The synthesis and mesomorphic behaviour of the 1,2,4,5-tetrasubstituted benzenes with (4-tridecyloxyphenyl)ethynyl and (4-tridecyloxyphenyl)carbonyloxy substituents

Norbert, W. D. J. Amilaprasadh; Goodby, John W.; Hird, Michael; Toyne, Kenneth J.

doi:10.1080/026782997209045

Cited by 19 publications

(15 citation statements)

References 32 publications

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“…The scaffold was substituted by amino acid derivatives in order to generate new ligands and pharmaceutical active compounds [130,131]. Although the tetra arm substituted core is reminiscent of a disc only three compounds with liquid crystalline behavior has been published (Figure 21) [187,188]. The symmetric mesogen with octyloxy chains 57e revealed only a crystalline (Cr 118 °C I), the elongation of the chains (tridecyloxy) lead to the observation of a monotropic nematic phase for 57f (Cr (74 °C N) 96 °C I) at fast cooling between crossed polarizers.…”

Section: Star Compounds With a Benzene Corementioning

confidence: 99%

Star-Shaped Conjugated Systems

2010

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The present review deals with the preparation and the properties of star-shaped conjugated compounds. Three, four or six conjugated arms are attached to cross-conjugated cores, which consist of single atoms (B, C+, N), benzene or azine rings or polycyclic ring systems, as for example triphenylene or tristriazolotriazine. Many of these shape-persistent [n]star compounds tend to π-stacking and self-organization, and exhibit interesting properties in materials science: Linear and non-linear optics, electrical conductivity, electroluminescence, formation of liquid crystalline phases, etc.

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Section: Star Compounds With a Benzene Corementioning

confidence: 99%

Star-Shaped Conjugated Systems

2010

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“…The use of an ester or an amide dipole will introduce a kink (A and B), whereas a single nonpolarized triple bond will favor a linear and flat arrangement of the subunits (C). [55] Notice that in the case of the amide linker in B additional supramolecular hydrogen bonding is expected to favor the stabilization of the mesophase. The 4'-substitution position was targeted to provide uncrowned ligands likely to p-stack in the solid state.…”

Section: Introductionmentioning

confidence: 98%

Tuning the Thermotropic and Lyotropic Properties of Liquid‐Crystalline Terpyridine Ligands

Camerel

Donnio

Bourgogne

et al. 2006

Chemistry A European J

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A rational synthetic strategy is developed to provide compact and simple terpyridine (terpy) mesogens that show liquid-crystallinity both as pure compounds and in organic solution (amphotropic compound). The use of a central 4-methyl-3,5-diacylaminophenyl platform equipped with two lateral aromatic rings, each bearing three appended aliphatic chains, allows connection of a 2,2':6',2''-terpyridine fragment through a polar group such as an ester, amide, or flat conjugated alkyne linker. For the T(12)ester and T(12)amide scaffolds, the mesophase is best described as a lamellar phase, in which the molecules self-assemble into columnar stacks held together in layers. In the T(12)amide case, the additional amide link results in significant stabilization of the lamellar phase. The driving forces for the appearance of columnar ordering are the hydrogen-bonding interactions of the amide groups, which induce head-to-tail pi-stacking of the terpy subunits. Replacing the polar linker by a nonpolarized but linear alkyne spacer, as in the T(12)ethynyl compound, provides a columnar mesophase organized in a rectangular lattice of p2gg symmetry. In this arrangement, two nondiscotic molecules arranged into dimers by hydrogen bonding and pi-pi stacking pile up in a head-to-tail manner to form columns. In addition, the T(12)amide compound proves to be an excellent gelator of cyclohexane, linear alkanes, and DMSO. The resulting robust and transparent gels are birefringent and formed by large aggregates that are readily aligned by shear-flow. TEM and freeze-fracture microscopy reveal that the gels have an original layered morphology made of fibers.

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“…Goodby et al have reported 1,2,4,5-tetrakis(4-tridecyloxyphenylethynyl)benzene that can potentially show the biaxial nematic phase; however, the observed monotropic nematic phase within a narrow temperature range deterred further investigation of its biaxiallity. 9 Taking advantage of the available bromo group, compound 2 can be readily modified to compounds showing geometries stepwise towards a rectangle for realization of the unstable nematic phase formed by 1,2,4,5-tetraynylbenzene. Herein, systematic geometrical deviations from the y-shaped geometry by attaching a rigid lateral group with various lengths to the rectangle while keeping the molecular dipole constant are performed to comprehend the influence on mesogenic properties upon varying the molecular shape towards a rectangular shape of the board-like tetraynylbenzene.…”

Section: Resultsmentioning

confidence: 99%

“…The role of the iodo group on mesogenic properties of 1 is comprehended by substituting with a Br (2), a Cl (3), and a H (4) atom. In addition, taking advantage of the available bromo group in 2, the geometry of 1 was modified stepwise from a rigid y-shape to a rigid rectangle, from compounds 4 to 7, 8 and 9, for realization of the unstable nematic behaviors of the Goodby et al reported board-like 1,2,4,5-tetrakis(4-tridecyloxyphenylethynyl)benzene 9 that was expected to potentially show the biaxial nematic phase.…”

Section: Introductionmentioning

confidence: 99%