Orientational Behavior of Nematic Liquid Crystals Containing a Soluble Ziegler-Natta Catalyst Under Magnetic Field

Akagi, Kazuo; Ito, Masahiro; Katayama, S.; Shirakawa, Hideki; Araya, Kotaro

doi:10.1080/00268948908042156

Cited by 11 publications

(8 citation statements)

References 8 publications

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“…These features were not observed in chlorobenzene, which suggests an environmental influence specific to 5CB. The size of the aligned 5CB domains varies depending on the strength of the applied magnetic field (15)(16)(17). At B 0 = 345 mT, a small fraction of 5CB remains unaligned, which generates, on average, a more polar environment than that of the aligned domains.…”

Section: Resultsmentioning

confidence: 99%

Quintet-triplet mixing determines the fate of the multiexciton state produced by singlet fission in a terrylenediimide dimer at room temperature

Chen

Krzyaniak

Nelson

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

113

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Singlet fission (SF) is a photophysical process in which one of two adjacent organic molecules absorbs a single photon, resulting in rapid formation of a correlated triplet pair (T1T1) state whose spin dynamics influence the successful generation of uncorrelated triplets (T1). Femtosecond transient visible and near-infrared absorption spectroscopy of a linear terrylene-3,4:11,12-bis(dicarboximide) dimer (TDI2), in which the two TDI molecules are directly linked at one of their imide positions, reveals ultrafast formation of the (T1T1) state. The spin dynamics of the (T1T1) state and the processes leading to uncoupled triplets (T1) were studied at room temperature for TDI2aligned in 4-cyano-4′-pentylbiphenyl (5CB), a nematic liquid crystal. Time-resolved electron paramagnetic resonance spectroscopy shows that the (T1T1) state has mixed5(T1T1) and3(T1T1) character at room temperature. This mixing is magnetic field dependent, resulting in a maximum triplet yield at ∼200 mT. The accessibility of the3(T1T1) state opens a pathway for triplet–triplet annihilation that produces a single uncorrelated T1state. The presence of the5(T1T1) state at room temperature and its relationship with the1(T1T1) and3(T1T1) states emphasize that understanding the relationship among different (T1T1) spin states is critical for ensuring high-yield T1formation from singlet fission.

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Section: Resultsmentioning

confidence: 99%

Quintet-triplet mixing determines the fate of the multiexciton state produced by singlet fission in a terrylenediimide dimer at room temperature

Chen

Krzyaniak

Nelson

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

113

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“…[44][45][46][47][48] This approach affords an alignment of even ultrathin films with semitransparency that is suitable for measurements of nonlinear optics. 49 The macroscopically aligned PA films prepared in a nematic liquid crystal under the gravity flow and magnetic field show high conductivities of 10 4 S/cm after iodine doping, and anisotropies of ca.…”

Section: Background Of Polyacetylene (Pa)mentioning

confidence: 98%

Helical Polyacetylene: Asymmetric Polymerization in a Chiral Liquid-Crystal Field

2009

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with expertise in functional conjugated polymers. His research interests have involved electrically conducting polymers and liquidcrystalline, luminescent, and photoresponsive conjugated polymers, with works focused on the synthesis of helical polyacetylene in the chiral nematic liquid-crystal field. He has also been engaged in development of liquid-crystalline aromatic conjugated polymers with linearly and circularly polarized optoelectronic properties. He graduated from the

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“…Meanwhile, the macroscopic alignment of H-PA has also been successfully carried out using the N*-LC reaction field with a monodomain structure, which was constructed using gravity flow or a magnetic field as an external perturbation. A vertical-orientation inducer is useful for the construction of vertically oriented N*-LC reaction fields, allowing an orientation control without any external force .…”

Section: Introductionmentioning

confidence: 99%

Hierarchically Controlled Helical Graphite Films Prepared from Iodine-Doped Helical Polyacetylene Films Using Morphology-Retaining Carbonization

2011

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One-handed helical graphite films with a hierarchically controlled morphology were prepared from iodine-doped helical polyacetylene (H-PA) films using the recently developed morphology-retaining carbonization method. Results from scanning electron microscopy indicate that the hierarchical helical morphology of the H-PA film remains unchanged even after carbonization at 800 °C. The weight loss of the film due to carbonization was very small; only 10-29% of the weight of the film before doping was lost. Furthermore, the graphite film prepared by subsequent heating at 2600 °C retained the same morphology as that of the original H-PA film and that of the helical carbon film prepared at 800 °C. The screwed direction, twisted degree, and vertical or horizontal alignment of the helical graphite film were well controlled by changing the helical sense, helical pitch, and orientation state of the chiral nematic liquid crystal (N*-LC) used as an asymmetric LC reaction field. X-ray diffraction and Raman scattering measurements showed that graphitic crystallization proceeds in the carbon film during heat treatment at 2600 °C. Transmission electron microscopy measurements indicate that ultrasonication of the helical graphite film in ethanol for several hours gives rise to a single helical graphite fibril. The profound potentiality of the present graphite films is exemplified in their electrical properties. The horizontally aligned helical graphite film exhibits an enhancement in electrical conductivity and an evolution of electrical anisotropy in which conductivity parallel to the helical axis of the fibril bundle is higher than that perpendicular to the axis.

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Orientational Behavior of Nematic Liquid Crystals Containing a Soluble Ziegler-Natta Catalyst Under Magnetic Field

Cited by 11 publications

References 8 publications

Quintet-triplet mixing determines the fate of the multiexciton state produced by singlet fission in a terrylenediimide dimer at room temperature

Quintet-triplet mixing determines the fate of the multiexciton state produced by singlet fission in a terrylenediimide dimer at room temperature

Helical Polyacetylene: Asymmetric Polymerization in a Chiral Liquid-Crystal Field

Hierarchically Controlled Helical Graphite Films Prepared from Iodine-Doped Helical Polyacetylene Films Using Morphology-Retaining Carbonization

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