Facile investigation of reversible nanostructure changes in flexible crystals

Hayashi, Shotaro

doi:10.21203/rs.3.rs-71849/v1

Cited by 3 publications

(5 citation statements)

References 25 publications

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“…For preparing a fluorescent microresonator (FM) in the present research, β-cyano-appended oligo( p -phenylenevinylene) (β-COPV) is used as a fluorescent dopant (Figure a) . The electronic absorption spectrum of a CHCl 3 solution of β-COPV shows two bands at 348 and 432 nm, which are attributed to π-π* and intramolecular charge-transfer transitions, respectively (Figure b).…”

Section: Resultsmentioning

confidence: 99%

Polymer Optical Microcavity Sensor for Volatile Organic Compounds with Distinct Selectivity toward Aromatic Hydrocarbons

et al. 2021

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A whispering-gallery mode (WGM) optical resonance sensor for volatile organic compounds (VOCs) is developed from polystyrene (PS) microspheres doped with fluorescent βcyano-appended oligo(p-phenylenevinylene) (β-COPV). The β-COPV-doped PS microspheres (MS COPV ) are formed by the miniemulsion method in a binary solvent. MS COPV expand upon permeation of VOCs into the PS matrix and exhibit a spectral shift of the WGM resonance peak. The permeation efficiency is highly dependent on the chemical affinity between the analyte and the polymer matrix, with exceptionally high selectivity toward aromatic hydrocarbons such as benzene, toluene, and xylenes (BTXs). The high selectivity and sensitivity of MS COPV are in clear contrast to those of conventional WGM sensors that just detect VOCs nonpreferentially through adsorption onto the surface.

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Section: Resultsmentioning

confidence: 99%

Polymer Optical Microcavity Sensor for Volatile Organic Compounds with Distinct Selectivity toward Aromatic Hydrocarbons

et al. 2021

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“…A photoluminescence (PL) spectrum of COPV in CHCl 3 features a unimodal emission band (Figure 2b, green solid line) centered at 515 nm, while the PL band in a solid state (Figure 2b, orange solid line) is centered at 607 nm due to the intermolecular donor-acceptor interaction. [26] COPV exhibits an aggregation-induced enhanced emission (AIEE) behavior: [27,28] The PL quantum yield (φ) of COPV in the solid state (0.95) is much larger than that in the solution state (0.41). The excellent φ of COPV crystal is particularly beneficial for developing optical experiments.…”

Section: Materials Characterizationmentioning

confidence: 99%

“…The single crystal of COPV belongs to triclinic system with a space group of P-1 (for detailed crystallographic data, see Table S1, Supporting Information), which was reported previously by one of the authors. [26] The constituent COPV molecules in FOC COPV stack on one another via π-π interactions to form a 1D column along the crystallographic a-axis (Figure S2b-e, Supporting Information). A powder X-ray diffraction (PXRD) profile of FOC COPV shows distinct diffraction peaks at 7.1°, 9.2°, and 18.5°, which are assignable to (001), (010), and (020) planes, respectively (Figure S2a, Supporting Information).…”

Section: Materials Characterizationmentioning

confidence: 99%

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Mechanically Flexible and Optically Tunable Organic Crystal Resonator

Zhao

Yamagishi

Oki

et al. 2021

Advanced Optical Materials

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molecules, organic crystals have been exploited for a wide range of optical applications, including waveguides, resonators, solid-state lasers, and sensors. [1][2][3] As well-demonstrated by the success of organic dye lasers featuring a wide feasible wavelength range, organic chemistry enables the fine-tuning of the emission band in the visible region by the precise modification of the molecular structure and associated electronic energetics in the steady and transient states. [4] Recently, researchers are focusing on the control of the morphology of the crystal grains to further exploit the optical properties of organic crystals. Fu and co-workers conducted the crystallization of π-conjugated molecules in a small-droplet on a quartz substrate to form toroidal microcrystals, in which the molecular fluorescence circularly propagated and exhibited whispering gallery mode (WGM) optical resonance and lasing. [5] In 2020, our group reported a morphology-and molecular orientation-dependent lasing behaviors of fluorescent dendrimer crystals, in which light is confined via WGM and Fabry-Pérot (FP) mode. [6] Organic crystals described above represent a unique and emergent materials group in optics. Nonetheless, because of the extreme fragility against an external bending stress, these organic crystals are still far behind their inorganic counterparts, which limits applications of organic crystals to practical devices that require mechanical assembling or that involve mechanical oscillations and impacts during operation. Recently, some groups, including us, coincidentally reported the synthesis of mechanically flexible organic crystals (FOCs) and establish a molecular strategy for FOCs, which was then followed by enthusiastic progressions from many other groups. [7][8][9][10][11][12][13] Mechanically flexible elastic and plastic organic crystals that work as an optical waveguide and resonators even after bending have also been used to develop microscopic all-organic photonic integrated circuits. [14][15][16][17][18][19][20][21] Along this line, optical resonators made of FOCs are also sought after as a future wavelength-and direction-tunable laser emitter. [23,24] However, the synthesis of flexible organic crystalline resonators remains a fundamental challenge so far because of the inherent optical loss during the light propagation along the longitudinal direction and the reflection at the end facets. [17,18] Tuning resonance properties by mechanical bending is, therefore, a far more formidable challenge in terms of both crystal engineering and optics.An organic single-crystal optical resonator that maintains its optical performance even upon mechanical bending remains a challenging target. Here, the first flexible organic crystal (FOC) that works as a tunable optical resonator as a function of bending angle is developed. A fluorescent π-conjugated molecule, cyano-substituted oligo(phenylenevinylene)s, is allowed to crystallize slowly, yielding a discrete rod-shape microcrystal (FOC COPV ). FOC COPV not only works as an ef...

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“…Conversely, Worthy et al [55] found that there is a qualitative difference in the crystal structure by investigating from elongation at the outside to contraction at the inside by focusing the beam in X-ray structural analysis of the bent cupper acetylacetonate, Cu(acac) 2 , crystal. The author proposed a facile method for investigating nanostructure changes of flexible organic crystals by using readily accessible X-ray equipment [56]. X-ray diffraction (XRD) with a curved jig, which applied macroscopic stress-strain (%), revealed reversible and quantitative crystal structure changes under bending stress and relaxation.…”

Section: Detailed Deformation Of Elastic Organic Crystalsmentioning

confidence: 99%

Elastic Organic Crystals of π-Conjugated Molecules: New Concept for Materials Chemistry

Hayashi

2020

Symmetry

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It is generally believed that organic single crystals composed of a densely packed arrangement of anisotropic, organic small molecules are less useful as functional materials due to their mechanically inflexible and brittle nature, compared to polymers bearing flexible chains and thereby exhibiting viscoelasticity. Nevertheless, organic crystals have attracted much attention because of their tunable optoelectronic properties and a variety of elegant crystal habits and unique ordered or disordered molecular packings arising from the anisotropic molecular structures. However, the recent emergence of flexible organic crystal materials showing plasticity and elasticity has considerably changed the concept of organic single crystals. In this review, the author summarizes the state-of-the-art development of flexible organic crystal materials, especially functional elastic organic crystals which are expected to provide a foothold for the next generation of organic crystal materials.

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Facile investigation of reversible nanostructure changes in flexible crystals

Cited by 3 publications

References 25 publications

Polymer Optical Microcavity Sensor for Volatile Organic Compounds with Distinct Selectivity toward Aromatic Hydrocarbons

Polymer Optical Microcavity Sensor for Volatile Organic Compounds with Distinct Selectivity toward Aromatic Hydrocarbons

Mechanically Flexible and Optically Tunable Organic Crystal Resonator

Elastic Organic Crystals of π-Conjugated Molecules: New Concept for Materials Chemistry

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