Novel Glassy Nematic Liquid Crystals for Non‐destructive Rewritable Optical Memory and Photonic Switching

Chen, Shaw H.; Chen, Huang-Ming; Geng, Yanhou; Jacobs, Stephen D.; Marshall, Kenneth; Blanton, Thomas N.

doi:10.1002/adma.200304836

Cited by 72 publications

(28 citation statements)

References 36 publications

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“…So far various types of photo-responsive liquid crystals have been reported. [45][46][47] The combination of liquid-crystalline and photochromic behaviour in molecular systems promises to be very useful in optical technological devices. Frigoli and Mehl 48 synthesized a class of roomtemperature nematic photo-switchable liquid crystals shown in Fig.…”

Section: Photochromic Liquid Crystalsmentioning

confidence: 99%

Photochromic bisthienylethene as multi-function switches

2007

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Bisthienylethenes (BTEs) are one of the most promising families of photochromic compounds because of their fatigue resistance and thermally irreversible properties for use in optoelectronic devices such as ultrahigh-density optical data storage, molecular switches, logic gates, molecular wires, sensors, and so on. This article describes recent development of switchable photochromic bisthienylethene materials, especially multi-switchable bisthienylethene materials including multi-color photochromic materials, multi-switchable organogelators and liquid crystals. We also highlight our recent contributions in this field.

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Section: Photochromic Liquid Crystalsmentioning

confidence: 99%

Photochromic bisthienylethene as multi-function switches

2007

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“…However, in most cases, the liquid-crystalline phase of azobenzene compound transferred to the isotropic phase on irradiation because of the unstabilization of the liquid-crystalline phase by cis-azobenzene [11][12][13][14][15][16][17]26]. It is still a great challenge to control the liquid-crystalline phase from one stable texture to the other by irradiation, which has been reported in liquid-crystalline diarylethene compounds [33,34].…”

Section: Introductionmentioning

confidence: 97%

Multiresponsive self-assembled liquid crystals with azobenzene groups

Chen

Zhou

et al. 2008

Journal of Colloid and Interface Science

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“…Liquid crystals provide versatile, sensitive, and anisotropic supramolecular matrices that respond with collective effects to small changes in their composition and thus they can amplify molecular chirality and motion efficiently into optical or mechanical responses . Coupling molecular photoswitches with liquid crystals has allowed developing light‐responsive molecular systems with applications ranging from optical memory writing to colorful displays . Combined with (helix‐based) cholesteric liquid crystals, molecular photoswitches have allowed creating and manipulating chiral topological structures, changing reflexion colors and polarization, detecting catalytic reactions, and developing soft rotating devices .…”

Section: Introductionmentioning

confidence: 99%

Long‐Lived Supramolecular Helices Promoted by Fluorinated Photoswitches

Huang

Orlova

Matt

et al. 2017

Macromol. Rapid Commun.

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light into work and power by soft polymer machines has been demonstrated also. [17] Light-responsive cholesteric liquid crystals can be prepared by dissolving a small percentage of chiral photoswitches in a (achiral) nematic liquid crystal host [4,18] (Figure 1). The propensity of these photoswitches, used as dopants, to induce a twist in a given host is characterized by their helical twisting power (HTP), defined as β = × × − ( ) 1 p c ee , where p is the pitch and corresponds to a full 360° rotation of the molecules along the helical axis, c is the concentration of the dopant in wt%, and ee is the enantiomeric excess of the dopant. Chiral switches are typically characterized by large twisting powers for their chirality and can be amplified across length scales effectively. [6] Azobenzenes are typically used as switchable dopants because their trans-cis photoisomerization is associated with large changes in both the geometry and the dipole moment of the molecule. While rod-like trans-azobenzenes are compatible with the nematic order, the bent-like cis-molecules disturb this molecular order significantly. Consequently, the HTP of the trans and the cis isomers are remarkably different. Moreover, coupling azobenzenes to elements of axial chirality yields both a large HTP in the ground state and a large variation of HTP under irradiation with light, compared to chiral azobenzenes that display point chirality only. [11,[19][20][21][22] Light-driven helix inversion has also been reported, when chiral azobenzene dopants with axial chirality were used as dopants. [23][24][25] However, the lack of thermal stability of the cisisomer remains a limitation to reaching the full potential of complex dynamic behavior in these supramolecular systems.Fluorinated azobenzenes display larger thermal stability than their classical counterparts, primarily because the repulsion between the nitrogen lone pairs that destabilizes the cis-isomer is lifted by electron-withdrawing effect of the fluorine atoms in ortho-position. [26][27][28][29] Here, we combine the axial chirality of a binaphthyl moiety with ortho-fluorination of an azobenzene moiety in molecular photoswitches that induce supramolecular helices in liquid crystals in both forms, and thus we demonstrate the photoengineering of long-lived supramolecular helices in soft matter. Results and DiscussionMolecules 1a and 1b were synthesized from commercially available starting materials. Their photochemistry and performance as dopants were investigated by comparing them to the reference azobenzenes 2a [19] and 2b [20,30] in the same Molecular PhotoswitchesChiral azobenzenes can be used as photoswitchable dopants to control supramolecular helices in liquid crystals. However, the lack of thermal stability of the cis-isomer precludes envisioning the generation of long-lived supramolecular helices with light. Here, this study demonstrates thermally stable and axially chiral azobenzene switches that can be used as chiral dopants to create supramolecular helices from (achiral) nematic liq...

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Novel Glassy Nematic Liquid Crystals for Non‐destructive Rewritable Optical Memory and Photonic Switching

Cited by 72 publications

References 36 publications

Photochromic bisthienylethene as multi-function switches

Photochromic bisthienylethene as multi-function switches

Multiresponsive self-assembled liquid crystals with azobenzene groups

Long‐Lived Supramolecular Helices Promoted by Fluorinated Photoswitches

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