研究者詳細 - 岡本　秀毅

論文 - 岡本　秀毅

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Photochemical synthesis and device application of acene–phenacene hybrid molecules, dibenzo[n]phenacenes (n = 5–7) 査読

Yanting Zhang, Ritsuko Eguchi, Shino Hamao, Kenta Goto, Fumito Tani, Minoru Yamaji, Yoshihiro Kubozono, Hideki Okamoto

Chemical Communications 57 ( 39 ) 4768 - 4771 2021年

Synthesis of [7]phenacene incorporating tetradecyl chains in the axis positions and its application in field-effect transistors 査読国際共著国際誌

Hideki Okamoto, Shino Hamao, Keiko Kozasa, Yanan Wang, Yoshihiro Kubozono, Yong-He Pan, Yu-Hsiang Yen, Germar Hoffmann, Fumito Tani, Kenta Goto

Journal of Materials Chemistry C 8 ( 22 ) 7422 - 7435 2020年

Synthesis of the extended phenacene molecules, [10]phenacene and [11]phenacene, and their performance in a field-effect transistor 査読国際共著国際誌

Hideki Okamoto, Shino Hamao, Ritsuko Eguchi, Hidenori Goto, Yasuhiro Takabayashi, Paul Yu-Hsiang Yen, Luo Uei Liang, Chia-Wei Chou, Germar Hoffmann, Shin Gohda, Hisako Sugino, Yen-Fa Liao, Hirofumi Ishii, Yoshihiro Kubozono

Scientific Reports 9 ( 1 ) 4009 - 4009 2019年12月

Solvent-induced multicolour fluorescence of amino-substituted 2,3-naphthalimides studied by fluorescence and transient absorption measurements 査読

Mayu Fujii, Misa Namba, Minoru Yamaji, Hideki Okamoto

PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES 15 ( 7 ) 842 - 850 2016年

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

A series of amino-2,3-naphthalimide derivatives having the amino functionality at 1-, 5-and 6-positions (1ANI, 5ANI and 6ANI, respectively) were prepared, and their photophysical properties were systematically investigated based on the measurements of steady-state absorption and fluorescence spectra, fluorescence lifetimes as well as transient absorption spectra. The ANIs efficiently fluoresced in solution, and the emission spectra appreciably shifted depending on the solvent polarity. 1ANI displayed only a slight fluorescence red-shift upon increasing the solvent polarity. In contrast, 5ANI and 6ANI showed marked positive solvatofluorochromism with large Stokes shifts displaying multicolour fluorescence; the fluorescence colours of 5ANI and 6ANI varied from violet-blue in hexane to orange-red in methanol. 5ANI and 6ANI, thus, serve as micro-environment responding fluorophores. In methanol, the intensity of the fluorescence emission band of 5ANI and 6ANI significantly reduced. Based on the fluorescence quantum yields and lifetimes, and transient absorption measurements, it has been revealed that internal conversion from the S-1 state of ANIs to the ground state was accelerated by the protic medium, resulting in a reduction in their fluorescence efficiency, while intersystem crossing from the S1 state to a triplet state was not responsible for the decrease of fluorescence intensity.

DOI： 10.1039/c6pp00048g

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Efficient Synthetic Photocyclization for Phenacenes Using a Continuous Flow Reactor 査読

Hideki Okamoto, Takamitsu Takane, Shin Gohda, Yoshihiro Kubozono, Kaori Sato, Minoru Yamaji, Kyosuke Satake

CHEMISTRY LETTERS 43 ( 7 ) 994 - 996 2014年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CHEMICAL SOC JAPAN

The continuous flow reaction technique has been applied to the photocyclization of 1,2-diarylethenes, the so-called Mallory reaction, to afford phenacenes in high chemical yields and efficiencies (114-288 mg h(-1)). The present technique will allow us to produce several grams of phenacenes at a time.

DOI： 10.1246/cl.140182

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An Extended Phenacene-type Molecule, [8] Phenacene: Synthesis and Transistor Application 査読

Hideki Okamoto, Ritsuko Eguchi, Shino Hamao, Hidenori Goto, Kazuma Gotoh, Yusuke Sakai, Masanari Izumi, Yutaka Takaguchi, Shin Gohda, Yoshihiro Kubozono

SCIENTIFIC REPORTS 4 5330-1-5330-8 2014年6月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

A new phenacene-type molecule, [8] phenacene, which is an extended zigzag chain of coplanar fused benzene rings, has been synthesised for use in an organic field-effect transistor (FET). The molecule consists of a phenacene core of eight benzene rings, which has a lengthy pi-conjugated system. The structure was verified by elemental analysis, solid-state NMR, X-ray diffraction (XRD) pattern, absorption spectrum and photoelectron yield spectroscopy (PYS). This type of molecule is quite interesting, not only as pure chemistry but also for its potential electronics applications. Here we report the physical properties of [8] phenacene and its FET application. An [8] phenacene thin-film FET fabricated with an SiO2 gate dielectric showed clear p-channel characteristics. The highest m achieved in an [8] phenacene thin-film FET with an SiO2 gate dielectric is 1.74 cm(2) V-1 s(-1), demonstrating excellent FET characteristics; the average mu was evaluated as 1.2(3) cm(2) V-1 s(-1). The mu value in the [8] phenacene electric-double-layer FET reached 16.4 cm(2) V-1 s(-1), which is the highest reported in EDL FETs based on phenacene-type molecules; the average m was evaluated as 8(5) cm(2) V-1 s(-1). The mu values recorded in this study show that [8] phenacene is a promising molecule for transistor applications.

DOI： 10.1038/srep05330

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Transistor application of alkyl-substituted picene 査読

Hideki Okamoto, Shino Hamao, Hidenori Goto, Yusuke Sakai, Masanari Izumi, Shin Gohda, Yoshihiro Kubozono, Ritsuko Eguchi

SCIENTIFIC REPORTS 4 5408-1-5408-6 2014年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

Field-effect transistors (FETs) were fabricated with a thin film of 3,10-ditetradecylpicene, picene-(C14H29)(2), formed using either a thermal deposition or a deposition from solution (solution process). All FETs showed p-channel normally-off characteristics. The field-effect mobility, m, in a picene-(C14H29)(2) thin-film FET with PbZr0.52Ti0.48O3 (PZT) gate dielectric reached similar to 21 cm(2) V-1 s(-1), which is the highest mu value recorded for organic thin-film FETs; the averagem mu value (<mu >) evaluated from twelve FET devices was 14(4) cm(2)V(-1) s(-1). The, m. values for picene-(C14H29)(2) thin- film FETs with other gate dielectrics such as SiO2, Ta2O5, ZrO2 and HfO2 were greater than 5 cm(2) V-1 s(-1), and the lowest absolute threshold voltage, vertical bar V-th vertical bar, (5.2 V) was recorded with a PZT gate dielectric; the average jVthj for PZT gate dielectric is 7(1) V. The solution-processed picene-(C14H29)(2) FET was also fabricated with an SiO2 gate dielectric, yielding mu = 3.4 x 10(-2) cm(2) V-1 s(-1). These results verify the effectiveness of picene-(C14H29)(2) for electronics applications.

DOI： 10.1038/srep05048

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S-2 fluorescence from picene vapor 査読

Takao Itoh, Minoru Yamaji, Hideki Okamoto

CHEMICAL PHYSICS LETTERS 570 26 - 28 2013年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Fluorescence, fluorescence excitation and absorption spectra of picene have been measured in the vapor phase. It is shown that picene vapor exhibits weak fluorescence from the S-2(pi, pi*) state in addition to strong S-1(pi, pi*) fluorescence. The S-2/S-1 fluorescence yield ratio is evaluated to be approximately 1.3 x 10(-2) following the excitation into the S-3 state. It is shown that the relative S-2 fluorescence quantum yield increases with increasing excitation energy, while the S-1 fluorescence yield is nearly invariant. Mechanism of the appearance of the S-2 fluorescence of picene vapor is discussed. (c) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.cplett.2013.03.055

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Photochemical synthesis and electronic spectra of fulminene ([6]phenacene) 査読

Hideki Okamoto, Minoru Yamaji, Shin Gohda, Kaori Sato, Hisako Sugino, Kyosuke Satake

RESEARCH ON CHEMICAL INTERMEDIATES 39 ( 1 ) 147 - 159 2013年1月

担当区分：筆頭著者,　責任著者記述言語：英語出版者・発行元：SPRINGER

Facile synthesis of fulminene ([6]phenacene) was achieved through the Mallory reaction of 1-(1-naphthyl)-2-(1-phenanthryl)ethene or the 9-fluorenone-sensitized photo-ring-closure of 1-(1-naphthyl)-2-(1-phenanthryl)ethane. The electronic spectral properties of fulminene were investigated for the first time using photoluminescence as well as transient absorption spectroscopy. The spectral features were compared with those of a series of lower phenacene homologs such as phenanthrene ([3]phenacene), chrysene ([4]phenacene), and picene ([5]phenacene). For the [n]phenacene series, both the fluorescence and phosphorescence bands linearly red-shifted with an increase in the number of the benzene rings (n). Trends in the energy levels of the excited singlet (E (S)) and the triplet (E (T)) states were expressed as E (s) = -2.6n + 89.1 (kcal mol(-1)) and E (T) = -1.8n + 66.2 (kcal mol(-1)), respectively. In the case of fulminene, laser flash photolysis displayed a transient spectrum with an absorption maximum (lambda (max) (T-T) ) at 675 nm, which was assigned as the triplet fulminene excited state. The lambda (max) (T-T) values for the [n]phenacene series showed a linear correlation as a function of the ring number n, given by an equation, lambda (max) (T-T) = 60n + 318 (nm).

DOI： 10.1007/s11164-012-0639-1

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Fabrication of high performance/highly functional field-effect transistor devices based on [6]phenacene thin films 査読

Ritsuko Eguchi, Xuexia He, Shino Hamao, Hidenori Goto, Hideki Okamoto, Shin Gohda, Kaori Sato, Yoshihiro Kubozono

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 15 ( 47 ) 20611 - 20617 2013年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Field-effect transistors (FETs) based on [6]phenacene thin films were fabricated with SiO2 and parylene gate dielectrics. These FET devices exhibit field-effect mobility in the saturation regime as high as 7.4 cm(2) V-1 s(-1), which is one of the highest reported values for organic thin-film FETs. The two- and four-probe mobilities in the linear regime display nearly similar values, suggesting negligible contact resistance at 300 K. FET characteristics were investigated using two-probe and four-probe measurement modes at 50-300 K. The two-probe mobility of the saturation regime can be explained by the multiple shallow trap and release model, while the intrinsic mobility obtained by the four-probe measurement in the linear regime is better explained by the phenomenon of transport with charge carrier scattering at low temperatures. The FET device fabricated with a parylene gate dielectric on polyethylene terephthalate possesses both transparency and flexibility, implying feasibility of practical application of [6] phenacene FETs in flexible/transparent electronics. N-channel FET characteristics were also achieved in the [6] phenacene thin-film FETs using metals that possess a small work function for use as source/drain electrodes.

DOI： 10.1039/c3cp53598c

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Facile Synthesis of Picene from 1,2-Di(1-naphthyl)ethane by 9-Fluorenone-Sensitized Photolysis 査読

Hideki Okamoto, Minoru Yamaji, Shin Gohda, Yoshihiro Kubozono, Noriko Komura, Kaori Sato, Hisako Sugino, Kyosuke Satake

ORGANIC LETTERS 13 ( 10 ) 2758 - 2761 2011年5月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

A facile formation of picene was achieved by photosensitization of 1,2-di(1-naphthyl)ethane using 9-fluorenone as a sensitizer. This sensitized photoreaction is the first photochemical cyclization of ethylene-bridged naphthalene moieties to afford the picene skeleton. 5,8-Dibromopicene, prepared by this procedure using 1,2-di[1-(4-bromonaphthyl)]ethane as the substrate, was readily converted to novel functionalized picenes by conventional substitution and cross-coupling reactions.

DOI： 10.1021/ol200874q

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Superconductivity in alkali-metal-doped picene 査読

Ryoji Mitsuhashi, Yuta Suzuki, Yusuke Yamanari, Hiroki Mitamura, Takashi Kambe, Naoshi Ikeda, Hideki Okamoto, Akihiko Fujiwara, Minoru Yamaji, Naoko Kawasaki, Yutaka Maniwa, Yoshihiro Kubozono

NATURE 464 ( 7285 ) 76 - 79 2010年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：NATURE PUBLISHING GROUP

Efforts to identify and develop new superconducting materials continue apace, motivated by both fundamental science and the prospects for application. For example, several new superconducting material systems have been developed in the recent past, including calcium-intercalated graphite compounds(1), boron-doped diamond(2) and-most prominently-iron arsenides such as LaO(1-x)F(x)FeAs (ref. 3). In the case of organic superconductors, however, no new material system with a high superconducting transition temperature (T(c)) has been discovered in the past decade. Here we report that intercalating an alkali metal into picene, a wide-bandgap semiconducting solid hydrocarbon, produces metallic behaviour and superconductivity. Solid potassium-intercalated picene (K(x)picene) shows T(c) values of 7K and 18 K, depending on the metal content. The drop of magnetization in Kxpicene solids at the transition temperature is sharp (<2 K), similar to the behaviour of Ca-intercalated graphite(1). The Tc of 18K is comparable to that of K-intercalated C(60) (ref. 4). This discovery of superconductivity in K(x)picene shows that organic hydrocarbons are promising candidates for improved T(c) values.

DOI： 10.1038/nature08859

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Air-assisted high-performance field-effect transistor with thin films of picene 査読

Hideki Okamoto, Naoko Kawasaki, Yumiko Kaji, Yoshihiro Kubozono, Akihiko Fujiwara, Minoru Yamaji

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 130 ( 32 ) 10470 - + 2008年8月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

A field-effect transistor (FET) with thin films of picene has been fabricated on SiO(2) gate dielectric. The FET showed p-channel enhancement-type FET characteristics with the field-effect mobility, mu, of 1.1 cm(2) V(-1) s(-1) and the on-off ratio of >10(5). This excellent device performance was realized under atmospheric conditions. The p increased with an increase in temperature, and the FET performance was improved by exposure to air or O(2) for a long time. This result implies that this device is an air (O(2))-assisted FET. The FET characteristics are discussed on the basis of structural topography and the energy diagram of picene thin films.

DOI： 10.1021/ja803291a

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Fluorescence response of a 4-trifluoroacetylaminophthalimide to iodide ions upon 254 nm irradiation in MeCN 査読

Hideki Okamoto, Hiroyuki Konishi, Mami Kohno, Kyosuke Satake

ORGANIC LETTERS 10 ( 14 ) 3125 - 3128 2008年7月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

The title trifluoroacetylaminophthalimide derivative produced a violet fluorescence (lambda(FL)(max) 392 nm) in MeCN, and it displayed a green emission (lambda(FL)(max) 506 nm) after irradiation at 254 nm in the presence of iodide ions. The corresponding amidate ion of the trifluoroacetamide was identified as the green fluorescence emitter. The deprotonation reaction may be caused by proton-abstracting solvated electrons generated by a photochemical charge-transfer-to-solvent process from I(-) to MeCN.

DOI： 10.1021/ol801184x

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Photoreaction of a 2,11-diaza[3.3]paracyclophane derivative: Formation of octahedrane by photochemical dimerization of benzene 査読

Hideki Okamoto, Kyosuke Satake, Hiroyuki Ishida, Masaru Kimura

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 128 ( 51 ) 16508 - 16509 2006年12月

Triplet-sensitized photolysis of the photoisomer of a 2,11-diaza[3,3](9,10)anthracenoparacyclophane: An adiabatic cycloreversion and a [2 pi a+2 pi a+2 sigma s] rearrangement in a triplet state of the biplanophane system 査読

H Okamoto, M Yamaji, K Satake, S Tobita, M Kimura

JOURNAL OF ORGANIC CHEMISTRY 69 ( 23 ) 7860 - 7868 2004年11月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

The triplet-sensitized photoreactions of the title biplanophane system 6, the photoisomer of a 2,11diaza[3,31(9,10)anthracenoparacyclophane derivative 5, were investigated by stationary and laserflash photolyses using xanthone (XT) and benzophenone (BP) as triplet sensitizers. Vaen photoisomer 6 underwent XT-sensitized irradiation, a triplet cyclophane 5 and a novel polycyclic product 7 were obtained via an adiabatic cycloreversion and a formal [2pia + 2 pia + 2sigmas] rearrangement, respectively. The maximum quantum yield for the formation of cyclophane 5 (0.69) and the upper-limit efficiency for the formation of polycycle 7 (0.31) were determined by laser photolysis techniques. For BP-sensitized photolysis of photoisomer 6, oxetane 8, in addition to triplet cyclophane 5 and polycycle 7, was formed by a Paterno-Biichi reaction. The quenching rate constant (k(q)) of triplet BP by photoisomer 6 (3.4 x 10(8) dm(3) Mol(-1) s(-1)) was found to be 1 order of magnitude smaller than that for XT (5.0 x 10(9) dm(3) mol(-1) s(-1)). On the basis of the relationship between k(q) and the triplet donor-acceptor energy gap, the triplet energy level of photoisomer 6 was estimated to be similar to71 kcal mol(-1). The photochemical and the photophysical processes involved in the sensitized photolyses are summarized in an energetic reaction diagram and discussed in detail.

DOI： 10.1021/jo048757m

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Highly emissive and robust diarylethene fluorophore incorporating imide-fused phenanthryl moieties 査読

Keito Nose, Minoru Yamaji, Tadashi Mori, Fumito Tani, Kenta Goto, Hideki Okamoto

Chemistry Letters 54 ( 5 ) 2025年5月

担当区分：責任著者掲載種別：研究論文（学術雑誌）出版者・発行元：Oxford University Press (OUP)

Abstract

The fluorescence properties and photostabilities of (E)-diarylethenes (DPEs), featuring two 3-phenanthryl moieties, were investigated. Pristine (E)-di-1,2-(3-phenanthryl)ethene and its ester derivative, respectively referred to as DPE-H and DPE-E, exhibited blue fluorescence. However, they underwent a two-step photoreaction sequence that yielded [7]helicenes, resulting in a gradual reduction of the fluorescence intensity. In contrast, the imide-fused derivative DPE-I displayed intense green fluorescence and it was unexpectedly photostable in solution, maintaining its highly efficient fluorescent nature even after prolonged light exposure. DPE-I, thus, provides a new type of highly efficient and robust diarylethene fluorophore.

DOI： 10.1093/chemle/upaf091

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Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra 査読

Yuuki Ishii, Minoru Yamaji, Fumito Tani, Kenta Goto, Yoshihiro Kubozono, Hideki Okamoto

Beilstein Journal of Organic Chemistry 21 670 - 679 2025年3月

担当区分：責任著者掲載種別：研究論文（学術雑誌）出版者・発行元：Beilstein Institut

[n]Phenacenes ([n] = 5–7), octafluorinated at the terminal benzene rings (F₈-phenacenes: F₈PIC, F₈FUL, and F₈7PHEN), were photochemically synthesized, and their electronic spectra were investigated to reveal the effects of the fluorination on the electronic features of phenacene molecules. F₈-Phenacenes were conveniently synthesized by the Mallory photoreaction of the corresponding fluorinated diarylethenes as the key step. Upon fluorination on the phenacene cores, the absorption and fluorescence bands of the F₈-phenacenes in CHCl₃ systematically red-shifted by ca. 3–5 nm compared to those of the corresponding parent phenacenes. The vibrational progressions of the absorption and fluorescence bands were little affected by the fluorination in the solution phase. In the solid state, the absorption band of F₈-phenacenes appeared in the similar wavelength region for the corresponding parent phenacenes whereas their fluorescence bands markedly red-shifted and broadened. These observations suggest that the intermolecular interactions of excited-state F₈-phenacene molecules are significantly different from those of the corresponding parent molecules, most likely due to different crystalline packing motifs.

DOI： 10.3762/bjoc.21.53

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その他リンク： https://www.beilstein-journals.org/bjoc/content/pdf/1860-5397-21-53.pdf

Biosensor Application of CMOS Inverter and Ring Oscillator with Organic Field-Effect Transistors 査読

Masaki Utsumi, Akihiko Fujiwara, Hidenori Goto, Hideki Okamoto, Nobuyuki Takeyasu, Yasunori Saitoh, Michihiro Suga, Yuichiro Takahashi, Hiroyuki Imanaka, Hiroki Taniguchi, Shintaro Yasui, Ritsuko Eguchi, Yoshihiro Kubozono

ACS Applied Electronic Materials 2025年2月

Solid-State Photoluminescence of Diphenylnaphthalenes Studied by Photophysical Measurements and Crystallographic Analysis 査読国際誌

29 ( 24 ) 5941 2024年12月

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