Synthesis and Structural Features

Cammidge, Andrew N.; Bushby, Richard J.

doi:10.1002/9783527620623.ch4

Cited by 81 publications

(38 citation statements)

References 217 publications

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“…19 Supra-molecular discotic mesophase structures driven by molecular recognition processes through non-covalent interactions have become an interesting research topic and a promising approach for practical applications and scientific challenges. 20,21 Non-covalent interactions include hydrogen (H)-bonding, electrostatic (ion-ion, ion-dipole, and dipoledipole) interactions, p-p stacking interactions, van der Waals interactions, and hydrophobic-hydrophilic effects along with others. [22][23][24][25][26][27][28][29][30][31] Since Lehn first discovered H-bonding induced supra-molecular LC phases, H-bonding has become a topic of major research due to its moderate bonding energy, directionality, selectivity and reversibility.…”

Section: Introductionmentioning

confidence: 99%

Phase behaviors and supra-molecular structures of a series of symmetrically tapered bisamides

et al. 2006

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A series of symmetrically tapered 1,4-bis[3,4,5-tris(alkan-1-yloxy)benzamido] benzene bisamides (CnPhBA, where n is the number of carbon atoms in the alkyl chains, n = 10, 12 and 16), was synthesized in order to investigate the effect of alkyl chain length on supra-molecular ordered structures induced by hydrogen (H)-bonding and micro-phase separation. These bisamides consist of a rigid aromatic bisamide core with three flexible alkyl chains at each end of the core. Major phase transitions and their origins in CnPhBA bisamides were studied with differential scanning calorimetry, one-dimensional (1D) wide angle X-ray diffraction (WAXD), infrared spectroscopy, and solid-state carbon-13 nuclear magnetic resonance experiments. The structures of these compounds in different phases were identified using 2D WAXD from oriented samples and were also confirmed by selected area electron diffractions in transmission electron microscopy from stacked single crystals and by computer simulations. All of the CnPhBA bisamides in this series formed a highly ordered oblique columnar (W OK ) phase and a low-ordered oblique columnar (W OB ) phase, similar to a recent report on C14PhBA.1 The two main driving forces in the formation of these two supra-molecular columnar structures were identified: One was the H-bond formation between N-H and CLO groups, and the other was the micro-phase separation between the bisamide cores and the alkyl chains. With increasing the length of alkyl tails, the isotropization temperature decreased, while the disordering temperature of the alkyl tails increased. The 2D lattice structures perpendicular to the columnar axis also increasingly deviated from the pseudohexagonal packing with increasing the alkyl tail length. However, the alkyl tail length did not have a significant influence on the packing along the columnar axis direction. Utilizing polarized optical microscopy, the phase identifications were also supported by the observation of texture changes and molecular arrangements inside of the micro-sized domains.

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Section: Introductionmentioning

confidence: 99%

Phase behaviors and supra-molecular structures of a series of symmetrically tapered bisamides

et al. 2006

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“…Typically, thermotropic hexagonal columnar phases are formed by anisometric disclike molecules [23] or by amphiphilic or polymeric tapershaped molecules.…”

Section: Pentaerythritol Tetrakis(34-dialkoxybenzoates)mentioning

confidence: 99%

The Importance of Micro Segregation for Mesophase Formation: Thermotropic Columnar Mesophases of Tetrahedral and other Low-Aspect-Ratio Organic Materials

et al. 1999

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Several low-aspect-ratio organic molecules [tetrahedral pentaerythritol derivatives, peracylated polyhydroxy compounds and aminoalcohols, a tetraphenylmethane derivative, a tetraphenylstannane, and a tetrahedral zinc bis(1,3-diketonate) all carrying long aliphatic chains] have been synthesized. These compounds were investigated by polarizing optical microscopy and differential scanning calorimetry, and some of them by X-ray diffraction. Most compounds show columnar liquid-crystalline mesophases. Their mesogenic properties are neither caused by a specific anisometric shape of these molecules nor by a strong amphiphilicity as known from conventional liquid crystals. Instead their mesogenity is mainly driven by micro segregation of the incompatible molecular parts (polar central regions and lipophilic alkyl chains) into wellorganized different microdomains. It is shown that, in analogy to block copolymers, the mesophase stability rises on enlarging the number of repeat units connected with each other and on increasing the degree of incompatibility between the incompatible segments. During the process of self-organization the average conformation of the molecules is changed in such a way that it allows a most efficient packing of the molecules. Consequently, rigid molecules with a fixed tetrahedral geometry are not mesogenic. The molecules described herein can be regarded as the most simple star-shaped low-aspect-ratio block molecules that form liquidcrystalline phases. They bridge the gap between classical amphiphilic mesogens, several nonconventional dendritic and oligomeric liquid crystals, and mesomorphic block copolymers.

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“…1- 18 On the other hand, gold nanorods (GNRs) have been extensively studied for their anisotropic properties and their applications not only in materials science but also in biosciences have been sought. 19,20 Here it is shown that GNRs can be easily inserted into the supramolecular order of DLCs without disturbing their mesomorphism.…”

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confidence: 99%

Gold nanorods embedded discotic nanoribbons

et al. 2013

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It is shown that gold nanorods (GNRs) can be easily inserted into the supramolecular order of discotic liquid crystals (DLCs) along the director without disturbing their mesomorphism. GNRs embedded discotic nanoribbons, useful for constructing devices like thin film transistors, sensors, etc., are prepared by simple solution processing of GNR-DLC nanocomposites.The self-assembling supramolecular columnar phases formed by discotic liquid crystals (DLCs) have been well recognized as onedimensional organic semiconductors useful in many devices like photovoltaic solar cells, light emitting diodes, thin film transistors, sensors, etc.1-18 On the other hand, gold nanorods (GNRs) have been extensively studied for their anisotropic properties and their applications not only in materials science but also in biosciences have been sought. 19,20 Here it is shown that GNRs can be easily inserted into the supramolecular order of DLCs without disturbing their mesomorphism. GNRs embedded discotic nanoribbons are formed simply by solution processing. These DLC-GNR nanocomposites were characterized from UV-Vis spectroscopy, transmission electron microscopy (TEM), polarizing optical microscopy (POM), differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and conductivity studies.Results indicate insertion of GNRs into the discotic matrix along the director (the long axis parallel to the length of the ribbon). Such supramolecular architectures are useful for constructing devices like thin film transistors, sensors, etc. Forming nanocomposites of nanoparticles with liquid crystals is an interesting field of study. Many groups have dispersed nanomaterials in the liquid crystalline system to align nanoparticles in an ordered manner while some others have functionalized nanoparticles with liquid crystalline molecules, [21][22][23][24] and also used them as optical bulk metamaterials. 25 We have previously doped the host discotics with carbonaceous, semiconducting and metallic nanoparticles and found interesting changes in their physical properties. 34 Here we show that such supramolecular triphenylene structure can be formed by a much simpler solution process. This provides an alternative to the vapour deposition technique wherein the sample has to be heated to higher temperatures, which would lead to decomposition of the organic molecules. Gold nanorods were prepared following the literature method (see ESI †) and characterized by UV-Vis spectroscopy and TEM (Fig. 1).UV-Vis spectra of gold nanorods in aqueous medium have two peaks, a small peak at 515 nm and a peak at 733 nm, which are transverse and longitudinal plasmon bands, respectively, typical of gold nanorods (Fig. 1b). 35 The band at 515 nm has a shoulder band at 581 nm, which is due to dog bone shape of gold nanorods which have slightly thicker edges compared to the middle portion. 36The TEM image of gold nanorods (Fig. 1a) shows that the nanorods prepared have an aspect ...

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Synthesis and Structural Features

Abstract: General Structural Features' In this contribution the nomenclature D for a columnar mesophase of disk-like molecules has been used, but the reader should appreciate that D,, D,, D, etc. are the same as Col,, Col,, Colt etc.

Cited by 81 publications

References 217 publications

Phase behaviors and supra-molecular structures of a series of symmetrically tapered bisamides

Phase behaviors and supra-molecular structures of a series of symmetrically tapered bisamides

The Importance of Micro Segregation for Mesophase Formation: Thermotropic Columnar Mesophases of Tetrahedral and other Low-Aspect-Ratio Organic Materials

Gold nanorods embedded discotic nanoribbons

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