Liquid crystals with restricted molecular topologies: supermolecules and supramolecular assemblies

Goodby, John W.; Mehl, Georg H.; Sáez, Isabel M.; Tuffin, Rachel P.; Mackenzie, Grahame; Auzély‐Velty, Rachel; Benvegnu, Thierry; Plusquellec, Daniel

doi:10.1039/a802762e

Cited by 190 publications

(99 citation statements)

References 37 publications

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“…1). Such a structure favors the formation of layers as reported for liquid-crystalline dendrimers 29 and siloxysilanes 30 which are analogous to 14, i.e. a central core is functionalized by a large number of mesogenic groups.…”

Section: Supramolecular Organizationmentioning

confidence: 87%

Design, mesomorphic properties, and supramolecular organization of [60]fullerene-containing thermotropic liquid crystals

2002

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Two concepts have been developed for the design of [60]fullerene-containing thermotropic liquid crystals, namely, the covalent and non-covalent concepts. In the covalent approach, C 60 was functionalized with liquidcrystalline addends (malonate and aldehyde derivatives) by applying either the Bingel reaction or the 1,3-dipolar cycloaddition reaction. In the non-covalent approach, a liquid-crystalline inclusion complex was obtained from mesomorphic cyclotriveratrylene (CTV) derivatives and C 60 . All of the covalent C 60 derivatives showed smectic A phases. In one case, an additional nematic phase was detected. The [C 60 ,(CTV) 2 ] complex gave rise to nematic-like and cubic phases. The covalent and noncovalent approaches demonstrate the various possibilities for C 60 to give rise to mesomorphic materials.

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Section: Supramolecular Organizationmentioning

confidence: 87%

Design, mesomorphic properties, and supramolecular organization of [60]fullerene-containing thermotropic liquid crystals

2002

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“…As already mentioned above, LCDrs self-assemble into a number of ordered phases depending on the dendrimer generation, chemical composition, temperature and other factors [14][15][16][17][18][19]. One of the most striking features is the ability of these molecules to adopt distinctly different conformations in different phases [51].…”

Section: Smectic Phase and The Smectic-isotropic Phase Transitionmentioning

confidence: 99%

“…Interesting examples include dendrimers, where a central dendritic core has been functionalised by a flexible chain and a terminal mesogenic group [9,10], multipedal mesogens containing a central octasilsesquioxane core [11] and fullerene containing liquid crystals [12,13]. Some of the recent exciting work in this area has been summarised in a number of excellent review articles [14][15][16][17][18][19], which draw parallels between polyphilic thermotropic liquid crystals, block copolymers and self-assembly in amphiphilic and biological systems.…”

Section: Introductionmentioning

confidence: 99%

Simulation of bulk phases formed by polyphilic liquid crystal dendrimers

Ilnytskyi¹,

Lintuvuori²,

Wilson³

2010

Condens. Matter Phys.

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A coarse-grained simulation model for a third generation liquid crystalline dendrimer (LCDr) is presented. It allows, for the first time, for a successful molecular simulation study of a relation between the shape of a polyphilic macromolecular mesogen and the symmetry of a macroscopic phase. The model dendrimer consists of a soft central sphere and 32 grafted chains each terminated by a mesogen group. The mesogenic pair interactions are modelled by the recently proposed soft core spherocylinder model of Lintuvuori and Wilson [J. Chem. Phys, 128, 044906, (2008)]. Coarse-grained (CG) molecular dynamics (MD) simulations are performed on a melt of 100 molecules in the anisotropic-isobaric ensemble. The model LCDr shows conformational bistability, with both rod-like and disc-like conformations stable at lower temperatures. Each conformation can be induced by an external aligning field of appropriate symmetry that acts on the mesogens (uniaxial for rod-like and planar for disc-like), leading to formation of a monodomain smectic A (Sm A ) or a columnar (Col) phase, respectively. Both phases are stable for approximately the same temperature range and both exhibit a sharp transition to an isotropic cubic-like phase upon heating. We observe a very strong coupling between the conformation of the LCDr and the symmetry of a bulk phase, as suggested previously by theory. The study reveals rich potential in terms of the application of this form of CG modelling to the study of molecular self-assembly of liquid crystalline macromolecules.

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“…15 This opens the way to fascinating new developments in the field of lanthanide-containing liquid crystals.…”

confidence: 99%

Luminescence-detected phase transitions in lanthanide-containing liquid crystals

et al. 2003

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Complexes between lanthanide nitrates and a pro-mesogenic 18-membered diaza-substituted coronand are luminescent both as powders and liquid crystals (between 87 and 195°C ), and the phase transitions are detected by monitoring luminescence intensity and lifetime.Liquid crystals are the main components of new-generation cost-saving colour displays and a great deal of research effort has been devoted to their development during the last two decades. 1 One disadvantage of these devices is their relatively low brightness, due to the use of polarisers and colour filters, and one way to overcome this shortcoming is the design of luminescent liquid crystals. While it is rather easy to find either photoluminescent sheets acting as filters or, even, organicbased luminescent liquid crystals, these materials display a broad-band, and usually blue, emission which is of little use in this context. On the other hand cathode-ray tubes rely on trichromatic phosphors emitting narrow bands in three basic colours, blue, green and red, and so do energy-saving luminescent lamps and tubes. Most of these phosphors contain rare-earth ions, Eu II (blue), Tb III (green) and Eu III (red). Henceforth the idea of introducing lanthanide ions in mesogenic phases. Metallomesogens are relatively new in the area of liquid crystals and they combine the properties of a liquid crystalline phase with the optical and magnetic properties of the metal ions they incorporate. The first liquid crystalline phase containing Ln III ions was reported by Piechocki. 2 Initially, it was thought that introducing bulky spherical ions in potentially mesogenic compounds could disrupt the required order to produce mesophases, but it turned out that many lanthanide-containing systems are amenable to form liquid crystalline phases, as reported in a recent comprehensive review article. 3 Basically, there are two ways of designing luminescent lanthanide-containing mesophases. The first, historical, one is the introduction of highly luminescent complexes into known liquid crystalline phases and successful attempts with bdiketonates have been reported. [4][5][6][7] The other one is the synthesis of luminescent complexes displaying mesogenic properties. 8,9 Metal-centred luminescent properties, particularly those of Eu III , have been taken advantage of to probe, at very low temperature, the degree of disorder around the metal ion in metastable liquid crystals based on europium laurate, 8 and to determine the second-rank crystal-field parameter through analysis of the 5 D 0 ? 7 F 1 transition in order to assess the magnetic anisotropy of europium-containing metallomesogens. 10,11 Here we present a new mesogenic class of luminescent lanthanide complexes built from a substituted diaza-18-crown-6 macrocyclic ligand, and we show, for the first time, how luminescence intensity and lifetime can be used to monitor the transitions from crystalline to liquid crystalline phases and vice-versa.Synthetic macrocycles are selective and versatile ligands for the complexation of trivalent ...

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Liquid crystals with restricted molecular topologies: supermolecules and supramolecular assemblies

Cited by 190 publications

References 37 publications

Design, mesomorphic properties, and supramolecular organization of [60]fullerene-containing thermotropic liquid crystals

Design, mesomorphic properties, and supramolecular organization of [60]fullerene-containing thermotropic liquid crystals

Simulation of bulk phases formed by polyphilic liquid crystal dendrimers

Luminescence-detected phase transitions in lanthanide-containing liquid crystals

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