Ring-alkyl connecting group effect on mesogenic properties of <i>p</i>-carborane derivatives and their hydrocarbon analogues

Jankowiak, Aleksandra; Kaszyński, Piotr; Tilford, William R.; Ohta, Kiminori; Januszko, Adam; Nakagawa, Takashi; Endo, Yasuyuki

doi:10.3762/bjoc.5.83

Cited by 11 publications

(3 citation statements)

References 43 publications

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“…20 Although A and B, possessing a p-carborane core, exhibit only the nematic phase, their thermal stability is inferior to that of 1 C7 , C, and D. This is in good accordance with the report of Kaszynski and co-workers that p-carborane derivatives usually exhibit only the nematic phase as their liquid crystalline phases. 6b,6c,6f,6g,6i,20,21 On the other hand, C and D, possessing a bicyclo [2.2.2]octane ring system and a 1,4-phenylene system as their cores, respectively, exhibit only smectic phases.…”

supporting

confidence: 78%

Alkoxyphenyl-Substituted Symmetric Liquid Crystalline Diamantane Derivatives

Gushiken¹,

Ujiie²,

Ubukata³

2011

Bulletin of the Chemical Society of Japan

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Eleven novel thermotropic rod-shaped liquid crystals composed of alkoxyphenyl (methoxy to decyloxy) or hexanoyloxyphenyl groups on both ends of the diamantane core have been synthesized and their liquid crystalline properties investigated. All of them behaved as liquid crystals at considerably high temperatures. When the alkoxy side chains are propyloxy or shorter, the clearing points are over 300°C. The clearing point of a liquid crystalline compound with two hexanoyloxy groups also exceeds 300°C. When the alkoxy groups on both ends of the molecule are octyloxy or longer, they showed only smectic phases as the mesophase. When they are shorter than octyloxy, the compounds showed nematic phases just below their clearing points. A nematic phase was also observed for the hexanoyloxy compound as well as the smectic A and B phases. However, as the bent-shaped adamantane-derived hexyloxyphenyl molecule did not show any liquid crystalline properties, the linear structures of the diamantane-derived molecules were crucial in generating liquid crystalline phases.Currently, liquid crystal displays (LCDs) are the major display devices for TVs, PCs, mobile phones, and other useful products. The liquid crystalline (LC) compounds for such devices should exhibit various significant properties before they are adopted for widespread use.1 The required physical properties for any type of display are: 1) a wide nematic-phase temperature range, 2) high chemical and thermal stability, and 3) low viscosity to attain short switching times. Although numerous molecules have been synthesized and studied to improve performance, the development of a single compound that satisfies all of the required properties has not yet been achieved. Therefore, most liquid crystals (LCs) for LCDs are a mixture of several different LC compounds, however, the mixing of multiple LCs lowers the nematicisotropic (NI) phase-transition temperature. In order to maintain a practical LC temperature range which is as wide as possible, it is necessary that LCs which have high NI phase transition temperatures be mixed together. 2Most rod-like LC compounds have a rigid but flat core structure and one or two flexible side chains, and may also have a polar functional group. 3 The rigid core is made up of one or more hydrocarbon rings and heterocycles such as 1,4-disubstituted benzene, trans-1,4-disubstituted cyclohexane, 2,5-disubstituted pyrimidine, and trans-2,5-disubstituted 1,3-dioxane rings. However, some liquid crystalline compounds possessing barrel-like thick core structures, such as bicyclo[2. Recently, much attention has focused on the molecular nanodiamond family called diamondoids, 8 which was first discovered in the pitch of crude petroleum.9 Diamondoids have a diamond-like saturated hydrocarbon skeleton based on threedimensionally fused cyclohexanes whose smallest member is adamantane. They have been studied extensively because of their interesting structural as well as physical properties. 1013A number of their chemical modifications have also been repo...

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supporting

confidence: 78%

Alkoxyphenyl-Substituted Symmetric Liquid Crystalline Diamantane Derivatives

Gushiken¹,

Ujiie²,

Ubukata³

2011

Bulletin of the Chemical Society of Japan

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“…These trends can be observed in homologous series, where increased chain length results in decreased clearing temperature for high‐temperature materials . A series of isostructural compounds containing p ‐carborane, BCO and benzene were synthesized to investigate the effect that different phenyl/alkyl connecting groups have on the mesogenic properties of LCs using thermal and optical methods . Results showed the order for mesophase stability in the series as (Alk)CH 2 CH 2 −<(Alk)OOC−<(Alk)CH 2 O−<(Alk)COO−.…”

Section: Applications Of Rigid‐linear Linkers In Molecular Rods and Rmentioning

confidence: 94%

Nonconjugated Hydrocarbons as Rigid‐Linear Motifs: Isosteres for Material Sciences and Bioorganic and Medicinal Chemistry

Locke

Bernhard

Senge

2019

Chemistry A European J

197

143

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Nonconjugated hydrocarbons, like bicyclo[1.1.1]pentane, bicyclo[2.2.2]octane, triptycene, and cubane are a unique class of rigid linkers. Due to their similarity in size and shape they are useful mimics of classic benzene moieties in drugs, so‐called bioisosteres. Moreover, they also fulfill an important role in material sciences as linear linkers, in order to arrange various functionalities in a defined spatial manner. In this Review article, recent developments and usages of these special, rectilinear systems are discussed. Furthermore, we focus on covalently linked, nonconjugated linear arrangements and discuss the physical and chemical properties and differences of individual linkers, as well as their application in material and medicinal sciences.

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“…2,5-Di(4-(diphenylamino)phenyl)cyclohexa-2,5-diene-1,4-dione ( 1 , Scheme ) was prepared according to the reported procedure . The treatment of 1 with NaBH 4 in MeOH led to the formation of 2,5-di(4-(diphenylamino)phenyl)benzene-1,4-diol ( 2 ).…”

Section: Resultsmentioning

confidence: 99%

A Dynamic Triradical: Synthesis, Crystal Structure, and Spin Frustration

et al. 2023

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Polyradicals, i.e., multispin organic molecules, are playing important roles in radical-based material applications for their spin−spin interaction. A dynamic covalently bonded multispin molecule may endow materials with added function such as memory and switching. However, such a species has yet to be reported. We here report the synthesis, characterization, and crystal structure of a dynamic triradical species. It is generated by the self-assembly of two molecules through a Lewis acid coupled electron transfer. The crystalline species is spin-frustrated without Jahn−Teller distortion at low temperature, while it dissociates back to diamagnetic starting material in solution at high temperature. The reversible process is tracked by variable-temperature NMR, EPR, and UV−vis−NIR spectroscopy. Isolation, property study, and dynamic bonding investigation on such a species lay the foundation for the design of functional polyradicals with potential application as memory or switching devices.

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Ring-alkyl connecting group effect on mesogenic properties of p-carborane derivatives and their hydrocarbon analogues

Cited by 11 publications

References 43 publications

Alkoxyphenyl-Substituted Symmetric Liquid Crystalline Diamantane Derivatives

Alkoxyphenyl-Substituted Symmetric Liquid Crystalline Diamantane Derivatives

Nonconjugated Hydrocarbons as Rigid‐Linear Motifs: Isosteres for Material Sciences and Bioorganic and Medicinal Chemistry

A Dynamic Triradical: Synthesis, Crystal Structure, and Spin Frustration

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