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47 results on '"Tahara, Hironobu"'

5. Photothermal Therapeutic Nanomaterials Composed of Plasmonic Aluminum Nanostructures for Effective Killing of Cells

Author

Honda, Jotaro, primary, Sugawa, Kosuke, additional, Tahara, Hironobu, additional, Danno, Miu, additional, Suzuki, Arisa, additional, Kurumi, Satoshi, additional, Kimura, Tsuyoshi, additional, Kosuge, Yasuhiro, additional, Ikake, Hiroki, additional, Hashimoto, Takeshi, additional, Hayashita, Takashi, additional, and Otsuki, Joe, additional

Published
2024
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8. One-pot C(sp3)–H difluoroalkylation of tetrahydroisoquinolines and isochromans via electrochemical oxidation and organozinc alkylation.

Author

Kamata, Kazuya, Kuriyama, Masami, Tahara, Hironobu, Nishikawa, Akira, Yamamoto, Kosuke, Demizu, Yosuke, and Onomura, Osamu

Subjects
TETRAHYDROISOQUINOLINES, AMINES, SCALABILITY, ETHERS, ALKYLATION
Abstract

The C(sp3)–H difluoroalkylation for the introduction of carbonylated CF2 groups into tetrahydroisoquinolines (THIQs) and isochromans has been achieved by using electrochemical oxidation and organozinc alkylation. This one-pot process proceeded smoothly under transition-metal catalyst- and chemical oxidant-free conditions, and the desired products were obtained in good to high yields with a broad scope, except for N-Boc-THIQ. In addition, the gram-scale experiment successfully demonstrated the promising scalability. This is the first example of an electrochemical method for C(sp3)–H difluoroalkylation of amines and ethers. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Photothermal therapeutic ability of copper open-shell nanostructures that are effective in the second biological transparency window based on symmetry breaking-induced plasmonic properties

Author

Sugawa, Kosuke, primary, Suzuki, Arisa, additional, Honda, Jotaro, additional, Yabuki, Taiku, additional, Tahara, Hironobu, additional, Hayakawa, Yutaro, additional, Furuya, Masato, additional, Ikake, Hiroki, additional, Kimura, Tsuyoshi, additional, Kosuge, Yasuhiro, additional, Kurumi, Satoshi, additional, Akiyama, Tsuyoshi, additional, Takase, Kouichi, additional, and Otsuki, Joe, additional

Published
2023
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15. Additional file 1 of Modulation Technique of Localized Surface Plasmon Resonance of Palladium Nanospheres by Coating with Titanium Dioxide Shell for Application to Photothermal Therapy Agent

Author

Hayakawa, Yutaro, Furuya, Masato, Tahara, Hironobu, Kosuge, Yasuhiro, Kimura, Tsuyoshi, Sugawa, Kosuke, and Otsuki, Joe

Abstract

Additional file1: Fig. S1. Optical properties of PdNS/TiO2 calculated by the Mie theory. Fig. S2. Optical properties of Au/PdNS/TiO2 calculated by the Mie theory. Fig. S3. TEM image of Au nanospheres. Fig. S4. Extinction, scattering, and absorption spectra of PdNS/TiO2 and Au/PdNS/TiO2 nanoparticles calculated by Mie theory. Fig. S5. Extinction spectra and TEM image for Au/PdNSs before and after the laser irradiation

Published
2022
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18. Performance Improvement of Triplet–Triplet Annihilation-Based Upconversion Solid Films through Plasmon-Induced Backward Scattering of Periodic Arrays of Ag and Al

Author

Sugawa, Kosuke, primary, Yoshinari, Satoshi, additional, Watanabe, Shiryu, additional, Ishida, Kosuke, additional, Jin, Shota, additional, Takeshima, Naoto, additional, Fukasawa, Toru, additional, Fukushima, Misa, additional, Katoh, Ryuzi, additional, Takase, Kouichi, additional, Tahara, Hironobu, additional, and Otsuki, Joe, additional

Published
2021
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19. A redox-active ionic liquid manifesting charge-transfer interaction between a viologen and carbazole and its effect on the viscosity, ionic conductivity, and redox process of the viologen

Author

Tahara, Hironobu, Tanaka, Yudai, Yamamoto, Shoko, Yonemori, Shigeki, Chan, Bun, Murakami, Hiroto, Sagara, Takamasa, Tahara, Hironobu, Tanaka, Yudai, Yamamoto, Shoko, Yonemori, Shigeki, Chan, Bun, Murakami, Hiroto, and Sagara, Takamasa

Abstract

Redox-active ionic liquids (RAILs) are gaining attention as a material that can create a wide range of functions. We herein propose a charge-transfer (CT) RAIL by mixing two RAILs, specifically a carbazole-based ionic liquid ([CzC4ImC1][TFSI]) as a donor and a viologen-based ionic liquid ([C4VC7][TFSI]2) as an acceptor. We investigated the effect of CT interaction on the physicochemical properties of the CT ionic liquid (CT-IL) using the results of temperature-dependent measurements of UV-vis absorption, viscosity, and ionic conductivity as well as cyclic voltammograms. We employed the Walden analysis and the Grunberg–Nissan model to elucidate the effect of the CT interaction on the viscosity and ionic conductivity. The CT interaction reduces the viscosity by reducing the electrostatic attraction between the dicationic viologen and TFSI anion. It also reduces the ionic conductivity by the CT association of the dicationic viologen and carbazole. The electrochemically reversible responses of the viologens in [C4VC7][TFSI]2 and CT-IL are consistent with the Nernstian and the interacting two-redox site models. Notably, the transport and electrochemical properties are modulated by CT interaction, leading to unique features that are not present in individual component ILs. The inclusion of CT interaction in RAILs thus provides a powerful means to expand the scope of functionalized ionic liquids., Chemical Science, 12(13), pp. 4872-4882; 2021

Published
2021

21. MOESM1 of Combined Use of Anisotropic Silver Nanoprisms with Different Aspect Ratios for Multi-Mode Plasmon-Exciton Coupling

Author

Takeshima, Naoto, Sugawa, Kosuke, Tahara, Hironobu, Jin, Shota, Noguchi, Masaki, Yutaro Hayakawa, Yamakawa, Yuhei, and Otsuki, Joe

Abstract

Additional file 1: Figure S1. Geometric models of AgPRs with various LSP resonance wavelengths. Figure S2. A Setup for the irradiation of LED light to a colloidal aqueous solution of Ag nanospheres. Figure S3. Normalized extinction and emission spectra of a toluene solution of TPP (1×10-6 M). Figure S4. Extinction spectra of colloidal aqueous solutions of AgPRs synthesized five times. Figure S5. (a) Enhancement factor of fluorescence obtained from fluorescence excitation spectra for TPP/AgPRs-500, TPP/AgPRs-560, TPP/AgPRs-645, and TPP-ternary (λem = 720 nm) at (i) 435 nm, (ii) 519 nm, (iii) 552 nm, (iv) 596 nm, and (v) 653 nm, respectively. (b) Absorption enhancement at the respective Q-band wavelengths.

Published
2020
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24. Plasmonic Silver Nanoprism-Induced Emissive Mode Control between Fluorescence and Phosphorescence of a Phosphorescent Palladium Porphyrin Derivative

Author

Takeshima, Naoto, primary, Sugawa, Kosuke, additional, Tahara, Hironobu, additional, Jin, Shota, additional, Wakui, Hiroki, additional, Fukushima, Misa, additional, Tokuda, Kyo, additional, Igari, Shuto, additional, Kanakubo, Kotomi, additional, Hayakawa, Yutaro, additional, Katoh, Ryuzi, additional, Takase, Kouichi, additional, and Otsuki, Joe, additional

Published
2019
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25. Mie Resonance-Enhanced Light Absorption of FeS2 Nanocubes in a Near-Infrared Region: Intraparticulate Synergy between Electronic Absorption and Mie Resonances

Author

Sugawa, Kosuke, primary, Matsubara, Mitsuaki, additional, Tahara, Hironobu, additional, Kanai, Daisuke, additional, Honda, Jotaro, additional, Yokoyama, Jun, additional, Kanakubo, Kotomi, additional, Ozawa, Hiroaki, additional, Watanuki, Yasuhiro, additional, Kojima, Yoshiyuki, additional, Nishimiya, Nobuyuki, additional, Sagara, Takamasa, additional, Takase, Kouichi, additional, Haga, Masa-aki, additional, and Otsuki, Joe, additional

Published
2019
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27. Precise Control of Localized Surface Plasmon Wavelengths Is Needed for Effective Enhancement of Triplet–Triplet Annihilation-Based Upconversion Emission

Author

Jin, Shota, primary, Sugawa, Kosuke, additional, Takeshima, Naoto, additional, Tahara, Hironobu, additional, Igari, Shuto, additional, Yoshinari, Satoshi, additional, Kurihara, Yuri, additional, Watanabe, Shiryu, additional, Enoki, Masami, additional, Sato, Kenta, additional, Inoue, Wataru, additional, Tokuda, Kyo, additional, Akiyama, Tsuyoshi, additional, Katoh, Ryuzi, additional, Takase, Kouichi, additional, Ozawa, Hiroaki, additional, Okazaki, Toshiya, additional, Watanabe, Takayuki, additional, and Otsuki, Joe, additional

Published
2018
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29. Electrochromism of a bipolar reversible redox-active ferrocene?viologen linked ionic liquid

Author

Tahara, Hironobu, Baba, Rei, Iwanaga, Kodai, Sagara, Takamasa, Murakami, Hiroto, Tahara, Hironobu, Baba, Rei, Iwanaga, Kodai, Sagara, Takamasa, and Murakami, Hiroto

Abstract

A ferrocene-viologen linked “bipolar” type redox-active ionic liquid ([FcC11VC1][TFSI]2) was synthesized as an electrochromic (EC) material that functions without any other additives: solvents, supporting electrolytes and sacrificial agents. The efficiency of a prototype symmetrical EC cell was 70 cm2 C?1 at 1.0 V. The EC process was stable even after over 10?000 potential cycles.

Published
2017

34. Metal-Enhanced Fluorescence Platforms Based on Plasmonic Ordered Copper Arrays: Wavelength Dependence of Quenching and Enhancement Effects

Author

Sugawa, Kosuke, Tamura, Takahiro, Tahara, Hironobu, Yamaguchi, Daisuke, Akiyama, Tsuyoshi, Otsuki, Joe, Kusaka, Yasuyuki, Fukuda, Nobuko, and Ushijima, Hirobumi

Abstract

Ordered arrays of copper nanostructures were fabricated and modified with porphyrin molecules in order to evaluate fluorescence enhancement due to the localized surface plasmon resonance. The nanostructures were prepared by thermally depositing copper on the upper hemispheres of two-dimensional silica colloidal crystals. The wavelength at which the surface plasmon resonance of the nanostructures was generated was tuned to a longer wavelength than the interband transition region of copper (>590 nm) by controlling the diameter of the underlying silica particles. Immobilization of porphyrin monolayers onto the nanostructures was achieved viaself-assembly of 16-mercaptohexadecanoic acid, which also suppressed the oxidation of the copper surface. The maximum fluorescence enhancement of porphyrin by a factor of 89.2 was achieved as compared with that on a planar Cu plate (CuP) due to the generation of the surface plasmon resonance. Furthermore, it was found that while the fluorescence from the porphyrin was quenched within the interband transition region, it was efficiently enhanced at longer wavelengths. It was demonstrated that the enhancement induced by the proximity of the fluorophore to the nanostructures was enough to overcome the highly efficient quenching effects of the metal. From these results, it is speculated that the surface plasmon resonance of copper has tremendous potential for practical use as high functional plasmonic sensor and devices.

Published
2024
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39. Photocurrent enhancement of porphyrin molecules over a wide-wavelength region based on combined use of silver nanoprisms with different aspect ratios

Author

Sugawa, Kosuke, primary, Takeshima, Naoto, additional, Uchida, Koji, additional, Tahara, Hironobu, additional, Jin, Shota, additional, Tsunenari, Natsumi, additional, Akiyama, Tsuyoshi, additional, Kusaka, Yasuyuki, additional, Fukuda, Nobuko, additional, Ushijima, Hirobumi, additional, Tsuchido, Yuji, additional, Hashimoto, Takeshi, additional, Hayashita, Takashi, additional, and Otsuki, Joe, additional

Published
2015
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41. Efficient Photocurrent Enhancement from Porphyrin Molecules on Plasmonic Copper Arrays: Beneficial Utilization of Copper Nanoanntenae on Plasmonic Photoelectric Conversion Systems

Author

Sugawa, Kosuke, Yamaguchi, Daisuke, Tsunenari, Natsumi, Uchida, Koji, Tahara, Hironobu, Takeda, Hideyuki, Tokuda, Kyo, Jin, Shota, Kusaka, Yasuyuki, Fukuda, Nobuko, Ushijima, Hirobumi, Akiyama, Tsuyoshi, Watanuki, Yasuhiro, Nishimiya, Nobuyuki, Otsuki, Joe, and Yamada, Sunao

Abstract

We demonstrated the usefulness of Cu light-harvesting plasmonic nanoantennae for the development of inexpensive and efficient artificial organic photoelectric conversion systems. The systems consisted of the stacked structures of layers of porphyrin as a dye molecule, oxidation-suppressing layers, and plasmonic Cu arrayed electrodes. To accurately evaluate the effect of Cu nanoantenna on the porphyrin photocurrent, the production of Cu2O by the spontaneous oxidation of the electrode surfaces, which can act as a photoexcited species under visible light irradiation, was effectively suppressed by inserting the ultrathin linking layers consisting of 16-mercaptohexadecanoic acid, titanium oxide, and poly(vinyl alcohol) between the electrode surface and porphyrin molecules. The reflection spectra in an aqueous environment of the arrayed electrodes, which were prepared by thermally depositing Cu on two-dimensional colloidal crystals of silica with diameters of 160, 260, and 330 nm, showed clear reflection dips at 596, 703, and 762 nm, respectively, which are attributed to the excitation of localized surface plasmon resonance (LSPR). While the first dip lies within the wavelengths where the imaginary part of the Cu dielectric function is moderately large, the latter two dips lie within a region of a quite small imaginary part. Consequently, the LSPR excited at the red region provided a particularly large enhancement of porphyrin photocurrent at the Q-band (ca. 59-fold), compared to that on a Cu planar electrode. These results strongly suggest that the plasmonic Cu nanoantennae contribute to the substantial improvement of photoelectric conversion efficiency at the wavelengths, where the imaginary part of the dielectric function is small.

Published
2017
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45. Optimizing the Distance between Upconversion Thin Films and Silver Nanoprisms for the Design of a High-Performance Plasmonic Triplet–Triplet Annihilation Upconversion System

Author

Honda, Jotaro, Sugawa, Kosuke, Fukumura, Seiya, Katoh, Ryuzi, Tahara, Hironobu, and Otsuki, Joe

Abstract

While the distance dependence of metal-enhanced fluorescence has been extensively studied for composite systems comprising fluorophores and metal nanoparticles, the corresponding distance dependence of triplet–triplet annihilation upconversion (TTA-UC) systems remains unexplored. Herein, we investigated the influence of the spatial distance between Ag nanoprisms (AgPRs) and TTA-UC thin films consisting of a palladium octaethylporphyrin (PdOEP) sensitizer and a 9,10-diphenylanthracene (DPA) emitter, aiming at enhancing the upconverted (UC) emission as efficiently as possible. Results indicated that the optimal distance for the examined system was significantly longer (12.6 nm) than those of typical metal-enhanced fluorescence systems (about 2 nm). We demonstrated that the UC emission enhancement factor can be expressed as a product including factors of the PdOEP photoexcitation rate, triplet–triplet energy transfer (TTET) efficiency from PdOEP to DPA, triplet excited DPA lifetime, and fluorescence efficiency of singlet excited DPA. We discovered that the AgPRs play a beneficial role in enhancing the PdOEP photoexcitation, whereas they exert detrimental effects on the other three factors. Among these three factors, quenching contributions by the decrease of the triplet excited DPA lifetime and DPA fluorescence efficiency were significant, making these the primary and secondary factors, respectively, for the UC emission quenching, particularly at short distances. These results demonstrate that the characteristic distance dependence of the UC emission enhancement is determined by the competing effects of beneficial PdOEP photoexcitation enhancement and the detrimental localized surface plasmon (and/or AgPR)-induced nonradiative decay of the triplet- and singlet excited DPA molecules. The findings offer valuable guidelines for the design of high-performance plasmonic TTA-UC systems.

Published
2023
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47. One-pot C(sp 3 )-H difluoroalkylation of tetrahydroisoquinolines and isochromans via electrochemical oxidation and organozinc alkylation.

Author

Kamata K, Kuriyama M, Tahara H, Nishikawa A, Yamamoto K, Demizu Y, and Onomura O

Abstract

The C(sp 3 )-H difluoroalkylation for the introduction of carbonylated CF 2 groups into tetrahydroisoquinolines (THIQs) and isochromans has been achieved by using electrochemical oxidation and organozinc alkylation. This one-pot process proceeded smoothly under transition-metal catalyst- and chemical oxidant-free conditions, and the desired products were obtained in good to high yields with a broad scope, except for N -Boc-THIQ. In addition, the gram-scale experiment successfully demonstrated the promising scalability. This is the first example of an electrochemical method for C(sp 3 )-H difluoroalkylation of amines and ethers.

Published
2024
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