The synthesis of alkoxybromotriphenylenes: new discotic liquid crystals and valuable precursors to ‘mixed tail’ discotics

Henderson, Philippe; Kumar, Sandeep; Rego, James A.; Ringsdorf, Helmut; Schuhmacher, Peter

doi:10.1039/c39950001059

Cited by 30 publications

(20 citation statements)

References 14 publications

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“…The features observed here, however, are close to the ones recently 2.2. Structure formation by the CT-twin molecules 3 Preliminary investigations have shown that the reported for triphenylene derivatives [14,15] and attributed to a plastic hexagonal columnar (Colhp ) phase. CT-twin molecules 3a and 3c exhibit an enantiotropic liquid crystalline phase characterized by a fan-shaped This phase is characterized by a three-dimensional correlation of the columns, while the molecules within texture [ 13 ].…”

Section: Introductionmentioning

confidence: 98%

Mesomorphic donor-acceptor twin molecules with covalently linked sheet-like pentaalkyne and nitrofluorenone sub-units

Goldmann¹,

Mahlstedt²,

Janietz³

1998

Liquid Crystals

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Charge-transfer (CT ) twin mesogens are presented which consist of sheet-like pentayne donor moieties with di erent peripheral substituents chemically linked with nitro substituted uorenone sub-units via¯exible alkyl spacers. A novel plastic rectangular columnar (Colrp) phase is reported for the laterally unsubstituted member of the pentayne based CT twins. The phase is characterized by a three-dimensional crystal-like correlation of ordered columns in a rectangular lattice, while the molecular sub-units are still able to perform relaxation motions.The attachment of peripheral substituents to the pentayne moieties results in a distortion of the three-dimensional positional order and the ® ve-fold alkyl substituted homologues exhibit a rectangular columnar ordered (Colro) mesophase. The rectangular lattice symmetries originate from the chemical linkage of the¯at donor and acceptor parts of the molecules placed in an alternating manner within neighbouring columns, and the regular intracolumnar periodicity is enhanced by charge-transfer interactions within the columns.A further structural modi® cation consists of the incorporation of an asymmetric carbon into the spacer sequence resulting in pentayne based CT-twin mesogens displaying a nematic columnar mesophase with a helical twisting of the columns ( N * col ). Dielectric investigations reveal an unusual dynamic behaviour of the donor± acceptor pentaynes. The glass relaxation process is characterized by the occurrence of two relaxation modes, both following a WLF behaviour, a feature which has not previously been reported to our knowledge for columnar phase-forming disc-like liquid crystal materials.

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Section: Introductionmentioning

confidence: 98%

Mesomorphic donor-acceptor twin molecules with covalently linked sheet-like pentaalkyne and nitrofluorenone sub-units

Goldmann¹,

Mahlstedt²,

Janietz³

1998

Liquid Crystals

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“…Compounds 88 now possess reactive sites capable of derivatisation via classical aromatic substitution chemistry. Thus, the bromination of 88 with Br 2 in methylene chloride provides the mesogenic bromoalkoxy-TP 91 in 98% yield (64). Friedel-Crafts acylation of 88 with acetyl chloride and aluminium trichloride proceeds in high yield with acylation occurring in the 2-position (90).…”

Section: Discotics Derived From Hydroxy-functionalised Triphenylenesmentioning

confidence: 98%

“…We first attempted its synthesis via triflate 87 reduction which can be easily prepared from hydroxyalkoxy-TP 78. Although the reduction was not successful, we discovered that triflate 87 is mesogenic over a broad temperature range with an unidentified phase occurring below the hexagonal discotic phase (64). Reduction of the phenolic groups of hydroxyalkoxy-TP has ultimately been accomplished by activation with a tetrazole unit followed by catalytic hydrogenation.…”

Section: Discotics Derived From Hydroxy-functionalised Triphenylenesmentioning

confidence: 98%

Hierarchical discs

Kumar

2009

Liquid Crystals Today

Self Cite

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The hierarchical self-assembly of disc-shaped molecules leads to the formation of discotic liquid crystals. These intriguing materials are of fundamental importance not only as models for the study of energy and charge migration in self-organised systems but also as functional materials for various device applications. This has generated tremendous interest in this field. In this review article, we have summarised our synthetic work on discotic liquid crystals.

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“…Monomeric, alkyl-substituted TPs have also been widely studied in the field of discotic liquid crystals owing to the formation of mesophases that are generally characterized by a high degree of organization. [6,7,[9][10][11] This structural perfection arises from the highly symmetric, disc-like aromatic core of TPs, which readily promotes their liquid crystallinity when decorated with peripheric alkyl chains. We were interested in the thermotropic behavior and the long-range selfassembly of the macrocyclic homologue 9, which preserved several important features of TP-based liquid crystals.…”

Section: Liquid Crystallinitymentioning

confidence: 99%

“…[3,4] Monomeric TP derivatives received considerable interest when their liquid-crystalline nature was first reported, [5] spurring research in 2,3,6,7,10,11-hexasubstituted TP mesogens in particular. [6][7][8][9][10][11] Liquid crystallinity is driven by the strong p-stacking tendency of the planar TP core and van der Waals interactions of lateral side chains. Hexa-A C H T U N G T R E N N U N G alkoxytriphenylenes are of significant interest as fast photoconductors for applications in xerography.…”

Section: Introductionmentioning

confidence: 99%

Molecular Triangles: Synthesis, Self‐Assembly, and Blue Emission of Cyclo‐7,10‐tris‐triphenylenyl Macrocycles

Schwab¹,

Qin²,

Pisula³

et al. 2011

Chemistry An Asian Journal

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A set of cyclo-7,10-tris-triphenylenyl macrocycles have been prepared by a Yamamoto cyclotrimerization protocol. In these novel macrocycles, three triphenylene units are covalently linked to each other, resulting in the formation of triangular-shaped molecules. The fully planar derivative revealed pronounced self-assembly behavior. NMR spectroscopy was used to determine the association constant in solution. 2D wide-angle X-ray scattering was applied to the study of the liquid crystallinity of this new discotic mesogen in the bulk state. Furthermore, nonplanar, laterally substituted derivatives were successfully tested as blue emitters in organic light-emitting diodes owing to their unique optoelectronic properties and their high stability. In this case, substitution with sterically demanding phenyl groups was efficiently used to suppress intermolecular packing, thus preventing undesired quenching effects.

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The synthesis of alkoxybromotriphenylenes: new discotic liquid crystals and valuable precursors to ‘mixed tail’ discotics

Cited by 30 publications

References 14 publications

Mesomorphic donor-acceptor twin molecules with covalently linked sheet-like pentaalkyne and nitrofluorenone sub-units

Mesomorphic donor-acceptor twin molecules with covalently linked sheet-like pentaalkyne and nitrofluorenone sub-units

Hierarchical discs

Molecular Triangles: Synthesis, Self‐Assembly, and Blue Emission of Cyclo‐7,10‐tris‐triphenylenyl Macrocycles

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