An investigation of the mesogenic properties of dibenzoquinoxaline derivatives

Babuin, Jarret; Foster, E. Johan; Williams, Vance E.

doi:10.1016/s0040-4039(03)01798-2

Cited by 24 publications

(19 citation statements)

References 16 publications

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“…A similar trend has been observed for series of both triphenylenes [15] and other dibenzophenazines [5], wherein increased chain lengths lead to depression of the phase transition temperatures and narrowing of the liquid crystalline phase range. The presence of the pyridyl nitrogen atom in these compounds appears to promote the formation of a liquid crystalline phase, since the previously reported phenyl analogues, Phen6 [16] and Phen10 [14] (figure 2), melt directly from a crystal to an isotropic liquid without forming a liquid crystalline phase.…”

Section: Resultsmentioning

confidence: 93%

“…The versatile approach previously developed for the synthesis of discotic liquid crystals by the coupling of a 2,3,6,7-tetraalkoxyphenanthrene-9,10-dione with 1,2-diamines such as 2a, 2b or 2c [5,6,14] provides a simple route to discotic mesogens containing a pyridine ring (P6, P10, SP6, SP10), as illustrated in scheme 1.…”

Section: Resultsmentioning

confidence: 99%

“…3,4-Diaminopyridine and 2,3-diaminopyridine were purchased from Aldrich and used without further purification. 2,3,6,7-Tetrahexyloxyphenanthrene-9,10-dione and 2,3,6,7-tetradecyloxyphenanthrene-9,10-dione [13,14], and compounds A6 and A10 [5] were synthesized as previously reported. 1 H NMR spectra were acquired using a Bruker AMX-400 400 MHz NMR spectrometer, and 13 C NMR spectra (125 MHz) were obtained using a Varian AS500 Unity Inova 500 MHz spectrometer.…”

Section: Methodsmentioning

confidence: 99%

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Modular assembly of elliptical mesogens

2007

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Discotic mesogens featuring a pyridine ring were synthesized, and were found either to form ordered hexagonal columnar liquid crystalline phases or melt directly from a crystal to an isotropic liquid, depending on the position of the pyridyl nitrogen atom. Binary mixtures of the mesogenic pyridine derivatives with a similar discotic mesogen having a carboxylic acid group resulted in the formation of modular elliptical complexes through hydrogen bonding. The binary mixtures were found to exhibit ordered hexagonal columnar or ordered rectangular columnar and nematic mesophases, depending on the length of the alkyl chains, and displayed dramatically different properties from their constituent components. Binary mixtures of the non-mesogenic pyridine derivatives with carboxylic acid-functionalized discotic mesogens did not result in the formation of hydrogen-bonded complexes.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Modular assembly of elliptical mesogens

2007

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“…[193] Die Substitution der Nitrilgruppen in 92 a durch Wasserstoff oder einen zusätzlichen anellierten Benzolring lieferte nichtmesomorphe Verbindungen. [194] Die elektronenziehenden Nitrilgruppen scheinen für das mesogene Verhalten entscheidend zu sein, da sie die p-p-Wechselwirkungen zwischen den aromatischen Kernen verstärken und so die Mesophase stabilisieren.…”

Section: Azatriphenylene Und Tricyclochinoxalineunclassified

Diskotische Flüssigkristalle: Von der maßgeschneiderten Synthese zur Kunststoffelektronik

et al. 2007

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Die meisten Menschen verbinden mit dem Begriff Flüssigkristalle sofort die Displays von Laptop‐Computern, Mobiltelefonen, Digitalkameras und anderen elektronischen Geräten. Im Unterschied zu ihren stäbchenförmigen (calamitischen) Verwandten, die erstmals 1907 von Vorländer beschrieben wurden, bieten aber die 1977 von Chandrasekhar entdeckten scheibenförmigen (diskotischen) Flüssigkristalle andere vielversprechende Verwendungsmöglichkeiten. Ihre einzigartige Anordnung in columnaren Mesophasen macht sie zu idealen Kandidaten für molekulare Drähte in vielen optischen und elektronischen Geräten, beispielsweise in Photokopierern, Laserdruckern, Solarzellen, organischen Leuchtdioden und Feldeffekttransistoren oder zur holographischen Datenspeicherung. Einer Übersicht über die verschiedenen Mesophasentypen und Charakterisierungsmethoden columnarer Flüssigkristalle folgen ausgewählte Beispiele aus den Hauptklassen columnarer Mesogene unter besonderer Berücksichtigung effizienter Syntheseverfahren, mesomorpher Eigenschaften und der für Anwendungen relevanten physikalischen Eigenschaften der Flüssigkristalle. Abschließend werden Anwendungsbeispiele und Perspektiven für einen Einsatz in den Materialwissenschaften und der molekularen Elektronik vorgestellt.

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“…In 1995, we reported for the first time that Compound B exhibits a Col ho mesophase in very wide temperature region, and that the Col ho mesophase structure was established by temperature-dependent X-ray diffraction study [8]. In 2003, Williams et al also reported the same homologues of Compound B [9,10]. In 1998, Rose et al reported that Compound C exhibits a Col mesophase in very narrow temperature region, but they did not perform the detailed identification of the mesophase [11].…”

Section: Introductionmentioning

confidence: 93%