Linearly polarized photoluminescence from an asymmetric cyclophane showing thermo- and mechanoresponsive luminescence

Sagara, Yasuyuki; Seki, Atsushi; Kim, Yuna; Tamaoki, Nobuyuki

doi:10.1039/c8tc02919a

Cited by 14 publications

(14 citation statements)

References 66 publications

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“…DSC measurements clarified the phase transition behavior of cyclophane 1 (Figure 3). A phase transition from isotropic to nematic was observed at 57.6 • C on cooling, and further cooling results in a glass transition at −15.1 • C. In contrast with unsymmetric cyclophanes investigated in our previous studies [23][24][25], no transitions to crystalline phases appear on the heating DSC traces. As shown in Figure 4, no clear peaks were observed in the X-ray diffraction pattern obtained from cyclophane 1 at r.t., which coincides with the fact that cyclophane 1 exhibits the nematic LC phase at r.t.…”

Section: Lc Propertiescontrasting

confidence: 61%

“…The course of our previous studies on luminescent cyclophanes [22][23][24][25][26][27][28][29] suggested that the introduction of a cyclic structure into luminophores is a promising way to achieve mechanoresponsive luminescent materials [3,4,[30][31][32][33][34][35][36]. Luminescent cyclophanes having longer spacers have been found to show nematic LC properties.…”

Section: Introductionmentioning

confidence: 99%

“…Here, we demonstrate a 1,6-diphenylpyrene-based, unsymmetric cyclophane showing a stable nematic phase at room temperature and exhibiting strong photoluminescence from the condensed state. The observed sky-blue photoluminescence was dominated by the emission species ascribed to assembled luminophores rather than monomers.Crystals 2019, 9, 92 2 of 10 two luminophores in an individual cycle [23][24][25]. Furthermore, the unsymmetric cyclophanes exhibit kinetically trapped LC phases with nematic molecular order after rapid cooling from the nematic state.…”

mentioning

confidence: 99%

“…Crystals 2019, 9, 92 2 of 10 two luminophores in an individual cycle [23][24][25]. Furthermore, the unsymmetric cyclophanes exhibit kinetically trapped LC phases with nematic molecular order after rapid cooling from the nematic state.…”

mentioning

confidence: 99%

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A 1,6-Diphenylpyrene-Based, Photoluminescent Cyclophane Showing a Nematic Liquid-Crystalline Phase at Room Temperature

2019

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Photoluminescent nematic liquid crystals have been an attractive research target for decades, because of their potential applications in optoelectrical devices. Integration of luminescent motifs into cyclic structures is a promising approach to induce low-ordered liquid-crystalline phases, even though relatively large and rigid luminophores are used as emitters. Here, we demonstrate a 1,6-diphenylpyrene-based, unsymmetric cyclophane showing a stable nematic phase at room temperature and exhibiting strong photoluminescence from the condensed state. The observed sky-blue photoluminescence was dominated by the emission species ascribed to assembled luminophores rather than monomers.

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Section: Lc Propertiescontrasting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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A 1,6-Diphenylpyrene-Based, Photoluminescent Cyclophane Showing a Nematic Liquid-Crystalline Phase at Room Temperature

2019

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“…Similar multi-lifetime emission decays were also observed for other luminescent cyclophanes featuring 1,5-disubstituted naphthalene moieties. 40,41 Emissive states with shorter lifetimes were observed for solution-cast 2-PU films. This change in emission decay is related to quenching by the NpI group, and reflects that in the solution-cast 2-PU films, the latter resides, on average, in the vicinity of the cycle.…”

Section: ■ Results and Discussionmentioning

confidence: 93%

Mechanoresponsive Behavior of a Polymer-Embedded Red-Light Emitting Rotaxane Mechanophore

Muramatsu

Sagara

Traeger

et al. 2019

ACS Appl. Mater. Interfaces

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A red-light-emitting photoluminescent supramolecular mechanophore based on an interlocked molecular motif is presented. The rotaxane-based mechanophore contains a cyclic compound featuring a π-extended 4,4-difluoro-4bora-3a,4a-diaza-s-indacene (BODIPY) dye as a red emitter that was threaded onto a dumbbell-shaped molecule containing an electron-poor 1,4,5,8-naphthalenetetracarboxylic diimide quencher at its center. Through two aliphatic hydroxyl groups attached to the dumbbell and the cycle, the mechanophore was covalently embedded into the backbone of a thermoplastic polyurethane elastomer. The mechanophore is only weakly photoluminescent in solution, indicating that the BODIPY's emission is efficiently quenched. Solution-cast films of the rotaxane-containing polymer, by contrast, show an appreciable photoluminescence, which suggests that during film formation some of the emitting cycles are trapped in positions away from the quencher. Interestingly, the emission intensity could be significantly reduced by swelling the films with an organic solvent and the emission increased again upon drying, suggesting that such solvent plasticization causes a reversible rearrangement. In both, dry and solvent-swollen films, uniaxial deformation caused a significant, reversible increase of the emission intensity, on account of mechanically induced shuttling of the emitters away from and back to the quenchers. It is shown that the properties of the polymer can be tuned by the solvent, and that such plasticizing extends the small palette of approaches that allow modification of the activation stress of a given materials system.

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Dynamic Mechanochromic Optics with Tunable Strain Sensitivity for Strain‐Responsive Digit Display

Mao

Zeng

Shen

et al. 2020

Advanced Optical Materials

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A facile but highly effective mechanochromism design is reported that is based on a bilayer structure consisting of a sputter‐coated metal light‐shielding layer atop a polydimethylsiloxane (PDMS) substrate containing a fluorescent dye, featuring transverse and/or longitudinal microscale cracks when stretched. The crack opening width on the light‐shielding layer upon stretching/releasing allows the UV radiation to activate the fluorescent dye in the PDMS matrix to exhibit luminescent color, which can be easily tuned with choice of fluorescent dyes. The strain response of the crack opening width can be fine‐tuned by applying various degrees of prestretching strain in the preparation process, resulting in customizable mechanochromic responses. Three types of mechanochromic devices are prepared as representative examples. The fluorescence intensity of these devices can be tuned to either increase or decrease with an increasing strain, or first decrease and then increase within the operating strain range. Moreover, this system can be further modified into a dynamic strain sensor with digit display function, allowing the strain degree of the device to be directly read. This design strategy can be easily adopted by fellow researchers and is expected to open a brand‐new avenue to tune mechanochromic response for various dynamic adaptive optics.

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Linearly polarized photoluminescence from an asymmetric cyclophane showing thermo- and mechanoresponsive luminescence

Abstract: The first cyclophane to exhibit linearly polarized photoluminescence in the liquid-crystalline and crystalline states is described.

Cited by 14 publications

References 66 publications

A 1,6-Diphenylpyrene-Based, Photoluminescent Cyclophane Showing a Nematic Liquid-Crystalline Phase at Room Temperature

A 1,6-Diphenylpyrene-Based, Photoluminescent Cyclophane Showing a Nematic Liquid-Crystalline Phase at Room Temperature

Mechanoresponsive Behavior of a Polymer-Embedded Red-Light Emitting Rotaxane Mechanophore

Dynamic Mechanochromic Optics with Tunable Strain Sensitivity for Strain‐Responsive Digit Display

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