Strong Aggregation‐Induced CPL Response Promoted by Chiral Emissive Nematic Liquid Crystals (N*‐LCs)

Li, Xiaojing; Li, Qian; Wang, Yuxiang; Quan, Yiwu; Chen, Dongzhong; Cheng, Yixiang

doi:10.1002/chem.201801186

Cited by 105 publications

(69 citation statements)

References 61 publications

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“…Nevertheless, as demonstrated deductively in this work, appropriate molecular designs such as the introduction of a phenyl ring suppress the nonradiative decays of HBT molecules, allowing sufficiently high Φ FL values in both aggregated (solid) and nonaggregated (LC mixtures) states. It had not been clarified so far whether the AIEE‐type fluorescent molecules were aggregated or dispersed in the LC hosts . Our experiments evidenced that HBT‐based ESIPT fluorescent molecules are molecularly dispersed in 5CB and their Φ FL values are not so decreased due to the appropriate molecular design.…”

Section: Resultsmentioning

confidence: 70%

“…Recently, several rod‐ and banana‐shaped fluorescent LCs have been used for polarized light emission . LC materials doped with AIEE dyes were also reported, aiming at the development of emissive LC displays or emergence of circularly polarized luminescence . Both types of the reports have not discussed in detail the energy dissipation processes via ESIPT or AIEE protocols in terms of molecular view.…”

Section: Introductionmentioning

confidence: 99%

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Highly Fluorescent Liquid Crystals from Excited‐State Intramolecular Proton Transfer Molecules

Zhang

Sakurai

Aotani

et al. 2018

Advanced Optical Materials

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solid-state emitters, electroluminescent devices, organic lasers, and so on. [1][2][3][4][5] Particularly, emission through excitedstate intramolecular proton transfer (ESIPT) mechanism with an extremely large Stokes shift [6][7][8][9] (anti-Kasha rule) suppresses excitation energy dissipation via self-absorption, providing attractive material platforms for optical device fabrication. [10,11] ESIPT is a photochemical process that produces a tautomer with a different electronic structure from the original excited form (Figure 1a). The requisite of chemical structures for ESIPT is the presence of an intramolecular hydrogen bond (H-bond) between the proton donor (OH and NH 2 ) and the proton acceptor (N and CO) groups close to one another in a single molecule. Recent notable reports on the ESIPT fluorophores include the polymorph-dependent emissive crystals, [12,13] double proton transfer process with an extra-large Stokes shift, [14] amplified spontaneous emission, [15][16][17] lasing system, [18][19][20] environment-sensitive multicolored materials, [21][22][23][24] and the use as emitters with electrically generated intramolecular proton transfers. [25] Most of ESIPT molecules show significant fluorescence in the solid states, not suffering from "concentration quenching" and thus serving as aggregation-induced emission enhancement (AIEE) materials. [26][27][28] The ESIPT process requires structural relaxations upon proton transfer, and thus a certain conformational freedom is allowed for the molecular structures. [29] The conformational freedom results in allowing the possible nonradiative pathways especially in solution (Figure 1b), giving AIEE characters to the ESIPT molecules. [30,31] The AIEE character is advantageous because light outputs from the systems are extremely high embedded into actual devices to avoid the concentration quenching. [32] However, most of the previous ESIPT as well as AIEE systems have been mostly reported in the rigid solid phase such as single crystals, polycrystals, or powders [11,12] -not in liquid crystals (LCs). Although columnar LCs with ESIPT-active cores were reported, [33,34] simple rod-shaped LC molecules embedded with ESIPT-active group have been limited. [35,36] In contrast to columnar and cubic liquid crystal phases with highly ordered structures, nematic as well as several smectic subphases can easily align macroscopically by rubbed surfaces, mechanical stimuli, and electric and magnetic fields. [37][38][39] Fluorescence via excited-state intramolecular proton transfer (ESIPT) provides strong light emission with a large Stokes shift and environment-sensitive unique spectral patterns. Particular systems including 2-(2-hydroxyphenyl) benzothiazole (HBT) serve as efficient solid-state emitters with the ESIPT mechanism and aggregation-induced emission enhancement (AIEE) property, but have not been used for liquid crystalline (LC) materials. Here, rod-shaped fluorescent LCs with ESIPT characters are newly developed based on the HBT motif. The design of the targeted mole...

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Section: Resultsmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Highly Fluorescent Liquid Crystals from Excited‐State Intramolecular Proton Transfer Molecules

Zhang

Sakurai

Aotani

et al. 2018

Advanced Optical Materials

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“…So far, using emissive N*LCs has been proved to be an effective method to amplify the g lum value. [37,38,155,[157][158][159][160] However, there is no report of the amplification of the g lum value of UC-CPL. Figure 17 shows the first example of enhanced UC-CPL emission in N*LCs.…”

Section: Liquid-crystal-enhanced Cplmentioning

confidence: 99%

“…Polarization of light can be regarded as part of a high-level visual perception since it contains a lot of potentially useful information about such visual features like the material content, surface shape, and local curvature of objects. [1] Among the different kinds of polarized light, circular polarized light is considered to be special, and has drawn great attention due to its potential application in 3D displays, [2,3] chiroptical materials, [4] although some other exciting strategies, including plasmon resonance, [33] Förster resonance energy transfer (FRET), [34,35] triplet-triplet-annihilation-based photon upconversion (TTA-UC) [36] and liquid crystals, [37][38][39] have also been reported as reliable pathways for amplifying the g lum value.…”

Section: Introductionmentioning

confidence: 99%

Circularly Polarized Luminescence in Nanoassemblies: Generation, Amplification, and Application

et al. 2019

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Yutao Sang obtained his B.Sc. and M.Sc. degrees in chemistry from Qingdao University, China. In 2016, he enrolled on a Ph.D. course at the Institute of Chemistry, Chinese Academy of Sciences (ICCAS), under the supervision of Prof. Minghua Liu, where he is currently in his third year. His ongoing research includes supramolecular chirality, chiroptical materials, and symmetry breaking of achiral molecules in gels and related systems. Pengfei Duan received his Ph.D. degree from the Institute of Chemistry, Chinese Academy of Sciences (CAS) in 2011 with Prof. Minghua Liu on chiral selfassembly in colloid and interface chemistry. He was a postdoctoral research fellow with Prof. Nobuo Kimizuka at Kyushu University, working on photon upconversion in self-assembled systems. In 2015, he became a professor at the National Center for Nanoscience and Technology (NCNST). His current research interests focus on photochemistry and photophysics in chiral supramolecular systems.

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“…The general approach to fabricate CPL-active materials is through a covalent bonding of luminophore with a chiral moiety [13][14][15]. Varieties of chiral moieties incorporated with luminophores by covalent bonds, such as chiral polymers [16][17][18], chiral metal complexes [19,20], and chiral liquid crystals [21,22], have been widely investigated as CPL candidates. However, the CPL properties of obtained chiral materials are some-times unpredictable, and a tedious synthesis process is always inevitable [23,24].…”

Section: Introductionmentioning

confidence: 99%

Dual-Mode Induction of Tunable Circularly Polarized Luminescence from Chiral Metal-Organic Frameworks

et al. 2020

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The general approach for fabricating solid-state materials showing circularly polarized luminescence (CPL) is still in its challenge. In this work, chiral metal-organic frameworks (MOFs) with full-color and white-color circularly polarized light emission are firstly achieved through a host-guest emitter-loading strategy. Chiral zeolitic imidazolate frameworks (ZIFs, a class of MOFs) are fabricated by a facile and simple mixed-ligand coassembly pathway. Meantime, achiral dyes, quantum dots (QDs), and upconversion nanoparticles (UCNPs) are easily loaded into the chiral ZIFs during the synthetic process. Size-matched dyes can be solely encapsulated into the chiral cages of ZIF, resulting in induced CPL and enhanced luminescence efficiency in solid-state ZIF⊃dye composites. Large-sized QDs, after embedding into the gap of the ZIF particles, also exhibited intense CPL activity. Furthermore, through modulating the blending ratio of colored dyes or QDs in chiral ZIFs, white light-emitting ZIFs with circular polarization could be constructed in a solid state. In addition, through loading rare earth element-based upconversion nanoparticles (UCNPs) into chiral ZIFs, upconverted CPL (UC-CPL) could be achieved with a high dissymmetry factor (glum). Thus, various achiral luminophores were endowed with CPL upon coupling with chiral ZIFs, which significantly deepened and enlarged the research scope of the chiroptical materials in a solid state.

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Strong Aggregation‐Induced CPL Response Promoted by Chiral Emissive Nematic Liquid Crystals (N*‐LCs)

Cited by 105 publications

References 61 publications

Highly Fluorescent Liquid Crystals from Excited‐State Intramolecular Proton Transfer Molecules

Highly Fluorescent Liquid Crystals from Excited‐State Intramolecular Proton Transfer Molecules

Circularly Polarized Luminescence in Nanoassemblies: Generation, Amplification, and Application

Dual-Mode Induction of Tunable Circularly Polarized Luminescence from Chiral Metal-Organic Frameworks

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