Design of chiral dimesogens containing cholesteryl groups; formation of new molecular organizations and their application to molecular photonics

Mallia, V. Ajay; Tamaoki, Nobuyuki

doi:10.1039/b106617j

Cited by 162 publications

(70 citation statements)

References 34 publications

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“…Using ChLCs, reversible colored states can be achieved for applications in full-color displays without the need for any color filter or polarizer. [1,2] The pitch of ChLCs is generally sensitive to the external perturbation and, thus, the LC state must be vitrified for memory-effect-related applications. We have demonstrated that light-driven erasable color recording is possible by doping the glass-forming ChLC, CD8 ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…[3,4] The sensitivity of ChLCs to external parameters, such as temperature, the presence of impurities, and light, has led to many practical applications and has been the subject of much theoretical research. [2,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Several mechanisms have been proposed to explain the role that the dopant molecules play in the modulation of the macroscopic chirality of ChLCs. [11,[24][25][26][27][28] Recently, we reported that the mechanism of the helical-pitch shift that is induced by achiral dopants (as well as in dimesogenic compounds) is due to enhancement of smectic A (SmA)-like clusters in the cholesteric phases.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis, Liquid‐Crystalline Properties, and Photo‐optical Studies of Photoresponsive Oligomeric Mesogens as Dopants in a Chiral Glassy Liquid Crystal

Akiyama

Mallia

Tamaoki

2006

Adv Funct Materials

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We have prepared photoresponsive oligomers that have molecular weights of ca. 4500, 8000, and 16 000 g mol–1 via the free‐radical polymerization of 4‐[4‐alkylphenylazo]phenoxyalkyl acrylates. All of the oligomers possess bilayer smectic A (SmA) and smectic B (SmB) phases. Increasing the concentration of these oligomeric dopants in a glass‐forming cholesteric liquid crystal causes a dramatic red‐shift in the reflection wavelength. The pitch shifts are very dependent on the alkyl chain lengths and molecular weights of the dopants. The oligomer that contains octyl chains and an octyl spacer, and that has a molecular weight of 4500 g mol–1 exhibits the largest shift in the reflection wavelength. UV exposure has been used to control the cholesteric reflection pitch of the oligomer‐cholesteric glassy liquid‐crystal mixture over the entire visible region of the electromagnetic spectrum and vitrifies the samples by rapid cooling from their cholesteric temperatures to 0 °C. Extremely stable, even at 70 °C, erasable, full‐color images have been created using this host–guest mixture.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis, Liquid‐Crystalline Properties, and Photo‐optical Studies of Photoresponsive Oligomeric Mesogens as Dopants in a Chiral Glassy Liquid Crystal

Akiyama

Mallia

Tamaoki

2006

Adv Funct Materials

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“…[8] The use of circularly polarized light (CPL) as the irradiation source has led to enantiomeric excess values in two chiral domains in the Bx phase of bent-core molecules. [9] Moreover, supramolecular chirality photoinduced by CPL has been reported in azopolymers [10] and in main-chain polymeric liquid-crystal systems doped with azobenzene-containing W-shaped molecules.…”

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confidence: 99%

Light‐Driven Supramolecular Chirality in Propeller‐Like Hydrogen‐Bonded Complexes That Show Columnar Mesomorphism

et al. 2007

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“…In a recent series of papers, a new molecular design concept, wherein nematic and chiral groups are chemically bonded to a volume-excluding core to prevent crystallization upon cooling, has been detailed. [6][7][8][9][10][11][12] These materials, however, were prepared using a multiple synthetic step and/or troublesome workup procedures. For the applications described above, materials with the highest possible glass transition temperature are needed to ensure sufficient room temperature stability of the devices.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Novel Glass-Forming Liquid Crystals Containing Acrylic Acid Trimer Core Unit and Mesogenic Moiety, and Their Use in Cholesteric Reflection Films

Nakanishi

Ueda

2007

Polym J

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ABSTRACT:A novel medium molecular mass liquid-crystalline (LC) material to form glassy nematic phase has been developed to provide uniformly aligned LC films. The LC material consists of an acrylic acid trimer as a core structure and a mesogenic moiety. The resulting LC trimer showed a nematic LC phase and vitrified to form monodomain films at room temperature. This glassy LC trimer is miscible with a chiral photochromic dopant, providing monodomain, aligned, defect-free cholesteric reflection films, the color of which is tunable by UV irradiation. 2 The degree of freedom of molecular motion is limited on losing fluidity by providing a high molecular weight or a crosslinked structure, and the helical molecular order is fixed.Glass-forming liquid crystals with a high glass transition temperature, such as LC polymers, can be aligned at elevated temperatures and then stabilized by cooling below their glass transition temperatures. However, LC polymers often do not undergo fast, defect-free alignment because of their entangled molecular chains.A good method for preparing birefringent films with complex optical functions is based on the photo-polymerization of reactive liquid crystals.3-5 These liquid crystals are aligned in the desired configuration in the monomeric state due to their low viscosities, and are subsequently converted into solid films through UV polymerization. Such birefringent films made with low molecular weight LCs, however, are not stable before UV irradiation because of crystallization at room temperature.For many optical and photonic applications, glassforming LCs represent a unique class of advanced materials that are capable of freezing the liquid-crystalline order into a solid state without crystallization. In a recent series of papers, a new molecular design concept, wherein nematic and chiral groups are chemically bonded to a volume-excluding core to prevent crystallization upon cooling, has been detailed. [6][7][8][9][10][11][12] These materials, however, were prepared using a multiple synthetic step and/or troublesome workup procedures. For the applications described above, materials with the highest possible glass transition temperature are needed to ensure sufficient room temperature stability of the devices. Another requirement is that the materials possess a broad nematic liquid crystal mesophase above their glass transition temperatures. Higher ordered mesophases, such as a smectic phase, are not preferred because of the difficulty in obtaining mono-domain films of these phases. 13In this paper, we present the design, synthesis and characterization of a novel medium molecular mass nematic liquid crystal (LC trimer), consisting of an acrylic acid trimer as the core structure and cyanobiphenyl benzoate as a mesogenic moiety. The LC trimer has an elevated glass transition temperature and exhibits both nematic and cholesteric phases with the addition of a chiral dopant.

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Design of chiral dimesogens containing cholesteryl groups; formation of new molecular organizations and their application to molecular photonics

Cited by 162 publications

References 34 publications

Synthesis, Liquid‐Crystalline Properties, and Photo‐optical Studies of Photoresponsive Oligomeric Mesogens as Dopants in a Chiral Glassy Liquid Crystal

Synthesis, Liquid‐Crystalline Properties, and Photo‐optical Studies of Photoresponsive Oligomeric Mesogens as Dopants in a Chiral Glassy Liquid Crystal

Light‐Driven Supramolecular Chirality in Propeller‐Like Hydrogen‐Bonded Complexes That Show Columnar Mesomorphism

Synthesis of Novel Glass-Forming Liquid Crystals Containing Acrylic Acid Trimer Core Unit and Mesogenic Moiety, and Their Use in Cholesteric Reflection Films

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