Crystallization of Large Planar Polycyclic Aromatic Hydrocarbons: The Molecular and Crystal Structures of Hexabenzo[bc,ef,hi,kl,no,qr]coronene and Benzo[1,2,3-bc:4,5,6-b'c']dicoronene

Goddard, Richard; Haenel, Matthias W.; Herndon, William C.; Krueger, C.; Zander, M.

doi:10.1021/ja00106a004

Cited by 194 publications

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“…Moreover, the phase transition temperature of the latter is lower by ∼10°C as a reason for the presence of two additional methylene carbons that make the molecule more flexible. Entries 5 and 6 show that both HBC-PhORf 4,8 (44) and HBC-PhORf 6,6 (45) have comparably high transition temperatures with a melting into the mesophase above 220°C, and this can be explained again by the extension of the flat core as well as the use of alkoxy chains. A minor decrease of the transition temperatures was also observed between these two extended HBC species as in the case of HBC-Rf 4,8 and HBC-Rf 6,6 (28, 29).…”

Section: Liquid Crystalline Propertiesmentioning

confidence: 97%

“…Vcell: volume of the hexagonal cell (h1.S), i.e., slice of column 3.5 Å thick. The molecular volume is defined by 44 VM ) VHBC + 6(nVCH 2 + mVCF 2 ) or VM ) VHBC-Ph + 6(nVCH 2 + mVCF 2 ), VHBC ) 650 Å 3 , and VHBC-Ph ) 1220 Å 3 . VCH 2 (T) ) 26.5616 + 0.02023T (T in°C, T0 ) 25°C) and VCF 2 (T) ) 40.815 + 0.03318T (T in°C, T0 ) 22°C).…”

Section: Liquid Crystalline Propertiesmentioning

confidence: 99%

“…This result was not expected considering the thermal behavior of the two related compounds just described. This may be linked to the greater flexibility of the longer methylene spacer as compared to that of HBC-PhORf 4,8 (44), which forces the fluorinated tails to adopt another conformation and, therefore, to the overall molecular disk to favor a columnar Col h phase formation rather than a lamellar arrangement ( Figure 10).…”

Section: Liquid Crystalline Propertiesmentioning

confidence: 99%

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Mesomorphic Hexabenzocoronenes Bearing Perfluorinated Chains

et al. 2005

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IntroductionExtended polyaromatic hydrocarbons (PAH) are finding increasing interest among other self-assembled supramolecular systems due to their pronounced tendency for formation of extended π-stacked assemblies. These have many potential properties, such as a high electron density which allows their use in promising applications in molecular electronics. 1 However, the main drawback of these rigid polycondensed molecules resides in the difficulty of their synthesis and their very low solubility which prevents their isolation and manipulation. Recently, Müllen and co-workers 2 succeeded in finding a versatile synthesis of hexa-perihexabenzocoronene (HBC), a polycondensed hexagonal molecule containing 13 benzene rings which shows a very high chemical stability 3 and which self-organizes into columnar stacks, by π-stacking, with an outstanding degree of order in the solid state. 4,5 Additionally, its solubility was improved by the addition of peripheral long aliphatic chains which at the same time bestows the molecule with a ditopic property: These HBC derivatives show a liquid crystalline (LC) state over a wide temperature range depending on the length of the aliphatic chain. 6 Moreover, these HBC derivatives exhibit the highest charge carrier mobility recorded so far for an organic molecule both in the solid and in the liquid crystalline states, 7 paving the way toward their application in the domain of electronic 8 and optoelectronic 9-11 devices.Nevertheless, the lateral interaction between the adjacent HBC stacks caused by the crystalline packing of their aliphatic side chains 12 constitutes a major drawback since it interferes with the formation of very long conducting π-stacks. Additionally, most of the HBCs bearing aliphatic chains are liquid crystalline just above room temperature, which leads to a second disadvantage since it induces a drastic decrease of their charge carrier mobilities, 13 which is reported to be due to "lateral" conduction and as a reason for the perturbation or the deterioration of an ideal liquid crystalline mesophase that dominates the conduction process. 14 * To whom correspondence should be addressed. Tel. (Office): +41 (0) Synthesis and characterization of new hexabenzocoronene (HBC) derivatives bearing perfluoroalkylated chains are described. These disc-shaped polycondensed aromatic hydrocarbons are known to self-assemble by π-stacking into columnar architectures. The peripheral decoration with perfluorinated chains, well-known for their low van der Waals forces, leads as expected to reduced intercolumnar interactions. Powder X-ray diffraction and differential scanning calorimetry of these perfluoroalkylated HBCs proved liquid crystalline (LC) properties whose transition temperatures, mesophase stability, and nature depend on the detailed structure of these side chains, i.e., the ratio between aliphatic and perfluorinated parts. On the other hand, the insertion of a phenyl spacer between the aromatic core and the lateral chains increases the LC transition temperature and, sur...

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Section: Liquid Crystalline Propertiesmentioning

confidence: 97%

Section: Liquid Crystalline Propertiesmentioning

confidence: 99%

Section: Liquid Crystalline Propertiesmentioning

confidence: 99%

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Mesomorphic Hexabenzocoronenes Bearing Perfluorinated Chains

et al. 2005

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“…A Le Bail refinement with the space group (P 21/a) and lattice constants of HBC as starting values shows that the solid state structure of BN-HBC and HBC are isotypic (see Supporting Information). The packing of HBC that crystallizes in the γ motif was discussed comprehensively by Goddard et al [11] We have reported earlier that the BN-HBC molecule is planar at the B3LYP/6-31G* level of theory. [5] Solid state 11 B magic angle spinning NMR provides further information on the environment of the boron atoms.…”

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confidence: 99%

Construction of an Internally B₃N₃‐Doped Nanographene Molecule

et al. 2015

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“…Hexa-peri-hexabenzocoronene (HBC) can be regarded as the smallest graphene fragment consisting of 13 fused benzene rings, and has a tendency to form a herringbone molecular packing configuration [9]. Wu et al reported that chemical modification of HBC with long alkyl chains results in the formation of discotic liquid-crystalline materials that exhibit high charge-carrier mobilities [10].…”

Section: Hexabenzocoronenesmentioning

confidence: 99%

Programmed self-assembly of largeπ-conjugated molecules into electroactive one-dimensional nanostructures

Yamamoto

2012

Science and Technology of Advanced Materials

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Electroactive one-dimensional (1D) nano-objects possess inherent unidirectional charge and energy transport capabilities along with anisotropic absorption and emission of light, which are of great advantage for the development of nanometer-scale electronics and optoelectronics. In particular, molecular nanowires formed by self-assembly of π-conjugated molecules attract increasing attention for application in supramolecular electronics. This review introduces recent topics related to electroactive molecular nanowires. The nanowires are classified into four categories with respect to the electronic states of the constituent molecules: electron donors, acceptors, donor-acceptor pairs and miscellaneous molecules that display interesting electronic properties. Although many challenges still remain for practical use, state-of-the-art 1D supramolecular nanomaterials have already brought significant advances to both fundamental chemical sciences and technological applications.

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Crystallization of Large Planar Polycyclic Aromatic Hydrocarbons: The Molecular and Crystal Structures of Hexabenzo[bc,ef,hi,kl,no,qr]coronene and Benzo[1,2,3-bc:4,5,6-b'c']dicoronene

Cited by 194 publications

References 0 publications

Mesomorphic Hexabenzocoronenes Bearing Perfluorinated Chains

Mesomorphic Hexabenzocoronenes Bearing Perfluorinated Chains

Construction of an Internally B₃N₃‐Doped Nanographene Molecule

Programmed self-assembly of largeπ-conjugated molecules into electroactive one-dimensional nanostructures

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Crystallization of Large Planar Polycyclic Aromatic Hydrocarbons: The Molecular and Crystal Structures of Hexabenzo[bc,ef,hi,kl,no,qr]coronene and Benzo[1,2,3-bc:4,5,6-b'c']dicoronene

Cited by 194 publications

References 0 publications

Mesomorphic Hexabenzocoronenes Bearing Perfluorinated Chains

Mesomorphic Hexabenzocoronenes Bearing Perfluorinated Chains

Construction of an Internally B3N3‐Doped Nanographene Molecule

Programmed self-assembly of largeπ-conjugated molecules into electroactive one-dimensional nanostructures

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Construction of an Internally B₃N₃‐Doped Nanographene Molecule