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Sayaka Nagai - One of the best experts on this subject based on the ideXlab platform.

  • sequential halochromic mechanochromic luminescence of pyridyl substituted solid state emissive dyes thermally controlled stepwise recovery of the original Emission Color
    CrystEngComm, 2019
    Co-Authors: Suguru Ito, Chika Nishimoto, Sayaka Nagai
    Abstract:

    Stimuli-responsive organic dyes that switch the Color of their solid-state Emission upon exposure to external stimuli represent an important class of materials due to their potential applications in various areas of sensing technology. Although an increasing number of multi-stimuli-responsive organic dyes have been reported in recent years, only a few solid-state fluorophores are known to respond to two kinds of stimuli in a stepwise and reversible manner. Herein, we report the sequential halochromic (acidochromic)/mechanochromic luminescence behavior of a pyridyl-substituted solid-state fluorophore. The solid-state Emission Color of this pyridyl-substituted dye was systematically shifted in the bathochromic direction by forming cocrystals with several benzoic acid derivatives that exhibit different pKa values. Upon grinding these cocrystals with a spatula, further bathochromic shifts of their maximum Emission wavelengths were observed upon amorphization. Conversely, the Emission Color and crystallinity can be recovered upon heating the ground samples of the cocrystals to their cold-crystallization transition temperature (Tc ∼ 100 °C). Heating the ground cocrystals further (185–260 °C) removes the benzoic acid derivatives, which restores the original Emission Color of the pyridyl-substituted dye. In other words, we have developed a new system that exhibits a two-step Emission Color recovery in response to temperature by combining halochromic and mechanochromic luminescence in series.

  • Sequential halochromic/mechanochromic luminescence of pyridyl-substituted solid-state emissive dyes: thermally controlled stepwise recovery of the original Emission Color
    CrystEngComm, 2019
    Co-Authors: Suguru Ito, Chika Nishimoto, Sayaka Nagai
    Abstract:

    Stimuli-responsive organic dyes that switch the Color of their solid-state Emission upon exposure to external stimuli represent an important class of materials due to their potential applications in various areas of sensing technology. Although an increasing number of multi-stimuli-responsive organic dyes have been reported in recent years, only a few solid-state fluorophores are known to respond to two kinds of stimuli in a stepwise and reversible manner. Herein, we report the sequential halochromic (acidochromic)/mechanochromic luminescence behavior of a pyridyl-substituted solid-state fluorophore. The solid-state Emission Color of this pyridyl-substituted dye was systematically shifted in the bathochromic direction by forming cocrystals with several benzoic acid derivatives that exhibit different pKa values. Upon grinding these cocrystals with a spatula, further bathochromic shifts of their maximum Emission wavelengths were observed upon amorphization. Conversely, the Emission Color and crystallinity can be recovered upon heating the ground samples of the cocrystals to their cold-crystallization transition temperature (Tc ∼ 100 °C). Heating the ground cocrystals further (185–260 °C) removes the benzoic acid derivatives, which restores the original Emission Color of the pyridyl-substituted dye. In other words, we have developed a new system that exhibits a two-step Emission Color recovery in response to temperature by combining halochromic and mechanochromic luminescence in series.

Suguru Ito - One of the best experts on this subject based on the ideXlab platform.

  • sequential halochromic mechanochromic luminescence of pyridyl substituted solid state emissive dyes thermally controlled stepwise recovery of the original Emission Color
    CrystEngComm, 2019
    Co-Authors: Suguru Ito, Chika Nishimoto, Sayaka Nagai
    Abstract:

    Stimuli-responsive organic dyes that switch the Color of their solid-state Emission upon exposure to external stimuli represent an important class of materials due to their potential applications in various areas of sensing technology. Although an increasing number of multi-stimuli-responsive organic dyes have been reported in recent years, only a few solid-state fluorophores are known to respond to two kinds of stimuli in a stepwise and reversible manner. Herein, we report the sequential halochromic (acidochromic)/mechanochromic luminescence behavior of a pyridyl-substituted solid-state fluorophore. The solid-state Emission Color of this pyridyl-substituted dye was systematically shifted in the bathochromic direction by forming cocrystals with several benzoic acid derivatives that exhibit different pKa values. Upon grinding these cocrystals with a spatula, further bathochromic shifts of their maximum Emission wavelengths were observed upon amorphization. Conversely, the Emission Color and crystallinity can be recovered upon heating the ground samples of the cocrystals to their cold-crystallization transition temperature (Tc ∼ 100 °C). Heating the ground cocrystals further (185–260 °C) removes the benzoic acid derivatives, which restores the original Emission Color of the pyridyl-substituted dye. In other words, we have developed a new system that exhibits a two-step Emission Color recovery in response to temperature by combining halochromic and mechanochromic luminescence in series.

  • Sequential halochromic/mechanochromic luminescence of pyridyl-substituted solid-state emissive dyes: thermally controlled stepwise recovery of the original Emission Color
    CrystEngComm, 2019
    Co-Authors: Suguru Ito, Chika Nishimoto, Sayaka Nagai
    Abstract:

    Stimuli-responsive organic dyes that switch the Color of their solid-state Emission upon exposure to external stimuli represent an important class of materials due to their potential applications in various areas of sensing technology. Although an increasing number of multi-stimuli-responsive organic dyes have been reported in recent years, only a few solid-state fluorophores are known to respond to two kinds of stimuli in a stepwise and reversible manner. Herein, we report the sequential halochromic (acidochromic)/mechanochromic luminescence behavior of a pyridyl-substituted solid-state fluorophore. The solid-state Emission Color of this pyridyl-substituted dye was systematically shifted in the bathochromic direction by forming cocrystals with several benzoic acid derivatives that exhibit different pKa values. Upon grinding these cocrystals with a spatula, further bathochromic shifts of their maximum Emission wavelengths were observed upon amorphization. Conversely, the Emission Color and crystallinity can be recovered upon heating the ground samples of the cocrystals to their cold-crystallization transition temperature (Tc ∼ 100 °C). Heating the ground cocrystals further (185–260 °C) removes the benzoic acid derivatives, which restores the original Emission Color of the pyridyl-substituted dye. In other words, we have developed a new system that exhibits a two-step Emission Color recovery in response to temperature by combining halochromic and mechanochromic luminescence in series.

Jun Yeob Lee - One of the best experts on this subject based on the ideXlab platform.

Takashi Kato - One of the best experts on this subject based on the ideXlab platform.

  • a stimuli responsive photoluminescent anthracene based liquid crystal Emission Color determined by thermal and mechanical processes
    Advanced Functional Materials, 2009
    Co-Authors: Yoshimitsu Sagara, Shogo Yamane, Toshiki Mutai, Koji Araki, Takashi Kato
    Abstract:

    Here, a photoluminescent liquid crystal that exhibits a change of Emission Color on the metastable–stable phase transition induced by external stimuli is prepared. A 2,6-diethynylanthracene derivative with amide groups and dendritic side chains exhibits a columnar phase on slow cooling from the isotropic phase and shows blue Emission in this columnar phase. In contrast, a cubic phase is obtained by rapid cooling from the isotropic phase. In the cubic phase, the 2,6-diethynylanthracene cores form excimers, resulting in yellow Emission. While the columnar phase is a stable liquid-crystalline (LC) phase, the cubic phase is a metastable LC phase. It is found that a change of the photoluminescent Color from yellow to blue is observed on the cubic-columnar phase transition induced by heating or mechanical shearing for this 2,6-diethynylanthracene derivative in the cubic phase. This change of photoluminescent Color is ascribed to the inhibition of excimer formation on the metastable–stable LC phase transition.

  • A Stimuli‐Responsive, Photoluminescent, Anthracene‐Based Liquid Crystal: Emission Color Determined by Thermal and Mechanical Processes
    Advanced Functional Materials, 2009
    Co-Authors: Yoshimitsu Sagara, Shogo Yamane, Toshiki Mutai, Koji Araki, Takashi Kato
    Abstract:

    Here, a photoluminescent liquid crystal that exhibits a change of Emission Color on the metastable–stable phase transition induced by external stimuli is prepared. A 2,6-diethynylanthracene derivative with amide groups and dendritic side chains exhibits a columnar phase on slow cooling from the isotropic phase and shows blue Emission in this columnar phase. In contrast, a cubic phase is obtained by rapid cooling from the isotropic phase. In the cubic phase, the 2,6-diethynylanthracene cores form excimers, resulting in yellow Emission. While the columnar phase is a stable liquid-crystalline (LC) phase, the cubic phase is a metastable LC phase. It is found that a change of the photoluminescent Color from yellow to blue is observed on the cubic-columnar phase transition induced by heating or mechanical shearing for this 2,6-diethynylanthracene derivative in the cubic phase. This change of photoluminescent Color is ascribed to the inhibition of excimer formation on the metastable–stable LC phase transition.

Soo Young Park - One of the best experts on this subject based on the ideXlab platform.

  • Strategic Emission Color tuning of highly fluorescent imidazole-based excited-state intramolecular proton transfer molecules
    Physical chemistry chemical physics : PCCP, 2012
    Co-Authors: Sanghyuk Park, Ji Eon Kwon, Soo Young Park
    Abstract:

    Highly fluorescent molecules harnessing the excited state intramolecular proton transfer (ESIPT) process are promising for a new generation of displays and light sources because they can offer very unique and novel optoelectronic properties which are different from those of conventional fluorescent dyes. To realize innovative ESIPT devices comprising full Emission Colors over the whole visible region, a molecular design strategy for predictable Emission Color tuning should be established. Here, we have developed a general strategy for a wide-range spectral tuning of imidazole-based ESIPT materials based on three different strategies – introduction of a nodal plane model, extension of effective conjugation length, and modification of heterocyclic rings. A series of nine ESIPT molecules were designed, synthesized and comprehensively investigated for their characteristic Emission properties. All these molecules commonly showed no clear and transparent visible range absorption with no absorption Color, but showed different Colors of intense photoluminescence over broad visible regions from 450 nm (HPI) to 630 nm (HPNO) depending on their molecular structure. With the aid of density functional theory and time-dependent DFT calculations using M06, wB97XD, and B3LYP parameters with the 6-31G(d,p) basis set, these tuned Emission bands of nine emitters were assigned from the stabilized excited state conformations that were derived from modified molecular structures.