grand Renewable Energy International Conference, Aug. 2014, English, Tokyo Big Sight, Tokyo, International conference

  [Invited]

  Invited oral presentation


• Time-Resolved EPR study on cofactor geometries and electronic couplings of primary charge-separated state inthe photosynthetic reaction center

  Yasuhiro Kobori, Nina Ponomarenko, James R. Norris Jr

  2nd Awaji International Workshop on “Electron Spin Science & Technology: Biological and Materials Science Oriented Applications, Jun. 2014, English, Awaji Island, Hyogo, Japan., International conference

  [Invited]

  Invited oral presentation


• 時間分解電子スピン共鳴法による有機薄膜太陽電池の光電流生成初期過程の観測：界面電子-正孔対の立体構造と電子状態

  KOBORI Yasuhiro

  次世代太陽電池の動向と展望 京を用いた新材料設計に向けて, Mar. 2014, Japanese, 理化学研究所 計算科学研究機構, Domestic conference

  Public discourse


• 有機分子による光エネルギー変換機能：光合成反応中心と有機薄膜太陽電池

  KOBORI Yasuhiro

  第7回ESRフォーラム研究会, Jul. 2013, Japanese, 九州大学医学部百年講堂, Domestic conference

  [Invited]

  Invited oral presentation


• Exploring Roles of Nanostructure and Entropy on Primary Charge Dissociation in Organic Photovoltaic Interfaces Using Transient EPR

  Yasuhiro Kobori

  The Awaji International Workshop on Electron Spin Science & Technology: Biological and Materials Science Oriented Applications, Jun. 2013, English, 淡路夢舞台国際会議場, International conference

  [Invited]

  Invited oral presentation


• 電荷移動によるスピンの動きを捉える

  小堀康博

  日本化学会春季年会特別企画「光化学の新展開」

  [Invited]

• Semiconductor Photocatalysts for Artificial Photosynthesis: Operando Characterization of Reaction Kinetics in Milliseconds

  大西 洋, 浦谷 浩輝, 長坂 将成, 小堀 康博

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Grant-in-Aid for Scientific Research (A), Kobe University, 01 Apr. 2022 - 31 Mar. 2025


• Interaction in Dynamic Exciton Studied by Electron Spin Polarization Imaging

  小堀 康博

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Transformative Research Areas (A), Grant-in-Aid for Transformative Research Areas (A), Kobe University, 19 Nov. 2020 - 31 Mar. 2025

  本研究では有機系分子を中心とした次世代の光エネルギー変換材料の創成に向け、分子機構の解明が重要な有機薄膜系や連結系において、動的エキシトンによるスピン系相互作用をオングストローム領域の三次元映像で可視化し、三重項励起子や電荷分離立体構造による動的機構・電子状態を明らかにした。領域内で連携して過渡種の運動性を特徴づけ、電子スピン分極の三次元画像から、時々刻々変化する励起子対、光電荷分離状態の立体配置、運動性による磁気的相互作用の変化を映像化すると共に、電子的カップリングを定量している。スピン変換、再結合性、電荷解離性や束縛性状態の立体配置と運動性を明らかにする。部位特異的分子運動とその周波数がどのようにスピン変換、電荷分離立体配置や電子的カップリングに寄与するかを紐解き、中間体電子軌道による再結合を有効に制御する電子状態など、分子論的特性によりデバイス高効率化や生命機能開拓への学理を拓いた。分子内シングレットフィッション系では、強く相関した多重励起子からの電子的相互作用による束縛を解く際にかかるねじれ振動モードと周波数を具体的に特徴づけるとともに、それによる解離多重励起子の立体構造の変化も明らかにした。さらに励起子解離による立体構造変化の分子論起源は不明であった。本研究では、電子構造論に基づき双性イオン構造による束縛励起子対からのテラヘルツ振動による開放として、具体的に記述することもできた。有機光触媒開発においては、光誘起電荷分離過程で生成する光触媒分子の電荷分離状態の中間体を特定し触媒サイクル機構を明らかにした。以上より、結晶性と非晶性を併せ持つ有機エレクトロニクス薄膜や有機光触媒のエントロピー効果と運動による電子的効果を用いるデバイス効率飛躍的向上化の知的基盤を獲得し、有機薄膜太陽電池開発で課題となっている超高効率化への指針を提示することができるようになってきた。


• Dynamic Exciton: Emerging Science and Innovation

  今堀 博, 小堀 康博, 佐伯 昭紀, 山田 容子, 東 雅大, 三ツ沼 治信, 梶 弘典, 山方 啓, 家 裕隆, 作田 絵里, 村上 達也, 鈴木 克明

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Transformative Research Areas (A), Grant-in-Aid for Transformative Research Areas (A), Kyoto University, 19 Nov. 2020 - 31 Mar. 2025

  本学術変革領域では、従来の光化学における「静的エキシトン」の概念を打ち破る学術領域「動的エキシトン学」の構築にむけ、分野融合・統合的研究を推進する。そのために総括班では、本領域全体での「学問分野の枠を超えた有機的連携の堅持」を最重要課題と位置づけ、期間内に全ての計画班員12名が役割分担して領域の推進に貢献する。特に、班長及び研究課題代表者による共同研究支援に加えて、若手研究者育成支援、女性研究者育成支援、国際活動支援、産学連携支援の五つの支援を柱に、様々な具体的施策により、領域の目標と方針を計画班員に周知徹底し、目標の達成に向け先導的な役割を達成を目指す。 研究領域全体の研究方針の作成は領域代表者の今堀と各班長、研究課題代表１－４を中心に行った。拡大運営委員会、領域会議等で計画班、公募班員全員が集まる機会を複数回設け、領域目標の周知・確認を繰り返し行った。また、広報活動の一環として、また領域目標の共有に向けて、領域ホームページ、プレスリリース、学会発表、アウトリーチ等も積極的に活用した。これらの機会を利用して、計画班員全員が互いの動的エキシトン研究の進捗を密に共有した。計画、公募班員は二ヶ月に一回程度、メールやZoomなどのインターネット会議で研究の進捗を各班長、研究課題代表に報告し 、各班長、研究課題代表は班長会議、研究課題会議、サイトビジットにより、計画、公募班全体の研究の進捗を把握した。これにより、必要に応じて適切なタイミングで、機動的な共同研究の提案、開始、とりまとめを行えた。


• Photon up-conversion promoted by molecular vibration

  小堀 康博

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory), Grant-in-Aid for Challenging Research (Exploratory), Kobe University, 30 Jun. 2022 - 31 Mar. 2024


• 一重項分裂を駆動力とする革新的光反応の開発

  羽會部 卓, 小堀 康博, 婦木 正明

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Fund for the Promotion of Joint International Research (Fostering Joint International Research (B)), Fund for the Promotion of Joint International Research (Fostering Joint International Research (B)), Keio University, 27 Oct. 2020 - 31 Mar. 2024

  一般に、分子の光吸収過程では一光子光学許容状態（1光子吸収→1励起子生成）のみが遷移可能であり、励起状態を介した化学反応の量子収率の最大値は100%である。さらに、分子会合体になると単量体と比較して励起子間の消滅により吸収した励起エネルギーが迅速かつ大幅に失活する。この光化学の重大な問題点の解決策として二分子近接下で1光子の吸収過程から2つの三重項励起子を生成する多励起子生成反応の一重項分裂(SF)が考えられ、三重項励起子の生成効率ΦTは200%まで向上する。この励起子の倍増が可能なSFを種々の反応系でより汎用性を高めるには材料開発を含む基礎物性評価と反応開発の両輪による基礎学理の構築が急務である。本研究では国際共同研究を通してSFを最大限活用できる逐次反応系の構築を目指す。 まず、SFで最も汎用性の高いペンタセンと比較して、T1のエネルギーがより高く、強相関の三重項対（TT）生成の発熱性がより乏しい特徴を有するテトラセンに着目した。従来的な構造パラメーターである電子カップリングだけでなく、新たに立体柔軟性に着目し、異なるスペーサー部位を有する計4種類の二分子連結体を合成した。その結果、小さな電子カップリングと大きな立体柔軟性を有する4,4’-ビフェニル基で連結したテトラセン二分子連結体において量論的な三重項量子収率（196 ± 12%）の実現に成功した。次に、ペンタセン修飾量子ドットの分子集合体系では光吸収後の量子ドットの励起状態からペンタセンへのS-Sエネルギーを介して近接ペンタセン間の量論的なSFが観測された。量子ドットの光吸収光子数に対する三重項量子励起子の収率はほぼ200%となり、量論的なS-Sエネルギー移動とSFの逐次反応の観測に成功した。


• Three-Dimension Visualizations of Electron Spin Polarization for Elucidating Molecular Motion Effect of Geometries of Multiexciton and Charge-Separated States

  小堀 康博, 大西 洋, 池田 浩, 羽會部 卓, 松木 陽, 濱田 守彦

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Grant-in-Aid for Scientific Research (A), Kobe University, 01 Apr. 2019 - 31 Mar. 2023, Principal investigator

  単一の光子から複数の三重項励起子を生むシングレットフィッション(一重項分裂)は有機薄膜太陽電池において飛躍的に高い光エネルギー変換効率をもたらす現象として世界的に注目されている。本研究では、時間分解電子スピン共鳴法をベースに世界最高性能の空間分解能を持つ中間体構造解析の画期的ツールとして独自に開発してきた「電子スピン分極イメージング法」を主たる手法とし、時々刻々と変化する多重励起子や光電荷分離状態の立体配置とその分子運動効果をナノ秒領域の三次元動画 (映像化)として実験的に特徴づけた。分子内シングレットフィッション系では、強く相関した多重励起子からの電子的相互作用による束縛を解く際にかかるねじれ振動モードと周波数を具体的に特徴づけるとともに、それによる解離多重励起子の立体構造の変化も明らかにした。さらに励起子解離による立体構造変化の分子論起源は不明であった。本研究では、電子構造論に基づき双性イオン構造による束縛励起子対からのテラヘルツ振動による開放として、具体的に記述することもできた。動物による磁気コンパスの働きを持つものの起源と考えられているクリプトクロムにおいては、光誘起電荷分離過程で生成する電荷分離状態の立体構造と配位水のゆらぎ分子運動による電子伝達機構の詳細を明らかにした。以上より、結晶性と非晶性を併せ持つ有機エレクトロニクス薄膜や生体タンパク質のエントロピー効果と運動による電子的効果を用いるデバイス効率飛躍的向上化の知的基盤を獲得し、有機薄膜太陽電池開発で課題となっている超高効率化への指針を提示することができるようになってきた。

  Competitive research funding


• Quantum Teleportation via Singlet Fission

  Kobori Yasuhiro

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory), Grant-in-Aid for Challenging Research (Exploratory), Kobe University, 30 Jul. 2020 - 31 Mar. 2022

  We have characterized spin entanglement transportations in the singlet-quintet multiexciton spin system by using the time-resolved electron paramagnetic resonance (TREPR) detections for several singlet-fission reaction systems. We have newly constructed a spin correlated triplet-pair model to account for the electron spin polarization observed in the spin states generated by the transportations of the spin entanglement via the dissociation of the singlet and quintet strongly coupled multiexciton composed of the four qubits system resulting in the two of the individual triplet excitons. Using this model, we have elucidated the quantum mechanical spin teleportation of the multiexcitons caused by vibration motions in the strongly coupled multiexcitons to weaken the spin-spin exchange interactions generating the weakly coupled multiexcitons resulting in the conformation changes in the individual triplet chromophores.


• Water Oxidation on Semiconductor Photocatalysts: How Completed under Dilute Photon Flux

  ONISHI HIROSHI

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Grant-in-Aid for Scientific Research (A), Kobe University, 01 Apr. 2019 - 31 Mar. 2022

  Researchers in Japan have developed semiconductor photocatalysts highly efficient for the overall water splitting reaction to produce H2 and O2. Why are they active? This is the fundamental question that drives this three-year research project. We developed two methods for characterization of photocatalysts working under water. Time-resolved detection of O2 released into water was achieved with platinum microelectrode. Infrared light absorption of photocatalyst particles irradiated with ultraviolet light for excitation was monitored on a diamond prism. The developed methods were successfully applied to NaTaO3 and SrTiO3 photocatalysts.

  Competitive research funding


• 3D visualization of geometries of photoinduced charge-separated states by development of electron spin polarization imaging method

  Kobori Yasuhiro

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory), Grant-in-Aid for Challenging Research (Exploratory), Kobe University, 30 Jun. 2017 - 31 Mar. 2020, Principal investigator

  We have developed a novel method of “3D spin polarization imaging” by which the anisotropic spin polarization is mapped to all possible magnetic field directions from the powder-pattern time-resolved electron paramagnetic resonance (EPR) spectra to obtain geometries of the photoinduced primary charge-separated (CS) state of quinone pre-reduced membranes of plant PSII from spinach in frozen solution and in oriented multilayers at 77 K. For this we have observed the primary CS states using an X-band time-resolved EPR method. From the imaging maps, we have characterized cofactor geometries and electronic coupling of the photoinduced primary CS state. It has been revealed that that the electronic coupling between the charges is significantly weak in the CS state separated by 1.5 nm, showing an importance of regulated cofactor-cofactor electronic interaction between a vinyl substituent and an accessory chlorophyll to inhibit the energy-wasting charge-recombination.

  Competitive research funding


• Geometry changes by photoinduced charge-separations in flavoproteins

  Kobori Yasuhiro

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Kobe University, 01 Apr. 2016 - 31 Mar. 2019, Principal investigator

  To understand the mechanism of navigating the Earth magnetic field by animals, we have clarified atomic-scale conformation changes in oxidized tryptophan residue in photoinduced charge-separated (CS) state in cryptochrome by using time-resolved electron paramagnetic resonance measurements with applying site directed mutagenesis for Xenopus laevis cryptochrome (Xcry) DASH. The intermediate charge-separated state as the secondary radical ion pair between reduced flavin adenine dinucleotide (FAD-) and the tryptophan377 (W377+) was characterized together with the terminal radical pair of FAD--W324+. The relative position and the orientation of the charges were precisely determined by our recently developed tool of the electron spin polarization imaging derived by the magnetophotoselection measurement at low temperature. We have clarified that the conformation changes in W377+ play important role for the hole-transfer reaction from the secondary intermediate of FAD--W377+.

  Competitive research funding


• Sodium Tantalate (NaTaO3) Photocatalysts: Why So Active for Water Splitting

  ONISHI HIROSHI, Hanggara Sudrajat, An Longjie, Zhou Yizhong, Ogura Takuya, Fujiwara Tomoya, Sato Takamasa, Teduka Yuya, Kosaka Takumu, Ichikuni Nobuyuki, Sasahara Akira, Wöll Christof, Babel Snadhya

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Grant-in-Aid for Scientific Research (A), Kobe University, 01 Apr. 2016 - 31 Mar. 2019

  Sodium tantalate (NaTaO3) is the first semiconductor photocatalyst which produces hydrogen-oxygen mixed bubbles in the overall water splitting reaction, when properly doped with metal cations. This research project has been organized to answer the question of why doping with metal cations raised the quantum efficiency of the reaction. In-depth studies focused on Sr cation doping revealed that the electron-hole recombination rate was reduced when Ta cations were exchanged with Sr cations. Sodium cations were simultaneously exchanged to balance the cationic and anionic charges to form NaTaO3-Sr(Sr1/3Ta2/3)O3 solid solution. In addition, the intra-particle distribution of Sr cations played an essential role. Strontium cations segregated to produce graded composition from the Sr-rich surface to the Sr-poor core. The bottom of the conduction band lifted up at the Sr-rich surface, and the excited electrons were driven to the Sr-poor core leaving holes at the surface.

  Competitive research funding


• Carrier diffusions and their electronic states at interfaces in perovskite solar cells

  Kobori Yasuhiro, HAYASE SHUJI, OGOMI YUHEI

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research, Grant-in-Aid for Challenging Exploratory Research, Kobe University, 01 Apr. 2014 - 31 Mar. 2017, Principal investigator

  In recent years, great attentions have been attracted on the perovskite solar cells as the next generation thin-film photovoltaics that can be low-cost, flexible and light. In this study, we observed photoinduced separated charges in the photoactive layers in the perovskite (CH3NH3PbI3) solar cells by using the time-resolved electron paramagnetic resonance spectroscopy for the three layer thin films (Spiro-OMeTAD/CH3NH3PbI3/TiO2 on a glass substrate) composed of the organic hole transport layer (Spiro-OMeTAD), the CH3NH3PbI3 layer and the mesoporous TiO2 fabricated by spin coating method on the mesoporous TiO2 films. We have characterized the spin density distributions of the trapped holes of the CH3NH3PbI3 layer at 110 K. Furthermore, from the ESP generated in the trapped hole, we have estimated the J coupling in the primary electron-hole pairs which will give us an insight on the electronic coupling of the Wannier excitons.

  Competitive research funding


• Photoexcited NaTaO3 photocatalysts observed with time-resolved ESR

  Onishi Hiroshi, KOBORI Yasuhiro, MIZUTANI Takao, PARK Yohan, AN Longjie, LI Haoliang

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research, Grant-in-Aid for Challenging Exploratory Research, Kobe University, 01 Apr. 2014 - 31 Mar. 2016

  (1) Time-resolved electron spin resonance spectra of Sr-doped NaTaO3 photocatalysts were observed. A microwave absorption induced by bandgap excitation was identified at g=1.995 with an absorption line width of 2 mT. (2) Sr-doped NaTaO3 photocatalysts produced core-shell structured NaTaO3-SrSr1/3Ta2/3O3 solid solution. The photocatalysts were chemically etched to examine the different roles of the core and shell with respect to the recombination of electrons and holes. Under excitation by Hg-Xe lamp irradiation, the steady-state population of electrons in the core-shell-structured photocatalyst with a bulk Sr concentration of 5 mol% increased by 130 times relative to that of the undoped photocatalyst. During etching for the first 10 min, the shell detached from the top of the core, and the electron population in the uncovered core further increased by 40%. This population enhancement indicates that electrons are excited in the core and recombined in the shell.


• Geometry and Orientation of Photoinduced Primary Charge-Separated State in the Photosystem II Reaction Center

  Yasuhiro Kobori, MINO HIROYUKI

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Kobe University, 01 Apr. 2013 - 31 Mar. 2016, Principal investigator

  We have developed a method to analyze geometries and molecular orientations of photoinduced charge-separated states by detections of the magnetic interactions by using the time-resolved paramagnetic resonance (TREPR) methods. We have employed multi-frequency TREPR spectroscopy to characterize the geometries and the electronic coupling of the photoinduced primary charge-separated states generated in the photosynthetic reaction centers and in the photosystem II reaction center of spinach. We have clarified molecular mechanisms of the efficient charge generations and of the preventions of the energy-wasting charge-recombinations.

  Competitive research funding


• Development of imaging probe to detect lipid derived radicals from whole body to cells

  YAMADA Kenichi, KOBORI Yasuhiro, AOKI Ichio, MIURA Daisuke

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Kyushu University, 01 Apr. 2012 - 31 Mar. 2015

  Lipid derived radicals and its metabolic products are closely involved in the pathogenesis of oxidative stress diseases such as inflammation and angiogenesis through the formation of protein or DNA complex. The starting point of lipid peroxide generation is lipid derived radicals which increase explosively via radical chain reaction. Therefore, the trapping of lipid derived radicals is useful to understanding the mechanism of formation of oxidative stress diseases, and to suppress the following chain reaction. On the other hands, nitroxides having stable unpaired electron allows spin trapping with carbon-centered radicals. Hence, in this study, we aimed to develop and evaluate lipid derived detection method using profluorescent nitroxide switching methods.


• さきがけ「電子スピンコヒーレンスによる有機太陽電池基板の電子伝達機能の解明」

  小堀 康博

  戦略的創造研究推進事業 個人型研究さきがけ, 2013, Principal investigator

  Competitive research funding


• Electron Transport Functions for Solar Energy Conversions in Nanometer-Scaled Organic Molecular Systems

  KOBORI Yasuhiro

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Shizuoka University, 2010 - 2012

  For development of the molecular solar-energy conversion systems, it is crucial to investigate how both the molecular geometry and the electronic structure of electron donor-acceptor (D-A) molecules contribute to the electronic coupling for the charge-separation (CS) and for the charge-recombination (CR) processes. In this study, we have developed theoretical methods to analyze the electron spin polarization detected by the time-resolved electron paramagnetic resonance (TREPR) spectroscopy for D-A systems to systematically characterize both the molecular geometry and the electronic coupling of the photoinduced charge-separated state inthe electron donor-acceptor (D-A) molecular systems for several D-A systems in photoactive proteins and in the active layers of the organic thin-film solar cells.


• Enzyme Activation Mechanism Probed by Photoinduced Radical Generation in Proteins Related to Nucleotides

  KOBORI Ysauhiro, MURAI Hisao

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Grant-in-Aid for Scientific Research (C), Shizuoka University, 2007 - 2009

  結核菌のカタラーゼ-ペロキシダーゼ(KatG)酵素における酵素反応初期過程を時間分解電子スピン共鳴法で室温において観測した。KatG-アントラキノンスルフォン酸イオン(薬物)の複合体において、レーザー光照射による光誘起電子移動反応を観測し、メチオニンカチオンラジカルと電子受容した薬物のアニオンラジカルで構成されるスピン相関ラジカル対をナノ秒領域で観測することに成功した。この薬物はKatGヘムポケット内部に存在し、近傍のヘム、トリプトファン、チロシン残基を介して高速の電荷分離過程が起こっていることが明らかになった。


• 光合成系分子のイノメートル電子移動反応における溶媒和形態変化

  小堀 康博

  日本学術振興会, 科学研究費助成事業 若手研究(B), 若手研究(B), 東北大学, 2001 - 2002

  液体中の遠距離電子移動系において、中間体ラジカルイオン対を取り巻く溶媒分子のナノスケール環境場からどのように静電的相互作用を受けているかを分子論的に解明することを目的とした。 光合成反応中心を構成するような比較的大きなサイズの分子として、亜鉛ポルフィリン-デュロキノン系に特に注目し、レーザー励起時間分解EPR法によりこれまで正確な測定が不可能であったクロロフィルやフラーレン分子の光誘起電子移動で生成する異常電子スピン分極を直接検出し、ラジカル対の電子スピン分極機構から、1ナノメートル程度の遠距離電子移動系における再配向エネルギー、一重項-三重項エネルギー差(J)の符号を得るため、溶質や溶媒に固有の値として精密にしかも一義的に定量した。 Jにおける電荷移動相互作用機構から、溶媒の極性や温度を変化させて電荷再結合自由エネルギーをチューニングすることによって符号が変化する結果を得られれば、J=0なる溶媒中でドナー、アセプターそれぞれの酸化還元電位を測定することにより、系に固有の再配向エネルギーλが一義的に決定される。そのため、数多くの溶質、溶媒系で測定し、溶質分子サイズ、溶質立体構造、置換基、溶媒極性などの効果を系統的に調べた。それぞれの分子系でマーカスの連続誘電体モデルがよく成り立っていることが明かとなった。


• 溶媒和ラジカルイオン対の交換相互作用検出による再配向エネルギーの精密測定

  小堀 康博

  日本学術振興会, 科学研究費助成事業 萌芽的研究, 萌芽的研究, 東北大学, 1999 - 1999

  光誘起電子移動反応過程の反応性を大きく支配する溶媒再配向エネルギーの値を精密に測定することを目的として電子供与体-受容体ラジカルイオン対系について以下の研究を行った。 1.時間分解EPR法を用いた溶媒和ラジカルイオン対の一重項-三重項エネルギー差(J)検出による溶媒再配向エネルギーの決定 (1)電荷移動型相互作用によるラジカルイオン対のJの理論を構築し、電荷再結合自由エネルギーと全再配向エネルギーが一致する点を境にラジカル間距離が約12Å離れたイオン対のJの符号が変化することを示した。 (2)時間分解EPR法によるJの符号に対する溶媒極性や温度効果から、デュロキノン-N,N-ジメチルアニリン等の電子供与体-受容体系に固有の溶媒再配向エネルギーの値を種々の溶媒中で精度良く決定した。溶媒再配向エネルギーの値がベンゼン誘導体の置換基の種類によって大きく異なることが見出された。 (3)時間分解蛍光分光測定による電荷移動錯体蛍光スペクトルから接触イオン対系の溶媒再配向エネルギーを得ることにより、(2)の結論を裏付けた。 2.溶媒再配向エネルギーの分子論的描像 以上の溶媒再配向エネルギーに対する置換基効果の結果はMarcusの連続誘電体モデルでは説明することができない。ベンゼン誘導体のイオン化に伴う置換基の構造変化が溶質と第一溶媒和圏の溶媒分子との静電相互作用に大きな影響を与えるため、溶媒再配向エネルギーが置換基の種類によって大きく異なることが示唆された。


• 外部磁場による励起分子-ラジカル系の反応制御

  小堀 康博

  日本学術振興会, 科学研究費助成事業 奨励研究(A), 奨励研究(A), 東北大学, 1997 - 1998

  1) 時間分析EPR法によるラジカルイオン対の交換相互作用機構(電荷移動型交換相互作用)の発見 光誘起電子移動反応で生成する様々な溶媒和ラジカルイオン対の交換相互作用(J)の符号が電荷再結合自由エネルギーに依存することを初めて見出した。この結果を統一的に説明するものとして、電子移動反応理論に基づく新しい交換相互作用の機構(電荷移動型交換相互作用)を提唱した。この機構から、Jの符号、大きさについての理論を確立した。 2) 時間分解EPR法によるラジカル-三重項分子間の交換相互作用 ラジカルと励起三重項分子間の相互作用で生成する電子スピン分極に対する温度効果を観測した。ラジカル-三重項対機構による電子スピン分極生成理論を構築し、それに基づく解析から、ラジカル-三重項対のJの大きさを見積もった。励起三重項種によってJが大きく異なることを初めて見出した。Jの大きさは、ラジカル誘起三重項消光過程が電子交換反応により進む系では、電子移動反応により進む系よりも1桁以上大きく、Jは消光機構の違いにより大きく影響を受けることが分かった。これは、電荷移動型交換相互作用で見積もられるJの大きさからも支持された。 3) 磁場効果測定によるラジカル-三重項分子間の交換相互作用 ラジカルによる励起三重項消光過程に対する外部磁場効果を時間分解蛍光法や過渡吸収法により観測した。様々な励起分子および、ラジカル種において、消光過程に対する磁場効果が見出され、外部磁場による反応制御が可能であることが明らかになった。ラジカル-三重項対機構に基づき磁場効果生成理論を構築し、それによる解析から、磁場効果生成機構が初めて明らかになった。消光過程が電子交換反応により進む系では、電子移動反応により進む系よりもJが1桁以上大きいことが磁場効果測定により直接的に示され、ラジカル-三重項対の交換相互作用機構が定量的に明らかになった。