Columnar phases of achiral vanadyl liquid crystalline complexes

Kilian, D.; Knawby, D.; Athanassopoulou, M. A.; Trzaska, Scott T.; Swager, Timothy M.; Wróbel, S.; Haase, Wolfgang

doi:10.1080/026782900202705

Cited by 54 publications

(19 citation statements)

References 19 publications

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“…Such a linear temperature dependency of ε in the H II phase was reported due to the high conductivity inside the inverse cylindrical structure. 16,46 In the Q phase ε remains almost constant with increasing temperature before its value decreases almost discontinuously at the phase transition into the H II phase (Figure 7(d)). Kresse et al 16 also observed a constant ε in an inverse cubic micellar phase, suggesting that this behavior is related to the isotropic ordering nature of the phase.…”

Section: Fig 6 Observed and Fitted Spectra Ofmentioning

confidence: 95%

Phase sensitive molecular dynamics of self-assembly glycolipid thin films: A dielectric spectroscopy investigation

Velayutham

Gan

et al. 2014

The Journal of Chemical Physics

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Glycolipid, found commonly in membranes, is also a liquid crystal material which can self-assemble without the presence of a solvent. Here, the dielectric and conductivity properties of three synthetic glycolipid thin films in different thermotropic liquid crystal phases were investigated over a frequency and temperature range of (10(-2)-10(6) Hz) and (303-463 K), respectively. The observed relaxation processes distinguish between the different phases (smectic A, columnar/hexagonal, and bicontinuous cubic Q) and the glycolipid molecular structures. Large dielectric responses were observed in the columnar and bicontinuous cubic phases of the longer branched alkyl chain glycolipids. Glycolipids with the shortest branched alkyl chain experience the most restricted self-assembly dynamic process over the broad temperature range studied compared to the longer ones. A high frequency dielectric absorption (Process I) was observed in all samples. This is related to the dynamics of the hydrogen bond network from the sugar group. An additional low-frequency mechanism (Process II) with a large dielectric strength was observed due to the internal dynamics of the self-assembly organization. Phase sensitive domain heterogeneity in the bicontinuous cubic phase was related to the diffusion of charge carriers. The microscopic features of charge hopping were modelled using the random walk scheme, and two charge carrier hopping lengths were estimated for two glycolipid systems. For Process I, the hopping length is comparable to the hydrogen bond and is related to the dynamics of the hydrogen bond network. Additionally, that for Process II is comparable to the bilayer spacing, hence confirming that this low-frequency mechanism is associated with the internal dynamics within the phase.

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Section: Fig 6 Observed and Fitted Spectra Ofmentioning

confidence: 95%

Phase sensitive molecular dynamics of self-assembly glycolipid thin films: A dielectric spectroscopy investigation

Velayutham

Gan

et al. 2014

The Journal of Chemical Physics

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“…Despite this spontaneous inversion, it is possible to use non-covalent interactions (for example, metal coordination to the calixarene, or hydrogen bonding with a guest molecule) to limit the motion, although doing so can prevent polarization reversal 85,86 . Once the core is fixed, the polarization can only be switched by rotating the mesogens or the entire assembly, which are both sterically unfavourable mechanisms 87,88 . Other systems, such as a tribenzocyclononene core with chiral side chains (Fig.…”

Section: Organization Of Molecular Dipolesmentioning

confidence: 99%

Supramolecular ferroelectrics

et al. 2015

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Supramolecular chemistry uses non-covalent interactions to coax molecules into forming ordered assemblies. The construction of ordered materials with these reversible bonds has led to dramatic innovations in organic electronics, polymer science and biomaterials. Here, we review how supramolecular strategies can advance the burgeoning field of organic ferroelectricity. Ferroelectrics - materials with a spontaneous and electrically reversible polarization - are touted for use in non-volatile computer memories, sensors and optics. Historically, this physical phenomenon has been studied in inorganic materials, although some organic examples are known and strong interest exists to extend the search for ferroelectric molecular systems. Other undiscovered applications outside this regime could also emerge. We describe the key features necessary for molecular and supramolecular dipoles in organic ferroelectrics and their incorporation into ordered systems, such as porous frameworks and liquid crystals. The goal of this Review is to motivate the development of innovative supramolecular ferroelectrics that exceed the performance and usefulness of known systems.

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“…Since obtaining discotic LCs with 1,3,6,8-tetraphenylpyrene core appears not to be a trivial task, we turned next to 3,4,5-trialkyloxybenzoyl units that are known to generate columnar LC phases when attached to a large variety of cores, [22,24,25] due to their ability to self-assemble via exo-recognition processes. [26] It has been very recently shown that compound 10, [27] based on a tetraphenylethene core four-fold-substituted with 3,4,5-tridecyloxybenzoyl units (see Scheme 5), forms an hexagonal columnar phase from 29 to 69 C on first heating, and a metastable hexagonal liquid crystalline columnar phase on further heating and cooling cycles.…”

Section: 45-tridodecyloxybenzoyl Unitsmentioning

confidence: 99%

1,3,6,8‐Tetraphenylpyrene Derivatives: Towards Fluorescent Liquid‐Crystalline Columns?

Halleux

Calbert

Brocorens

et al. 2004

Adv Funct Materials

156

112

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Tetraphenylpyrene has been selected as a discotic core to promote liquid‐crystalline fluorescent columns in view of its high fluorescence quantum yield in solution and ease of substitution by flexible lateral side chains. The synthesis and characterization of ten new derivatives of pyrene have been carried out; the pyrene core has been substituted at the 1,3,6,8‐positions by phenylene rings bearing alkoxy, ester, thioether, or tris(alkoxy)benzoate groups on the para position; the compounds have been characterized by mass spectrometry and 1H NMR and UV‐vis spectroscopies. In order to generate liquid‐crystalline phases, the nature, number, and size of the side chains as well as the degree of polarity around the tetraphenylpyrene core have been varied. However, the desired liquid‐crystalline behavior has not been observed. The supramolecular order together with the absorption and emission properties in solution and the solid state are discussed and compared to theoretical predictions. Quantum‐chemical calculations rationalize the high solid‐state fluorescence of a tetraphenylpyrene derivative for which the crystal structure has been determined.

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Columnar phases of achiral vanadyl liquid crystalline complexes

Cited by 54 publications

References 19 publications

Phase sensitive molecular dynamics of self-assembly glycolipid thin films: A dielectric spectroscopy investigation

Phase sensitive molecular dynamics of self-assembly glycolipid thin films: A dielectric spectroscopy investigation

Supramolecular ferroelectrics

1,3,6,8‐Tetraphenylpyrene Derivatives: Towards Fluorescent Liquid‐Crystalline Columns?

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