Liquid-Crystalline Physical Gels:  Self-Aggregation of a Gluconamide Derivative in Mesogenic Molecules for the Formation of Anisotropic Functional Composites

Yabuuchi, Kazuhiro; Rowan, Alan E.; Nolte, Roeland J. M.; Kato, Takashi

doi:10.1021/cm9904887

Cited by 56 publications

(49 citation statements)

References 20 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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“…7(a)), can gel nematic liquid crystals [14]. In the nematic gel the gelator is found to form a twisted fibrous structure with the nematic trapped in the pockets created by the fibres [15]. The interaction of the surface of the fibres with the director should be expected, therefore, to compete with the magnetic field for the alignment of the director.…”

Section: Disordering Of the Director In Nematic Gelsmentioning

confidence: 99%

On the creation of director disorder in nematic liquid crystals

Luckhurst

2006

Thin Solid Films

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“…A selection of some representatives includes 1,3:2,4-di-O-benzylidene-dsorbitol (DBS), [17][18][19] 2,3-bis-n-decyloxyanthracene, [20,21] cholesterol derivatives, [22][23][24] fluorinated or bolaform amides, [25,26] symmetrical dialkylamides, [27] symmetrical mono-and bisureas, [8,[28][29][30] nonsymmetrical bisureas, [31] and N-n-octyl-d-gluconamide. [32,33] Recently, we added to this selection a class of amphiphilic molecules consisting of a head moiety capable of forming intermolecular hydrogen bonds and a hydrophobic long alkyl chain. [34] In more detail, the investigated molecules consist of three different structural units: an apolar terminal cyclohexyl group, a hydrogen-bond-forming segment based on p-phenylenediamines with amide and urea groups, and a long alkyl chain with more than eight carbon atoms.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Structure–Property Relationships of Amphiphilic Organogelators

Mohmeyer

Schmidt

2007

Chemistry A European J

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A series of low-molecular-weight amphiphilic molecules was synthesized and investigated for their ability to gel organic solvents. These amphiphilic molecules are composed of a head-group moiety capable of forming intermolecular associations through hydrogen bonds and n-alkyl chains of various lengths. This paper describes the continuation of recently published work, in which this class of gelators was presented for the first time. Here, the focus addresses systematically three different structural variations of the head-group moiety: 1) the rigidity, 2) the type and strength of the hydrogen-bond-forming units, and 3) the reduction of the intermolecular interaction by incorporating a lateral substituent. The gelation behavior was investigated in p-xylene and in several polar solvents. The aim was to establish structure-property relationships and to provide organogelators capable of forming gels at low concentrations with adjustable sol-gel transition temperatures and good optical quality. For some individual compounds of the series this property profile was achieved. For the investigated solvents, with particular compounds, sol-gel transition temperatures above 100 degrees C with a reasonable concentration of gelator are obtainable.

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Liquid-Crystalline Physical Gels: Self-Aggregation of a Gluconamide Derivative in Mesogenic Molecules for the Formation of Anisotropic Functional Composites

Cited by 56 publications

References 20 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

On the creation of director disorder in nematic liquid crystals

Synthesis and Structure–Property Relationships of Amphiphilic Organogelators

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