Updated on 2024/08/09

Information

 

写真a

 
NAGATA MASAKAZU
 
Organization
Institute for Advanced Study Academic Researcher
Title
Academic Researcher
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Papers

  • Development of Hydrogen-Bonded Dimer-Type Photoluminescent Liquid Crystals of Fluorinated Tolanecarboxylic Acid

    Shigeyuki Yamada, Mitsuki Kataoka, Keigo Yoshida, Masakazu Nagata, Tomohiro Agou, Hiroki Fukumoto, Tsutomu Konno

    Crystals   13 ( 1 )   25 - 25   2022.12

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    Language:Others   Publishing type:Research paper (scientific journal)  

    Functional molecules possessing photoluminescence (PL) and liquid-crystalline (LC) behaviors, known as photoluminescent liquid crystals, along with a small molecular structure, have attracted significant attention. Fluorinated tolane skeletons are small π-conjugated structures, which are promising candidates for such functional molecules. These structures were revealed to exhibit strong PL in solid state but no LC behavior. Based on a report on hydrogen-bonded dimer-type LC molecules of carboxylic acid, in this study, we designed and synthesized a series of fluorinated tolanecarboxylic acids (2,3,5,6-tetrafluoro-4-[2-(4-alkoxyphenyl)ethyn-1-yl]benzoic acids) as promising PLLC molecules. Evaluation of the LC behavior revealed that fluorinated tolanecarboxylic acids with a longer alkoxy chain than a butoxy chain exhibited nematic LC behavior. Additionally, fluorinated tolanecarboxylic acids showed intense PL in the solution and crystalline states. Notably, fluorinated tolanecarboxylic acid with an aggregated structure in the nematic LC phase also exhibited PL with a slight blue shift in PL maximum wavelength compared to the crystalline state. The present fluorinated tolanecarboxylic acid exhibiting PL and LC characteristics in a single molecule can be applied to thermoresponsive PL materials, such as a PL thermosensor.

    DOI: 10.3390/cryst13010025

  • Photophysical and thermophysical behavior of D-π-A-type fluorinated diphenylacetylenes bearing an alkoxy and an ethoxycarbonyl group at both longitudinal molecular terminals

    Shigeyuki Yamada, Mitsuki Kataoka, Keigo Yoshida, Masakazu Nagata, Tomohiro Agou, Hiroki Fukumoto, Tsutomu Konno

    Journal of Fluorine Chemistry   261-262   110032 - 110032   2022.9

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    DOI: 10.1016/j.jfluchem.2022.110032

  • Fused-Nonacyclic Multi-Resonance Delayed Fluorescence Emitter Based on Ladder-Thiaborin Exhibiting Narrowband Sky-Blue Emission with Accelerated Reverse Intersystem Crossing. International journal

    Masakazu Nagata, Hyukgi Min, Erika Watanabe, Hiroki Fukumoto, Yoshiyuki Mizuhata, Norihiro Tokitoh, Tomohiro Agou, Takuma Yasuda

    Angewandte Chemie (International ed. in English)   60 ( 37 )   20280 - 20285   2021.9

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    Language:English   Publishing type:Research paper (scientific journal)  

    Developing organic luminophores with unique capability of strong narrowband emission is both crucial and challenging for the further advancement of organic light-emitting diodes (OLEDs). Herein, a nanographitic fused-nonacyclic π-system (BSBS-N1), which was strategically embedded with multiple boron, nitrogen, and sulfur atoms, was developed as a new multi-resonance thermally activated delayed fluorescence (MR-TADF) emitter. Narrowband sky-blue emission with a peak at 478 nm, full width at half maximum of 24 nm, and photoluminescence quantum yield of 89 % was obtained with BSBS-N1. Additionally, the spin-orbit coupling was enhanced by incorporating two sulfur atoms, thereby facilitating the spin-flipping process between the excited triplet and singlet states. OLEDs based on BSBS-N1 as a sky-blue MR-TADF emitter achieved a high maximum external electroluminescence quantum efficiency of 21.0 %, with improved efficiency roll-off.

    DOI: 10.1002/anie.202108283

  • Effect of Fluoroalkyl-Substituent in Bistolane-Based Photoluminescent Liquid Crystals on Their Physical Behavior

    Shigeyuki Yamada, Yizhou Wang, Masato Morita, Qingzhi Zhang, David O’Hagan, Masakazu Nagata, Tomohiro Agou, Hiroki Fukumoto, Toshio Kubota, Mitsuo Hara, Tsutomu Konno

    Crystals   11 ( 4 )   450   2021.4

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    <jats:p>Photoluminescent liquid crystals (PLLCs) have attracted significant attention owing to their broad applicability in thermosensing and PL switching. Extensive efforts have been made to develop bistolane-based PLLCs containing flexible units at both molecular terminals, and it has been revealed that their PL behavior can switch with the phase transition between the crystalline and LC phases. Although slight modulation of the flexible unit structure dramatically alters the LC and PL behaviors, few studies into the modification of the flexible units have been conducted. With the aim of achieving dynamic changes in their physical behaviors, we developed a family of bistolane derivatives containing a simple alkyl or a fluoroalkyl flexible chain and carried out a detailed systematic evaluation of their physical behaviors. Bistolanes containing a simple alkyl chain showed a nematic LC phase, whereas switching the flexible chain in the bistolane to a fluoroalkyl moiety significantly altered the LC phase to generate a smectic phase. The fluoroalkyl-containing bistolanes displayed a stronger deep blue PL than their corresponding non-fluorinated counterparts, even in the crystalline phase, which was attributed to the construction of rigid molecular aggregates through intermolecular F···H and F···F interactions to suppress non-radiative deactivation.</jats:p>

    DOI: 10.3390/cryst11040450

  • Synthesis of Carbazole-Fused Azaborines via a Pd-Catalyzed C-H Activation-Cyclization Reaction

    Nagata Masakazu, Oshiro Taku, Mizuhata Yoshiyuki, Tokitoh Norihiro, Hosoya Takaaki, Yamada Shigeyuki, Konno Tsutomu, Fukumoto Hiroki, Kubota Toshio, Agou Tomohiro

    Bulletin of the Chemical Society of Japan   94 ( 1 )   21 - 23   2021.1

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    Language:English  

    Carbazole-fused azaborines were synthesized via a Buchwald-Hartwig amination followed by a Pd-catalyzed C-H activation-cyclization reaction. These azaborines exhibited red-shifted absorptions and photoluminescence emissions compared to those of dibenzoazaborines, suggesting the efficient HOMO-LUMO energy gap decrease by the carbazole-annulation. The carbazole-fused azaborines showed improved electrochemical stability compared with the previously reported dibenzoazaborine derivatives.

    DOI: 10.1246/bcsj.20200129

Academic Activities

  • 審査・評価

    第60回化学関連支部合同九州大会  ( Japan ) 2023.7

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    Type:Competition, symposium, etc.