Liquid Crystalline and Monotropic Phase Behaviors of 2,3,6,7,10,11-Hexa(4‘-octyloxybenzoyloxy)triphenylene Discotic Molecules

Tang, Benjamin Y.; Ge, Jason J.; Zhang, Anqiu; Calhoun, Bret H.; Chu, Peng-Cheng; Wang, Huabin; Shen, Zhihao; Harris, Frank W.; Cheng, Stephen Z. D.

doi:10.1021/cm0006897

Cited by 21 publications

(27 citation statements)

References 41 publications

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“…11a). 47,48 Interestingly enough, even in the low-temperature phase at 30 C, as shown in Fig. 11b, the major texture has not changed, although at the low-temperature of 30 C, a more ordered phase has been introduced (Fig.…”

Section: Thermodynamic Transition Propertiesmentioning

confidence: 87%

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From crystals to columnar liquid crystal phases: molecular design, synthesis and phase structure characterization of a series of novel phenazines potentially useful in photovoltaic applications

et al. 2010

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Section: Thermodynamic Transition Propertiesmentioning

confidence: 87%

“…This set of results reveals that 7a, which is often observed in columnar LC phases. 47,48 Further cooling to a temperature region below 190 C, the phase texture of TQPP-[t-Bu] 2 -[OC 10 H 21 ] 4 changed suddenly to a crystalline morphology (Fig. 7b).…”

Section: Thermodynamic Transition Propertiesmentioning

confidence: 99%

From crystals to columnar liquid crystal phases: molecular design, synthesis and phase structure characterization of a series of novel phenazines potentially useful in photovoltaic applications

et al. 2010

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“…[19] In the second case, the columnar monotropic phase was converted into another stable, columnar mesophase before reaching the RT crystalline phase. [20] Another interesting type of monotropic phase formed by HOBT-C8 molecules was studied by Cheng and co-workers, [21,22] who found an intermediate monotropic crystalline phase between a mesophase and a stable crystal. Some other examples of columnar monotropic phases were reported for non-conventional star-shaped molecules.…”

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confidence: 99%

Templating Crystal Growth at the Nanometer‐Scale with a Monotropic Columnar Mesophase

et al. 2005

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Since their discovery, columnar mesophases have become increasingly important in fundamental research and in practical applications [1,2] due to their peculiar supramolecular architectures that allow one-dimensional charge transport. Although the most studied columnar phases are formed by disc-shaped molecules, it is now recognized that such phases can also be formed by dendrimers, [3,4] main-or side-chain polymers with [5,6] or without [7±9] mesogenic moieties, phasmids, [10,11] and board-shaped molecules. [12] For most applications, the organization of the columnar phase at different spatial scales, as well as its temperature and time stabilities are of primary importance. Indeed, at the local scale the mutual mesogen orientation and intracolumnar ordering directly affects charge migration [13,14] and could possibly be tailored to maximize electron orbital overlap. The electronic and optical properties of the liquid-crystalline (LC) phases also strongly depend on the large-scale structure. In particular, the organization at the mesoscopic scale, ranging from several nanometers to some hundreds of nanometers, must be tailored to control features such as the size and orientation of the LC monodomains. This spatial scale is, however, not easily assessable by conventional techniques [15] as it falls in the gap between the resolution of conventional optical observations and X-ray diffraction. As far as temperature and time stability of the phases are concerned, it is worth noting that the phase diagrams of systems forming LC columnar mesophases are generally complex. This is often not only due to a rich polymorphism of these systems, but also to the heating/cooling irreversibility of phases, i.e., the appearance of monotropic phases. The latter are typically observed on cooling when the phase that is energetically more stable is bypassed because of the slow (re)crystallization kinetics. It is important to note that crystallization of the mesophases was previously studied in some detail for highly ordered smectic phases (G and H) formed by calamitic molecules. [16] Compared to the monotropic nematic and smectic phases formed by polymers, [17,18] the columnar LC monotropic phases have been less extensively studied. [19±22] Two of the first LC molecules displaying monotropic columnar phases were observed by Giroud-Godquin et al. [23] (in metallomesogens) and by Billard et al. [24] (in rufigallol hexa-n-octanoate). In the first case, the room temperature (RT) crystal was formed on cooling via a rectangular columnar phase, which was absent during subsequent heating. [19] In the second case, the columnar monotropic phase was converted into another stable, columnar mesophase before reaching the RT crystalline phase. [20] Another interesting type of monotropic phase formed by HOBT-C8 molecules was studied by Cheng and co-workers, [21,22] who found an intermediate monotropic crystalline phase between a mesophase and a stable crystal. Some other examples of columnar monotropic phases were reported for non-conventional star-...

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“…Here, the high charge-carrier mobility is usually a result of the efficient face-to-face π -stacking of the molecules. Since the charge-carrier mobility is determined by the extent of electronic overlap between the disc-like π -system cores, hexabenzocoronenes do usually show larger charge-carrier mobilities than triphenylenes (10 −2 cm 2 /V s for 17 (R = C 3 H 7 ) vs. 0.7 cm 2 /V s for 20 (R = C 12 H 25 )) [88][89][90][91][92][93][94][95]. The thermodynamic stability of the columnar mesophase can be stabilized by introducing additional aromatic interactions (18, 19, 21) without any loss of charge-carrier mobility [89,[96][97][98][99].…”

Section: Aggregation Of Thermotropic Disc-like Moleculesmentioning

confidence: 99%

Supramolecular Organization of $$\pi $$-Conjugated Oligomers

Lützen

2015

Bottom-Up Self-Organization in Supramolecular Soft Matter

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Bottom-up engineering of π -conjugated systems for optoelectronic devices has emerged into one of the most interesting and challenging fields in materials sciences as it offers the chance to control materials down to the nanoscale by designing molecular components with specific properties. The key problem is, however, that excellent molecular properties do not necessarily lead to similar good macroscopic properties of the bulk material. To achieve this one has to be able to master the supramolecular properties between the individual π -conjugated molecules as well. This part will describe the different approaches that have been employed to affect the supramolecular aggregation of π -conjugated oligomers by CH-π -and π -π -interactions of the π -conjugated molecular framework of the oligomers but also via amphiphilic interactions, hydrogen bonding, or metal coordination of additional functional groups introduced into the oligomers in order to control the supramolecular assembly in the desired manner. IntroductionBottom-up engineering of π -conjugated systems for optoelectronic devices has emerged into one of the most interesting and challenging fields in materials sciences as it offers the chance to control materials down to the nanoscale by designing molecular components with specific properties [1][2][3][4]. As a consequence scientists and engineers both from academia and industry quickly joined forces to merge the fields of nanoscience and nanotechnology. Thereby, the synthesis of new molecules is guided by the results of device physicists and engineers, while the device performance improves with the progress in the synthesis of new compounds.The key problem is, however, that excellent molecular properties do not necessarily lead to similar good macroscopic properties of the bulk material. To achieve this A. Lützen (B)

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Liquid Crystalline and Monotropic Phase Behaviors of 2,3,6,7,10,11-Hexa(4‘-octyloxybenzoyloxy)triphenylene Discotic Molecules

Cited by 21 publications

References 41 publications

From crystals to columnar liquid crystal phases: molecular design, synthesis and phase structure characterization of a series of novel phenazines potentially useful in photovoltaic applications

From crystals to columnar liquid crystal phases: molecular design, synthesis and phase structure characterization of a series of novel phenazines potentially useful in photovoltaic applications

Templating Crystal Growth at the Nanometer‐Scale with a Monotropic Columnar Mesophase

Supramolecular Organization of $$\pi $$-Conjugated Oligomers

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