研究成果

ピロロピロールとトリス(ペンタフルオロフェニル)ボランから構成される超分子複合体の結晶化誘起発光特性

Tris(pentafluorophenyl)borane-pyrrole[3,2-b]pyrrole hybrids: Studies on the solid-state structure and the crystallization-induced enhanced emission

Sou Hatanaka, Toshikazu Ono, Yoshio Yano, Daniel T. Gryko, Yoshio Hisaeda

ChemPhotoChem, 2019, in press. 

シアノ基を含むピロロピロール誘導体とトリス(ペンタフルオロフェニル)ボランのホウ素ー窒素結合を介した超分子複合体を溶液中での反応およびボールミルを用いた固相合成を用いて調製しました。複合体形成による発光波長の長波長化を達成するとともに、また固体状態では分子配列やC-H•••F水素結合の働きにより、結晶化誘起発光を示すことを見出しました。複合体は非極性溶媒中で比較的安定に存在することも明らかとしました。
本研究は、ポーランド科学アカデミーのDaniel T. Gryko教授との共同研究の成果です。

This paper demonstrates that the quadrupolar nature of acceptor‐donor‐acceptor pyrrolo[3,2‐b]pyrrole systems can be substantially modified via the formation of boron–nitrogen (B–N) bonds between peripheral CN groups and B(C6F5)3. This coordination enables a strong bathochromic shift of emission for both the solid crystalline state as well as in certain solvents. The B–N complex, or co‐crystal, was effectively isolated from the reaction between a pyrrolo[3,2‐b]pyrrole with two cyanophenyl moieties and tris(pentafluorophenly)borane (TPFB), which were mixed in non‐polar solvents or prepared via liquid‐assisted solid‐state synthesis in a ball mill. An investigation of the structure­–property relationship confirmed that the intermolecular B–N bond influences the bathochromic shift in the absorption and emission spectra and that crystallization induced emission enhancement was observed owing to the benefits of the molecular packing style and the intermolecular C–H•••F interactions. The postsynthetic strategy involves hybridization of molecules on a molecular level, which should provide a variety of novel photofunctional materials.

酸化還元活性なメゾ置換ポルフィセンを配位子とするコバルト錯体の電気化学特性と触媒反応活性

Electrochemical properties and catalytic reactivity of cobalt complexes with redox-active meso-substituted porphycene ligands

Taro Koide, Zihan Zhou, Ning Xu, Yoshio Yano, Toshikazu Ono, Zhongli Luo, Hisashi Shimakoshi and Yoshio Hisaeda

Journal of Porphyrins and Phthalocyanines, 2019, in press.

https://doi.org/10.1142/S1088424619500780

酸化還元活性なメゾ置換ポルフィセンを配位子とするコバルト錯体の電気化学特性と触媒反応に関する論文がJournal of Porphyrins and Phthalocyaninesに掲載されました。

これまでの研究から、ポルフィセンコバルト錯体を還元すると、中心コバルトではなく配位子であるポルフィセンが還元されラジカルアニオンが生成し、ハロゲン化アルキルと反応してコバルトー炭素結合を生成することを明らかにしていました。本論文では、ポルフィセンの周辺修飾による電位制御によって錯体の反応性を変化させるとともに、触媒反応への応用について報告しました。触媒反応においても、反応に用いる還元電位が変化することによって生成物比率も変化することを明らかとしました。

 

The cobalt complexes of meso-aryl substituted porphycenes were synthesized and characterized. The reduction potentials of the complexes were shifted to the positive side depending on the strength of the electron-withdrawing properties of the meso-substituents, while the optical properties, such as the absorption spectra of these complexes, were similar. This suggests that the energy levels of the molecular orbitals of the complexes were changed by the meso-substituents while the gaps of the orbitals were not significantly changed. The one-electron reduction of the complex did not afford the Co(I) species, but the ligand-reduced radical anion, which was characterized by electrospectrochemistry. The generated ligand-reduced species reacted with alkyl halides to form the Co(III)-alkyl complex. As a result, the reduction potential of the electrolytic reaction could be directly controlled by the substituents of the porphycene. The catalytic reaction with trichloromethylbenzene was also performed and it was found that the ratio of the obtained products was changed by the reduction potentials of the catalyst, . the cobalt porphycenes.

レドックス活性なイオン液体の開発

 

Redox active ionic liquid as efficient mediator and solvent for visible light-driven B12 catalytic reaction

H. Shimakoshi, N. Houfuku, C. Chen, Yoshio Hisaeda

Green Energy & Environment., 2019, 4, 116-120. (Front Cover)

イオン液体は、その多彩なデザイン性と特異な物性から、新しい機能性液体として様々な用途で使用されています。特に電気化学の分野では、良好なイオン伝導性と広い電気化学窓を有することより、電解液として利用されています。これらの用途では、イオン液体は溶媒や反応場としてのみ利用されており、イオン液体の持つ性質を十分には引き出していないとも言えます。我々は、ピリジニウム系イオン液体を連結させた構造であるメチルビオローゲンが良好な電子メディエーター能を有する点に着目し、その半構造であるピリジニウム系イオン液体が、同様に電子メディエーターを有し、様々な電子移動システムに応用出来るのではないかと考え、レドックス活性なイオン液体開発を行いました。本論文は、Green Energy & Environment 誌のイオン液体特集号のBack coverに採択され、とても高い評価を受けました。本研究は、法福紀之君(修士)と分子システム化学国際コース二期生の陳麗さん(博士)の研究成果です

We report a development of redox active ionic liquid used as the solvent and mediator for a visible light driven catalytic reaction by the B12 complex. The present study will provide a useful guidepost for the novel function of ionic liquid in the catalytic chemistry.

ナフタレンジイミド誘導体を用いたセンサーアレイによる有機化合物の高感度検出法の開発

Inclusion crystals as vapochromic chemosensors: fabrication of a mini-sensor array for discrimination of small aromatic molecules baased on side-chain engineering of naphthalenediimide derivatives

Toshikazu Ono, Yoshifumi Tsukiyama, Sou Hatanaka, Yuma Sakatsume, Tomoki Ogoshi, Yoshio Hisaeda

J. Mater. Chem. C. 2019, 7, 9726-9734. 

ナフタレンジイミド誘導体を用いた有機化合物に対するベイポクロミック材料の開発に関する報告です。側鎖修飾の違いによって、固気界面の分子認識能を大きくチューニングすることが可能なことを見出しました。以前に報告した論文(Chem. Eur. J. 2016, 22, 10346)の続報となります。本論文は、京都大学の生越教授との共同研究の成果です。

Vapochromism, chromism induced by vapor desorption/absorption, has received considerable attention in recent years due to its potential applications in chemical sensors for toxic gases and vapors. In this paper, a set of naphthalene diimide (NDI) derivatives with various bulky groups is investigated for chromogenic and fluorogenic detection of small aromatic molecules in the vapor phase. Among the studied compounds, NDI with a 2-benzophenone unit in its structure exhibited a unique vapochromic/vapoluminescent behavior toward toluene, p-xylene, 4-fluorotoluene, and anisole. Detection limits in the parts-per-million (ppm) range are accomplished with some compounds. Optical measurements and X-ray crystal structure analyses clearly suggested that intermolecular charge-transfer interactions between the electron-deficient NDI and the electron-rich aromatic guest molecules as well as the inherent porosity of the sensor materials contribute to their unique sensing abilities. Discrimination of xylene isomers was demonstrated by taking advantage of selective inclusion phenomena. Two binary sensor ensembles, including our previously reported NDI derivative, enable the construction of a mini-sensor array that can be used to discriminate benzene derivatives—including xylene isomers—with the naked eye. The present simple, low-cost, metal-free, and effective sensor materials may promote practical applications with advantages relative to other known sensor materials.

 

ジピロエテンの酸化カップリングを利用した非対称ポルフィセンの合成とその光・電気化学特性

Symmetry reduction of porphycenes with finely tuned optical and electronic properties through oxidative cyclization of E/Z-mixed dipyrroethenes

Ning Xu, Toshikazu Ono, Yoshio Hisaeda

Chem. Eur. J. 2019, 25, 11680-11687.

ジピロエテンを前駆体とした非対称ポルフィセンの合成法に関する報告です。光物性、電気化学特性も併せて評価を行いました。以前に報告した、グラムスケールポルフィセン合成法の開発に関する研究(RSC Adv. 2018, 8, 39269-39273)の続報となります。

The main obstacle to a widespread application of porphycenes lies in the lack of efficient and economical method of their production. Discovery of new synthetic methodology of porphycene derivatives are important for fine‐tuning of optical and electrochemical properties. Herein, the preparation of a set of AABB‐, ABAB‐, and ABBA‐type meso‐tetrasubstituted unsymmetric porphycenes is reported. Their synthesis involved the acid‐catalyzed oxidative coupling of AA‐ and BB‐dipyrroethenes, or AB‐type dipyrroethenes, as precursors in yields of up to 19%. The structures were unambiguously confirmed by X‐ray crystallography. The type and position of substituents in the unsymmetric porphycenes enabled fine‐tuning of the optical and electronic properties, which are discussed using UV/vis absorption, fluorescence spectroscopies, cyclic voltammetry, and density functional theory calculations.

塩ー共結晶連続体を活用した光機能性材料:ピリジン修飾ICT色素と酸複合体による外部刺激応答材料

Salt–cocrystal continuum for photofunction modulation: Stimuli-responsive fluorescence color-tuning of pyridine modified intramolecular charge-transfer dyes and acid complexes

Yoshio Yano, Toshikazu Ono, Sou Hatanaka, Daniel T. Gryko, Yoshio Hisaeda

J. Mater. Chem. C. 2019, 7, 8847-8854. (Inside Back Cover)

本研究では、ピリジンを含む有機色素と有機酸との酸ー塩基複合体を調製し、その固体発光色が有機色素へのプロトン化度の違いにより制御可能なことを見出しました。プロトン化度の違いは、酸と塩基のpKaの差(ΔpKa)および結晶構造に決定付けられます。中でも0 < ΔpKa < 3の領域が共結晶になるか塩になるかの不安定領域であることに着目し、これを溶媒分子の吸脱着を刺激とすることでプロトン化度の切り替えを生じ、結果としてその固体発光色制御が可能なことを見出しました。塩ー共結晶連続体を利用した新たな材料設計の報告です。
本研究は、ポーランド科学アカデミーのDaniel T. Gryko教授との共同研究の成果です。本研究は高い評価を受け、Inside Back Coverに選ばれました。

The regulation of proton transfer dynamics between acid–base complexes is of significant interest in the pharmaceutical industry and materials chemistry. However, the extent of proton transfer in the solid state is difficult to predict, and identifying the salts (protonation), cocrystals (hydrogen bond), and salt–cocrystal continuum (partially protonated states) remain challenging topics. Here we report the three states (salts/cocrystals/salt–cocrystal continuum) can be distinguished by photoluminescent color changes based on acid–base complexes consisting of a pyridine-modified pyrrolopyrrole dye and organic acids. Structure-property relationships of 10 complexes indicated that ΔpKa value (pKa (protonated base) – pKa (acid)) and the crystalline environment determine the extent of proton transfer, which governs the intramolecular charge–transfer (ICT) strength of the complexes and tunes the photoluminescence properties. Enhancement of the ICT strength leads to a bathochromic shift of emission from blue to green to yellow under UV-light. The salt–cocrystal continuum (0 < ΔpKa < 3) showed vapochromism/vapofluorochromism against CH2Cl2, owing to the extent of proton transfer from the acid to the pyridine moiety of the dye being modulated by inclusion and desorption of CH2Cl2. This study suggests that the rational design of photoluminescence acid–base complexes is useful for obtaining novel photofunctional materials.

ビタミンB12酵素反応に学ぶ電解ジフルオロアルキル化反応

Learning from Vitamin B12-mediated reactions: Cobalt(III)–carbon bond‐assisted catalytic C–H difluoroacylation of (hetero)arenes by controlled‐potential electrolysis

Md. J. Hossain, Toshikazu Ono, Yoshio Yano, Yoshio Hisaeda

ChemElectroChem, 2019, in press. (Front Cover, Cover Profile)

This paper is dedicated to special collections for  “Organic Electrosynthesis”, Guest Editors: Profs.Robert Francke, Dan Little, and Shinsuke Inagi.

有機化合物へのジフルオロアルキル基の導入は、医薬品、農薬、機能性材料等の開発の観点から重要です。本研究では、ビタミンB12酵素反応に学び、電解ジフルオロアルキル化反応を達成しました。以前に報告したビタミンB12を用いた電解トリフルオロメチル化反応、パーフルオロアルキル化反応 (Chem. Commun., 2017, 53, 10878-10881)の続報となります。

The synthesis of difluoromethylated (CF2R) (R = H, alkyl/aryl, CO2R, etc) compounds has received considerable attention in recent years. In this study, the cobalt(III)–carbon bond‐mediated catalytic C–H difluoroacylation of unactivated arenes and heteroarenes using BrCF2CO2Et is reported. This catalytic cycle is based on a valence change of the cobalt catalyst, a naturally derived vitamin B12 derivative, driven by controlled‐potential electrolysis at ‐0.8 V vs. Ag/AgCl under visible‐light irradiation in DMSO. A broad substrate scope is demonstrated and two compounds were characterized by X‐ray crystal structures. Mechanistic studies showed that the reaction proceeds through a radical pathway mediated by homolytic cleavage of the cobalt(III)–carbon bond. Over 100 turnover number was observed due to the inherent stability of vitamin B12 framework. This naturally derived catalytic system has potential applications in medicinal chemistry and materials science.

超分子集積化技術を利用した多色・白色発光材料の開発

Flexible-Color Tuning and White-Light Emission in Three-, Four-, and Five-component Host/Guest Co-crystals by Charge–Transfer Emissions as well as Effective Energy Transfers

Toshikazu Ono, Yoshio Hisaeda

J. Mater. Chem. C, 2019, 7, 2829-2842. (Front Cover, Hot Paper)

本研究では、3成分、4成分、5成分結晶の創製を通じて、励起光照射下にて多色・白色発光を示す超分子発光体の開発を行いました。ナフタレンジイミド誘導体(NDI)とトリスペンタフルオロフェニルボラン(TPFB)から形成される超分子ホスト(NDI-TPFB)が、複数種の芳香族ゲストを取り込み、結晶を生成します。得られた多成分結晶は、NDIとゲストの間で発光性電荷移動錯体を形成し、取り込むゲスト分子の種類に依存して青色〜近赤外発光を示します。水色と橙色発光を示すゲスト分子を混合することで、白色発光が得られることを見出しました。本論文は高い評価を受け、J. Mater. Chem. C誌の表紙絵に採択され、Hot Paperに選出されました。

Three-, four-, and five-component host/guest crystals with multi-color and white light emission is described. Our strategy is based on confinement of aromatic donor guests in supramolecular acceptor hosts. The supramolecular acceptor hosts (NDI–TPFB) were composed of N,N’-dipyrid-3-yl-1,4,5,8-naphthalenediimide (NDI) with two tris(pentafluorophenyl)borane (TPFB) linked by boron–nitrogen dative bonds as Lewis acid–base pairs, which spontaneously formed upon mixing the components. In the first part, a set of three-component crystals with 14 different aromatic guests were characterized to elucidate the structure–property relationships. In the latter part, a series of 17 types of four- and five-component crystals were formed with the use of binary or ternary guest inclusion systems, and their structural and photophysical properties were investigated. Among them, 14 types of crystals were formed effectively without destroying the crystal structure, as determined by X-ray diffraction and fluorescence microscope. Notably, flexible color tuning, including white light emission, was realized by tuning the guest ratio and the combinations. Various intermolecular interactions such as C–H•••F interactions, π-π stacking, charge-transfer interactions, and inclusion phenomena were important to forming the crystals. This approach yields a rational solution of multicomponent crystals could be potentially useful for obtaining novel photofunctional solid-state systems.

 

空気と可視光を資源とする有用化合物合成

Visible Light-driven One-pot Amide Synthesis Catalyzed by the B12 Model Complex under Aerobic Conditions

Hui Tian, Hisashi Shimakoshi, Toshikazu Ono, Yoshio Hisaeda

ChemPlusChem, 2019, 84, 237-240.

DOI: 10.1002/cplu.201800522

本研究では、可視光を駆動力とし、空気中の酸素を酸素源として、有害なトリクロロメチル化合物からワンポットで、有用なアミド化合物を合成する手法を見出しました。触媒には天然由来のビタミンB12の誘導体を用い、クーリンで高効率な反応システムの開発に成功しました。本論文は、Front coverに採択され、またeditor’s choiceに選出され、とても高い評価を受けました。本研究は、分子システム化学国際コース一期生の田輝さん(博士)の研究成果です。

A visible light responsive catalytic system with the B12 complex as the catalyst and [Ir(dtbbpy)(ppy)2]PF6 as the photosensitizer was developed, which provides a convenient and efficient way for the amide synthesis.  Based on this method, trichlorinated organic compounds were converted to amides in the presence of an amine under aerobic conditions at room temperature in an one-pot procedure.  As this protocol is free from hazardous reagents, extra additives, noble metals, and dangerous gas, the present method provides a novel and efficient approach for the amide synthesis under mild and easily controlled conditions.

グラムスケールのポルフィセン合成法の開発

Gram-scale synthesis of porophycene derivatives by oxidative macrocyclizations of E/Z-mixed 5,6-diaryldipyrroethenes 

Toshikazu Ono, Ning Xu, Daiki Koga, Toshihiro Ideo, Manabu Sugimoto, Yoshio Hisaeda

RSC Adv. 2018, 8, 39269-39273. (Open Access)

グラムスケールのポルフィセン合成法に関する報告です。5,6-ジアリルジピロロエテンを前駆体とし、酸触媒と酸化剤を最適化することにより、3段階合成で総収率20%を超えるポルフィセン誘導体の合成を達成しました。熊本大学の杉本先生との共同研究の成果です。Open Accessの論文です。

The gram-scale production of porphycene derivatives is reported. This has been achieved by acid-catalyzed ring closure of an E/Z-mixture of 5,6-diaryldipyrroethenes, resulting in the formation of meso-tetraarylporphycenes in yields of up to 80%. E/Z-isomerization of the 5,6-diaryldipyrroethenes under acidic conditions was key to proceed the effective macrocyclization.

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