Molecular design of viologens to exhibit low-order liquid-crystalline phases

Naka, Yumiko; Arai, Soichi; Ohgi, Yusuke; Takahashi, M; Le, Khoa V.; Sasaki, Takeo

doi:10.1039/d1ma01126j

Cited by 2 publications

(1 citation statement)

References 34 publications

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“…Since an LC molecule are easily miscible with an LC molecule, we thought that a viologen that exhibits thermotropic LC phases may be used as a light-sensitive moiety for liquid crystals. Although it has been reported viologens exhibit thermotropic LC phases [17][18][19][20][21][22][23][24][25][26] , unfortunately, the molecular structural design of viologen forming the LC phase lacks variety. The common viologen is a molecule with a 4,4'-bipyridine core and long alkyl chains attached at both ends, but it exhibits higher-order LC phases such as the SmB phase.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of low-order liquid-crystalline viologens and their photo-responsive behavior

Naka,

Le,

Sasaki

2024

Emerging Liquid Crystal Technologies XIX

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Viologens that exhibit a low-order liquid-crystalline (LC) phase at ambient temperatures can be used photo-sensitive moieties in LC materials. We synthesized viologens having an asymmetric core, while maintaining its stimulusresponsive properties, with the aim of forming a low order LC phase at ambient temperature. The obtained viologens having an asymmetric core exhibited low-order LC phases with no regularity in the direction of the molecular short axis. Furthermore, we synthesized a viologen derivative having a symmetric core. We found that the development of loworder LC phases was observed, when the rod core was asymmetried by changing the position and number of ionic bonds. It was suggested that the intermolecular interactions were weakened by varying the position of the ionic bonding sites to asymmetrize the core. The photo-responsive behavior of the viologen having an asymmetric core was investigated. The viologen having an asymmetric core was mixed with the nematic LC compound (5CB and 7OCB) to prepare homogeneously aligned films. The change in the alignment of the mesogens was successfully induced by triggering a one-electron reduction reaction of the viologen moieties by light irradiation.

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