| Nobuhiro Yanai | Last modified date：2024.04.18 |
Associate Professor /
Biofunctional Chemistry /
Department of Applied Chemistry /
Faculty of Engineering
Papers
| 1. | , [URL]. |
| 2. | Kana Orihashi, Akio Yamauchi, Miku Inoue, Bhavesh Parmar, Saiya Fujiwara, Nobuo Kimizuka, Mizue Asada, Toshikazu Nakamura, Nobuhiro Yanai*, Radical qubits photo-generated in acene-based metal–organic frameworks, Dalton Trans., 53, 872-876, 2023.12, [URL]. |
| 3. | Keita Sakamoto, Tomoyuki Hamachi, Katsuki Miyokawa, Kenichiro Tateishi, Tomohiro Uesaka, Yuki Kurashige,* Nobuhiro Yanai*, Polarizing agents beyond pentacene for efficient triplet dynamic nuclear polarization in glass matrices, Proc. Natl. Acad. Sci. U.S.A., 10.1073/pnas.2307926120, 120, 44, e2307926120, 2023.10, [URL]. |
| 4. | Kana Orihashi, Akio Yamauchi, Saiya Fujiwara, Mizue Asada, Toshikazu Nakamura, Joseph Ka-Ho Hui, Nobuo Kimizuka, Kenichiro Tateishi, Tomohiro Uesaka, Nobuhiro Yanai*, Spin-Polarized Radicals with Extremely Long Spin-Lattice Relaxation Time at Room Temperature in a Metal-Organic Framework, J. Am. Chem. Soc., 10.1021/jacs.3c09563, 145, 50, 27650-27656, 2023.12, [URL]. |
| 5. | Tomoyuki Hamachi, Koki Nishimura, Keita Sakamoto, Yusuke Kawashima, Hironori Kouno, Shunsuke Sato, Go Watanabe, Kenichiro Tateishi, Tomohiro Uesaka, Nobuhiro Yanai*, Triplet dynamic nuclear polarization of pyruvate via supramolecular chemistry, Chem. Sci., 10.1039/D3SC04123A, 14, 13842-13850, 2023.11, [URL]. |
| 6. | , [URL]. |
| 7. | Naoyuki Harada, Masanori Uji, Baljeet Singh, Nobuo Kimizuka, Nobuhiro Yanai , Porous film impregnation method for record-efficiency visible-to-UV photon upconversion and subsolar light harvesting, 11, 8002, 2023.03, [URL]. |
| 8. | Koki Nishimura, Reiya Yabuki, Tomoyuki Hamachi, Nobuo Kimizuka, Kenichiro Tateishi, Tomohiro Uesaka, and Nobuhiro Yanai, Dynamic Electron Polarization Lasting More Than 10 μs by Hybridizing Porphyrin and TEMPO with Flexible Linkers, J. Phys. Chem. B, 127, ５, 1219, 2023.01, [URL]. |
| 9. | Reiya Yabuki, Koki Nishimura, Tomoyuki Hamachi, Naoto Matsumoto, and Nobuhiro Yanai*, Generation and Transfer of Triplet Electron Spin Polarization at the Solid–Liquid Interface, J. Phys. Chem. Lett. , 14, 20, 4754, 2023.05, [URL]. |
| 10. | Masanori Uji, Till J. B. Zähringer, Christoph Kerzig, Nobuhiro Yanai, Visible-to-UV Photon Upconversion: Recent Progress in New Materials and Applications, Angewandte Chemie, 10.1002/anie.202301506, e202301506, 2023.06, [URL]. |
| 11. | Pankaj Bharmoria, Fredrik Edhborg, Hakan Bildirir, Yoichi Sasaki, Shima Ghasemi, Anders Mårtensson, Nobuhiro Yanai, Nobuo Kimizuka, Bo Albinsson, Karl Börjesson, Kasper Moth-Poulsen, Recyclable optical bioplastics platform for solid state red light harvesting via triplet-triplet annihilation photon upconversion, JOURNAL OF MATERIALS CHEMISTRY A, 10.1039/d2ta04810h, 10, 40, 21279-21290, 2022.10. |
| 12. | Naoto Matsumoto, Koki Nishimura, Nobuo Kimizuka, Yusuke Nishiyama, Kenichiro Tateishi, Tomohiro Uesaka, and Nobuhiro Yanai, Proton Hyperpolarization Relay from Nanocrystals to Liquid Water, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 10.1021/jacs.2c07518, 2022, 144, 39, 18023–18029, 2022.09. |
| 13. | Haklae Lee, Myung-Soo Lee, Masanori Uji, Naoyuki Harada, Jeong-Min Park, Jiyeon Lee, Sung Eun Seo, Chul Soon Park, Jinyeong Kim, Seon Joo Park, Suk Ho Bhang, Nobuhiro Yanai, Nobuo Kimizuka, Oh Seok Kwon, and Jae-Hyuk Kim, Nanoencapsulated Phase-Change Materials: Versatile and Air-Tolerant Platforms for Triplet-Triplet Annihilation Upconversion, ACS APPLIED MATERIALS & INTERFACES, 10.1021/acsami.1c21080, 14, 3, 4132-4143, 2022.01. |
| 14. | Yoichi Sasaki, Nobuhiro Yanai,* Nobuo Kimizuka*, Osmium Complex-Chromophore Conjugates with Both Singlet-to-Triplet Absorption and Long Triplet Lifetime through Tuning of the Heavy-Atom Effect br, INORGANIC CHEMISTRY, 10.1021/acs.inorgchem.1c03129, 61, 16, 5982-5990, 2022.04. |
| 15. | Masanori Uji, Naoyuki Harada, Nobuo Kimizuka,* Masaki Saigo, Kiyoshi Miyata, Ken Onda, Nobuhiro Yanai*, Heavy metal-free visible-to-UV photon upconversion with over 20% efficiency sensitized by a ketocoumarin derivative, JOURNAL OF MATERIALS CHEMISTRY C, 10.1039/d1tc05526g, 10, 12, 2022.03, Efficient triplet-triplet annihilation-based photon upconversion (TTA-UC) from visible to UV light without using heavy metals is still a challenging task. Here we achieve a record-high TTA-UC efficiency of 20.3% among 100% maximum by employing a ketocoumarin derivative as a triplet sensitizer, which shows strong visible absorption, weak UV absorption, and efficient intersystem crossing. |
| 16. | Saiya Fujiwara, Naoto Matsumoto, Koki Nishimura, Nobuo Kimizuka, Kenichiro Tateishi, Tomohiro Uesaka, Nobuhiro Yanai*, Triplet Dynamic Nuclear Polarization of Guest Molecules through Induced Fit in a Flexible Metal-Organic Framework, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 10.1002/anie.202115792, 61, 9, 2022.02. |
| 17. | Tsubasa Kashino, Rena Haruki, Masanori Uji, Naoyuki Harada, Masanori Hosoyamada, Nobuhiro Yanai,* Nobuo Kimizuka*, Design Guidelines for Rigid Epoxy Resins with High Photon Upconversion Efficiency: Critical Role of Emitter Concentration, ACS APPLIED MATERIALS & INTERFACES, 10.1021/acsami.1c17021, 2022.01. |
| 18. | Mio Koharagi, Naoyuki Harada, Keisuke Okumura, Junji Miyano, Shota Hisamitsu, Nobuo Kimizuka,* Nobuhiro Yanai*, Green-to-UV photon upconversion enabled by new perovskite nanocrystal-transmitter-emitter combination, NANOSCALE, 10.1039/d1nr06588b, 13, 47, 19890-19893, 2021.12, The first example of triplet–triplet annihilation-based photon upconversion (TTA-UC) from green light to ultraviolet (UV) light sensitized by lead halide perovskite nanocrystals is demonstrated. The combination of a new transmitter that extracts triplet energy from perovskite and a UV emitter with a low triplet energy level lengthens the excitation wavelength of perovskite-sensitized upconverted UV emission.. |
| 19. | David Bossanyi, Yoichi Sasaki, Shuanqing Wang, Dimitri Chekulaev, Nobuo Kimizuka, Nobuhiro Yanai, Jenny Clark, In optimized rubrene-based nanoparticle blends for photon upconversion, singlet energy collection outcompetes triplet-pair separation, not singlet fission, J. Mater. Chem. C, 10.1039/D1TC02955J, 2021.11, [URL]. |
| 20. | David G. Bossanyi, Yoichi Sasaki, Shuangqing Wang, Dimitri Chekulaev, Nobuo Kimizuka, Nobuhiro Yanai, and Jenny Clark, Spin Statistics for Triplet–Triplet Annihilation Upconversion: Exchange Coupling, Intermolecular Orientation, and Reverse Intersystem Crossing, ACS Au, 10.1021/jacsau.1c00322, 2021.10, [URL]. |
| 21. | Akio Yamauchi, Saiya Fujiwara, Koki Nishimura, Yoichi Sasaki, Kenichiro Tateishi, Tomohiro Uesaka, Nobuo Kimizuka, Nobuhiro Yanai, Design Guidelines to Elongate Spin-Lattice Relaxation Times of Porphyrins with Large Triplet Electron Polarization, JOURNAL OF PHYSICAL CHEMISTRY A, 10.1021/acs.jpca.1c01839, 125, 20, 4334-4340, 2021.05, [URL]. |
| 22. | Yoichi Sasaki, Shogo Amemori, Nobuhiro Yanai, Nobuo Kimizuka, Singlet-to-triplet absorption for near-infrared-to-visible photon upconversion, Bull. Chem. Soc. Jpn. , 94, 1760-1768, 2021.04, [URL]. |
| 23. | Tsubasa Kashino, Masanori Hosoyamada, Rena Haruki, Naoyuki Harada, Nobuhiro Yanai,* Nobuo Kimizuka*, Bulk Transparent Photon Upconverting Films by Dispersing High-Concentration Ionic Emitters in Epoxy Resins, ACS Appl. Mater. Interfaces , 13, 11, 13676-13683, 2021.03, [URL]. |
| 24. | Tomoyuki Hamachi, Koki Nishimura, Hironori Kouno, Yusuke Kawashima, Kenichiro Tateishi*, Tomohiro Uesaka, Nobuo Kimizuka*, Nobuhiro Yanai*, Porphyrins as Versatile, Aggregation-Tolerant, and Biocompatible Polarizing Agents for Triplet Dynamic Nuclear Polarization of Biomolecules, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 10.1021/acs.jpclett.1c00294, 12, 10, 2645-2650, 2021.03, [URL]. |
| 25. | Pankaj Bharmoria, Shota Hisamitsu, Yoichi Sasaki, Tejwant Singh Kang, Masa-aki Morikawa, Biplab Joarder, Kasper Moth-Poulsen, Hakan Bildirir, Anders Mårtensson, Nobuhiro Yanai,* Nobuo Kimizuka*, Photon upconverting bioplastics with high efficiency and in-air durability, J. Mater. Chem. C, 10.1039/D1TC00287B, 2021.02, [URL]. |
| 26. | Bruno Ehrler,* Nobuhiro Yanai,* Lea Nienhaus*, Up- and down-conversion in molecules and materials, JOURNAL OF CHEMICAL PHYSICS, 10.1063/5.0045323, 154, 7, 2021.02, [URL]. |
| 27. | Mika Kinoshita, Yoichi Sasaki, Shogo Amemori, Naoyuki Harada, Zhanhao Hu, Zonghao Liu, Luis K. Ono, Yabing Qi,* Nobuhiro Yanai,* Nobuo Kimizuka*, Photon Upconverting Solid Films with Improved Efficiency for Endowing Perovskite Solar Cells with Near-Infrared Sensitivity, CHEMPHOTOCHEM, 10.1002/cptc.202000143, 4, 11, 5271-5278, 2020.11. |
| 28. | Hisanori Nagatomi, Leighanne C. Gallington, Subhadip Goswami, Jiaxin Duan, Karena W. Chapman, Nobuhiro Yanai, Nobuo Kimizuka, Omar K. Farha, and Joseph T. Hupp*, Regioselective Functionalization of the Mesoporous Metal-Organic Framework, NU-1000, with Photo-Active Tris-(2,2 '-bipyridine)ruthenium(II), ACS OMEGA, 10.1021/acsomega.0c04823, 5, 46, 30299-30305, 2020.11. |
| 29. | Naoyuki Harada, Yoichi Sasaki, Masanori Hosoyamada, Nobuo Kimizuka* and Nobuhiro Yanai *, Discovery of Key TIPS‐Naphthalene for Efficient Visible‐to‐UV Photon Upconversion under Sunlight and Room Light, Angew. Chem. Int. Ed., 60, 1, 142-147, 2020.10, [URL]. |
| 30. | Biplab Joarder, Arijit Mallick, Yoichi Sasaki, Mika Kinoshita, Rena Haruki, Yusuke Kawashima, Nobuhiro Yanai, Nobuo Kimizuka, Near-Infrared-to-Visible Photon Upconversion by Introducing an S−T Absorption Sensitizer into a Metal-Organic Framework, ChemNanoMat, 10.1002/cnma.202000019, 6, 6, 916-919, 2020.06, Triplet-triplet annihilation-based photon upconversion (TTA-UC) of near-infrared (NIR) light to visible light in the solid-state remains as a great challenge due to the sensitizer aggregation that impedes the efficient triplet energy transfer. Herein, we successfully introduce a molecular sensitizer exhibiting direct singlet-to-triplet (S–T) absorption into a new emitter-based metal-organic framework (MOF) to achieve an efficient triplet sensitization and a NIR-to-visible TTA-UC in the solid-state.. |
| 31. | , [URL]. |
| 32. | , [URL]. |
| 33. | Karina Shimizu, Shota Hisamitsu, Nobuhiro Yanai, Nobuo Kimizuka, José N. Canongia Lopes, Photon Upconversion in TTA-Inducing Ionic Liquids Pinpointing the Role of IL Nanostructured Media Using MD Simulations, The journal of physical chemistry. B, 10.1021/acs.jpcb.0c00768, 124, 15, 3137-3144, 2020.04, The use of task-specific chromophoric ionic liquids as energy transfer media in triplet-triplet annihilation photon upconversion (TTA-UC) processes has produced several examples of systems with signifficantly enhanced performances. In this work, we use molecular dynamics simulations to probe the relation between the nanostructure of chromophoric ionic liquids and their ability to achieve high TTA-UC quantum yields. The existing atomistic and systematic force fields commonly used to model different ionic liquids are extended to include substituted anthracene moieties, thus allowing the modeling of several chromophoric ionic liquids. The simulation results show that the polar network of the ionic liquids can orient the anthracene moieties within the nonpolar domains preventing direct contacts between them but allowing orientations at the optimal distance for triplet energy migration.. |
| 34. | Hironori Kouno, Kana Orihashi, Koki Nishimura, Yusuke Kawashima, Kenichiro Tateishi, Tomohiro Uesaka, Nobuo Kimizuka, Nobuhiro Yanai, Triplet dynamic nuclear polarization of crystalline ice using water-soluble polarizing agents, Chemical Communications, 10.1039/d0cc00836b, 56, 26, 3717-3720, 2020.04, Triplet dynamic nuclear polarization (triplet-DNP) allows hyperpolarization at a moderate temperature. While the triplet-DNP of water is strongly desired, water-soluble triplet polarizing agents have not yet been reported. Herein, the first example of triplet-DNP of crystalline ice is demonstrated by molecularly dispersing a novel water-soluble polarizing agent into ice.. |
| 35. | Shota Hisamitsu, Junji Miyano, Keisuke Okumura, Joseph Ka Ho Hui, Nobuhiro Yanai, Nobuo Kimizuka, Visible-to-UV Photon Upconversion in Nanostructured Chromophoric Ionic Liquids, ChemistryOpen, 10.1002/open.201900304, 9, 1, 14-17, 2020.01, Visible-to-ultraviolet (vis-to-UV) triplet-triplet annihilation based photon upconversion (TTA-UC) is achieved in a non-volatile chromophoric ionic liquid (IL) for the first time. A novel IL is synthesized by combining UV-emitting anion 4-(2-phenyloxazol-5-yl)benzenesulfonate (PPOS) and trihexyltetradecylphosphonium cation (P66614). The nanostructured organization of chromophoric anions is demonstrated by synchrotron X-ray and optical measurements. When the IL is doped with a triplet sensitizer tris(2-phenylpyridinato)iridium(III) (Ir(ppy)3), the visible-to-UV TTA-UC with a relatively low threshold excitation intensity of 61 mW cm−2 is achieved. This is due to a large triplet diffusion coefficient in the IL (1.4×10−7 cm2 s−1) as well as a high absorption coefficient 15 cm−1 and a long PPOS triplet lifetime of 1.55 ms, all implemented in the condensed IL system. This work demonstrates the unique potential of ILs to control chromophore arrangements for desired functions.. |
| 36. | Shota Hisamitsu, Junji Miyano, Keisuke Okumura, Joseph Ka-Ho Hui, Nobuhiro Yanai, Nobuo Kimizuka, Visible-to-UV Photon Upconversion in Nanostructured Chromophoric Ionic Liquids, ChemistryOpen, 10.1002/open.201900358, 9, 1, 2020.01, Invited for this month's cover picture is the group of Professor Nobuhiro Yanai and Nobuo Kimizuka at Kyushu University. The cover picture shows visible-to-ultraviolet (vis-to-UV) triplet-triplet annihilation-based photon upconversion (TTA-UC) via triplet exciton diffusion in a chromophoric ionic liquid (IL). Chromophore moieties spontaneously form continuous arrays in non-polar nano-domains of the IL. The close arrangement of the chromophores in the IL allowed effective diffusion of triplet excitons, resulting in the vis-to-UV TTA-UC at a low excitation intensity. Read the full text of their Communication at 10.1002/open.201900304.. |
| 37. | Yoichi Sasaki, Mio Oshikawa, Pankaj Bharmoria, Hironori Kouno, Akiko Hayashi-Takagi, Moritoshi Sato, Itsuki Ajioka, Nobuhiro Yanai, Nobuo Kimizuka, Near-Infrared Optogenetic Genome Engineering Based on Photon-Upconversion Hydrogels, Angewandte Chemie - International Edition, 10.1002/anie.201911025, 58, 49, 17827-17833, 2019.12, Photon upconversion (UC) from near-infrared (NIR) light to visible light has enabled optogenetic manipulations in deep tissues. However, materials for NIR optogenetics have been limited to inorganic UC nanoparticles. Herein, NIR-light-triggered optogenetics using biocompatible, organic TTA-UC hydrogels is reported. To achieve triplet sensitization even in highly viscous hydrogel matrices, a NIR-absorbing complex is covalently linked with energy-pooling acceptor chromophores, which significantly elongates the donor triplet lifetime. The donor and acceptor are solubilized in hydrogels formed from biocompatible Pluronic F127 micelles, and heat treatment endows the excited triplets in the hydrogel with remarkable oxygen tolerance. Combined with photoactivatable Cre recombinase technology, NIR-light stimulation successfully performs genome engineering resulting in the formation of dendritic-spine-like structures of hippocampal neurons.. |
| 38. | Hak Lae Lee, Jung Hwan Park, Hyun Seok Choe, Myung Soo Lee, Jeong Min Park, Naoyuki Harada, Yoichi Sasaki, Nobuhiro Yanai, Nobuo Kimizuka, Jintao Zhu, Suk Ho Bhang, Jae Hyuk Kim, Upconverting Oil-Laden Hollow Mesoporous Silica Microcapsules for Anti-Stokes-Based Biophotonic Applications, ACS Applied Materials and Interfaces, 10.1021/acsami.9b06620, 11, 30, 26571-26580, 2019.07, A recyclable, aqueous phase functioning and biocompatible photon upconverting system is developed. Hollow mesoporous silica microcapsules (HMSMs) with ordered radial mesochannels were employed, for the first time, as vehicles for the post-encapsulation of oil phase triplet-triplet annihilation upconversion (TTA-UC), with the capability of homogeneous suspension in water. In-depth characterization of such upconverting oil-laden HMSMs (UC-HMSMs) showed that the mesoporous silica shells reversibly stabilized the encapsulated UC oil in water to allow efficient upconverted emission, even under aerated conditions. In addition, the UC-HMSMs were found to actively bind to the surface of human mesenchymal stem cells without significant cytotoxicity and displayed upconverted bright blue emission under 640 nm excitation, indicating a potential of our new TTA-UC system in biophotonic applications. These findings reveal the great promise of UC-HMSMs to serve as ideal vehicles not only for ultralow-power in vivo imaging but also for stem cell labeling, to facilitate the tracking of tumor cells in animal models.. |
| 39. | Hironori Kouno, Yusuke Kawashima, Kenichiro Tateishi,* Tomohiro Uesaka, Nobuo Kimizuka,* and Nobuhiro Yanai*, Nonpentacene Polarizing Agents with Improved Air Stability for Triplet Dynamic Nuclear Polarization at Room Temperature, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 10.1021/acs.jpclett.9b00480, 10, 9, 2208-2213, 2019.05, 核磁気共鳴を用いた分光法（NMR）や画像化法（MRI）は非破壊的に分子の構造や運動性を分析できる手法であるが、その感度が非常に低いため、例えばMRIにおいては観測対象が主に生体内に大量に存在する水に限られてきた。感度が低い原因は核スピンの偏極率が低いためであり、その偏極率を向上させる技術として動的核偏極法（DNP）がある。中でも光励起三重項の大きな電子スピン偏極を核スピン偏極へと移行するtriplet-DNPは室温で核スピンの偏極率を高めることが出来る。 これまでtriplet-DNPの偏極源は主にペンタセンに限られてきたが、ペンタセンは空気中で容易に酸化されてしまい、今後triplet-DNPを溶存酸素が存在するバイオ応用へと展開する上で解決すべき問題である。そこで電子吸引性の窒素原子を導入したジアザペンタセンやジアザテトラセンが、高性能かつ空気中で安定な初めての偏極源であることを示した。. |
| 40. | Hironori Kouno, Yoichi Sasaki, Nobuhiro Yanai,* and Nobuo Kimizuka*, Supramolecular Crowding Can Avoid Oxygen Quenching of Photon Upconversion in Water, Chemistry - A European Journal, 10.1002/chem.201806076, 25, 24, 6124-6130, 2019.04. |
| 41. | Hironori Kouno, Yoichi Sasaki, Nobuhiro Yanai, Nobuo Kimizuka, Supramolecular Crowding Can Avoid Oxygen Quenching of Photon Upconversion in Water, Chemistry - A European Journal, 10.1002/chem.201900795, 25, 24, 2019.04, Invited for the cover of this issue is the group of Nobuhiro Yanai and Nobuo Kimizuka at Kyushu University. The image depicts the photon upconverting self-assemblies of amphiphilic chromophores in water. Read the full text of the article at 10.1002/chem.201806076.. |
| 42. | Francesco Meinardi,* Marco Ballabio, Nobuhiro Yanai, Nobuo Kimizuka, Alberto Bianchi, Michele Mauri, Roberto Simonutti, Alessandra Ronchi, Marcello Campione, and Angelo Monguzzi*, Quasi-thresholdless Photon Upconversion in Metal-Organic Framework Nanocrystals, Nano Letters, 10.1021/acs.nanolett.9b00543, 19, 3, 2169-2177, 2019.03. |
| 43. | Pankaj Bharmoria, Nobuhiro Yanai, Nobuo Kimizuka, Recent progress in photon upconverting gels, Gels, 10.3390/gels5010018, 5, 1, 2019.03, Recent progress in the development of gels showing triplet-triplet annihilation based photon upconversion (TTA-UC) is reviewed. Among the two families of upconverting gels reported, those display TTA-UC based on molecular diffusion show performances comparable to those in solutions, and the TTA-UC therein are affected by dissolved molecular oxygen. Meanwhile, air-stable TTA-UC is achieved in organogels and hydrogels by suitably accumulating TTA-UC chromophores which are stabilized by hydrogen bonding networks of the gelators. The unique feature of the air-stable upconverting gels is that the self-assembled nanostructures are protected from molecular oxygen dissolved in the microscopically interconnected solution phase. The presence of the bicontinuous structures formed by the upconverting fibrous nanoassemblies and the solution phase is utilized to design photochemical reaction systems induced by TTA-UC. Future challenges include in vivo applications of hydrogels showing near infrared-to-visible TTA-UC.. |
| 44. | Rena Haruki, Hironori Kouno, Masanori Hosoyamada, Taku Ogawa, Nobuhiro Yanai,* and Nobuo Kimizuka*, Oligo(ethylene glycol)/alkyl-modified Chromophore Assemblies for Photon Upconversion in Water, Chemistry - An Asian Journal, 10.1002/asia.201801666, 2019.01. |
| 45. | Nobuhiro Yanai, Kengo Suzuki, Taku Ogawa, Yoichi Sasaki, Naoyuki Harada, Nobuo Kimizuka, Absolute Method to Certify Quantum Yields of Photon Upconversion via Triplet-Triplet Annihilation, Journal of Physical Chemistry A, 10.1021/acs.jpca.9b08636, 2019.01, For the consistent development of the field of photon upconversion via triplet-triplet annihilation (TTA-UC), it is pivotal to know the true quantum yield of TTA-UC emission. Although TTA-UC quantum yields have been determined by common relative measurements using quantum yield standards, there is still a discrepancy between the reported values even for the benchmark sensitizer-emitter pair of platinum(II) octaethylporphyrin (PtOEP) and 9,10-diphenylanthracene (DPA). Here, to resolve this situation, we show a method to obtain the absolute quantum yield of TTA-UC photoluminescence. The difficulty in obtaining absolute TTA-UC quantum yield by the integrating sphere measurement is to accurately calibrate the contribution of reabsorbed upconverted emission by triplet sensitizers. The reabsorption correction is successfully carried out by comparing sensitizer phosphorescence with and without the integrating sphere. An absolute TTA-UC quantum yield of the PtOEP-DPA pair is obtained as 36%, which shows a good agreement with the relative TTA-UC quantum yield. An absolute TTA-UC quantum yield of another red-to-blue TTA-UC pair, platinum(II) meso-tetraphenyltetrabenzoporphyrin (PtTPBP) and 2,5,8,11-tetra-tert-butylperylene (TTBP), is obtained as 27%. These absolute TTA-UC quantum yields can be used as certified values to check the measurement setup and sample condition for determining relative TTA-UC quantum yields in each laboratory.. |
| 46. | Koki Nishimura, Hironori Kouno, Kenichiro Tateishi, Tomohiro Uesaka, Keiko Ideta, Nobuo Kimizuka, Nobuhiro Yanai, Triplet dynamic nuclear polarization of nanocrystals dispersed in water at room temperature, Physical Chemistry Chemical Physics, 10.1039/c9cp03330k, 21, 30, 16408-16412, 2019.01, While dynamic nuclear polarization using photo-excited triplet electrons (triplet-DNP) can improve the sensitivity of nuclear magnetic resonance at room temperature, it has not been carried out in water. Here, we report the first example of triplet-DNP in water by downsizing the conventional bulk crystals to nanocrystals.. |
| 47. | Keisuke Okumura, Nobuhiro Yanai, Nobuo Kimizuka, Visible-to-UV photon upconversion sensitized by lead halide perovskite nanocrystals, Chemistry Letters, 10.1246/cl.190473, 48, 11, 1347-1350, 2019.01, Visible-to-UV photon upconversion based on triplet-triplet annihilation (TTA-UC) sensitized by lead halide perovskite nanocrystals is demonstrated for the first time. The surface modification of nanocrystals with energy transmitter ligands plays a key role in the effective triplet sensitization, resulting in high TTA-UC efficiency over 4%. This work proves the promising potential of perovskite nanocrystals as a versatile, next-generation triplet sensitizer.. |
| 48. | Ah-Young Jee, Nobuhiro Yanai, and Steve Granick*, Comparing Geometry and Chemistry When Confined Molecules Diffuse in Monodisperse Metal-Organic Framework Pores, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 10.1021/acs.jpclett.8b02810, 9, 22, 6399-6403, 2018.11. |
| 49. | Saiya Fujiwara, Masanori Hosoyamada, Kenichiro Tateishi,* Tomohiro Uesaka, Keiko Ideta, Nobuo Kimizuka,* and Nobuhiro Yanai*, Dynamic Nuclear Polarization of Metal-Organic Frameworks Using Photoexcited Triplet Electrons, Journal of the American Chemical Society, 10.1021/jacs.8b10121, 140, 46, 15606-15610, 2018.11, 原子が持つ微小な磁石である核スピンの振る舞いを電磁波の吸収・放出から観測することで、分子の構造や運動性を非破壊的に分析することができます。この技術は、化学の分野では核磁気共鳴（NMR）分光法、医療の現場では磁気共鳴画像法（MRI）として欠かせないツールとなっています。しかし、これらの感度は他の分析法と比較すると非常に低く、例えばMRIでは主に生体内に膨大に存在する水分子の1H核の画像化に限定されています。 感度が低い原因は核スピンの低い偏極率ですが、その偏極率を向上させる技術が動的核偏極（Dynamic Nuclear Polarization; DNP）法です。中でも、特定の分子（偏極源）を光励起し、三重項電子に出現する大きな偏極を核の偏極へと移行するTriplet-DNP法は、核スピンの偏極率を室温で大幅に向上できるため近年注目を集めています。しかし従来のTriplet-DNP法は、高感度化したい生体分子を取り込むことが難しい有機結晶、もしくは室温で偏極を蓄積することが難しいガラス中でのみ行われており、高感度MRIへの応用は制限されていました。 今回、室温における生体分子の高感度MRI観測に繋がるナノ多孔性材料の核偏極化を行いました。多孔性材料として近年注目を集める多孔性金属錯体（MOF）を用い、Triplet-DNPによってMOF骨格の1H核を室温で高偏極化することに成功しました。偏極が保たれる時間を長くするため部分的に重水素化を施したMOFに新たに設計した偏極源（ペンタセン誘導体）を導入し、得られた複合体に対して光照射による電子スピンの偏極の生成とマイクロ波照射による1H核への偏極移行を行いました。このTriplet-DNP処理後に複合体のNMR信号強度に明確な増強が見られ、MOF骨格の1H核が約50倍高偏極化されたことが確認されました。 MOFは構成分子や金属イオンの種類によって容易に細孔サイズや表面特性を制御可能であるため、本研究で初めて実証されたTriplet-DNPによるMOFの高偏極化は、今後様々な生体分子を細孔内で高偏極化し、高感度MRI観測を可能にするシステムの開拓へと繋がることが期待されます。. |
| 50. | Pankaj Bharmoria, Shota Hisamitsu, Hisanori Nagatomi, Taku Ogawa, Masa-aki Morikawa, Nobuhiro Yanai,* and Nobuo Kimizuka*, Simple and Versatile Platform for Air-Tolerant Photon Upconverting Hydrogels by Biopolymer-Surfactant-Chromophore Co-assembly, Journal of the American Chemical Society, 10.1021/jacs.8b05821, 140, 34, 10848-10855, 2018.08, 生体高分子と界面活性剤の複合体マトリックス中に色素分子を高濃度に分散することで空気中においてアップコンバージョンを示すヒドロゲルを合成することに成功した。複雑な合成を必要とせず、複合体の構造を制御することで容易に空気中で高効率なフォトン・アップコンバージョンを得ることが出来る。. |
| 51. | Biplab Joarder, Nobuhiro Yanai, Nobuo Kimizuka, Solid-State Photon Upconversion Materials Structural Integrity and Triplet-Singlet Dual Energy Migration, Journal of Physical Chemistry Letters, 10.1021/acs.jpclett.8b02172, 9, 16, 4613-4624, 2018.08, Triplet-triplet annihilation-based photon upconversion (TTA-UC) is a process wherein longer-wavelength light (lower-energy photons) is converted into shorter-wavelength light (higher-energy photons) under low excitation intensity in multichromophore systems. There have been many reports on highly efficient TTA-UC in solution; however, significant challenges remain in the development of solid-state upconverters in order to explore real-world applications. In this Perspective, we discuss the advantages and challenges of different approaches for TTA-UC in solvent-free solid systems. We consider that the energy migration-based TTA-UC has the potential to achieve ideal materials with high UC efficiency at weak solar irradiance. While the UC performance of such systems is still limited at this moment, we introduce recently developed important concepts to improve it, including kinetic/thermodynamic donor dispersion in acceptor assemblies, defectless crystals, and triplet-singlet dual energy migration. Future integration of these concepts into a single material would realize the ideal TTA-UC system.. |
| 52. | Taku Ogawa, Masanori Hosoyamada, Brett Yurash, Thus-Quyen Nguyen,* Nobuhiro Yanai,* and Nobuo Kimizuka*, Donor-Acceptor-Collector Ternary Crystalline Films for Efficient Solid-State Photon Upconversion, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 10.1021/jacs.8b04542, 140, 28, 8788-8796, 2018.07, 高効率なフォトン・アップコンバージョンを得るうえで、発光体（アクセプター）から増感剤（ドナー）への逆エネルギー移動をいかに阻害するか、ということが重要な課題であった。本研究においてドナー、アクセプターに加えて第三成分として高い蛍光量子収率を示すコレクターを導入することにより、コレクターからドナーへの逆エネルギー移動を抑制し、高効率なフォトン・アップコンバージョン材料を得ることに成功した。. |
| 53. | A. Monguzzi, M. Ballabio, N. Yanai, N. Kimizuka, D. Fazzi, M. Campione, F. Meinardi, Correction to Highly fluorescent metal-organic-framework nanocomposites for photonic applications (Nano Letters (2018) 18:1 (528-534) DOI: 10.1021/acs.nanolett.7b04536), Nano Letters, 10.1021/acs.nanolett.8b01871, 18, 6, 2018.06, On page 531, column 2, there is a typo in eq 2. The correct exponent for the term between parentheses is-6 not6.. |
| 54. | Masanori Hosoyamada, Nobuhiro Yanai, Keisuke Okumura, Takayuki Uchihashi, and Nobuo Kimizuka, Translating MOF chemistry into supramolecular chemistry: soluble coordination nanofibers showing efficient photon upconversion, Chem. Commun., 10.1039/C8CC01594E, 2018.04, [URL]. |
| 55. | Taku Ogawa, Nobuhiro Yanai, Saiya Fujiwara, Thus-Quyen Thai Nguyen, and Nobuo Kimizuka, Aggregation-free Sensitizer Dispersion in Rigid Ionic Crystals for Efficient Solid-State Photon Upconversion and Demonstration of Defect Effects, J. Mater. Chem. C, 6, 5609-5615, 2018.04, [URL]. |
| 56. | Marleen Haring, Alex Abramov, Keisuke Okumura, Indrajit Ghosh, Burkhard Konig, Nobuhiro Yanai, Nobuo Kimizuka, and David Diaz Diaz, Air-sensitive Photoredox Catalysis Performed under Aerobic Conditions in Gel Networks, J. Org. Chem., 10.1021/acs.joc.8b00797, 2018.04, [URL]. |
| 57. | Taku Ogawa, Nobuhiro Yanai, Hironori Kouno, Nobuo Kimizuka, Kinetically controlled crystal growth approach to enhance triplet energy migration-based photon upconversion, Journal of Photonics for Energy, 10.1117/1.JPE.8.022003, 8, 2, 2018.04, Improving efficiency of triplet-triplet annihilation-based photon upconversion (TTA-UC) in crystalline media is challenging because it usually suffers from the severe aggregation of the donor (sensitizer) molecules in acceptor (emitter) crystals. We show a kinetically controlled crystal growth approach to improve donor dispersibility in acceptor crystals. As the donor-acceptor combination, a benchmark pair of platinum(II) octaethylporphyrin (PtOEP) and 9,10-diphenylanthracene (DPA) is employed. A surfactant-assisted reprecipitation technique is employed, where the concentration of the injected PtOEP-DPA solution holds the key to control dispersibility; at a higher PtOEP-DPA concentration, a rapid crystal growth results in better dispersibility of PtOEP molecules in DPA crystals. The improvement of donor dispersibility significantly enhances the TTA-UC quantum yield. Thus, the inherent function of donor-doped acceptor crystals can be maximized by controlling the crystallization kinetics.. |
| 58. | Kazuma Mase, Yoichi Sasaki, Yoshimitsu Sagara, Nobuyuki Tamaoki, Christoph Weder, Nobuhiro Yanai, Nobuo Kimizuka, Stimuli-Responsive Dual-Color Photon Upconversion A Singlet-to-Triplet Absorption Sensitizer in a Soft Luminescent Cyclophane, Angewandte Chemie - International Edition, 10.1002/anie.201712644, 57, 11, 2806-2810, 2018.03, Reversible emission color switching of triplet–triplet annihilation-based photon upconversion (TTA-UC) is achieved by employing an Os complex sensitizer with singlet-to-triplet (S-T) absorption and an asymmetric luminescent cyclophane with switchable emission characteristics. The cyclophane contains the 9,10-bis(phenylethynyl)anthracene unit as an emitter and can assemble into two different structures, a stable crystalline phase and a metastable supercooled nematic phase. The two structures exhibit green and yellow fluorescence, respectively, and can be accessed by distinct heating/cooling sequences. The hybridization of the cyclophane with the Os complex allows near-infrared-to-visible TTA-UC. The large anti-Stokes shift is possible by the direct S-T excitation, which dispenses with the use of a conventional sequence of singlet–singlet absorption and intersystem crossing. The TTA-UC emission color is successfully switched between green and yellow by thermal stimulation.. |
| 59. | Kazuma Mase, Yoichi Sasaki, Yoshimitsu Sagara, Nobuyuki Tamaoki, Christoph Weder, Nobuhiro Yanai, and Nobuo Kimizuka, Stimuli-Responsive Dual-color Photon Upconversion: an S-T Absorption Sensitizer in a Soft Luminescent Cyclophane, Angew. Chem. Int. Ed. , 57, 2806-2810, 2018.02, [URL], 近年、三重項-三重項消滅に基づくフォトン・アップコンバージョン (TTA-UC) の新たな展開として、外部刺激による発光スイッチングが注目されている。しかし、これまでの研究報告例は発光のON/OFFスイッチングに限られており、UC発光色を可逆的に変化させた例は無かった。UC発光色のスイッチングが容易でない理由として、次の二点があげられる。まず、外部刺激によって相互に変換可能な二種類の秩序構造を分子が形成でき、それぞれの秩序構造内で三重項エネルギー拡散が起きる必要がある点、次に秩序構造変化に伴い発光が長波長シフトしても、励起波長とUC発光波長の差 (アンチストークスシフト) が十分に確保できる点である。この二点を満たす系の構築を目指し、室温で二種類の秩序構造を示すシクロファン1を、三重項増感剤として基底一重項から励起三重項への直接S-T吸収が可能なOs錯体と融合させた。 シクロファン 1 は、結晶相 (G-form：緑色発光) と、高温で現れるネマチック相を急冷することで得られる過冷却ネマチック相 (Y-form：黄色発光)をそれぞれ室温で形成し、熱刺激により相互に変換することができる。そこで、項間交差によるエネルギー損失のないS-T吸収を示すOs錯体を用いて1の三重項励起状態を増感することで、G-formだけでなく、より長波長領域に発光を示すY-formにおいてもTTA-UC発光を観測することに成功した。すなわち、UC発光色を熱刺激により可逆的にスイッチングすることに初めて成功した。. |
| 60. | Shogo Amemori, Rakesh Kumar Gupta, Marcus Leo Bohm, James Xiao, Uyen Huynh, Tomoki Oyama, Kenji Kaneko, Akshay Rao, Nobuhiro Yanai, and Nobuo Kimizuka, Hybridizing semiconductor nanocrystals with metal-organic frameworks for visible and near-infrared photon upconversion, Dalton Trans., 10.1039/C7DT04794K, 2018.02, [URL]. |
| 61. | Hisanori Nagatomi, Nobuhiro Yanai, Teppei Yamada, Kanji Shiraishi, Nobuo Kimizuka, Synthesis and Electric Properties of a Two-Dimensional Metal-Organic Framework Based on Phthalocyanine, Chemistry - A European Journal, 10.1002/chem.201705530, 24, 8, 1806-1810, 2018.02, Complexation of copper(II) 2,3,9,10,16,17,23,24-octahydroxy-29H,31H-phthalocyanine (CuPcOH) with copper(II) ions gives a two-dimensional (2D) metal-organic framework (MOF). This is the first report of a phthalocyanine-based MOF. This 2D MOF was obtained as a black powder and showed an electrical conductivity of 1.6×10−6 S cm−1 at 80 °C. When this MOF is used as a cathode of lithium ion battery (LIB), large charge/discharge capacities of 151/128 mAh g−1 were obtained. In addition, it showed a good stability during 200 charge/discharge cycles. The obtained LIB performance mainly originates from the electrically conductive and redox-active framework of the phthalocyanine-based 2D MOF and its hierarchical microporous/mesoporous structure.. |
| 62. | Shota Hisamitsu, Nobuhiro Yanai, Hironori Kouno, Eisuke Magome, Masaya Matsuki, Teppei Yamada, Angelo Monguzzi, Nobuo Kimizuka, Two-dimensional structural ordering in a chromophoric ionic liquid for triplet energy migration-based photon upconversion, Physical Chemistry Chemical Physics, 10.1039/c7cp06266d, 20, 5, 3233-3240, 2018.02, A novel chromophoric ionic liquid (IL) with two-dimensional (2D) nanostructural order is developed, and its structure-property relationship is investigated by harnessing photon upconversion based on triplet energy migration. An ion pair of 9,10-diphenylanthracene-2-sulphonate (DPAS) and asymmetric quaternary phosphonium ion exhibited both ionic crystal (IC) and supercooled IL phases at room temperature. Single crystal X-ray analysis of the IC phase showed an alternate alignment of polar (ionic) and non-polar (non-ionic) layers, and this layered structure was basically maintained even in the IL phase. The diffusion length of triplet excitons in the IL phase, obtained by the analysis of upconverted emission in succession to triplet-triplet annihilation (TTA), is larger than the domain size estimated from powder X-ray analysis. This suggests that triplet excitons in chromophoric ILs can diffuse over the nanostructured domains.. |
| 63. | Daisuke Kichise, Kazuma Mase, Shigenori Fujikawa, Nobuhiro Yanai, and Nobuo Kimizuka, Specific Uniaxial Self-assembly of Columnar Perylene Liquid Crystals in Au Nanofin Arrays, Chem. Lett., 47, 354-357, 2018.01, [URL]. |
| 64. | Hisanori Nagatomi, Nobuhiro Yanai, Teppei Yamada, Kanji Shiraishi, and Nobuo Kimizuka, Synthesis and Electric Properties of a Two-Dimensional Metal-Organic Framework based on Phthalocyanine, Chem.-Eur. J., 24, 1806-1810, 2018.01, [URL]. |
| 65. | Daisuke Kichise, Kazuma Mase, Shigenori Fujikawa, Nobuhiro Yanai, and Nobuo Kimizuka, Specific Uniaxial Self-assembly of Columnar Perylene Liquid Crystals in Au Nanofin Arrays, Chem. Lett., 47, 354-357, 2018.01, [URL]. |
| 66. | Taku Ogawa, Nobuhiro Yanai, Saiya Fujiwara, Thuc Quyen Nguyen, Nobuo Kimizuka, Aggregation-free sensitizer dispersion in rigid ionic crystals for efficient solid-state photon upconversion and demonstration of defect effects, Journal of Materials Chemistry C, 10.1039/c8tc00977e, 6, 21, 5609-5615, 2018.01, Solid-state photon upconversion based on triplet-triplet annihilation (TTA-UC) has attracted much interest because of its potential to circumvent the loss of sub-bandgap photons in photovoltaic cells. There are two important long-standing questions for TTA-UC in solid crystals. Why is the UC efficiency often low in crystalline systems? What is the rational strategy to construct efficient upconverting crystals? In this work, these issues are addressed by employing a simple model system where ionic interactions play a key role. When crystals of an anthracene-based ionic acceptor (emitter) are grown in the presence of anionic donor (sensitizer) molecules, the donor molecules are spontaneously taken up and dispersed homogeneously in acceptor crystals without aggregation. Highly efficient UC is achieved as a consequence of quantitative triplet energy transfer (TET) from the incorporated donor to the surrounding acceptor. It is found that the mechanical grinding of the donor-doped single crystals leads to a significant decrease in UC efficiency, suggesting that trap sites formed in the crystals have a significant negative impact on the UC performance. The important fundamental knowledge obtained from the current ionic crystal system offers rational design guidelines towards the development of efficient TTA-UC systems in the solid-state.. |
| 67. | A. Monguzzi, M. Ballabio, N. Yanai, N. Kimizuka, D. Fazzi, M. Campione, F. Meinardi, Highly Fluorescent Metal-Organic-Framework Nanocomposites for Photonic Applications, Nano Letters, 10.1021/acs.nanolett.7b04536, 18, 1, 528-534, 2018.01, Metal-organic frameworks (MOFs) are porous hybrid materials built up from organic ligands coordinated to metal ions or clusters by means of self-assembly strategies. The peculiarity of these materials is the possibility, according to specific synthetic routes, to manipulate both the composition and ligands arrangement in order to control their optical and energy-transport properties. Therefore, optimized MOFs nanocrystals (nano-MOFs) can potentially represent the next generation of luminescent materials with features similar to those of their inorganic predecessors, that is, the colloidal semiconductor quantum dots. The luminescence of fluorescent nano-MOFs is generated through the radiative recombination of ligand molecular excitons. The uniqueness of these nanocrystals is the possibility to pack the ligand chromophores close enough to allow a fast exciton diffusion but sufficiently far from each other preventing the aggregation-induced effects of the organic crystals. In particular, the formation of strongly coupled dimers or excimers is avoided, thus preserving the optical features of the isolated molecule. However, nano-MOFs have a very small fluorescence quantum yield (QY). In order to overcome this limitation and achieve highly emitting systems, we analyzed the fluorescence process in blue emitting nano-MOFs and modeled the diffusion and quenching mechanism of photogenerated singlet excitons. Our results demonstrate that the excitons quenching in nano-MOFs is mainly due to the presence of surface-located, nonradiative recombination centers. In analogy with their inorganic counterparts, we found that the passivation of the nano-MOF surfaces is a straightforward method to enhance the emission efficiency. By embedding the nanocrystals in an inert polymeric host, we observed a +200% increment of the fluorescence QY, thus recovering the emission properties of the isolated ligand in solution.. |
| 68. | Shogo Amemori, Rakesh Kumar Gupta, Marcus Leo Böhm, James Xiao, Uyen Huynh, Tomoki Oyama, Kenji Kaneko, Akshay Rao, Nobuhiro Yanai, Nobuo Kimizuka, Hybridizing semiconductor nanocrystals with metal-organic frameworks for visible and near-infrared photon upconversion, Dalton Transactions, 10.1039/c7dt04794k, 47, 26, 8590-8594, 2018.01, Hybrid materials consisting of semiconductor nanocrystals and metal-organic frameworks (MOFs) were prepared for the first time to achieve photon upconversion based on triplet-triplet annihilation (TTA-UC) in the solid-state, which allowed TTA-UC with large anti-Stokes shifts in the visible and near-infrared regions.. |
| 69. | Hisanori Nagatomi, Nobuhiro Yanai, Nobuo Kimizuka, Reentrant Gel-Sol-Gel transition of a lipophilic Co(II) coordination polymer, Chemistry Letters, 10.1246/cl.170881, 47, 1, 97-99, 2018.01, A reentrant gel-sol-gel phase transition in organic media is achieved for a single-component, thermoresponsive Co(II)-based coordination polymer bridged by suitably designed lipophilic 1,2,4-triazole ligands. Its green chloroform solution at room temperature turns into a blue gel upon heating, whereas it is transformed to a yellow gel by cooling. These unique thermal phase transitions are reversible and occur all by themselves, which originate from the simultaneous pursuit of entropy-driven changes in coordination structures and enthalpydriven interactions between the coordination polymers.. |
| 70. | Daisuke Kichise, Kazuma Mase, Shigenori Fujikawa, Nobuhiro Yanai, Nobuo Kimizuka, Specific uniaxial self-assembly of columnar perylene liquid crystals in au nanofin arrays, Chemistry Letters, 10.1246/cl.171228, 47, 3, 354-357, 2018.01, Self-assembly of liquid crystalline tetrakis(2-ethylhexyl) perylene-3,4,9,10-tetracarboxylate (C8PTC) in periodically aligned Au nanofin arrays (Au-NFs) is investigated. C8PTC forms columnar hexagonal liquid crystalline assemblies oriented parallel to the glass substrate, while the in-plane orientation of the long columnar axis is perpendicular to the surface of Au- NFs. This unique alignment reflects the interaction between the aromatic π-surface and the bare gold surface of NFs. This work provides a new perspective to design and control molecular selfassembly confined in the designed surface nanopatterns.. |
| 71. | Masanori Hosoyamada, Nobuhiro Yanai, Keisuke Okumura, Takayuki Uchihashi, Nobuo Kimizuka, Translating MOF chemistry into supramolecular chemistry Soluble coordination nanofibers showing efficient photon upconversion, Chemical Communications, 10.1039/c8cc01594e, 54, 50, 6828-6831, 2018.01, A method for synthesizing coordination nanofibers by extracting the structural motifs of metal-organic frameworks (MOFs) is demonstrated. In these soluble nanofibers, multiple chromophores with largely different sizes and shapes can be arranged at desired compositions, and excited triplet energy migrates among the densely assembled chromophore arrays, showing an efficient photon upconversion even at very low concentration.. |
| 72. | Angelo Monguzzi, Marco Ballabio, Nobuhiro Yanai, Nobuo Kimizuka, Daniele Fazzi, Marcello Campione, and Francesco Meinardi, Highly Fluorescent Metal-Organic-Framework Nanocomposites for Photonic Applications, Nano Lett., 18, 528-534, 2017.12, [URL]. |
| 73. | aku Ogawa, Nobuhiro Yanai, Hironori Kouno, and Nobuo Kimizuka, Kinetically controlled crystal growth approach to enhance triplet energy migration-based photon upconversion, J. Photon. Energy, 8, 022003, 2017.11, [URL]. |
| 74. | Hisanori Nagatomi, Nobuhiro Yanai and Nobuo Kimizuka, Reentrant Gel-Sol-Gel Transition of a Lipophilic Co(II) Coordination Polymer, Chem. Lett., 47, 97-99, 2017.11, [URL]. |
| 75. | Shota Hisamitsu, Nobuhiro Yanai, Hironori Kouno, Eisuke Magome, Masaya Matsuki, Teppei Yamada, Angelo Monguzzi, and Nobuo Kimizuka, Two-dimensional structural ordering in a chromophoric ionic liquid for triplet energy migration-based photon upconversion, Phys. Chem. Chem. Phys., 20, 3233-3240, 2017.11, [URL]. |
| 76. | Nobuhiro Yanai, Nobuo Kimizuka, New Triplet Sensitization Routes for Photon Upconversion Thermally Activated Delayed Fluorescence Molecules, Inorganic Nanocrystals, and Singlet-to-Triplet Absorption, Accounts of Chemical Research, 10.1021/acs.accounts.7b00235, 50, 10, 2487-2495, 2017.10, ConspectusPhoton upconversion based on triplet-triplet annihilation (TTA-UC) has attracted much interest because of its possible applications to renewable energy production and biological fields. In particular, the UC of near-infrared (NIR) light to visible (vis) light is imperative to overcome the Shockley-Queisser limit of single-junction photovoltaic cells, and the efficiency of photocatalytic hydrogen production from water can also be improved with the aid of vis-to-ultraviolet (UV) UC. However, both processes have met limitations in the wavelength range, efficiency, and sensitivity for weak incident light.This Account describes recent breakthroughs that solve these major problems, new triplet sensitization routes to significantly enlarge the range of conversion wavelength by minimizing the energy loss during intersystem crossing (ISC) of triplet sensitizers or bypassing the ISC process. The photochemical processes of TTA-UC in general start with the absorption of longer wavelength incident light by triplet sensitizers, which generate the triplet states via ISC. This ISC inevitably accompanies the energy loss of hundreds of millielectronvolts, which significantly limits the TTA-UC with large anti-Stokes shifts.The small S1-T1 gap of molecules showing thermally activated delayed fluorescence (TADF) allows the sensitization of emitters with the highest T1 and S1 energy levels ever employed in TTA-UC, which results in efficient vis-to-UV UC. As alternatives to molecular sensitizers in the NIR region, inorganic nanocrystals with broad NIR absorption bands have recently been shown to work as effective sensitizers for NIR-to-vis TTA-UC. Their small exchange splitting minimizes the energy loss during triplet sensitization. The modification of nanocrystal surfaces with organic acceptors via coordination bonds allows efficient energy transfer between the components and succeeding TTA processes.To remove restrictions on the energy loss during ISC, molecules with direct singlet-to-triplet (S-T) excitation are employed as triplet sensitizers. Although the S-T absorption is spin forbidden, large spin-orbital coupling occurs for appropriately designed metal complexes, which allow S-T absorption in the NIR region with large absorption coefficients. While the triplet lifetime of such S-T absorption sensitizers is often short (less than microsecond), the integration of the molecular sensitizers with emitter assemblies allows facile Dexter energy transfer to the surrounding emitter molecules, leading to efficient NIR-to-vis UC emission through triplet energy migration (TEM) in the condensed state. By judicious modification of the chromophore structures, the first example of NIR-to-blue UC has also been achieved.It is essential to combine these new triplet sensitization routes with an upconverted energy collection (UPCON) approach in molecular assemblies to effectively populate emitter triplets and to overcome remaining issues including back energy transfer. We propose two overall materials designs for the TEM-UPCON strategy, core-shell-shell structures and trilayer structures composed of triplet donor, acceptor, and energy collector. The fusion between triplet science and chemistry of self-assembly would overcome previous difficulties of NIR-to-vis and vis-to-UV TTA-UC toward real-world applications ranging from energy to biology.. |
| 77. | Nobuhiro Yanai and Nobuo Kimizuka, New Triplet Sensitization Routes for Photon Upconversion: Thermally Activated Delayed Fluorescence Molecules, Inorganic Nanocrystals, and Singlet-to-Triplet Absorption, Acc. Chem. Res., 50, 2487-2495, 2017.09, [URL]. |
| 78. | Keisuke Okumura, Masaya Matsuki, Teppei Yamada, Nobuhiro Yanai and Nobuo Kimizuka, Sensitizer-Free Photon Upconversion in Single-Component Brominated Aromatic Crystals, ChemistrySelect, 2, 7597-7601, 2017.08, [URL]. |
| 79. | Kazuma Mase, Keisuke Okumura, Nobuhiro Yanai and Nobuo Kimizuka, Triplet Sensitization by Perovskite Nanocrystals for Photon Upconversion, Chem. Commun., 10.1039/C7CC03087H, 53, 8261-8264, 2017.06, [URL], フォトン・アップコンバージョンの課題の一つに、三重項増感剤の系間交差によるエネルギーロスが原因でアンチストークスシフトの幅が狭まってしまうという問題があった。そこで鉛ハライドペロブスカイトを三重項増感剤として利用し、太陽光程度の非常に低強度の励起光でフォトン・アップコンバージョンを達成することに成功した。中でも、ペロブスカイトの表面に有機分子を修飾することが三重項エネルギー移動に非常に重要であるという基本的な設計指針を見出すことが出来た。. |
| 80. | Yoichi Sasaki, Shogo Amemori, Nobuhiro Yanai, Nobuo Kimizuka, Hironori Kouno, Near infrared-to-blue photon upconversion by exploiting direct S-T absorption of a molecular sensitizer, J. Mater. Chem. C, 10.1039/C7TC00827A, 2017.05, [URL]. |
| 81. | Pengfei Duan, Deepak Asthana, Takuya Nakashima, Tsuyoshi Kawai, Nobuhiro Yanai, Nobuo Kimizuka, All-or-none switching of photon upconversion in self-assembled organogel systems, Faraday Discussions, 10.1039/c6fd00170j, 196, 305-316, 2017.01, Aggregation-induced photon upconversion (iPUC) based on a triplet-triplet annihilation (TTA) process is successfully developed via controlled self-assembly of donor-acceptor pairs in organogel nanoassemblies. Although segregation of donor from acceptor assemblies has been an outstanding problem in TTA-based UC and iPUC, we resolved this issue by modifying both the triplet donor and aggregation induced emission (AIE)-type acceptor with glutamate-based self-assembling moieties. These donors and acceptors co-assemble to form organogels without segregation. Interestingly, these donor-acceptor binary gels show upconversion at room temperature but the upconversion phenomena were lost upon dissolution of the gels on heating. The observed changes in TTA-UC emission were thermally reversible, reflecting the controlled assembly/disassembly of the binary molecular systems. The observed on/off ratio of UC emission was much higher than that of the aggregation-induced fluorescence of the acceptor, which highlights the important role of iPUC, i.e., multi-exciton TTA for photoluminescence switching. This work bridges iPUC and supramolecular chemistry and provides a new strategy for designing stimuli-responsive upconversion systems.. |
| 82. | Yoichi Sasaki, Shogo Amemori, Hironori Kouno, Nobuhiro Yanai, Nobuo Kimizuka, Near infrared-to-blue photon upconversion by exploiting direct S-T absorption of a molecular sensitizer, Journal of Materials Chemistry C, 10.1039/c7tc00827a, 5, 21, 5063-5067, 2017.01, Triplet-triplet annihilation-based photon upconversion (TTA-UC) from NIR to blue light remains a great challenge. Here, we employ a direct singlet-to-triplet (S-T) excitation to circumvent an energy loss associated with the intersystem crossing (ISC) of triplet sensitizers. The TTA-UC based on the S-T absorption (STUC) allowed an efficient NIR (λ = 724 nm)-to-blue (λ = 462 nm) upconversion with a large anti-Stokes shift of 0.97 eV.. |
| 83. | Keisuke Okumura, Masaya Matsuki, Teppei Yamada, Nobuhiro Yanai, Nobuo Kimizuka, Sensitizer-Free Photon Upconversion in Single-Component Brominated Aromatic Crystals, ChemistrySelect, 10.1002/slct.201701769, 2, 25, 7597-7601, 2017.01, A new methodology of single-component photon upconversion (UC) based on S0-to-T1 (S−T) absorption is demonstrated. Although the S−T absorption is spin-forbidden, modification of anthracene chromophores with heavy bromine atoms allows the direct population of the excited triplets in crystals upon near-infrared (NIR) excitation with incident light intensities of ∼W cm−2. The consequent triplet energy migration (TEM) and triplet-triplet annihilation (TTA) events in crystals lead to blue UC emission with a large anti-Stokes shift over 0.9 eV. The generality of the S−T absorption-based UC is further confirmed with crystals of brominated perylene-derivatives that show a green UC emission under a longer-wavelength NIR excitation (λex=856 nm). The single-component UC with large anti-Stokes shifts observed for brominated aromatic crystals compensates for the shortcomings of conventional two-component solid UC system, i. e., energy losses intrinsic to the intersystem crossing of the sensitizers and the triplet energy transfer from sensitizer to emitter. It offers a simple and complementary UC methodology to the conventional two-photon absorption (TPA) and TTA-UC.. |
| 84. | Kazuma Mase, Keisuke Okumura, Nobuhiro Yanai, Nobuo Kimizuka, Triplet sensitization by perovskite nanocrystals for photon upconversion, Chemical Communications, 10.1039/c7cc03087h, 53, 59, 8261-8264, 2017.01, The potential of three-dimensional (3D) metal-halide perovskites to sensitize organic triplets is unveiled. Nanocrystals of surface-modified inorganic cesium lead halide perovskites (CsPbX3, X = Br/I) are found to work as efficient triplet sensitizers for photon upconversion based on triplet-triplet annihilation (TTA-UC) at low excitation intensity.. |
| 85. | DUAN PENGFEI, Deepak Asthana, Takuya Nakashima, Tsuyoshi Kawai, Nobuhiro Yanai, Nobuo Kimizuka, All-or-None Switching of Photon Upconversion in Self-Assembled Organogel Systems, Faraday Discussions, 10.1039/C6FD00170J, 196, 305-316, 2016.07, [URL]. |
| 86. | Shogo Amemori, Yoichi Sasaki, Nobuhiro Yanai, Nobuo Kimizuka, Near Infrared-to-Visible Photon Upconversion Sensitized by a Metal Complex with Spin-Forbidden yet Strong S0-T1 Absorption, J. Am. Chem. Soc., 10.1021/jacs.6b04692, 138, 8702-8705, 2016.06, [URL]. |
| 87. | Hironori Kouno, Taku Ogawa, Shogo Amemori, Prasenjit Mahato, Nobuhiro Yanai, Nobuo Kimizuka, Triplet energy migration-based photon upconversion by amphiphilic molecular assemblies in aerated water, Chem. Sci., 10.1039/C6SC01047D, 2016.04, [URL]. |
| 88. | Keisuke Okumura, Kazuma Mase, Nobuhiro Yanai, Nobuo Kimizuka, Employing Core-Shell Quantum Dots as Triplet Sensitizer for Photon Upconversion, Chem.-Eur. J., 10.1002/chem.20160998, 2016.04, [URL]. |
| 89. | Nobuhiro Yanai, Mariko Kozue, Shogo Amemori, Kabe Ryota, CHIHAYA ADACHI, Nobuo Kimizuka, Increased Vis-to-UV upconversion performance by energy level matching between a TADF donor and high triplet energy acceptors, J. Mater. Chem. C, 10.1039/C6TC01816E, 4, 6447-6451, 2016.04, [URL]. |
| 90. | Nobuhiro Yanai, Nobuo Kimizuka, Recent emergence of photon upconversion based on triplet energy migration in molecular assemblies, Chem. Commun., 22, 2060-2067, 2016.03, [URL]. |
| 91. | Nobuhiro Yanai, Nobuo Kimizuka, Masa-aki Morikawa, Photon Upconversion and Molecular Solar Energy Storage by Maximizing the Potential of Molecular Self-Assembly, Langmuir, 10.1021/acs.langmuir.6b03363, 32, 12304-12322, 2016.03, [URL]. |
| 92. | Masanori Hosoyamada, Nobuhiro Yanai, Taku Ogawa, Nobuo Kimizuka, Molecularly Dispersed Donors in Acceptor Molecular Crystals for Photon Upconversion under Low Excitation Intensity, Chemistry - A European Journal, 10.1002/chem.201503318, 22, 6, 2060-2067, 2016.02, For real-world applications of photon upconversion based on the triplet-triplet annihilation (TTA-UC), it is imperative to develop solid-state TTA-UC systems that work effectively under low excitation power comparable to solar irradiance. As an approach in this direction, aromatic crystals showing high triplet diffusivity are expected to serve as a useful platform. However, donor molecules inevitably tend to segregate from the host acceptor crystals, and this inhomogeneity results in the disappointing performance of crystalline state TTA-UC. In this work, a series of cast-film-forming acceptors was developed, which provide both regular acceptor alignment and soft domains of alkyl chains that accommodate donor molecules without segregation. A typical triplet sensitizer, PtII octaethylporphyrin (PtOEP), was dispersed in these acceptor crystals without aggregation. As a result, efficient triplet energy transfer from the donor to the acceptor and diffusion of triplet excitons among regularly aligned anthracene chromophores occurred. It resulted in TTA-UC emission at low excitation intensities, comparable to solar irradiance. Overcoming donor aggregation: A long-standing problem of aromatic-crystal-based photon upconversion (UC), donor aggregation in the acceptor crystal, is solved herein by modifying the acceptor with multiple alkyl chains. This improved the donor-to-acceptor energy-transfer efficiency, leading to effective UC processes even at low excitation intensities comparable to solar irradiance (see figure).. |
| 93. | Masanori Hosoyamada, Nobuhiro Yanai, Nobuo Kimizuka, Molecularly Dispersed Donors in Acceptor Molecular Crystals for Photon Upconversion under Low Excitation Intensity, Chem.-Eur. J., 22, 2060-2067, 2016.01. |
| 94. | Keisuke Okumura, Kazuma Mase, Nobuhiro Yanai, Nobuo Kimizuka, Employing Core-Shell Quantum Dots as Triplet Sensitizers for Photon Upconversion, Chemistry - A European Journal, 10.1002/chem.201600998, 22, 23, 7721-7726, 2016.01, A new family of surface-functionalized CdSe/ZnS core-shell quantum dots (csQD) has been developed, which work as triplet sensitizers for triplet-triplet annihilation-based photon upconversion (TTA-UC). The surface modification of csQD with acceptor molecules plays a key role in the efficient relay of the excited energy of csQD to emitter molecules in the bulk solution, where the generated emitter triplets undergo triplet-triplet annihilation that leads to photon upconversion. Interestingly, improved UC properties were achieved with the core-shell QDs compared with core-only CdSe QDs (cQD). The threshold excitation intensity, which is defined as the necessary irradiance to achieve efficient TTA process, decreases by more than a factor of four. Furthermore, the total UC quantum yield is enhanced more than 50-fold. These enhancements should be derived from better optical properties of csQD, in which the non-radiative surface recombination sites are passivated by the shell layer with wider bandgap.. |
| 95. | Nobuhiro Yanai, Mariko Kozue, Shogo Amemori, Ryota Kabe, Chihaya Adachi, Nobuo Kimizuka, Increased vis-to-UV upconversion performance by energy level matching between a TADF donor and high triplet energy acceptors, Journal of Materials Chemistry C, 10.1039/c6tc01816e, 4, 27, 6447-6451, 2016.01, A question at issue in triplet-triplet annihilation-based photon upconversion (TTA-UC) has been how to maximize the anti-Stokes shift, which requires minimization of the energy losses in intersystem crossing (ISC) of donors and consequent energy transfer (TTET) to acceptors. This is resolved by the energy level matching between a thermally activated delayed fluorescence (TADF) sensitizer and emitters with the highest triplet and singlet energy levels.. |
| 96. | Nobuhiro Yanai, Nobuo Kimizuka, Recent emergence of photon upconversion based on triplet energy migration in molecular assemblies, Chemical Communications, 10.1039/c6cc00089d, 52, 31, 5354-5370, 2016.01, An emerging field of triplet energy migration-based photon upconversion (TEM-UC) is reviewed. Highly efficient photon upconversion has been realized in a wide range of chromophore assemblies, such as non-solvent liquids, ionic liquids, amorphous solids, gels, supramolecular assemblies, molecular crystals, and metal-organic frameworks (MOFs). The control over their assembly structures allows for unexpected air-stability and maximum upconversion quantum yield at weak solar irradiance that has never been achieved by the conventional molecular diffusion-based mechanism. The introduction of the "self-assembly" concept offers a new perspective in photon upconversion research and triplet exciton science, which show promise for numerous applications ranging from solar energy conversion to chemical biology.. |
| 97. | Hironori Kouno, Taku Ogawa, Shogo Amemori, Prasenjit Mahato, Nobuhiro Yanai, Nobuo Kimizuka, Triplet energy migration-based photon upconversion by amphiphilic molecular assemblies in aerated water, Chemical Science, 10.1039/c6sc01047d, 7, 8, 5224-5229, 2016.01, A molecular self-assembly approach is developed to resolve an outstanding issue in triplet energy migration-based photon upconversion (TEM-UC), that is, air-stable TEM-UC in water. Amphiphilic cationic acceptor (emitter) molecules self-assemble in water via hydrophobic and hydrogen bonding interactions, with which anionic donor (sensitizer) molecules are integrated through electrostatic interactions. Triplet energy is quantitatively transferred from the excited donor to the acceptor, which is followed by effective triplet energy migration among the pre-organized acceptors. It leads to TTA and concomitant UC emission in water. The dense acceptor chromophore arrays with extended hydrogen bonding networks show efficient barrier properties against molecular oxygen, as demonstrated by the stable UC emission even in air-saturated water.. |
| 98. | Shota Hisamitsu, Nobuhiro Yanai, Nobuo Kimizuka, Photon-Upconverting Ionic Liquids Effective Triplet Energy Migration in Contiguous Ionic Chromophore Arrays, Angewandte Chemie - International Edition, 10.1002/anie.201505168, 54, 39, 11550-11554, 2015.09, Inspired by the bicontinuous ionic-network structure of ionic liquids (ILs), we developed a new family of photofunctional ILs which show efficient triplet energy migration among contiguously arrayed ionic chromophores. A novel fluorescent IL, comprising an aromatic 9,10-diphenylanthracene 2-sulfonate anion and an alkylated phosphonium cation, showed pronounced interactions between chromophores, as revealed by its spectral properties. Upon dissolving a triplet sensitizer, the IL demonstrated photon upconversion based on triplet-triplet annihilation (TTA-UC). Interestingly, the TTA-UC process in the chromophoric IL was optimized at a much lower excitation intensity compared to the previous nonionic liquid TTA-UC system. The superior TTA-UC in this IL system is characterized by a relatively high triplet diffusion constant (1.63×10-6 cm2 s-1) which is ascribed to the presence of ionic chromophore networks in the IL.. |
| 99. | Shogo Amemori, Nobuhiro Yanai, Nobuo Kimizuka, Metallonaphthalocyanines as triplet sensitizers for near-infrared photon upconversion beyond 850 nm, Physical Chemistry Chemical Physics, 17, 22557-22560, 2015.08, [URL], In triplet–triplet annihilation-based photon upconversion (TTA-UC), the utilization of near-infrared (NIR) light with a wavelength longer than 850 nm remains an outstanding issue. We realized this by employing metallonaphthalocyanines as triplet sensitizers; upon excitation of NIR light (856 nm), upconverted emission was observed in the visible range with remarkable photostability.. |
| 100. | Shota Hisamitsu, Nobuhiro Yanai, Nobuo Kimizuka, Photon-Upconverting Ionic Liquids: Effective Triplet Energy Migration in Contiguous Ionic Chromophore Arrays, Angew. Chem., Int. Ed., 54, 11550-11554, 2015.08, 低エネルギーの光を高エネルギーの光に変換する技術であるフォトン・アップコンバージョンの実用化に不可欠な、太陽光程度の弱い光で効率を最大化する有機―無機複合材料を世界で初めて開発しました。我々は既に分子組織化を利用し溶液中で高効率なアップコンバージョンに成功していましたが、そこで困難であった溶媒を含まない固体中での高効率化に今回成功しました。フォトン・アップコンバージョンは、太陽電池や人工光合成の効率を飛躍的に向上するなどの再生可能エネルギー技術への応用が期待されており、学術的のみならず産業的にも大きな波及効果をもたらす成果です。. |
| 101. | Shogo Amemori, Nobuhiro Yanai, Nobuo Kimizuka, Metallonaphthalocyanines as triplet sensitizers for near-infrared photon upconversion beyond 850 nm, Physical Chemistry Chemical Physics, 10.1039/c5cp02733k, 17, 35, 22557-22560, 2015.08, In triplet-triplet annihilation-based photon upconversion (TTA-UC), the utilization of near-infrared (NIR) light with a wavelength longer than 850 nm remains an outstanding issue. We realized this by employing metallonaphthalocyanines as triplet sensitizers; upon excitation of NIR light (856 nm), upconverted emission was observed in the visible range with remarkable photostability.. |
| 102. | Nobuhiro Yanai, Nobuo Kimizuka, Front-line polymer science Molecular self-assembly and photon upconversion, kobunshi, 64, 7, 439-443, 2015.07, Photon upconversion (UC) is the key technology to overcome the thermodynamic efficiency limits in solar energy conversion devices. Triplet-triplet annihilation (TTA)-based UC has drawn increasing attention in recent years, primarily because of its occurrence with lowintensity, noncoherent light as the excitation source. To date, efficient TTA-UC has been achieved in solution because diffusion of triplet molecules is essential for energy transfer processes. However, the use of volatile organic solvents and deactivation of triplet states by molecular oxygen significantly disturb their practical applications. Although recently the TTA-based UC has been investigated in solid polymer films, the slow molecular diffusion limits the efficiency of TTA-UC. To solve these problems, we are proposing a paradigm shift from molecular diffusion to energy migration. Assemblies of donor and acceptor display a sequence of efficient donor-to-acceptor triplet-triplet energy transfer (TTET), triplet energy migration, and TTA in the self-assembled state.. |
| 103. | Taku Ogawa, Nobuhiro Yanai, Angelo Monguzzi, Nobuo Kimizuka, Highly Efficient Photon Upconversion in Self-Assembled Light-Harvesting Molecular Systems, Scientific Reports, 5, 10882, 2015.06, [URL], エネルギーの光を高エネルギーの光に変換する技術のフォトン・アップコンバージョンの実用化に必要な、高効率で、太陽光などの弱い光でも機能し、空気中で安定である条件を満たす分子組織体を世界で初めて開発しました。 フォトン・アップコンバージョンは、これまで利用できなかった弱いエネルギーの光を利用可能にする技術であり、太陽電池や人工光合成の効率を飛躍的に向上するなどの、再生可能エネルギー技術への応用が期待されます。. |
| 104. | Pengfei Duan, Nobuhiro Yanai, Yuki Kurashige, Nobuo Kimizuka, Aggregation-induced photon upconversion through control of the triplet energy landscapes of the solution and solid states, Angewandte Chemie - International Edition, 10.1002/anie.201501449, 54, 26, 7544-7549, 2015.06, Aggregation-induced photon upconversion (iPUC) based on control of the triplet energy landscape is demonstrated for the first time. When a triplet state of a cyano-substituted 1,4-distyrylbenzene derivative is sensitized in solution, no upconverted emission based on triplet-triplet annihilation (TTA) was observed. In stark contrast, crystalline solids obtained by drying the solution revealed clear upconverted emission. Theoretical studies unveiled an underlying switching mechanism: the excited triplets in solution immediately decay back to the ground state through conformational twisting around a C-C bond and photoisomerization, whereas this deactivation path is effectively inhibited in the solid state. The finding of iPUC phenomena highlights the importance of controlling excited energy landscapes in condensed molecular systems. Affairs of state: Whereas a cyano-substituted 1,4-distyrylbenzene derivative shows no upconverted (UC) emission in solution, a clear upconverted emission is observed for solution-cast crystals (see picture). The difference is attributed to immediate decay of excited triplets through conformational twisting and isomerization being possible in solution but not in the solid state.. |
| 105. | Taku Ogawa, Nobuhiro Yanai, Angelo Monguzzi, Nobuo Kimizuka, Highly Efficient Photon Upconversion in Self-Assembled Light-Harvesting Molecular Systems, Scientific reports, 10.1038/srep10882, 5, 2015.06, To meet the world's demands on the development of sunlight-powered renewable energy production, triplet-triplet annihilation-based photon upconversion (TTA-UC) has raised great expectations. However, an ideal highly efficient, low-power, and in-air TTA-UC has not been achieved. Here, we report a novel self-assembly approach to achieve this, which enabled highly efficient TTA-UC even in the presence of oxygen. A newly developed lipophilic 9,10-diphenylanthracene-based emitter molecule functionalized with multiple hydrogen-bonding moieties spontaneously coassembled with a triplet sensitizer in organic media, showing efficient triplet sensitization and subsequent triplet energy migration among the preorganized chromophores. This supramolecular light-harvesting system shows a high UC quantum yield of 30% optimized at low excitation power in deaerated conditions. Significantly, the UC emission largely remains even in an air-saturated solution, and this approach is facilely applicable to organogel and solid-film systems.. |
| 106. | Shota Hisamitsu, Nobuhiro Yanai, Shigenri Fujikawa, Nobuo Kimizuka, Photoinduced Crystallization in Ionic Liquids: Photodimerization-induced Equilibrium Shift and Crystal Patterning, Chemistry Letters, 7, 908-910, 2015.05, [URL], An ionic liquid (IL) composed of 9–anthracene carboxylate anion and ammonium cation possessing three diethylene glycol chains shows photo–triggered dimerization of anthracence chromophores. It causes segregation and crystallization of protonated 9–anthracene carboxylic acid dimer, which is associated with the concurrent liberation of the free amine in the IL. This work provides a new molecular design for photoresponsive ILs, whose first application for site–selective photo–patterning is demonstrated.. |
| 107. | DUAN PENGFEI, Nobuhiro Yanai, Yuki Kurashige, Nobuo Kimizuka, Aggregation-Induced Photon Upconversion through Control of theTriplet Energy Landscapes of the Solution and Solid States, Angew. Chem. Int. Ed., 54, 7554-7549, 2015.05, [URL], Aggregation-induced photon upconversion (iPUC) based on control of the triplet energy landscape is demonstrated for the first time. When a triplet state of a cyano-substituted 1,4-distyrylbenzene derivative is sensitized in solution, no upconverted emission based on triplet–triplet annihilation (TTA) was observed. In stark contrast, crystalline solids obtained by drying the solution revealed clear upconverted emission. Theoretical studies unveiled an underlying switching mechanism: the excited triplets in solution immediately decay back to the ground state through conformational twisting around a C[DOUBLE BOND]C bond and photoisomerization, whereas this deactivation path is effectively inhibited in the solid state. The finding of iPUC phenomena highlights the importance of controlling excited energy landscapes in condensed molecular systems.. |
| 108. | DUAN PENGFEI, Nobuhiro Yanai, Hisanori Nagatomi, Nobuo Kimizuka, Photon Upconversion in Supramolecular Gel Matrixes: Spontaneous Accumulation of Light-Harvesting Donor-Acceptor Arrays in Nanofibers and Acquired Air Stability, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 10.1021/ja511061h, 137, 5, 1887-1894, 2015.02, [URL], 三重項―三重項消滅を利用したフォトン・アップコンバージョン（TTA-UC）はエネルギーからバイオまで幅広い分野での応用が期待されているが、励起三重項が空気中の酸素によって消光されてしまう致命的な問題を有する。今回我々は、超分子ゲルファイバー中に色素分子を高密度に自己組織化させれば、大気下においてもTTA-UCを発現できることを見いだしたので報告する(Figure 1)。超分子ゲルを形成する際にドナー、アクセプターを加えておくだけで空気中においてTTA-UCを観測できた。また、色素の種類を変えることで近赤外光から可視光、赤色光から緑色光、緑色光から青色光、可視光から紫外光への波長変換を達成した。. |
| 109. | Shota Hisamitsu, Nobuhiro Yanai, Shigenori Fujikawa, Nobuo Kimizuka, Photoinduced crystallization in ionic liquids Photodimerization-induced equilibrium shift and crystal patterning, Chemistry Letters, 10.1246/cl.150261, 44, 7, 908-910, 2015.01, An ionic liquid (IL) composed of 9-anthracenecarboxylate anion and ammonium cation possessing three diethylene glycol chains shows phototriggered dimerization of anthracence chromophores. It causes segregation and crystallization of protonated 9-anthracenecarboxylic acid dimer, which is associated with the concurrent liberation of the free amine in the IL. This work provides a new molecular design for photoresponsive ILs, whose first application for site-selective photopatterning is demonstrated.. |
| 110. | DUAN PENGFEI, Nobuhiro Yanai, Nobuo Kimizuka, A Bis-Cyclometalated Iridium Complex as a Benchmark Sensitizer for Efficient Visible-to-UV Photon Upconversion, Chem. Commun., 10.1039/c4cc05718j, 50, 13111-13113, 2014.10, [URL], 可視光から紫外光領域への三重項-三重項消滅機構によるフォトンアップコンバージョン（TTA-UC）は、光触媒の高効率化をはじめ多くの応用が期待されるが、効率の低さが問題となっている。この原因として、ドナーならびにアクセプター分子の三重項エネルギー準位を制御する方法論が確立されていないことや、低いアクセプターの発光量子収率が挙げられる。本研究ではこの領域におけるUC効率の向上を目指し、新規アクセプター分子の設計・合成を行った。 紫外域に発光を持ち、高い発光量子収率を示すアクセプターとしてスチルベン誘導体を合成し、UCを検討した。445 nmの波長で励起したところ355 nm に明確なUC発光が観測され、その効率は1.4%とこれまでで最も高い値であった。. |
| 111. | DUAN PENGFEI, Nobuhiro Yanai, Nobuo Kimizuka, Photon Upconverting Liquids : Matrix-Free Molecular Upconversion Systems Functioning in Air, J. Am. Chem. Soc., 2013, 135, 19056-19059, 10.1021/ja411316s, 135, 19056-19059, 2013.12, [URL], 低エネルギーの光を高エネルギーの光に変換する機能を有する“フォトン・アップコンバージョン”液体システムを世界で初めて開発した．従来のアップコンバージョン技術が抱えていた①空気中（酸素の存在下）で機能しない，②揮発性の有機溶媒を用いる，③短い励起寿命の間に２つの励起分子が拡散衝突する必要がある などの問題を一挙に解決するものであり，学術的にも応用的にも大きなインパクトを与える画期的な成果である．. |
| 112. | Melinda Sindoro, Nobuhiro Yanai, Ah-Young Jee, Steve Granick, Collidal-sized Metal-Organic Frameworks: Synthesis and Applications, Acc. Chem. Res., 10.1021/ar400151n, 47, 459-469, 2013.12, Colloidal metalorganic frameworks (CMOFs), nanoporous colloidal-sized crystals that are uniform in both size and polyhedral shape, are crystals composed of metal ions and organic bridging ligands, which can be used as building blocks for self-assembly in organic and aqueous liquids. They stand in contrast to conventional metalorganic frameworks (MOFs), which scientists normally study in the form of bulk crystalline powders. However, powder MOFs generally have random crystal size and shape and therefore do not possess either a definite mutual arrangement with adjacent particles or uniformity. CMOFs do have this quality, which can be important in vital uptake and release kinetics. In this Account, we present the diverse methods of synthesis, pore chemistry control, surface modification, and assembly techniques of CMOFs. In addition, we survey recent achievements and future applications in this emerging field. There is potential for a paradigm shift, away from using just bulk crystalline powders, towards using particles whose size and shape are regulated. The concept of colloidal MOFs takes into account that nanoporous MOFs, conventionally prepared in the form of bulk crystalline powders with random crystal size, shape, and orientation, may also form colloidal-sized objects with uniform size and morphology. Furthermore, the traditional MOF functions that depend on porosity present additional control over those MOF functions that depend on pore interactions. They also can enable controlled spatial arrangements between neighboring particles. To begin, we discuss progress regarding synthesis of MOF nano- and microcrystals whose crystal size and shape are well regulated. Next, we review the methods to modify the surfaces with dye molecules and polymers. Dyes are useful when seeking to observe nonluminescent CMOFs in situ by optical microscopy, while polymers are useful to tune their interparticle interactions. Third, we discuss criteria to assess the stability of CMOFs for various applications. In another section of this Account, we give examples of supracrystal assembly in liquid, on substrates, at interfaces, and under external electric fields. We end this Account with discussion of possible future developments, both conceptual and technological.. |
| 113. | Hirotaka Ejima, Nobuhiro Yanai, James P. Best, Melinda Sindoro, Steve Granick, Frank Caruso, Near-Incompressible Faceted Polymer Microcapsules from Metal-Organic Framework Templates, Advanced Materials, 10.1002/adma.201302442, 25, 5767-5771, 2013.08, Faceted polymer microcapsules are prepared from metal-organic framework (MOF) templates. The MOF templates are removable under mild aqueous conditions. The obtained microcapsules are stiffer than their spherical counterparts, reflecting the near-incompressibility of the facet edges, and indicating that the faceting might be a useful strategy for controlling the mechanical properties of polymer microcapsules.. |
| 114. | Nobuhiro Yanai, Nobuo Kimizuka, Formation, assembly, and function of nano- And micron-sized coordination polymer particles, KOBUNSHI RONBUNSHU, 10.1295/koron.70.235, 70, 6, 235-241, 2013.06, Coordination polymers with infinite network structures were synthesized by self-assembly between metal ions and organic bridging ligands in solution. By choosing different metal ions and organic ligands, coordination polymers can show various intriguing functions. In particular, functions based on guest inclusion into the coordination networks have attracted much attention from the viewpoint of host-guest chemistry. Importantly, one can rationally form coordination polymers that are either crystalline or amorphous. Crystalline nanoporous structures can adsorb small molecules. On the other hand, an adoptive self-assembly of amorphous networks enables an inclusion of large nanomaterials such as nanoparticles and proteins. Making nano- and micron-sized particles of such functional coordination polymers will lead to a wider range of applications and new functions. This review introduces the methodology of how to prepare coordination nano- and micron-particles, how to assemble the coordination particles into supraparticular structures, and how to functionalize the coordination particles based on guest inclusion phenomena.. |
| 115. | Takashi Uemura, Gosuke Washino, Yanai Nobuhiro, Susumu Kitagawa, Controlled Encapsulation of Photo-Responsive Macromolecules in Porous Coodination Polymer, Chem. Lett., 42, 222-223, Editor's Choice, 2013.02. |
| 116. | Takashi Uemura, Gosuke Washino, Nobuhiro Yanai, Susumu Kitagawa, Controlled encapsulation of photoresponsive macromolecules in porous coordination polymer, Chemistry Letters, 10.1246/cl.2013.222, 42, 3, 222-223, 2013.02, A photoresponsive controlled adsorption system based on a porous coordination polymer (PCP) was fabricated, using azobenzene tethered with poly(ethylene glycol) (PEG-AB) as macromolecular guests. Specific adsorption behavior of trans-PEG-AB into the nanochannels of a PCP was observed in an EtOH medium. When this composite was irradiated with UV light in EtOH, isomerization of PEG-AB from the trans to the cis form resulted in release of PEG-AB because of the large changes in the molecular shape and solubility of PEG-AB. Subsequent visible light irradiation induced photoisomerization of PEG-AB, which led to readsorption of PEG-AB into the nanochannels.. |
| 117. | Yanai Nobuhiro, Melinda Sindoro, Jing Yan, Steve Granick, Electric Field-Induced Assembly of Monodisperse Polyhedral Metal-Organic Framework Crystals, J. Am. Chem. Soc., 135, 34-37, 2013.01, 多孔性金属錯体のマイクロ結晶を電場をかけることにより配向を制御して集積化し、超結晶構造を形成することに成功した。大面積で結晶の配向を制御する簡易かつ効果的な方法論となりうる。また電場下での多面体粒子の集合を初めて明らかにしたため、コロイド自己集合の分野に新たな領域をもたらした。. |
| 118. | Nobuhiro Yanai, Melinda Sindoro, Jing Yan, Steve Granick, Electric field-induced assembly of monodisperse polyhedral metal-organic framework crystals, Journal of the American Chemical Society, 10.1021/ja309361d, 135, 1, 34-37, 2013.01, Monodisperse polyhedral metal-organic framework (MOF) particles up to 5 μm in size, large enough to enable in situ optical imaging of particle orientation, were synthesized by the strategy of simultaneous addition of two capping ligands with different binding strength during crystallization. Upon dispersing them in ethylene glycol and applying AC electric field, the particles facets link to form linear chains. We observe well-regulated crystal orientation not only for rhombic dodecahedra all of whose facets are equivalent, but also for truncated cubes with nondegenerate facets. After removing the electric field, chains disassemble if their facets contain even modest curvature, but remain intact if their facets are planar. This assembly strategy offers a general route to fabricate oriented polyhedral crystal arrays of potential interest for new applications and functions.. |
| 119. | Yanai Nobuhiro, Takashi Uemura, Susumu Kitagawa, Behavior of Binary Guests in a Porous Coordination Polymer, Chem. Mater., 24, 4744-4749, 2012.12. |
| 120. | Nobuhiro Yanai, Takashi Uemura, Susumu Kitagawa, Behavior of binary guests in a porous coordination polymer, Chemistry of Materials, 10.1021/cm3031768, 24, 24, 4744-4749, 2012.12, Controlling the condensed state of multiple guests in nanoporous media is critical to many applications, but an understanding of this phenomenon in pores smaller than a few nanometers is still unavailable. In this work, we investigate the aggregation state of binary guests, poly(ethylene glycol) (PEG), and long-chain normal alkanes, in subnanometer channels of a porous coordination polymer (PCP) by monitoring their thermal transition behaviors. PEG and alkanes are immiscible in the bulk and their melting transitions are not affected by each other. Meanwhile, in the PCP nanochannels, the transition temperature and the heat of the binary-guest system were significantly different from when PEG or an alkane was individually included. This suggests the formation of microscopically segregated domain structures of PEG and alkane in the host crystal. The transition behaviors gradually varied by changing the introduction ratio between PEG and alkane, and thus the aggregation states of the two guests were successfully controlled by the simple variation of relative amounts. This methodology offers a promising route to control spatial configurations of multiple guest molecules in nanoporous matrices for advanced applications.. |
| 121. | Masakazu Higuchi, Kohei Nakamura, Satoshi Horike, Yuh Hijikata, Nobuhiro Yanai, Tomohiro Fukushima, Jungeun Kim, Kenichi Kato, Masaki Takata, Daisuke Watanabe, Shinji Oshima, Susumu Kitagawa, Design of flexible lewis acidic sites in porous coordination polymers by using the viologen moiety, Angewandte Chemie - International Edition, 10.1002/anie.201203834, 51, 33, 8369-8372, 2012.08, Charged up: A novel porous coordination polymer with a charged organic surface (COS) comprising a zwitterionic organic linker, viologen, has been synthesized. The COS shows strong Lewis acidity accompanied with flexibility, and the isosteric heat of H2 adsorption is 9.5 kJ mol-1, which is comparable to that of open metal sites (OMSs).. |
| 122. | Nobuhiro Yanai, Steve Granick, Directional self-assembly of a colloidal metal-organic framework, Angewandte Chemie - International Edition, 10.1002/anie.201109132, 51, 23, 5638-5641, 2012.06, MOFs get attraction: Supraparticle self-assembly of a colloidal metal-organic framework (MOF) is achieved through simple capillary and van der Waals attractions. When suspensions of MOF particles are allowed to evaporate, hexagonal packings with controlled crystal orientation result (see scheme). The self-assembly can be visualized at the single-particle level.. |
| 123. | Nobuhiro Yanai, Takashi Uemura, Wataru Kosaka, Ryotaro Matsuda, Tetsuhiro Kodani, Meiten Koh, Takashi Kanemura, Susumu Kitagawa, Inclusion and dielectric properties of a vinylidene fluoride oligomer in coordination nanochannels, Dalton Transactions, 10.1039/c2dt11891b, 41, 14, 4195-4198, 2012.04, The dynamics of oligo(vinylidene fluoride) (OVDF) confined in regular nanochannels of a porous coordination polymer (PCP) was studied by means of dielectric spectroscopy. The OVDF chains in the PCP nanopores showed two Arrhenius-type relaxation processes at lower temperatures than the relaxation temperature observed for the neat OVDF, showing the enhanced mobility of the confined OVDF.. |
| 124. | J. Alberto Rodríguez-Velamazán, Miguel A. González, José A. Real, Miguel Castro, M. Carmen Muñoz, Ana B. Gaspar, Ryo Ohtani, Masaaki Ohba, Ko Yoneda, Yuh Hijikata, Nobuhiro Yanai, Motohiro Mizuno, Hideo Ando, Susumu Kitagawa, A switchable molecular rotator Neutron spectroscopy study on a polymeric spin-crossover compound, Journal of the American Chemical Society, 10.1021/ja206228n, 134, 11, 5083-5089, 2012.03, A quasielastic neutron scattering and solid-state 2H NMR spectroscopy study of the polymeric spin-crossover compound {Fe(pyrazine)[Pt(CN) 4]} shows that the switching of the rotation of a molecular fragment-the pyrazine ligand-occurs in association with the change of spin state. The rotation switching was examined on a wide time scale (10 -13-10 -3 s) by both techniques, which clearly demonstrated the combination between molecular rotation and spin-crossover transition under external stimuli (temperature and chemical). The pyrazine rings are seen to perform a 4-fold jump motion about the coordinating nitrogen axis in the high-spin state. In the low-spin state, however, the motion is suppressed, while when the system incorporates benzene guest molecules, the movements of the system are even more restricted.. |
| 125. | Nobuhiro Yanai, Takashi Uemura, Masafumi Inoue, Ryotaro Matsuda, Tomohiro Fukushima, Masahiko Tsujimoto, Seiji Isoda, Susumu Kitagawa, Guest-to-host transmission of structural changes for stimuli-responsive adsorption property, Journal of the American Chemical Society, 10.1021/ja2115713, 134, 10, 4501-4504, 2012.03, We show that structural changes of a guest molecule can trigger structural transformations of a crystalline host framework. Azobenzene was introduced into a flexible porous coordination polymer (PCP), and cis/trans isomerizations of the guest azobenzene by light or heat successfully induced structural transformations of the host PCP in a reversible fashion. This guest-to-host structural transmission resulted in drastic changes in the gas adsorption property of the host-guest composite, displaying a new strategy for creating stimuli-responsive porous materials.. |
| 126. | Nobuhiro Yanai, Koji Kitayama, Yuh Hijikata, Hiroshi Sato, Ryotaro Matsuda, Yoshiki Kubota, Masaki Takata, Motohiro Mizuno, Takashi Uemura, Susumu Kitagawa, Gas detection by structural variations of fluorescent guest molecules in a flexible porous coordination polymer, Nature Materials, 10.1038/nmat3104, 10, 10, 787-793, 2011.10, The development of a new methodology for visualizing and detecting gases is imperative for various applications. Here, we report a novel strategy in which gas molecules are detected by signals from a reporter guest that can read out a host structural transformation. A composite between a flexible porous coordination polymer and fluorescent reporter distyrylbenzene (DSB) selectively adsorbed CO2 over other atmospheric gases. This adsorption induced a host transformation, which was accompanied by conformational variations of the included DSB. This read-out process resulted in a critical change in DSB fluorescence at a specific threshold pressure. The composite shows different fluorescence responses to CO2 and acetylene, compounds that have similar physicochemical properties. Our system showed, for the first time, that fluorescent molecules can detect gases without any chemical interaction or energy transfer. The host-guest coupled transformations play a pivotal role in converting the gas adsorption events into detectable output signals.. |
| 127. | Nobuhiro Yanai, Takashi Uemura, Noriyuki Uchida, Silvia Bracco, Angiolina Comotti, Piero Sozzani, Tetsuhiro Kodani, Meiten Koh, Takashi Kanemura, Susumu Kitagawa, End-functionalization of a vinylidene fluoride oligomer in coordination nanochannels, Journal of Materials Chemistry, 10.1039/c1jm10632e, 21, 22, 8021-8025, 2011.06, The utility of basic sites of porous coordination polymers (PCPs) for the end-functionalization of oligo(vinylidene fluoride) (OVDF) is demonstrated. Densely arranged carboxylate moieties on the PCP pore walls act as basic sites and allow the efficient elimination reaction of the terminal group of OVDF to proceed. The progress of the reaction of an OVDF precursor in the PCP nanochannels was evidenced using solid state 19F NMR spectroscopy. From 19F and 1H NMR and IR measurements of the product isolated from the composite obtained, the terminal -CH2CF 2I moiety of OVDF was shown to be successfully converted to a -CHCF2 group. Because of the large surface area of the PCP materials, the OVDF precursor easily accessed the basic sites, resulting in a large increase in the rate of the elimination reaction. In addition, a notable effect of the porous structure of PCPs upon the elimination reaction was observed.. |
| 128. | Satoru Shimomura, Nobuhiro Yanai, Ryotaro Matsuda, Susumu Kitagawa, Impact of metal-ion dependence on the porous and electronic properties of TCNQ-dianion-based porous coordination polymers, Inorganic Chemistry, 10.1021/ic1015498, 50, 1, 172-177, 2011.01, A series of TCNQ-dianion-based porous coordination polymers [M(TCNQ)bpy] (M = Fe, Zn, Mn, Co, Cd) have been synthesized and characterized. The synthesis reactions of these compounds are promoted by the addition of ascorbic acid, which is the key to obtaining a high yield. They form almost identical three-dimensional pillared layer structures with the M-TCNQ two-dimensional layers linked by bpy pillar ligands. The electronic properties of these compounds vary depending on the constitutional metal ions and guest molecules. We found that the electronic interaction between metal ions and TCNQ moieties in the frameworks strongly impacted the electronic properties of the compounds.. |
| 129. | Nobuhiro Yanai, Takashi Uemura, Satoshi Horike, Satoru Shimomura, Susumu Kitagawa, Inclusion and dynamics of a polymer-Li salt complex in coordination nanochannels, Chemical Communications, 10.1039/c0cc04799f, 47, 6, 1722-1724, 2011.01, A complex of polyethylene glycol with LiBF4 was incorporated into the nanochannels of a porous coordination polymer, where a liquid-like mobility of the Li ions was attained, even within the highly constrained geometry.. |
| 130. | Takashi Uemura, Nobuhiro Yanai, Satoshi Watanabe, Hideki Tanaka, Ryohei Numaguchi, Minoru T. Miyahara, Yusuke Ohta, Masataka Nagaoka, Susumu Kitagawa, Unveiling thermal transitions of polymers in subnanometre pores., Nature Communications, 1, 2010.12, The thermal transitions of confined polymers are important for the application of polymers in molecular scale devices and advanced nanotechnology. However, thermal transitions of ultrathin polymer assemblies confined in subnanometre spaces are poorly understood. In this study, we show that incorporation of polyethylene glycol (PEG) into nanochannels of porous coordination polymers (PCPs) enabled observation of thermal transitions of the chain assemblies by differential scanning calorimetry. The pore size and surface functionality of PCPs can be tailored to study the transition behaviour of confined polymers. The transition temperature of PEG in PCPs was determined by manipulating the pore size and the pore-polymer interactions. It is also striking that the transition temperature of the confined PEG decreased as the molecular weight of PEG increased.. |
| 131. | Sareeya Bureekaew, Satoshi Horike, Masakazu Higuchi, Motohiro Mizuno, Takashi Kawamura, Daisuke Tanaka, Nobuhiro Yanai, Susumu Kitagawa, One-dimensional imidazole aggregate in aluminium porous coordination polymers with high proton conductivity, Materials for Sustainable Energy A Collection of Peer-Reviewed Research and Review Articles from Nature Publishing Group, 10.1142/9789814317665_0032, 232-237, 2010.01, The development of anhydrous proton-conductive materials operating at temperatures above 80 °C is a challenge that needs to be met for practical applications. Herein, we propose the new idea of encapsulation of a proton-carrier molecule-imidazole in this work-in aluminium porous coordination polymers for the creation of a hybridized proton conductor under anhydrous conditions. Tuning of the host–guest interaction can generate a good proton-conducting path at temperatures above 100 °C. The dynamics of the adsorbed imidazole strongly affect the conductivity determined by 2H solid-state NMR. Isotope measurements of conductivity using imidazole-d4 showed that the proton-hopping mechanism was dominant for the conducting path. This work suggests that the combination of guest molecules and a variety of microporous frameworks would afford highly mobile proton carriers in solids and gives an idea for designing a new type of proton conductor, particularly for high-temperature and anhydrous conditions.. |
| 132. | Takashi Uemura, Nobuhiro Yanai, Satoshi Watanabe, Hideki Tanaka, Ryohei Numaguchi, Minoru T. Miyahara, Yusuke Ohta, Masataka Nagaoka, Susumu Kitagawa, Unveiling thermal transitions of polymers in subnanometre pores, Nature communications, 10.1038/ncomms1091, 1, 7, 2010.01, The thermal transitions of confined polymers are important for the application of polymers in molecular scale devices and advanced nanotechnology. However, thermal transitions of ultrathin polymer assemblies confined in subnanometre spaces are poorly understood. In this study, we show that incorporation of polyethylene glycol (PEG) into nanochannels of porous coordination polymers (PCPs) enabled observation of thermal transitions of the chain assemblies by differential scanning calorimetry. The pore size and surface functionality of PCPs can be tailored to study the transition behaviour of confined polymers. The transition temperature of PEG in PCPs was determined by manipulating the pore size and the pore-polymer interactions. It is also striking that the transition temperature of the confined PEG decreased as the molecular weight of PEG increased.. |
| 133. | Sareeya Bureekaew, Satoshi Horike, Masakazu Higuchi, Motohiro Mizuno, Takashi Kawamura, Daisuke Tanaka, Nobuhiro Yanai, Susumu Kitagawa, One-dimensional imidazole aggregate in aluminium porous coordination polymers with high proton conductivity, Nature Materials, 10.1038/nmat2526, 8, 10, 831-836, 2009.10, The development of anhydrous proton-conductive materials operating at temperatures above 80 °C is a challenge that needs to be met for practical applications. Herein, we propose the new idea of encapsulation of a proton-carrier molecule-imidazole in this work-in aluminium porous coordination polymers for the creation of a hybridized proton conductor under anhydrous conditions. Tuning of the host-guest interaction can generate a good proton-conducting path at temperatures above 100 °C. The dynamics of the adsorbed imidazole strongly affect the conductivity determined by 2 H solid-state NMR. Isotope measurements of conductivity using imidazole-d4 showed that the proton-hopping mechanism was dominant for the conducting path. This work suggests that the combination of guest molecules and a variety of microporous frameworks would afford highly mobile proton carriers in solids and gives an idea for designing a new type of proton conductor, particularly for high-temperature and anhydrous conditions.. |
| 134. | Takashi Uemura, Yu Kadowaki, Nobuhiro Yanai, Susumu Kitagawa, Template synthesis of porous polypyrrole in 3D coordination nanochannels, Chemistry of Materials, 10.1021/cm901361m, 21, 18, 4096-4098, 2009.09, A template synthesis of PPy was demonstrated in 3D coordination channels to give a polymer material with a certain porosity., that has also revealed the pore functions characteristic of PPy. The study has also reported a feasible method for providing a porous structure of polypyrrole by oxidative polymerization of pyrrole in the 3D channels of 1 and the subsequent isolation of the resulting PPy. The experiment prepared the network structure of PPy in 3D channels of 1, and then could be isolated by removal of the host matrix. The PPy was isolated by ammonia that exhibited the maximum adsorption ability, and the amount of adsorption was almost independent of the ammonia concentration in the isolation process. The methodology proposed by the study exhibit potential advantages not only for tailored design of porous structures by tuning the host matrix or preparation conditions but also for developing new porous properties based on attractive functions of polymers.. |
| 135. | Masakazu Higuchi, Daisuke Tanaka, Satoshi Horike, Hirotoshi Sakamoto, Kohei Nakamura, Yohei Takashima, Yuh Hijikata, Nobuhiro Yanai, Jungeun Kim, Kenichi Kato, Yoshiki Kubota, Masaki Takata, Susumu Kitagawa, Porous coordination polymer with pyridinium cationic surface, [Zn 2(tpa)2(cpb)], Journal of the American Chemical Society, 10.1021/ja900373v, 131, 30, 10336-10337, 2009.08, (Chemical Equation Presented) We have synthesized a porous coordination polymer containing a pyridinium cation as an organic linker and have investigated the methanol absorptive ability of the pyridinium cationic surface. The result implies that the pyridinium cationic surface participates in the strong adsorption of methanol.. |
| 136. | Takashi Uemura, Nobuhiro Yanai, Susumu Kitagawa, Polymerization reactions in porous coordination polymers, Chemical Society Reviews, 10.1039/b802583p, 38, 5, 1228-1236, 2009.04, Recent developments in polymerizations within the nanochannels of porous coordination polymers (PCPs) are covered in this tutorial review. The characteristic features of PCPs are regular structures, controllable channel sizes and shapes, a designable surface functionality, and flexible frameworks, which can be utilized for precision polymer synthesis and specific polymer confinement. This review discusses promising approaches to multiple controls of polymer structures, analysis systems for low-dimensional polymer assemblies and the construction of PCP–polymer nanohybrids, which are strong enticements to researchers in the areas of inorganic, materials and polymer chemistry.. |
| 137. | Nobuhiro Yanai, Takashi Uemura, Masaaki Ohba, Yu Kadowaki, Mitsuhiko Maesato, Mikihito Takenaka, Shotaro Nishitsuji, Hirokazu Hasegawa, Susumu Kitagawa, Fabrication of two-dimensional polymer arrays Template synthesis of polypyrrole between redox-active coordination nanoslits, Angewandte Chemie - International Edition, 10.1002/anie.200803846, 47, 51, 9883-9886, 2008.12, (Figure Presented) A redox sandwich: Oxidative and intercalative polymerization of pyrrole was conducted within the nanoslits of a layered open coordination framework containing redox-active sites. The resulting polypyrrole, which can be isolated from the host framework, exists as stacked sheet polymer objects, the orientation and morphology of which are directly related to those of the original coordination-polymer template.. |
| 138. | Daisuke Tanaka, Masakazu Higuchi, Satoshi Horike, Ryotaro Matsuda, Yoshinori Kinoshita, Nobuhiro Yanai, Susumu Kitagawa, Storage and sorption properties of acetylene in jungle-gym-like open frameworks, Chemistry - An Asian Journal, 10.1002/asia.200800112, 3, 8-9, 1343-1349, 2008.09, The acetylene-sorption properties of six porous coordination polymers (PCPs), [M2(L)2(dabco)]n (dabco=1,4- diazabicyclo[2.2.2]octane, M=Cu2+ (1), Zn2+ (2), L=1,4-benzenedicarboxylate (bdc; 1a, 2a), 1,4-naphthalenedicarboxylate (ndc; 1b, 2b), 9,10-anthracenedicarboxylate (adc; 1c, 2c)), were investigated. The acetylene sorption isotherms of 1 and 2 measured at 195 K are of type I and show a steep increase at low relative pressures. The sorption properties of carbon dioxide at 195 K were also investigated. Compounds 1 and 2 showed a large difference in onset pressure between acetylene sorption isotherms, although the difference between the carbon dioxide sorption isotherms is not so significant. In particular, 2c displayed a remarkable affinity for acetylene. The acetylene sorption isotherm at 298 K showed that the adsorption amounts for 2c and 2b at 298 K, 1 atm (101 and 106 mLg-1, respectively) were higher than those of other conventional porous materials. Notably, of the compounds 1 and 2, the porous crystals 2c had the highest affinity for acetylene.. |
| 139. | Shin Ichiro Noro, Nobuhiro Yanai, Susumu Kitagawa, Tomoyuki Akutagawa, Takayoshi Nakamura, Binding properties of solvatochromic indicators [Cu(X)(acac)(tmen)] (X = PF6- and BF4-, acac- = acetylacetonate, tmen = N,N,N′,N′-tetramethylethylenediamine) in solution and the solid state, Inorganic chemistry, 10.1021/ic800685z, 47, 16, 7360-7365, 2008.08, The solvatochromic indicator [Cu(acac)(tmen)(H2O)] ·PF6 (1·H2O) has been synthesized and crystallographically characterized. 1·H2O binds an H 2O molecule at the Cu(II) axial site, while the PF6 - anion is coordination free. The binding properties of [Cu(PF 6)(acac)(tmen)] (1) and [Cu(BF4)(acac)(tmen)] (2) have been investigated in solution and the solid state. The donor number of the PF6- anion (DNPF6) was determined from the UV-vis spectra of 1 in 1,2-dichloroethane. The value of DNPF6 of the PF6- anion is slightly larger than that of the tetraphenylborate anion (BPh4-), which is known as a noncoordinating anion. In the solid state, 1 and 2 reversibty bind and release H2O molecules at the Cu(II) axial sites. The coordinated H 2O molecules in 2 are more easily removed than those in 1 because of the strong Lewis basicity of the BF4- anion compared to the PF6- ion. The lower melting point of 1 versus 2 is attributed to the loose binding of the PF6- anions to the Cu(II) centers, which induces the dynamic nature of the crystal.. |
| 140. | Nobuhiro Yanai, Wakako Kaneko, Ko Yoneda, Masaaki Ohba, Susumu Kitagawa, Reversible water-induced magnetic and structural conversion of a flexible microporous Ni(II)Fe(III) ferromagnet, Journal of the American Chemical Society, 10.1021/ja069166b, 129, 12, 3496-3497, 2007.03, A cyanide-bridged bimetallic ferromagnet, [Ni(dipn)]2[Ni(dipn)(H2O)][Fe(CN)6]2·11H2O (dipn = N,N-di(3-aminopropyl)amine) providing a 3-D microporous framework, shows reversible ferromagnet/paramagnet conversion associated with a gaseous water-induced crystal-to-amorphous-like phase transformation.. |
| 141. | T. Uemura, K. Kitagawa, D. Hiramatsu, N. Yanai, S. Kitagawa, N. Sato, Controlled polymerization in functional coordination spaces utilizing γ-ray irradiaion, KURRI Progress Report, 2006.04. |
| 142. | Nobuhiro Yanai, Takashi Uemura, Masaaki Ohba, Susumu Kitagawa, Nano-hybrids from molecule-based magnet hosts and conducting polymers towards multi-function, 55th SPSJ Annual Meeting Polymer Preprints, Japan - 55th SPSJ Annual Meeting, 55, 1506, 2006, Porous coordination polymers have been paid great attention for their high regularity, flexibility and porosity. Here we studied on synthesis of novel nano-hybrid materials consist of magnetic frameworks and conducting polymers. A magnetic framework 1 [Ni(dmen)2]2[Fe(CN) 6](PhBSO3) 4H2O has a 2-D layered framework (Fig.1) with FeIII redox centers and is expected to proceed intercalative oxidative polymerization of pyrrole. Insertion of pyrrole monomers and polymerization inside the compound 1 have been confirmed by XRD,IR,UV and SQUID measurements.. |
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