Anisotropic Self-Aggregation of an Anthracene Derivative:  Formation of Liquid-Crystalline Physical Gels in Oriented States

Kato, Takashi; Kutsuna, Takaaki; Yabuuchi, Kazuhiro; Mizoshita, Norihiro

doi:10.1021/la025809z

Cited by 69 publications

(55 citation statements)

References 31 publications

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“…Since its discovery in the late 80 s, [14,15] PEDOT has proven to be an outstanding polymer for its electrochromic properties, high conductivity, and high stability in the doped form. [16] It has already found useful applications as antistatic film coatings, [17,18] electrochromic windows, [19] and as a hole-injection material in polymer OLEDs and PLEDs. [20] Further, water-soluble PEDOT derivatives have been used as polyelectrolytes in layer-by-layer assembled systems for electrochromic applications.…”

Section: Methodsmentioning

confidence: 99%

Photoresponsive Anisotropic Soft Solids: Liquid‐Crystalline Physical Gels Based on a Chiral Photochromic Gelator

et al. 2003

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Liquid crystals show unique optical properties due to their anisotropic molecular alignment. Liquid-crystalline (LC) materials are applied to optical information display and storage devices because the modulation of the LC molecular alignment can be induced by external stimuli such as heat, electric fields, and light, leading to changes in the macroscopic optical properties. Of these, light has the advantages of providing stimuli i) to specific chromophores in the molecules by selective-wavelength irradiation, ii) to sub-micrometer-sized areas, and iii) in non-contact with targets. To use light stimuli for the induction of changes in the LC molecular alignment, photochromic reactions are effective.[1±9] The photochromic reactions can reversibly change phases, the director of LC molecules, and the periodicity of molecular alignment. Introduction of photochromic properties to LC composite systems will be useful for the development of the liquid crystals as advanced functional materials. Recently, the combination of liquid crystals and fibrous aggregates of gelators, which are self-assembled by intermolecular interactions such as hydrogen bonding and p±p interactions, has been found to form LC physical gels.[10±19] The LC physical gels show unique optical properties and dynamic functions caused by cooperative effects of liquid crystals and a fibrous network of gelators.[10±21] The LC molecules in the gels respond to external stimuli such as heat and electric fields because of their microphase-separated structures, although they are moderately fixed by the fibrous network of the gelators. If photochromic properties are introduced into these LC physical gels, dynamic change in anisotropic composite structures, which is not available for the physical gels of common organic solvents, can be induced by the light stimuli. Here, we report that photoresponsive LC physical gels exhibit new properties as anisotropic materials: i) the photoinduced structural changes between two different LC gel states;ii) the application of these structural changes to re-writable information recording. These gels were prepared by the addition of trans-(1R,2R)-bis(acylamino)cyclohexane (1) [22] to a room-temperature nematic liquid crystal, 4-cyano-4¢-pentylbiphenyl (2) (Fig. 1). Compound 1 is a newly designed chiral gelator with photochromic azobenzene moieties.When a mixture consisting of the liquid crystal 2 and a small amount of gelator 1 with trans-azobenzene moieties (trans-1) is heated, it becomes an isotropic liquid (isotropic sol state) due to the dissociation of hydrogen bonds (Fig. 2a). Upon subsequent cooling, trans-1 first self-assembles through hydrogen bonds of amide units, leading to the formation of a normal isotropic gel. For example, the sol±gel transition of the mixture containing 3 wt.-% of 1 occurs at 64 C. On further cooling, 2 forms the mesomorphic state in the aggregated network of trans-1 at 34 C inducing the transition to the nematic LC gel at room temperature (Fig. 2b).The photoinduced gel±sol transition of the LC phy...

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Section: Methodsmentioning

confidence: 99%

Photoresponsive Anisotropic Soft Solids: Liquid‐Crystalline Physical Gels Based on a Chiral Photochromic Gelator

et al. 2003

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“…Die phasengetrennte Struktur der Gele kann durch Verwendung von Gelbildnern mit geeigneten Umwandlungseigenschaften eingestellt werden (Abbildung 30). [24,[298][299][300][301] Tritt die Faserbildung des Gelbildners oberhalb der Klärtemperatur der flüssigkristallinen Komponente auf (Abbildung 30 A, Typ I), so entsteht ein zufällig im isotropen Medium dispergiertes Fasernetzwerk (Abbildung 30 B). Im Unterschied dazu lagert sich der Gelbildner in einer flüssig-kristallinen Phase zu orientierten selbstorganisierten Fasern zusammen, und es entsteht ein orientiertes flüssigkristallines Gel (Abbildung 30 A, Typ II).…”

Section: Strukturen Physikalischer Flüssigkristalliner Geleunclassified

Funktionelle flüssigkristalline Aggregate: selbstorganisierte weiche Materialien

2005

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Dynamische weiche Materialien werden im 21. Jahrhundert an Bedeutung gewinnen. Zwar sind diese Funktionsmaterialien nicht so beständig wie Metalle, Keramiken oder Plastik, dafür reagieren sie aber gut auf externe Reize. Geordnete weiche Materialien können dynamische Funktionen erfüllen. Flüssigkristalle aus selbstorganisierten Molekülen sind ein Beispiel hierfür: Sie eignen sich möglicherweise zum Elektronen‐, Ionen‐ oder Stofftransport sowie als sensorisch, katalytisch, optisch oder biologisch aktive Materialien. Um diese Funktionen auszuschöpfen, benötigt man unkonventionelle Materialentwürfe. Hier beschreiben wir aktuelle Ansätze zur Funktionalisierung von Flüssigkristallen und zeigen, wie das Design von Flüssigkristallen durch supramolekulare Aggregation und Nanophasentrennung zu einer Vielfalt selbstorganisierter Funktionsmaterialien führt.

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“…241,242 Nematic LC physical gels showing electro-optical switching in the light-scattering mode have been reported. [257][258][259][260][261] As shown in Figure 14d, LC gels composed of randomly dispersed fibers and polydomain LC structures exhibit light scattering. However, after application of an electric field, the LC molecules reorient in the direction of the field forming a monodomain homeotropic alignment.…”

Section: Functional Lc Polymers and Networkmentioning

confidence: 93%

“…By the alignment of the LC phase, the formation of anisotropic functional fibrous aggregates can be induced. 257 This approach has been applied to prepare conductive selfassembled fibers by using a gelator bearing an electro-active moiety such as tetrathiafulvalene (Figure 14e). 265,266 Similar approach has been used to prepare magneto-active fibers.…”

Section: Functional Lc Polymers and Networkmentioning

confidence: 99%

Functional liquid-crystalline polymers and supramolecular liquid crystals

Kato

Uchida

Ichikawa

et al. 2017

Polym J

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The design and functions of liquid-crystalline (LC) polymers with classifying them into conventional-, supramolecular-, dendriticand network-type LC polymers are described. LC polymers show new functions as new devices in the field of energy and environment by incorporating mesogenic moieties exhibiting photonic, electronic and ionic functions. Supramolecular LC polymers show dynamic and unique properties because the mesogenic moieties are built with non-covalent interactions. Dendritic-type LC polymers exhibit liquid crystallinity by nanosegregation of aromatic and aliphatic moieties. Dendritic fork-like mesogens have also been prepared. A variety of nonmesogeic functional building blocks including fullerene, π-conjugated moieties, catenane, rotaxane and others can be incorporated into LC phases by attaching these dendritic moieties. LC networks are constructed in situ polymerization of polymerizable nematic or nanostructured liquid crystals. The specific characteristics of the LC networks have generated new research trends to develop well-defined polymers that exhibit optical, transport and separation properties. In these materials, through suitable design of LC monomers, the preservation of smectic, columnar and bicontinuous cubic phases has been successfully used for the development of membranes with one-dimensional, two-dimensional and three-dimensional nanostructures.

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Anisotropic Self-Aggregation of an Anthracene Derivative: Formation of Liquid-Crystalline Physical Gels in Oriented States

Cited by 69 publications

References 31 publications

Photoresponsive Anisotropic Soft Solids: Liquid‐Crystalline Physical Gels Based on a Chiral Photochromic Gelator

Photoresponsive Anisotropic Soft Solids: Liquid‐Crystalline Physical Gels Based on a Chiral Photochromic Gelator

Funktionelle flüssigkristalline Aggregate: selbstorganisierte weiche Materialien

Functional liquid-crystalline polymers and supramolecular liquid crystals

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